Flywheel oil leak, high oil pressure and burning oil

[rlepecha]

I've been fitting and sorting out an engine for my bus for the last week. I started it up today and its burning oil, running 65psi oil pressure at cold idle (over 100 psi at 3000 rpm) and pissing oil out of the bell housing.

I replaced the flywheel oil seal in the engine with a dual lip version before I put it in the bus. End float on crank is 4 thou.
I have also had the heads off to polish the inlets and exhaust ports, fitted new exhaust valves all round. All the barrels, rings and pistons looked OK, barrels still had clear honing marks.

Oil pump is a CB Maxi 3 hosed up to Golf TDI oil filter and then back to the case. Oil is 5w40 fully syn.

Am missing something obvious here? What the hell has happened with this engine.

Could the high oil pressure be contributing to any of the other engine issues? Or am is it just blowing past the rings and out the flywheel seal.. There is no leak at the pulley end.
I

 

[jonboylaw]

The oil pressure is very high, is the pressure relief system working? The piston my be stuck.


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[rlepecha]

The oil pressure is very high, is the pressure relief system working? The piston my be stuck.


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I am going to check that when I've got the engine out, I took both the relief valves out and replaced both pistons and springs and they all seemed fine at that point.

I took the exhaust off yesterday and looking at the traces of oil(lots of it) in the exhaust its both cylinder 3 and 1 which are burning oil, 2 and 4 are OK. I haven't got a compression tester so I'm going to take out the plugs from 2 and 4, turn it over by hand to confirm compression on 3 and 1. I definitely had good compression on all 4 before I put the engine in, but the amount of oil its burning indicates otherwise..

 

[Bay-low71]

I would say the majority of your issues are as a result of the high oil pressure. When you changed the pressure relief and pressure control caps and springs were the free to move up and down the bore? and were the replacement springs the same compression setting? If it was ok before try to revert back and try to eliminate it. Good luck, can't remember but do you have to pull the motor to get at these pressure relief etc? I didn't think you needed to, but could be wrong


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[Trikky2]

As already posted, check the oil pressure relief.

First one only governs the oil cooler. It's number 2 that dumps excess pressure.



Some grit or swarf may be jamming the relief valve and the problem is then greatly exacerbated by the non stock oil pump.

Excess oil pressure could then be forcing its way past the flywheel oil seal.

As for 1 and 3 being oily. Is the vehicle parked on a camber with those cylinders lower?

Have you checked the oil level in the case?

The reason i ask is because too high an oil level in the sump and parked on a slope can allow oil to seep past the rings and into the combustion chamber.

If your oil level has mysteriously risen then check your fuel pump for internal leaking and the carbs for flooding past the needle valve.

 

[rlepecha]

Thanks for the replies guys..

The relief pistons and springs were the standard type. No EMPI oil booster kit or anything like that. I will check that they are not stuck through the week.

Vehicle was on a flat. I tried bringing the oil level down to the bottom mark on the dipstick after it was full and it made no difference to the burning of the oil.

I have now taken the engine out and fitted the old one back in (which overheats when driven above 50mph, reaches near 130℃) as I go away to Scotland for a week next weekend and need to look at the new one in more detail clearly....

I think given the amount of oil that was pouring out of the bell housing, the flywheel seal is probably completely stuffed now and I will replace again. I checked compression on cyl 1 and 3 and could easily turn the engine over by hand(no spanner, just spinning the pulley), seems there is very very little compression on them two cylinders now. Heads will be coming off again to have a proper look, shouldn't be valves leaking as they were freshly lapped and set.

 

[Trikky2]

Well from what you say it seems you will indeed have to investigate further, maybe rings?
Let us know what you find.

 

[rlepecha]

Will do, I'll see what I find. Think I'll end up throwing a new set of barrels, pistons and rings on for peace of mind, is it worth spending the extra £90 on Mahle cast pistons over Brazilian cast pistons?

 

[*Sam*]

Not sure if this helps but a friend has some brand new 1641 B and Ps I believe they are Mahle.

 

[jonboylaw]

Sam, if you are indicating that they are for sale, then it may help him. Not clear from your post


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[*Sam*]

Sorry didn't mean to confuse anyone yes last time I spoke to him they were for sale.

 

[rlepecha]

Update -

Stripped one of the heads of tonight, first to look at cylinder 3 which was one that was clearly burning oil (oil in heat exchanger exhaust pipe). Obviously number 3 is the most prone to warping and such hence why I looked at that one first.

I've had a good look at the cylinder, piston and all rings. All the rings are suitably tight within the cylinder and no light gaps can be seen around them. Paying close attention to the oil scraper as this would be the most likely one to let oil past.

Looking at the pistons I have come to the conclusion that the high oil pressure would result in high oil flow into the back of the piston, thus potentially partially filling the back of the piston which is over lubricating the barrel walls. This would also indicate why only cyl. 3+4 were burning oil, they are first on the oil rail thus will see higher pressure.

I have removed both oil relief plugs, neither were overly tight in the bores and fell out with light taps to the case. I have compared the new oil relief pistons and springs with the old ones, both new springs seem to have a higher spring rate and the larger spring is a couple of mm longer than the old ones. Both new pistons are ~2mm longer than the old ones. I have reverted back to the old pistons and seals, given that the increased spring rate and larger sizes would increase oil pressure.

I will be checking the flywheel seal later this week and attempting to turn the engine over with a drill to see what oil pressure I get at idle speeds with the old oil reliefs. I am not sure these minor changes will rectify the 80+psi oil pressures but I can't imagine what else would be contributing to it.

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For any one that may wish to know how the road trip in Scotland went; It was great, weather not the best the first few days (snow, hail and high winds) but we made the most of it.. Drove on some great roads with brilliant scenery. The old engine was using 1ltr of oil every 500 or so miles which is not good, I think its a combination of leaks and also burning some oil due to the overheating.

 

[jonboylaw]

Great news you managed to get away using the old engine. Where did you visit up here? Would love to know the route. Pity is was not this week's as it is great weather at the moment.


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[rlepecha]

Great news you managed to get away using the old engine. Where did you visit up here? Would love to know the route. Pity is was not this week's as it is great weather at the moment.


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I will upload the basic route later, we didn't camp anywhere that was not a campsite due to the weather. Would've had a fair bit more freedom if we had camped for free in places.
I do believe we should've probably stopped 2 nights at each place or reduced the travel times between each one(was 2-3 hours a day), because there was little time to sight see apart from en-route.


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Engine update, thought I would do a basic compression test on the engine yesterday, wound a plug into each cylinder and turned it over.. Because the case has no ancillaries at the moment I can clearly hear that all 4 cylinders bleed pressure into the case very quickly, I cannot feel much compression on the engine even with a touch of ail in each barrel.
I double checked this with the current engine in the bus, that engine will rotate backwards on itself if you turn it over into compression. That is what I would expect the new engine to do but it isn't.

I've also checked that the oil relief at the end of the bearing rail is opening correctly using compressed air at 30psi and oil in the gallery. Relief opens with no issue.

So given all this, I've now ordered a new set of 1600 Mahle cast B&P's from Cool Air. Hopefully this should be the last of the issue.

 

[rlepecha]

Engine re-fitted yesterday and ran today, no oil leaks, good pressure 19psi idle and about 60 psi at 3000 rpm when warm.
Oil temperature is about 107 degrees after a 55mph run for 30 minutes.
So the oil temperature is still high, just like my old engine; back to the drawing board.

 

[Trikky2]

New rings, pistons and barrels will run hotter to start with as they bed in.

Should run cooler after a few hundred miles.

 

[rlepecha]

Still trying to solve the high temperature issue. Engine has done about 400 miles, I've re-jetted my carbs as they were runninglean, this made no difference. Thive just fitted a 13 row mocal oil cooler under the bus with a thermostatic sandwich plate, oil got to 109c after 5 or so minutes at 60mph.

Timing etc is correct, still looking to find the cause.
I'm going to make a scoop for the separate oil cooler tomorrow to aid its cooling ability, it currently seems to be doing sod all.

 

[Trikky2]

Have you tested the oil temp gauge?

 

[rlepecha]

Have you tested the oil temp gauge?

Yes, reads nearly spot on 100c in boiling water.

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[Trikky2]

Hmm. Puzzling one this. After 400 miles the engine temp should have dropped by now.

Have you checked the ignition advances to a max of 28 to 32 at around 3000 rpm without the vac advance connected?

Reason I ask is because if the advance is sticking it could cause it to run hot plus some of the aftermarket ones have been known to under advance - particularly the 009 copies.