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Rear main leaking, fresh rebuild
by
myke_w
on 09 Oct, 2006 17:21
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I recently rebuilt the 1.6 TD in my diesel vanagon and drove it around town for 2 weeks with no issues. I then took a road trip on the highway and got the revs up pretty high, and for sustained periods, with oil temps reaching 125-130 at which point I noticed an oil leak aat the rear main.
Any speculation on why this might be? I am using a diesel spec 10w30 precisely to avoid this kind of issue.
I am kind of at a loss because I am fairly ceryain I installed the seal correctly. The crank was also checked for runout on the thrust bearing surface and wasn't out of spec..
Any idears?
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#1
by
macsdub
on 09 Oct, 2006 19:50
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it could be one of those core plugs in the block back there too
theres a 36mm,and a 14/15mm? plug also
the 15mm plug is a pressurized oil galley
i had one leak and ruin a clutch disc
its a very shallow plug too,theres a few styles,dont let it block that oil passage inside going up to the top end
remove the clutch+backplate ,see if its all oily,it may leave a spot
of course it could still be a seal issue
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#2
by
myke_w
on 10 Oct, 2006 18:09
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At the rate it's leaking (slow), I can't see how it could be the galley plug popped out but I'll have to check, but I would think that would leak more when cold if that were the case because there's more pressure. Like I mentioned, the seal didn't leak until well into 500 miles on the motor so I'm confused...
I was wondering if it's possible that when building boost say 15 psi... that in the early stages of the motor where the rings aren't seated, that boost pressure enters the crankcase through blowby (possibly because of an insuffiecient valve cover vent) has to escape somewhere and goes through the rear main? Aside from having installed it wrong, This about the only seal failure situation I can dream up that doesnt involve exceess lash, or failed install. BTW along with high temps, and high speeds, high boost was a factor, I topped out at 15 which I know isn't alot but could it be enough to blow past the rings on a new motor? any advice is welcome..
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#3
by
HarryMann
on 10 Oct, 2006 18:28
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Those oil temps are high - those 1.6TDs in vanagons get hot anyway, and bothered too.. . and seriously limits their life.
The oil will be very thin at those temps, and obviously more likely to get past a suspect seal. Was this a VW seal or some other replacement.
You're right, the breathing on these might be a bit compromised which might be a factor.
As also blowby, but not due to the boost as much as the running in - did you by chance take it easy for first 500 miles or did you conciously attempt to get cylinder sealing developed quickly, upping the cylinder pressures progressively quickly in longer and longer bursts?
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#4
by
myke_w
on 10 Oct, 2006 20:21
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Those oil temps are high - those 1.6TDs in vanagons get hot anyway, and bothered too.. . and seriously limits their life.
The oil will be very thin at those temps, and obviously more likely to get past a suspect seal. Was this a VW seal or some other replacement.
It was a reinz seal IIRC
You're right, the breathing on these might be a bit compromised which might be a factor.
As also blowby, but not due to the boost as much as the running in - did you by chance take it easy for first 500 miles or did you conciously attempt to get cylinder sealing developed quickly, upping the cylinder pressures progressively quickly in longer and longer bursts?
I took it easy for the first 200 or so, then I started to try to get it worn inmore as you described...
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#5
by
HarryMann
on 11 Oct, 2006 02:57
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If you are worried those rings haven't bedded down well, a compression test should show that up in absolute values, as they all should be fairly even.
Does it appear to breathing heavily with the breather tube off?
Exactly 4.5 litres of oil in it? Type of oil?
A big oil cooler up front is a good idea on these trucks, but requires 10m run of oil hose.
An alternative is to hook the oil/water heat exchanger up to a separate radiator/fan/coolant circuit - the rear boxes behind the tail-light is a good place - a motorcycle type radiator/fan/pump a good idea. Its just possible to get a 10" diameter fan in the floor of that compartment - and depending if this is a Doka or a bus body, the air comes in the side vents or down the Snorkel box from the high inlet vent. Everything else needs sealing off, fan should vent downwards of course.
Some fit small intercoolers in the left hand rear box, but often don't arrange the fan design and fresh air inlet very well, air mustn't come from the engine compartment which runs very hot.
Another mod is to punch large holes in the engine flap and stand off the number plate, to at least get some air venting out of the engine compartment.
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#6
by
HarryMann
on 11 Oct, 2006 09:22
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Andrew,
Everybody over here quotes 4.5 litres, and we know that too much creates problems with the 52 angled over TD installation.
Intercooler sounds good - what then now are your max EGTs? (just interested thats all)
To get anything like the oil cooling that a large cooler up front gives, you will have to pay a lot of attention to the detail design if its in that rear box. I have done it, and still not finished the detail ducting to ensure the fan pulls air only through the oil cooler and not from just about everywhere else. It currently makes little difference to oil temp, and even front mounted ones only knock 10 to 15 degrees off.
All the European kits for oil coolers are based on fairly large hoses going up front to a 19 or 25 row cooler for these TDs. The agreement generally is that just cannot go large enough on these engines in the rear of a vanagon/transporter when overboosted and producing 90 or more HP. The temperature put into the oil by it lying about in the cylinder head and going through the turbo is very high. Additional oil volume is about .75 litres with 1/2" bore tubes, .5 litres of which is in the cooler. The general concensus is that if you can change the oil frequently, .75 litres or a bit less is sufficiently diluted at each change, or if worried, just drain the cooler down.
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#7
by
HarryMann
on 13 Oct, 2006 04:00
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If I put more than 4 qrts into my 2.0L ABA gas Vanagon, it starts blasting it all through the intake on corners. Nasty mess. Never a problem if I keep it to 4 qrts though
And can be a big problem with canted over VW diesels in those trucks too - even at 4.5 litres if the turbo seals or the breather aren't quite up to scratch, and corner hard to the right, expect a very nasty experience - running on oil. Still not sure if its getting through the seals from the return pipe or down the inlet from the breather. This is what cracks heads too I think - the detonation, grey smoke and noise is beyond belief. Quite how they can stand it for 5 ~ 10 seconds sometimes I don't know!
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#8
by
macsdub
on 13 Oct, 2006 08:43
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At the rate it's leaking (slow), I can't see how it could be the galley plug popped out but I'll have to check, but I would think that would leak more when cold if that were the case because there's more pressure. Like I mentioned, the seal didn't leak until well into 500 miles on the motor so I'm confused...
my 15mm galley plug was loose,it was a very slow leak,and yea it was like 8 months after i rebuilt it
when i put a punch on it to remove it(plug) i saw it move a little
i knew then that that was my leak
i made a preluber out of an old distributor
i spun the oil pump,and i saw it leak from the plug
the 36mm plug has no pressurized oil against it
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#9
by
larry104
on 17 Oct, 2006 07:28
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One other thing has been nagging at me. I have heard previously that high oil pressure can cause seals to blow, and that is why you used 10w-30. I don't understand how high oil pressure will cause the seals to blow. None of the seals in the engine are under oil pressure and so I don't see how it is relevent. Can anyone shed light on why the pressure in the oiling system would have anything to do with blowing seals all of which have a total pressure release channel going to the pan?
Andrew
I agree with you. The main bearing journals and sealing surfaces are separate. There's only internal crankcase pressure. I suppose blow-by from poor sealing piston rings could pressurize the crankcase and cause seals to leak. But the oil pan and lower end vent through the valve cover breather becuase the oil passages between the head and block are connected (of course).
Other causes of seal leakage may be a defective seal; the spring that loads the sealing lip may have come off during assembly; the crank sealing surface is rough and ruined the sealing lip; or the seal could be leaking on the O.D. Or, it may not be the seal at all and could be the interface where the seal holder and block touch the oil pan sealing surface. I put a dab of RTV there before installing the pan. Could also be the gasket between the seal holder and block. I suppose the seal holder, if over-torqued, could distort and leak .
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#10
by
Baxter
on 17 Oct, 2006 15:18
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Ref oil level.
I may be able to shed some light on the oil level quandry.
I have seen in manuals, specifically US manuals a much shorter oil filter than we use here, dunno if thats where our extra capacity comes from.
If I service a factory 1.6TD T3 then I add 4.5l of engine oil with an new filter and this will bring the level on the dipstick to just below the max mark, I don not fill them to the max mark as it causes problems of a smokey kind! I use 15w40 oil and never have any problems. I learnt my oil level nouse from my m-tdi, that was a bugger, if you took notice of the dip stick it would smoke it's knob off, it was like the "Red Arrows" had done a fly by! If I emptied it, filled it with 4.5l and a fresh filter and then re-marked the dipstick it was fine.
The Autodata info on the subject also says 4.5l with a fresh filter.