Discussion in 'Bay Tech Clinic' started by Chidori, Oct 10, 2016.
Cheers mate, VW's are my disease, can't help myself!!
Out of curiosity,
is it the same case you had before the rebuild....eg, your engine?
There is not much that can go wrong with the oil system unless it simply hasn't been put back together correctly.
To me, given it has been apart a couple of times and now may have a pressure problem where previously it didn't and apart from the obvious such as bearing clearances, wonder if the relief valve/spring is correct for the case...may have been inadvertently/unknowingly replaced with something else. I'm interested to know what they have done to determine the state of the oil pump as being satisfactory for service considering you can't buy new OG style ones off the shelf so easily.
The more infected people of your calibre and expertise, on the Kombi Club, the better.
Are you interested by chance, in doing a T3 gearbox rebuild (2wd) ?
No harm in asking, and no problem if you say you are not really set up to do such things yet.
great to see you back posting Andrew you were a great help to me in the early days of kombi ownership
I'm not sure to be honest what was done re oil pump. However, I know for the first build he re-used the old one because he said it was still within spec.
However for the 2nd build he used a different oil pump that he had on hand. The oil cooler is also very new - I replaced it before it was rebuilt.
He's checked all the oil galleys for swarf, etc. Machinist and himself have triple checked clearances for bearings, etc.
If there's a decent aftermarket oil pump available on the market, I'd look at buying that.
I also didnt replace the crank and rods - they were just machined and balanced where required - along with the flywheel.
How different would a wrong relief valve/spring look? And if it was incorrect - would this cause the oil light to only come on when engine hot after freeway run?
Out of all the engines he's ever built - this is the only one he's ever experienced this drama with.
It's got us all stumped. I'd love to have a look at the case once it's apart again, but then again, I wouldn't even know what I was looking for.
It's quite possible we will never know! It's more than likely we'll rebuild again using a replacement case and hopefully that solves the issues.
In regard to pumps, I have new billet 30mm Type IV spec pumps in stock. These are true Type IV pumps, not 'modified Type 1 pumps', they fit correctly and are a work of art.
You would need to strip the case, then replace ALL the gallery plugs with tapered thread pipe plugs as it will blow out originals.
There are different springs (different load rating and length) and different pistons depending on which case you have.
Earlier cases also have an Oil pressure control valve under #1 cylinder.
If any of these are stuck open for any reason(siezed after washing/ swarf, etc) or have the wrong relief height/spring pressure, your oil pressure will be incorrect/insufficient.
This is why I ask if it is your original case (and likely original relief pistons/springs). Case gallery plugs MUST be fully stripped after line boring to remove swarf, otherwise it will chew out all your bearings. There is NO WAY to get it all out until you remove all the plugs, scrub and evacuate all the galleries.
sorry - i did forget to mention that it is the same case... I assume the spring/piston can't be checked without re-opening the case?
Given he's been building these for over 20 years and this is the first type of issue he's had like this- I'm sure he has a pretty good idea of what he's doing.
I know of plenty of people who have engines from this builder- lots of people on here too - with rave reviews - so whatever it is - i'm sure it isn't an easy thing to find.
I'll pass these ideas on to him though - if he hasn't read them on here already and see what he comes up with. Thanks as always 1500!
All of it can be checked without dismantling the engine completely. Having said that it ALL should have been removed from the case before/after machining to enable detail cleaning to take place. All it takes is one piece of swarf to wreck things.
The big problem is that you can't 'undo' the damage of a low pressure fail.
The aftermarket bearings these days also leave a bit to be desired where I have seen them incorrectly manufactured.
Update from my mechanic:
Oil pressure at cold: 42
Oil pressure at hot: 3
I'm thinking cracked case... but since the case has been looked over so many times and the fault never found -i guess we may never know. Time to rebuild AGAIN with a new case.
What reason to suspect cracked case?
What weight oil?
Assume those pressures at idle.
What is the hot at 3k rpm?
I'll be seeing him tomorrow so I'll ask for more detail.
Suspected cracked case, because everything that can be measured has been measured multiple times according to mechanic and also everything that could be replaced has been replaced - other than crank.
Have tried 3 different weight oils from run in oil to standard to 40 weight i believe. All showed same symptoms of oil light on at idle after freeway run.
What oil temps are you getting? Is the oil pressure relief valve stuck therefore bypassing the oil cooler.. Hence higher temps =lower oil pressure
Just a thought
Very possible. However the mechanic tells me that the valves were both checked after the first rebuild and replaced the springs(?) to rule that out. So it's probably unlikely but I'm not sure if there's any way to tell that?
To rule it out put your oil temp sip stick back in and see what temps... And how quick.. It's getting there
Should be over 60PSI cold/15-20PSI hot @idle, especially with an oil like Penrite HPR30. You either have a pressure control(something stuck open) or clearance problem.
Have you checked over the relief/control valves? Sure they didn't use Type 1 relief parts(not that they should every have a reason to)?
And we might have a Winner!! Replaced springs? why?
Type 4 springs and relief pistons ARE different to Type 1. They are ALSO different between years in a Type 4 case. Length/load of springs need to be checked. Piston dimensions/shape also needs to be verified against engine number+case part #. The relief screw plug is also different to Type 1.
Did they drill/tap and plug any of the oil galleries? There are a couple you don't want to drill too deeply on...well the large one where the fuel pump pushrod bushing goes through the gallery. This is one where the bushing needs to be pressed out partially to drill/tap a thread. then fit a shallow pipe plug to clear it when back in place. This is not a problem on an EFI case. Drilling through the bushing will expose the fuel pump pushrod bore.
If it is an earlier case with a second oil pressure control valve, also needs checking, will be under #1 cylinder behind a big triple-square socket plug.
Chidori Are you SURE this van is not possessed?
Are you saying there is a difference in a 2lt case between a carb & fuel injected re oil flow?
If so ..what is that difference?
I've been 'chasing' understanding of heat in these motors since I joined KC.
Dave, the RHS main gallery of which the core plug is behind the flywheel is one of three that like to leak or come loose and blow out. On a carbed case , the bush for the mechanical fuel pump goes through this gallery at the flywheel end where the injected case is not drilled in the first place. To plug it properly, you need to tap out the bush so it clears the gallery in order to tap a tapered thread carefully so that when you install a plug it only threads in and tightens on the taper without bottoming out on the fuel pump pushrod bush once you have tapped it back in. If you drill through the bush in trying to prepare the bore for a tapered thread, you WILL create an internal oil leak at the fuel pump pushrod. If you leave the pushrod out(aka put a delete on the pump flange and remove the pushrod) and have drilled into the bushing, then you oil will bleed out through the holes and back into the case. The plug also needs to clear the flywheel and the timing magnets on it, so needs slight turning down on the head but leaving enough of a hex socket to tighten it up. Cleveland gallery plugs are ideal for this spot with only slight skimming needed. My point is here that once you replace it and do it correctly, a) you can clean out all galleries after machining/on rebuild, b) install a new oil pump which will hold good and long term oil pressure which will give you more options for performance cooling and holding good oil films at all critical wear points and you don't have to use Treacle ("extra 10 Penrite engine honey") so you can carry away localised heat faster and deal with it through the cooler, c) you will NEVER need to worry about it ever popping out like they do.
Heat is created purely by mixtures and timing(or more lack there of).
If you run them lean, even slightly, the combustion flame gets MUCH hotter and the cooling system cannot deal with it.
This brings on detonation( which is just like hitting your long block at the cylinder heads with a sledge hammer..will create the same damage ultimately). If you change the cam, volumetric efficiency(cam, comp, heads, valves, exhaust, etc) it needs a run on the dyno to get mixtures UNDER LOAD at around 12.7-12.9:1 AFR. Timing when doing this needs to be plotted at load points during this run for peak power at those points, then the distributor mech advance reset accordingly to that.
You then have the load/light cruise function(vacuum can on the distributor) where when you are, say at 90-100kmhr and are just feathering the accelerator pedal to keep it there. Your throttle valves will be almost closed, therefore only giving the motor a SPARSE mixture (not lean, just not much fuel AND air at the same time). When lit by the spark plug this mixture takes much longer to burn to reach the maximum thrust on the piston, therefore you need to light it earlier. The vacuum can creates the advance under LOW PRESSURE(high vacuum? whatever you want to refer to it as) with the signal coming from just under the partially closed throttle valve. The vacuum signal is cut off when the throttle valve is fully closed. The can advances timing by another 10-12 degrees under this condition to light the flame earlier, to utilise the desired thrust on the piston at the right moment and ensure it is all just about done by the time the exhaust valve starts to open.
If you don't have this light cruise function then your timing is too late under the "cruise" condition(which is how we drive 80% of the time), leading to the mixture still burning past the exhaust valve and in to the exhaust port. This condition overheats the exhaust valve and overheats the exhaust port(and the head) leading to all sorts of problems like burnt valves, dropped seats(as they fall out from the heat) and inducing more destructive detonation which smashes the spark plug, piston, rings piston pins, crank, crankcase and bottom end bearings, not to mention the oil leaks from the increased crankcase pressure pushing oil out past seals and flanges. Lean burning also creates the same issues, and when lean misfires occur, will do the same to the oil.
Other by-products of the lack of above control are "roasted" spark plugs, excessive valve and seat wear(regularly changing/reducing valve clearances)...
Evidence of detonation can be seen on spark plugs where insulators around the electrodes show "peppering", as if somebody has lightly sprinkled ground pepper on them...tiny ceramic blisters. If you get them hotter, they start melting
Worn camshafts create heat as the spent gases take longer to leave the motor.
Bottom line is;
good compression and camshaft
Correct mixtures (no worn carbs or mish mash of parts, there are about 100 different specs of Type IV carbs and only about a dozen of those really suitable these days).
Correct timing (original distributors rebuilt are fantastic, with timing in all the right places, rock-steady idle/perfect acceleration/perfect cruise and power with great economy..why would you change it?).
All the cooling system is there and working(including the thermostat setup, they are more efficient when up to temp and stay there with great heaters in winter as the thermostat redirects into heater boxes when cold). Piston ring/guide wear also greatly reduces.
All pre-heat functions are there and working(creates steady air temp to maintain tune and fast warm up, no fuel condensation in manifolds when cold).
Lack of any of the above WILL create more fuel consumption and much shorter engine life.
Anything sound familiar?
Hydraulic cases have a shorter oil pickup neck as the oil pressure relief port is also drilled into the oil pump intake. There are differences in spring and piston specs, depending on the year/case # as relief drillings are positioned differently too..
For example, if you use a slightly shorter/weaker spring or a plug that is not as deeply threading, then relief pressure will be too low. Type IV relief pistons also differ in length and shape.
I'll dig up some specs.
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