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Keeping the Aircooled engine cool

Discussion in 'Engine & Transmission' started by 1500king, May 15, 2009.

  1. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    [FONT=Verdana, Geneva, Arial, sans-serif][SIZE=-1]Why do the English drink warm beer?[/SIZE][/FONT]
    [FONT=Verdana, Geneva, Arial, sans-serif][SIZE=-1][/SIZE][/FONT]
    [FONT=Verdana, Geneva, Arial, sans-serif][SIZE=-1]Lucas makes the refrigerators.[/SIZE][/FONT]


    [FONT=Verdana, Geneva, Arial, sans-serif][SIZE=-1]Alexander Graham Bell invented the Telephone.
    Thomas Edison invented the Light Bulb.
    Joseph Lucas invented the Short Circuit.[/SIZE][/FONT]
     
  2. wirrah

    wirrah Well-Known Member

    Messages:
    2,637
    Location:
    Lower Hunter, NSW
    Not warm. Room temperature. Here that is warm :cry: There is a different matter ;)

    I :heart: English Ale
     
  3. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    No, it's 'orrible:cry:

    I called into some village around Lincs(?) where tourist don't usually go and asked for a can of coke. The old guy behind the counter says with a proud look on his face and a strong accent like old Ned from To the Manor Born, "You'd not be from around here then. You'd be from down under!" as he scratched around under the counter in his tiny little fridge, "You'd be wanting it cold then!"
     
  4. nikferatu

    nikferatu Active Member

    Messages:
    1,447
    Location:
    Bracken Ridge, Brisbane
    Hey, if you're going to wander off on the wrong side of the Iron Curtain then you're on your own!


    Why do Lada's have heated rear windows? So the Russkis can keep their hands warm while they are pushing them home!
     
  5. 1500king

    1500king Well-Known Member

    Messages:
    1,659
    Location:
    Adelaide, SA
    well, at least he was sort of prepared for you!!!
     
  6. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    1968~79 VW Type 2 Starting handle

    Beginning sometime in the late-1970s, my family's second-hand, British specification, 1973 VW 1600 Type 2 Kombi, Westfalia Continental campervan, suffered sporadic episodes of what is now described as "Dead Starter Motor Syndrome" (Technical Information Leaflet No. 13, VW Type 2 Owners' Club, 1998), whereby the starter motor would fail to operate, showing no signs of even a click, from the starter solenoid. Typically, this would occur, after the engine had been run for sometime and stopped for one reason or another. See the following topic threads, for details of this and other episodes, in the life of this vehicle:

    Members Rides > 34+ years with a VW Kombi: There's never been a dull moment!

    http://forums.kombiclub.com/showthread.php?t=22180

    Bay Tech Clinic > Fuel System & Electrics > "Electronic" projects to safeguard the VW Type 2 & other vehicles

    http://forums.kombiclub.com/showthread.php?t=22177

    Three particularly memorable occurrences, were when we stopped at a petrol filling station, on the way to the ferry terminal, to cross the English Channel to France, when called upon to disembark from another cross-Channel ferry a few years later and once after stalling at some traffic lights in France. Removal of the offending starter motor, followed by disassembly, thorough cleaning (including removal of any oxide coating of the commutator and electrical connections), lubrication, reassembly and refitting, did much to improve matters, but there were still occasional re-occurences.

    Having spent my early formative years, being schooled by my father, to start his second-hand 1949 Morris-8 Series-E, using the starting handle, we later took the opportunity in 1988/89, to have the 1973 VW 1600 Type 2 Kombi, upgraded with this very useful backup facility. Many years later, I learned that some or all German & Swiss, military specification, 1968~79 VW Type 2s, were so equipped; probably as a factory-fitted option. Refer to the following article, for an illustration of the 1970 model:

    Paul Knight, "Buying a Type 2", Volksworld magazine, June 2002, pages 100~103.

    The beauty of the starting handle, is that relatively little battery voltage, is needed to operate the ignition system and actually turning over the engine, requires minimal physical effort.

    For those who drive vehicles (especially those with automatic transmission, which cannot be push, bump or tow started) in remote areas, such as the Austalian outback, where one might not see another vehicle for several days, a starting handle could mean the difference between life and death. After removing the spark plugs to eliminate compression, one can use a starting handle, to slowly unbog a vehicle from mud or soft sand, or even climb a sand dune, as demonstrated in the World War 2 movie film, "Ice Cold in Alex".

    The celebrated Arthur Barraclough, had reason to be thankful, for having retro-fitted this facility. After the starter motor failed during one of Arthur's long overland trips, he constantly used the starting handle, to start the 1976~79 VW 2000 Type 2 engine, which was fitted to "Rosie", his 1970 VW '1600' Type 2. Jump starting from another car's battery, would have been impossible; even assuming such assistance were available.

    [​IMG]

    Bay Window Bus > Arthur Barraclough's, much vaunted, modified, 1970 VW Type 2

    http://www.thesamba.com/vw/forum/viewtopic.php?t=196043

    I have also since learned of an electrical-circuit upgrade, which involves operating the starter solenoid, via a high-current accessory relay, to reduce voltage losses, by providing a much shorter supply cable and fewer intermediate connections, between the battery and the starter solenoid; a sensible upgrade which I am implementing as part of my DIY custom wiring loom:

    Bay Tech Clinic > Fuel System & Electrics > Uprated, replacement, modular wiring loom, for the 1968~79 VW Type 2

    http://forums.kombiclub.com/showthread.php?t=22179

    There is also another electrical upgrade, suggested by Bob Wallace (a fellow member of the VW Type 2 Owners' Club), whereby one uses a dashboard mounted switch and a starter-solenoid (of the type associated with bendix-gear-inertia-type starter motors - in essence, an ultra heavy-duty relay) to automatically jump-start the main battery, from a second auxiliary battery. As refinement of this idea, I shall use a steering-column mounted, momentary push-button or toggle switch, whereby one must hold the momentary switch, whilst operating the starter.

    The discontinuation of the starting handle, was a retro-grade step in my opinion, but some "modern" cars still retained this facility, including the late-model Citroën 2CV and possibly the Citroën GS, both of which had air-cooled engines.

    During the 1960s & 1970s, my Uncle Horace (former Royal Navy engineering artificer, during World War 2 and source of my first Australian & Ceylonese coins) had a Morris Minor saloon, whilst Uncle Donald had a Ford Prefect. The Morris Minor now has cult status and is regaining popularity as a durable, economical, easily maintained car, with excellent spare-parts availability; the body panels being hand made in Ceylon, where I saw innumerable Morris Minor taxis, in Colombo, during my holiday in 1983. Many of the mechanical components from the later Morris Marina are compatible and one can even selectively upgrade and modernise them, by retro-fitting components such as quartz-halogen headlamps, electrically-heated, laminated windscreens, plus rain-sensing windscreen wipers and other things.

    Ultra-modern cars are becoming excessively large & heavy, plus probably being far too complex & sophisticated, to be maintained and repaired even by professional mechanics, yet alone the DIY mechanic, as highlighted by the following recent article:

    Robert N. Charette (IEEE Spectrum), "This Car Runs on Code", Discovery News, Friday 5th February 2010.

    http://news.discovery.com/tech/toyota-recall-software-code.html

    « Roughly one-third of all the software in cars is devoted just to diagnostics, according to a former automotive engineer I spoke to. But even with all that diagnostic information produced, car mechanics often cannot determine the exact cause of the trouble. »

    « Broy told me that more than 50 percent of the ECUs that mechanics replace in cars are technically error free: They exhibit neither a hardware nor a software problem. Mechanics replace the ECUs simply because they don’t have a better way to fix them, he says. "The garages and the maintenance people are really at a point where repairing a car is too complex and demanding [for them]", says Broy. Remote diagnostics and repair are likely to render mechanics obsolete for many tasks. In the not-so-distant future, says Broy, when you have a problem with the computer system in your car, you will go to your garage, where your car will be connected to a network so that off-site OEM specialists can download data, do the analysis and then upload a software correction. »


    These cars might be generally more reliable than their much older counterparts, but remote from the main centres of population and their state-of-the-art motor-vehicle workshops, it is better to retain simpler technology vehicles, which can be repaired by the side of the road, using relatively basic tools and diagnostic instruments. Besides which, it is possible to improve the durability & reliability of older vehicles, using modern developments, but without increasing the overall complexity of critical systems.
     
    Last edited: Jun 23, 2010
  7. 1500king

    1500king Well-Known Member

    Messages:
    1,659
    Location:
    Adelaide, SA
    Why didn't you just replace the faulty ignition switch? People fry their ignition switches (terminals melt back into the switch casing) when they try to upgrade headlights, put foglights and extra accessories on through the ignition circuit. Or looking at the condition of that motor, what condition was the starter motor in considering it was out of sight and out of mind until the car didn't start!
     
    Last edited: Jun 5, 2009
  8. nikferatu

    nikferatu Active Member

    Messages:
    1,447
    Location:
    Bracken Ridge, Brisbane
    I laughed when you had plenty of good things to say about the Morris Minor but said nothing about the Ford Prefect. That said it all I think!

    My Dad, his brother, and their father all had Morris Minors - Dad had several including a Traveller (long ago). I also learnt to drive in his early fifties Australian assembled sedan, doing laps of the back yard. It was sad to see it eventually go, it was definitely part of the family furniture.

    The Ford Prefect had a ridiculous east-west coach spring suspension which would apparently take a fair distance to return to level after any kind of corner. Most of the time it would have had a list to one side or the other!
     
  9. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    Ignition switch & starter motor condition!

    We didn't have a faulty ignition switch! :rolleyes: When I removed (after learning how to remove it - not properly described in the available Haynes manuals!) and inspected it several years later, the ignition switch was still in good condition, with no sign of burnt contacts or melted housing; even after using two 100/80W H4 headlamp bulbs.

    When I removed and cleaned the starter motor, it appeared to be in good condition, but the commutator and connection terminals were dirty and no longer lustrous.
     
  10. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    Keeping the air-cooled engine cool

    Here is a slightly revised version of my checklist re causes of air-cooled engine overheating and related matters, which were published just over 10 years ago, by the British, Volkswagen Type 2 Owners' Club, as follows:

    Nigel Skeet, "Air-Cooled VW: Causes of Engine Overheating, Poor Engine Performance & Poor Fuel Economy", Transporter Talk, Issue 40, April 1999, Pages 28~29.


    AIR-COOLED VOLKSWAGENS : CAUSES OF ENGINE OVERHEATING, POOR ENGINE PERFORMANCE & POOR FUEL ECONOMY

    Compiled & Written by Nigel A. Skeet

    The following checklist, is a summary of the many factors which either individually or collectively, might lead to engine overheating, poor performance or poor economy of air-cooled engines. The last European VW vehicle to be equipped with an air-cooled engine, was manufactured in 1983, so relatively few mechanics (either the DIY owner, independent or franchised VW garage workshops) fully appreciate the importance of the cover plates, seals and grommets, to the correct functioning of the engine cooling system.

    Of the air-cooled VWs I have examined, belonging to fellow owners who purchased them in the later stages of the vehicles' lives, many have been missing vital components of the cooling system; particularly cover plates, engine compartment perimeter foam-seal, sparkplug connector seals, plus other less obvious omissions. On more than a few occasions, there have been missing, one or more of the large coverplates which isolate the engine compartment from the vehicle underside, the purpose of which is to prevent hot reject air from the cooling system, being recycled back into the inlet of the cooling system.

    Any owner of an air-cooled VW, who is uncertain of its service history and the competence of the attendent mechanics, regarding AIR-COOLED engines, is strongly advised to consult the appropriate workshop manuals and conduct a full inventory of all cover plates, hoses, clips, seals and grommets, to ensure that all are present and correctly fitted.

    Air-cooled engines are particularly prone to overheating as a result of weak fuel-air mixtures at full throttle and/or over-advanced ignition timing. Many engines have been fitted with all-centrifugal "009" or "050" ignition distributors, which give satisfactory performance with modified racing engines, but are not well suited to road going engines, which need additional vacuum advance, to eliminate acceleration 'flat-spots', at just above idling speed, plus optimisation of torque and fuel economy, under part-load conditions.

    POOR PERFORMANCE & ECONOMY

    1. Blocked or restrictive air filter and/or air-filter housing & trunking.
    2. Incorrect carburettor or fuel injection specification.
    3. Incorrect carburettor or fuel injection adjustment settings.
    4. Carburettor and/or inlet manifold icing, during cold, damp weather.
    4. Poorly functioning ignition system (misfiring or less than optimum spark at sparkplug).
    5. Incorrect ignition distributor specifications.
    6. Incorrect static ignition timing and/or centrifugal ignition-timing advance characteristics and/or vacuum ignition-timing advance characteristics - dependent upon ignition distributor specification or faults (e.g. sticking centrifugal mechanism and/or contact breaker base plate and/or leaking vacuum advance canister) or inlet manifold vacuum.
    7. Air leaks in inlet manifold casting (rare cases of porous casting!), gaskets, connections or hoses - leads to a leaner fuel-air mixture and change in inlet manifold vacuum.
    8. Air leaks in vacuum brake servo canister, connections or hoses - leads to a leaner fuel-air mixture and change in inlet manifold vacuum.
    9. Holes, Restrictions or obstructions in exhaust system.
    10. Worn, engine cylinder-head valve guides, which affects inlet manifold vacuum and pressurises the crankcase.
    11. Loss of engine compression, owing to incorrectly adjusted or burnt valves, worn cylinder barrels, pistons and piston rings.
    12. Underinflated tyres.
    13. Presence of non-aerodynamic roofrack and/or luggage and tarpaulin cover.
    14. Binding brakes and/or wheel bearings and/or drive-shaft constant velocity joints.
    15. Misalignment of the front and/or rear wheels (toe-in, toe-out, steering offset ans excessive camber).
    16. Incorrect wheel and/or tyre sizes - affects overall engine gearing (i.e. MPH per 1000 RPM) and may affect steering offset (dependent upon tyre external diameter, wheel offset and 'kingpin inclination').
    17. Mismatching of vehicle weight & aerodynamic drag, overall engine gearing (i.e. MPH per 1000 RPM) and engine power & torque characteristics (i.e. maximum power @ RPM and maximum torque @ RPM).


    OVERHEATING

    1. Loose or glazed fan belt, resulting in belt slippage (not applicable to crankshaft-driven cooling fans of VW 411 & 412, 1972~79 VW 17/18/2000 Type 2, 1980~83 VW 16/2000 Type 25, VW 15/1600 Type 3 and VW-Porsche 914/4).
    2. Faulty or incorrectly adjusted, cooling-fan, air-flow control flaps or thermostat bellows.
    3. Dirt clogging the cylinder head/barrel cooling fins and/or oil-cooler matrix.
    4. Debris (e.g. cloth rag, leaves, paper, etc.) lodged inside fan housing or engine coverplates, obstructing air flow to finned cylinder barrels & cylinder heads and/or oil-cooler matrix.
    5. Dirt and/or oil on internal surfaces of fan blades, fan housing and coverplates, hence increasing flow resistance and hence reducing flow rate of cooling air.
    6. Restriction or blockage of cooling-system, air-intake trunking and/or vehicle bodywork grilles.
    7. Thick rust deposits on cylinder barrel cooling fins.
    8. Carbonised oil encrustation on the internal surfaces of the crankcase, cylinder-head valve rocker boxes & covers.
    9. Missing, damaged or incorrectly fitted foam seal, around edge of engine compartment.
    10. Missing or hole-damaged coverplates and/or gaps between adjacent engine coverplates.
    11. Missing alternator sealing ring (circular - VW Part No. 021 903 203 or elliptical - VW Part No. 022 903 203), or alternator adjustment-bolt inspection cover, for VW 411 & 412, 1972~79 VW 17/18/2000 Type 2 and VW-Porsche 914/4.
    12. Missing, partially disconnected or hole-damaged air hoses from VW 12/13/15/1600 Type 1, 2, 181 & 182 (excluding 1980~83 VW 1600 Type 2) engine fan housing to heating system connections of exhaust silencer (i.e. muffler) or heat exchanger; dependent upon type of exhaust system fitted.
    13. Missing or improperly fitted clamp from VW 12/13/15/1600 Type 1, 2, 181 & 182 (excluding 1980~83 VW 1600 Type 2) heat exchanger, to heating system connections of exhaust silencer (i.e. muffler); dependent upon type of exhaust system fitted.
    14. Missing or inadequately sealed heat exchanger covers (covers heat exchanger to engine cooling fan connections), for VW 411 & 412, 1972~79 VW 17/18/2000 Type 2 and VW-Porsche 914/4.
    15. Unsealed holes in coverplates (e.g. missing sparkplug lead seals, duct perimeter seals and grommets).
    16. Pre-heater air hose for the standard air filter is missing or partially disconnected. Where an after-market air filter, lacking an pre-heat facility, has been fitted, the connection supplying hot air from the vicinity of the cylinder barrel (VW 1600 Types 1 & 2, with single carburettor or fuel injection - cylinder No. 2; VW 17/18/2000 Type 2 & 4, with twin carburettors - cylinder No. 1; VW 17/18/2000 Type 2 & 4, with fuel injection - cylinder No. 2), has not been blanked off.
    17. Missing sheet-steel air-deflector plates, which wrap around lower portion of cylinder barrels.
    18. Incorrect carburettor or fuel injection specification.
    19. Incorrect carburettor or fuel injection adjustment settings.
    20. Incorrect ignition distributor specification.
    21. Incorrect static ignition timing and/or centrifugal ignition-timing advance characteristics and/or vacuum ignition-timing advance characteristics - dependent upon ignition distributor specification or faults (e.g. sticking centrifugal mechanism and/or contact breaker base plate and/or leaking vacuum advance canister) or inlet manifold vacuum.
    22. Air leaks in inlet manifold casting (rare cases of porous casting!), gaskets, connections or hoses - leads to a leaner fuel-air mixture and change in inlet manifold vacuum.
    23. Air leaks in vacuum brake servo canister, connections or hoses - leads to a leaner fuel-air mixture and change in inlet manifold vacuum.
    24. Holes, restrictions or obstructions in exhaust system.
    25. Incorrect fuel octane rating for the engine.
    26. Reduced lubrication owing to lack of oil pressure or restrictions in the oil galleries.
    27. Binding brakes and/or wheel bearings and/or drive-shaft constant velocity joints.
     
    Last edited: Jun 21, 2009
    Mr Beckstar likes this.
  11. 1500king

    1500king Well-Known Member

    Messages:
    1,659
    Location:
    Adelaide, SA
    :wtf:

    We don't put salt on the roads or flush the cooling system down here with sea water(or any at all), so no need to worry about that....
    Really, what I've been saying all along. If you are experiencing the rest of the items you listed besides the few that matter, you really shouldn't be driving a Kombi.
     
  12. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    Keeping the air-cooled engine cool

    It doesn't require salt use on the roads, for there to be significant rusting of cast-iron cylinder barrels! Normal climatic conditions, with damp air are sufficient, especially where there is fine, drizzly rain, mist or fog.

    Even warm weather with high relative humidity during the daytime and a significant temperature drop overnight, resulting in condensation of dew on the surfaces, will initiate noticeable progression of the corrosion process. Once rusting has commenced, the rust particles make excellent nucleation sites, on which dew readily forms. In fact, the warmer the weather, the more rapid the corrosion, under high-humidity conditions!

    The additional points I made, should be obvious to those who are properly conversant with automotive engineering, general physics & technology and/or the specific characteristics of the air-cooled engine and its cooling system.

    Sadly, there are many owners, plus several "professional mechanics", new to air-cooled-engined vehicles, who are ignorant about many of these things, so I endeavoured to imagine, all the stupid things which people might have done or might be persuaded to do. As I mentioned in my introduction, I have seen all too many daft things, which have been done to these vehicles, mostly as a consequence of ignorance.
     
  13. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    Keeping the air-cooled engine cool

    The following, are various relevant extracts, from a variety of books, dealing with oil temperature, cylinder-head temperature and related issues:

    Tom Wilson, "How To Rebuild Your Volkswagen Air-Cooled Engine", HP Books, 1987, ISBN 0-89586-225-5 [Chapter 5 - Crankcase & Cylinder Reconditioning, pages 75~99]

    Extract from Page 85, re oil temperature, oxidation & carbonisation, plus crankcase elasticity:

    « Oil temperature is a good clue to bottom-end temperature. About 220ºF (i.e. 104•4ºC) is the limit for dependable case longevity. At 220ºF (i.e. 104•4ºC) the magnesium case is 2% elastic. At 240ºF (i.e. 116•6ºC), elasticity reaches 6% and the case easily distorts from crank whip, inertia loads and combustion pressure. »

    Nigel Skeet's note: The elasticity of a magnesium alloy crankcase, at elevated temperatures, is only of major concern with VW Type 1 & Type 3 style air-cooled engines. VW Type 4 style air-cooled engines, have an aluminium alloy crankcase, which is more tolerant of higher oil temperatures. There is reputed to be an exception; a European specification, VW Type 4 style engine, with a VO-Series, magnesium alloy crankcase, but in which vehicle type it was used, was not specified.

    « Unfortunately, VWs don't come with an oil temperature gauge. Adding one is a smart idea while you have the engine disassembled; after-market suppliers offer different kits. I assume you don't know exactly what the engine's oil tempearature has been. In that case, go by smell and carbon deposits. Regular oil begins to lose its lubricating properties at about 250ºF (i.e. 121•1ºC). When this happens the oil burns and leaves a rank smell. If you've passed an oil refinery, you know the smell I'm referring to. »

    « Excessive heat will also bake carbon onto the case walls, leaving tell-tale crusty deposits in all the nooks and crannies. Examine the crankshaft for baked-on carbon. You won't find large flaky deposits on the crank because they would be flung off. Instead, look for a general overall blackness with very little gloss. Normally the crank is a deep brown. But when oil bakes on it, it turns black from carbon. If the heat was extreme, like from a spun rod bearing, the crank will be turned blue at the hottest spots, fading to flat black in the relatively cooler areas. »



    Bill Fisher, "How To Hot Rod Volkswagen Engines", HP Books, 1970, ISBN 0-912656-03-4 [Lubrication, Cooling & Breathing Chapter, pages 88~102]

    Extract from Page 89, re cylinder-head temperature & oil temperature:

    « We do not know of any published figures for VW cylinder head temperatures, but some Corvair figures may be of interest. A Chevy dealer bulletin advised cylinder-head temperatures as:

    200ºF to 300ºF (i.e. 93•3ºC to 148•9ºC) at idle;

    350ºF to 475ºF (i.e. 176•7ºC to 246•1ºC) at 30 to 60 MPH (i.e. 48 to 96 km/h) cruise;

    460ºF to 575ºF (237•8ºC to 301•7ºC) from 3,000 to 5,000 RPM at full-throttle.

    These figures were for the turbosupercharged Spyder models. »


    « According to Mackerle, oil temperatures should be maintained above 176ºF (i.e. 80•0ºC) to keep down friction loss and dilution by gasoline, and should not exceed 230ºF (i.e. 110•0ºC) for continuous operation. Upto 230ºF (i.e. 110•0ºC) may be considered permissible for short bursts. »

    « Crown's Ted Trevor says, "280ºF (i.e. 137•8ºC) may be deplorable, but it's not an uncommon condition in a high-HP VW or Corvair". Jeff Quick of ACE claims that upto 275ºF (i.e. 135•0ºC) can be considered acceptable with a good 40 to 50-weight oil. »



    Julius Mackerle, "Air Cooled Motor Engines", Cleaver Hume Press (London) & STNL (Prague), 1961.

    Extract from Page 230, re cylinder-head temperature versus cylinder-head material strength & detonation:

    « Cylinder head temperature must be as low as possible in order to maintain high volumetric efficiency and with it high engine performance. When considereing air-cooled light alloy cylinder heads, it must be remembered that the strength of the alloys shows a rapid drop above 200ºC. Figure 188 shows the variation in strength of aluminium alloys used for cylinder head construction with temperature [28]. »

    « In petrol engines, local overheating of the combustion chamber leading to detonation, must be prevented. Special attention must be paid to the region adjacent to the exhaust valve seat and the sparking plug. According to recent experience, the temperature of the inner cylinder head surface should not exceed 235ºC to 250ºC. Temporary, but by no means continuous, local temperatures may be as high as 270ºC. »

    « Under normal running conditions, temperatures over 220ºC are to be avoided in view of the possiblity of a temperature rise due to lean mixture running and the accompanying risk of detonation. In aircraft engines this temperature may reach 300ºC for a short period during take-off. »


    Extract from Page 240, re cylinder-head temperature, compression ratio & detonation:

    « The occurence of detonation is aided by hot parts in the combustion chamber such as, for example, the exhaust valve. It is the danger of exhaust valve overheating which prevents the use of higher compression ratios. »

    Extract from Pages 241~242, re cylinder-head temperature & cooling-fan power consumption:

    « With a view to the economy of performance for cooling and the amount of heat removed by cooling, it would be advisible to choose the highest possible cylinder head temperature. In preceding chapters the point has been made that in order to reduce cylinder head temperature by 10ºC, the fan input must be multiplied by 2•3. This calls for the exercise of extreme caution in deciding the correct cylinder head temperature. The highest admissible temperature for heads of cast aluminium alloys is 235ºC with individual hotspots of 250ºC at the most. Higher temperatures cannot be tolerated. »

    « Figure 188 shows the variation in strength of several aluminium alloys used for cylinder heads with temperature. A considerable reduction of strength of material is evident at temperatures above 200ºC. The composition of these alloys is given in table 37. The reduction of strength at high temperature need not manifest itself through cracks only, but may result in permanent deformation, especially at the pressure gas seal between the cylinder head and cylinder. »
     
  14. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    Keeping the air-cooled engine cool

    The following, are various further relevant extracts, from a variety of books, dealing with oil temperature, cylinder-head temperature and related issues:

    A. Graham Bell, "Performance Tuning in Theory & Practice - Four Strokes", Chapter 8 - Lubrication & Cooling, pages 188~189 & 194~195, Haynes Publishing Group, 1981, ISBN 0-85428-275-6.

    Extract from pages 188~189, re supplementary oil cooler:

    « No matter how good your oil is, it must be maintained at the correct temperature to lubricate effectively. A good deal of engine wear takes place, because engines are operated with cold oil and/or water. An engine should never be driven hard until the oil reaches 50ºC. The ideal operating temperature is 80~90ºC. It can go as high as 150ºC for short periods but oil breakdown and excessive oxidation will take place above this temperature. »

    « To maintain the oil at 80~90ºC, an oil cooler will be necessary for a competition vehicle. This should be matt black to aid heat radiation. The oil lines connecting the oil system to the oil cooler should be at least 1/2 inch, and preferably 5/8 ~ 3/4 inch bore, so as not to restrict oil flow. Some oil cooler take-off sandwich blocks which fit between the oil pump and filter are particularly bad in this respect. I have seen sandwich blocks for the English Fords that require the oil to travel through two 90º bends. If you must use a sandwich block, pattern after the one fitted to the Twin Cam Escorts. »

    « In hotter climates, high performance road vehicles may also need an oil cooler. It is always a worry recommending an oil cooler for a road car or bike because for a good deal of the time the oil will be over-cooled, particularly during the winter. Cold oil promotes engine wear and sludge build-up so be sure to fit a shutter or blind in front of the oil cooler to prevent air passing through it when driving and/or weather conditions, are not conducive to a high oil temperature. »

    « Before you decide on an oil cooler for a road machine, be sure you really need one. Fit an oil temperature gauge and determine your oil temperature in mid-summer. If under normal driving conditions your oil temperature is in excess of 140ºC, fit an oil cooler. However, if it stays around 110~120ºC and climbs to 140ºC only when you run at full throttle for quite a few miles, you will be wasting your time and causing yourself unnecessary trouble by fitting an oil cooler. »

    « Air-cooled car engines almost always require additional oil cooling capacity when modified for more power. However, as they are usually rear engined vehicles, the extra oil cooler should be placed in a more direct air stream, preferably at the front of the car. The plumbing required makes this quite an involved operation , and you will need a two-stage oil pump, one stage to ciculate the oil through the engine and the other to pump it to the oil cooler and back to the sump. »

    « A less radical conversion for the VW is to adapt the Porsche 356 oil cooler and fit a deep well oil sump with both internal and external finning. The internal fins increase the heat absorbancy rate from the oil to the sump. The external fins must be painted matt black to obtain peak radiation efficiency. »


    Note particularly, the references to sandwich-plate design, oil supply-hose bores, two-stage oil pump and operating-temperature conditions, which indicate the necessity for a supplementary oil cooler.

    Extract from pages 194~195, re engine air-cooling system:

    « If your engine is air-cooled there is not a great deal that you can do to increase the engine cooling capacity to cope with higher power outputs. Therefore it is essential to ensure that the cooling system provided by the vehicle's manufacturer is operating at 100% capacity. »

    « Heat radiation from the cooling fins is retarded by the presence of oil and mud, so ensure that the fins are clear. Fins that are silver coloured can have their radiating capacity improved by a coat of matt black paint. »

    « Anything which is obstructing air flow onto the head and cylinder should, if possible, be moved to another location. I am amazed by the number of bikers who persist in fixing lights, air horns and oil colloers in front of the engine. The idea should be to encourage air flow over the engine, not restrict it. »

    « Air-cooled cars rely on a fan to circulate cooling airover the head and cylinder. Think carefully before you decide to modify a cooling system of this type as there are several arrangements in service from the various manufacturers. Without a proper understanding of the system any modification could spell disaster for the engine. »

    « The first consideration is whether the air inlet or outlet is ducted, because it is important to to keep the inlet and outlet separated. If the inlet is taking in hot air that has just been expelled from the outlet, overheating and even a blow up could result. »

    « On the VW Beetle the outlet is ducted (Nigel Skeet's note: This is also true, of the 1968~79 VW Type 2, for both VW Type 1 & Type 4 style engines). The fan intake is open inside the engine compartment and the hot air is exhausted beneath the engine tray. Therefore hot air from under the car must not be allowed to enter the engine compartment. Ensure that all the tinware is properly fitted and sealed with Silastic. Check rubbers around the spark plug caps; hot air escaping through there will be recirculated. Badly planned body modifications may also allow the entry of hot air into the engine compartment, so look into this as well. »

    « The Type 3 and 4 VW use a ducted intake. The outlet is open and the space between the engine and body is not sealed. In this instance you must ensure that the inlet duct remains sealed and that any modifications do not bring the inlet and outlet so close that hot air will be recirculated. »

    « Most air-cooled cars have their air intake in a low pressure area which reduces the amount of air available for cooling. Never, ever, fit a different pulley to slow the fan. Some claim that this gives better cooling because the fan is more efficient at lower speeds. Also they feel because less power is being used to drive the fan, performance will increase. I have found the opposite to be true; slow up the fan and blow up the engine. »


    Note particularly, the reference to isolating the cooling-system inlet from the expelled hot air, to prevent hot-air reciculation and consequent engine overheating.

    I personally have copies of Bill Fisher's, Tom Wilson's & Graham Bell's books, but the book by Julius Mackerle, is one that I borrowed briefly from the university library, and photocopied a few selected pages about cylinder-head temperature, when I was taking a one-year postgraduate course in scientific computing, during 1990~91, at the Royal Military College of Science, Shrivenham, on the border of Wiltshire & Oxfordshire, England.
     
  15. 1500king

    1500king Well-Known Member

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    A bit like that oil cooler in your engine bay pic...or the spade mounted on the engine.....
     
    Last edited: Dec 19, 2009
  16. 1500king

    1500king Well-Known Member

    Messages:
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    Please do not start quoting corvair junk on here as it has NO relevance to the VW and is destructive at those temps. The Magnesium Type IV case is infact the "W" code case and was used in the early 1700 Type 4's. The Later Type IV cases are NOT "Aluminium alloy" as it does not contain any other metal besides Aluminium. Good oils are thermally stable to around 150C, only the Old school stuff and supermarket oils burn away as you describe.
     
  17. 1500king

    1500king Well-Known Member

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    Folks do NOT EVER paint your oil coolers, paint is a plastic in solution and will reduce thermal conductivity between the aluminium and air.
     
  18. 1500king

    1500king Well-Known Member

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    Did you check the wear on the switch dog under the lock barrel?
     
  19. Nigel

    Nigel Member

    Messages:
    628
    Location:
    Canvey Island, Essex, UK
    Intermittent starter fault

    Are you referring to the peg & slot configuration, whereby the rotating peg of the lock-cylinder mechanism, engages in the rotating plastic slot of the electrical ignition switch, similar to a dog clutch, or the ignition-distributor drive?

    If so, I found no obvious signs of wear in either the peg or the slot, when several years later, I removed the ignition switch and key-operated starter lock, for reason of modifying the electrical system and other upgrades. In fact, both appeared to be in as-new condition; the vehicle having very little overall mileage - just over 64,000 to date!
     
  20. 1500king

    1500king Well-Known Member

    Messages:
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    Location:
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    Yes, thats it...There is also a pin where the dog attaches to the barrel which also flog out.
     

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