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A theory re. overheating

Discussion in 'Engine & Transmission' started by kommodius, Apr 2, 2009.

  1. kommodius

    kommodius Active Member

    Hi all.
    I have a wee theory that I'd like to put to you and please feel free to attack it with gusto if you disagree.

    This morning my bus (1977 2 litre micro) got too warm after only 30 minutes driving. No oil temp. gauge but you just "know" if you know what I mean. (sorry Brennden!:D)

    Da Boyz and I had stopped for coffee and toast before school and the bus wasn't keen on restarting.
    After about 5 kms she lost power and stopped.
    "Vapour lock", sez I to myself and the world in general, "have to let her cool and try again".
    Da Boyz got a lift from a passing schoolmate and I waited for a while.
    After 30 minutes or so the bus would start, rev and then die.

    Being relatively tool-less I called the RAA. (first time in many years!)

    The guy arrived and fiddled about and reckoned the fuel pump was on its way out. (the analogy of prostrate issues seemed to fit!) He got me going though and even followed me part of the way home. Great bloke.

    Now to the theory:
    • fuel pump not delivering enough fuel 'cos it's not well
    • less than required fuel delivery = lean mixture
    • lean mixture = hot engine
    I had been thinking that I had problems with the carbs but now I'm thinking the problem is with the fuel pump.
    I shall test my theory by fitting an electric (4 psi) pump to see if that makes the old girl run cooler.

    Attack away!!

    Ray & da Boyz
     
  2. Vanders

    Vanders Active Member

    Messages:
    1,450
    Location:
    Launceston, Tasmania
    Sounds palusable Ray. Don't forget that you will need a relay for the electric pump, so it doesn't keep pumping if the motor stalls while the ignition is on in the event (heaven forbid) of an accident.
     
  3. Bulli

    Bulli New Member

    Messages:
    626
    Location:
    south australia
    Personally, I would change to heavier gauge strings ... but I'm thinking you're right :)
     
  4. cbus

    cbus Well-Known Member

    Messages:
    13,570
    Location:
    sunshine coast
    Agree lack of fuel as a first option as symptoms same when filter blocked.

    Maybe put pressure guage on fuel line to check before spending the bucks. Check flow and pressure.
    Have heard mixed reports on the $60 square pumps. Some tested and giving widely varying pressures. Have been recomended the $120? ones as being better on quality control. Im sure Tom would have good info on this.
    Pressure regulaters also recomended when using electric pumps. A few knowlegeable folks have gone this path and I will be doing the same .
    cheers
    col
     
  5. kommodius

    kommodius Active Member

    Thanks for the responses guys.
    No need for a pressure check I reckon cbus. When I pulled the line from the carbs T and spun her over there was barely a dribble (hence the prostate analogy!) not the "highly inflamable money-shot" that you'd expect.

    My VW mechanic Guru, Bob from VolksCare suggested a "push" pump fitted under the tank (gravity fed) on rubber mounts delivering 4 - 4.5 psi. No regulator needed if the pump's wired through the coil, (engine stops, pump stops) earthed to chassis.
    The recommended unit is $100.00 even. Can't remember the brand/model but I will let you all know how it goes.

    Hopefully a cooler engine as well as better fuel delivery.

    Heavier strings won't help unless they're flat-wound Bulli ! :lol: Even then you'd have to use a glass slide (ceramic and metal wouldn't cut it unless the resonator had a live biscuit and very high action :wtf:)

    Ray & da Boyz
     
  6. cbus

    cbus Well-Known Member

    Messages:
    13,570
    Location:
    sunshine coast
    Yeah. Analogy about right:)
    No fuel does usually equate to no pressure.:(

    The pressure reg was to limit pressure as some have found an issue with too much pressure altering fuel adj. Think its meant to be 4lb max from memory.

    Did the same with coil. Easy to disconnect pump as well when mucking around in engine bay with ign on and you dont want pump making a racket.
    cheers
    col
     
  7. Good one Ray LOL!!

    I have a facet type pump on my bus now as the Holley red crapped itself. I run no reg unlike with the holley and car runs perfect. It will pump hard when there is no fuel until it reaches the set pressure level then pump rate slows right down. Only supplies fuel as the engine needs it. Mine is also connected to the coil so i can unplug it easily to do things like set points and hear when points are sparking.

    Could be the reason your car is running hot as it is lean as!! What colour is the inside of your tail pipe?? will differ depending on what fuel you run as well.

    New pump, reset mixtures, reset timing and points and go for a drive and see what gives. Even throw it on a dyno to get a good tune and set mixtures spot on. Good HP gains and smooth drivability to be made with good tune on a dyno!!
     
  8. Van Housing

    Van Housing Well-Known Member

    Messages:
    10,434
    Location:
    Yarraville Vic
    It may also explain reported persistent overheating problems despite the engine being replaced (eg Cammo....). Same faulty mechanical fuel pump?
     
  9. All the carby fidling in the world and it still runs lean LOL
     
  10. kommodius

    kommodius Active Member

    I am well pleased to read your comments Brennden, though the colour of the inside of her tail pipe would suggest rich rather than lean. "Black as a black man's cloak." I run high octane fuel.
    Maybe I am on the right track though. (It was only a theory)
    My plugs say "lean", my timing/tuning says "not". But my engine sez "too hot!".
    Valve clearances, ignition timing, points gap are to the book.
    I don't have access to a Dyno, but would love to try her.

    Maybe you're right Woz, I'm hoping to find out.

    We'll see I guess.

    Ray & da Boyz
     
  11. Aging Surfie

    Aging Surfie New Member

    Messages:
    82
    Location:
    Waikiki Western Australia
    The delivery from the fuel pump does not make an engine run lean or hot. Lean / rich running is adjusted by the air fuel mixture or changing the size of the jets to allow more or less fuel. The pump delivers fuel to the carbie bowls, regulated by the needle and set. If the bowls empty you have no fuel to the engine so no fuel for the fire the spark. You will simply stop going. One the pump fills the bowls again of you go.

    Go the Facet pump. They do not need regutating but do tick away all the time.

    Deano
     
  12. Bulli

    Bulli New Member

    Messages:
    626
    Location:
    south australia
    Ahhh, D'addario Chromes and a Stella bottle neck :)
     
  13. kombidaze

    kombidaze Member

    Messages:
    466
    Location:
    Uki NSW
    kommodius
    i will assume that you have standard solex carbies atop your 2 litre motor and as aging surfer has said it is the mixture ratio air/fuel that determines lean or rich. my suggestion based on my understanding that a good deal of the time you are relying on the idle circuit to get you from point a to b and to adjust that circuit ie more fuel as compared to air you open up maybe a 1/4 of a turn the idle mixture screws which are located down around the throttle plates on the outside of your solexes, (hard to find and you need a short smallish flat bladed screwdriver to tweek em) if you do this you will then have to readjust the central idleing system but it will richen up your mixture, and another thought is make sure you ain't sucking air in from below the carbies, a squirt around with those aerosol starter/ether cans will soon tell you cause the motor will rev up.
    best
    john
     
  14. kommodius

    kommodius Active Member

    Thanks for the comments folks and I have to admit that my theory seems to have been shot out of the water by Deano and John.

    Which brings me to theory #2!

    T'other day whilst fiddling aboot with the carbs and fuel lines in preperation for the electric pump ( ........... no! .......... I haven't done it yet!!) I noticed lots of fumes from the crankcase breather.
    Those fumes are heading into the air filter and therefore into my long suffering carbs!

    Is it possible that my unwell mechanical pump is allowing fuel into the crankcase and therefore causing the fumes?
    Could that be one of the reasons for my bus' less than optimal performance?

    What other causes could there be for excess crankcase fumes?
    Oil was changed (Penrite 30/50) less than 500 kms ago.

    Ray & da Boyz
     
  15. kombidaze

    kombidaze Member

    Messages:
    466
    Location:
    Uki NSW
    if there is petrol in your oil you would get a pretty good indication of it on your dip stick reading if so then you have a needle and seat problem which should be attended to or you have a problem with a float not "floating" the other thing that comes to mind regarding overheating issues is maybe your distibutor is not advancing as it should it can happen that the advance weights get gummed up with dried out lubricant there is a sight window in the side of kombi distibutors plasticy thing pull it out and squirt a bit of inox in there maybe free things up a bit other than that (not meaning to be your mum or anything) did you replace the little bits of tin ware that sit flush against the underside of your barrels when you rebuilt that motor?? the other maybe is - the automatic chokes are stuffed either both or one fairly easy to check pull the air cleaner tubes turn on the ignition and see if they open up equally.
    just some thoughts
    best
    john
     
  16. RatCamper

    RatCamper New Member

    Messages:
    121
    Location:
    Berrigan region NSW
    I'm using an electric diaphragm pump from some kind of mitsubishi. Not sure if I'd call it a facet pump though, as it's a big cylindrical thing. Works great. had the motor running a couple of days ago up on ramps with the fuel line hanging because I'm tackling a few jobs. Looked a little unsettling. about once a second the fuel line would give two twitches like a heartbeat.
    I'm also running a tachometric relay and another fusebox for the choke, pump, and reversing lights (I know that's redundant).

    DON'T be tempted to put the coil on after the relay.
    If you do this, when you turn the engine off after running, the alternator light will provide enough current to keep the relay tripped and the engine won't stop unless you do something like turn on the indicator. I also think, although am not sure that in that state the regulator is not functioning.
     
  17. kommodius

    kommodius Active Member

    Thanks John.

    all the tinware's there, the distributor has been stripped and cleaned, the chokes have been disarmed and there's no indication of fuel in the oil.

    BUT! :eek:

    My timing strip (the plastic arc with degree marks) was split!
    I'd been timing the engine too advanced because it was in the wrong place!
    Replaced it and re-timed the ignition.
    Kombi is as cool as a cool thing that's been in the fridge even after climbing some fairly steep hills.

    Oops!

    Ray & da Boyz
     
    peter drogi likes this.
  18. dbs

    dbs Member

    Messages:
    949
    Location:
    Melbourne
    I think this is a great case study in looking at the alternatives when it comes to a hot kombi. The germans did a pretty good job of designing this beast and adding scoops and water coolers etc is treating the symptoms but not the cause.

    Good work Ray, maybe this thread might get some others looking beyond the symptoms.

    happy cruising
     
  19. kommodius

    kommodius Active Member

    Thanks mate.

    ........................................ I still feel like a bit of a twonk though!:eek:

    Ray & da Boyz
     
  20. emby

    emby Active Member

    Messages:
    2,005
    Location:
    Wights Mountain, QLD
    Ray. It's sharing moments like those that help most of us out.

    Don't feel like a twonk...you sorted it. Good on ya. Well done
     

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