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Discussion Starter #1
As some of you will recall, I completely replaced the engine oil cooler lines and the oil filter housing to stop a fairly serious loss of oil from those components a short while back.

I have been carefully monitoring the engine bay to see if I figure out where other oil leaks are occuring but so far nothing obvious. I originally suspected the crank pulley seal but there's no fresh oil showing up around that area with the exception of a small amount that appears to be coming from the timing cover seal.

What's making me concerned is that the oil level is still going down noticably over the course of a week or so. Nothing like it was before I did the oil filter housing and cooler lines (it was going down a litre over 1 to 2 days!), but I'm topping up with 1/2+ litre weekly at present.

A few other possible oil leak sources I can think of are:

- turbo. It's oil-cooled only. Like the crank pulley, I can't see any fresh oil leak evidence and I renewed the feed and drain pipe seals some time back.
- engine block itself. I haven't done a compression test since the engine runs well, but it's a very old engine and the rings, etc. could be very worn.
- front oil seal. This one would require full engine/trans removal as with an auto trans that seal is not accessible until the engine and trans are separated.

THe burnt smell I noticed from the ATF may be a symptom of the last possibility, and being oil mixing with oil, ATF and oil probably don't show the same obvious indications that occur when coolant gets into oil.

I know for certain that the engine oil cooler does not leak, nor do the new cooler hoses, or the filter housing, or the oil pressure sender mounting.

I have been using a slightly thicker synth oil (Shell HX7) to partly address the oil loss since I re-did the cooler and filter housing.

Short of pulling engine to actually get at the front seal, what else can I do in order to identify where the oil loss is occuring from?

I might do a compression test on the engine next time I get the chance just for the sake of it and see what the results are. :cool: Is it possible that the HG or something related to that could be causing the oil leak? (noting that there is no evidence at all of oil contaminating the coolant - it's nice and green and there's no residue or 'scum' line around the inside of the coolant tank). Likewise the oil appears to be clear of any coolant.

Comp test should hopefully give some results to refer against other observations.

Craig.
 

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I don't know but my 84 900 T is currently leaking oil from the front seal (crankshaft) and I think perhaps the oil pump housing as well - a simple o ring to replace and fix, I only say this because I do get oil smell occasionally when coming off the highway and despite regularly washing the steering rack and front of engine to try get a better idea there always seems to be a smooth smear across the firewall side of engine... The other thing it could be is leaking out the rear seal, it generally accumulates under the flywheel and drops down the flywheel hole and runs all over the front underneath of the transmission, I have no idea if mine is doing this but it's pretty oily down there...

you sound like your using great volumes of oil though, if it's not dropping on the ground it sounds unlikely to be an external leak!?

Let me know if you find, because I am looking into mine as well, getting ready to do the water pump gaskets and then the front seal and oil pump o ring over the next few weeks...

bought rear seal but only realised you need to make a special tool for it the other day! disappointing!
 

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Discussion Starter #4
That is a lot of oil you are using. Do you get any smoke from the exhaust? And if so when?
The car gives a fair bit of white smoke (heaps of condensation) for the first couple of minutes on a cold day or whenever the humidity has been really high and the car has sat for a while not running (by a while I mean it's fully cooled down to ambient temp), but after that nothing. No black/blue smoke which would indicate oil burning in the turbo and exhaust at least none that I've seen when the car is running and I'm not in it.

The front crankshaft seal possibility sticks in my head but when I get to where my compression tester is I want to see what that reveals. Perhaps nothing, but it might give some more info to cross-reference with other observations.

When I had the intake piping apart a while back I did notice a signficant amount of oil residue in it but I don't really know what is considered 'normal' with that. I know the engine itself is old (after all the car is 30 years old) so it's highly likely the pistons and rings are quite worn if they've never been replaced.

Craig.
 

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bought rear seal but only realised you need to make a special tool for it the other day! disappointing!

Special tool ? to tap a seal in square an plumb ? WOW .. I really do need to spend some time in the bentley .
You will be fine Ed , get in flush , not an issue ..
 

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When I had the intake piping apart a while back I did notice a signficant amount of oil residue in it but I don't really know what is considered 'normal' with that.
I think, within reason, it's normal. I get quite a lot, and I don't use any oil at all between changes. I think most of this oil comes from the PCV breather pipe into the intake.

PS. You have got your PCV valve in the right way round and it's functioning correctly, ie, air can pass from the valve-cover to the throttle body.
 

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You need to get a fibre optic scope that will let you look at your valve faces without taking the car apart. It is possible that your oil consumption is due to excessinve wear of the valve guides. Evidence would be a build up of deposits on the valve faces, since an 8V does not use seals, and the valve stem clearance is the seal. Flywheel seal leaks should be noticeable as a puddle when sitting, under the motor on the skidpan. the drain for the flywheel /torque converter area is similar to the manual transmission drain point. For the most part, I find that ATF feels much thinner at any given temperature than dino motor oils, since my only synthetic experience is with turbine oils.
 

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Special tool ? to tap a seal in square an plumb ? WOW .. I really do need to spend some time in the bentley .
You will be fine Ed , get in flush , not an issue ..
Hey like I said no experienced but I read that in the Bentley so I'm guilty as charged!

Good to know Les, I'm keen to have a crack at it in the near future!

off topic but I'll ask while you're around, where are the coolant drain plugs on the engine block, and on an 8v do they cause problems, how do you fix?

Just curious as I've finally got all the leaks on my 900 sorted! but remembered I've never known where to look to inspect these plugs
 

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Hey like I said no experienced but I read that in the Bentley so I'm guilty as charged!

Good to know Les, I'm keen to have a crack at it in the near future!

off topic but I'll ask while you're around, where are the coolant drain plugs on the engine block, and on an 8v do they cause problems, how do you fix?

Just curious as I've finally got all the leaks on my 900 sorted! but remembered I've never known where to look to inspect these plugs
Block plugs are under the exhaust manifold, while the heater mount plug and block drain screw are near the power steering pump. There may be head plugs, but I haven't looked for them.
 

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Discussion Starter #10
You need to get a fibre optic scope that will let you look at your valve faces without taking the car apart. It is possible that your oil consumption is due to excessinve wear of the valve guides. Evidence would be a build up of deposits on the valve faces, since an 8V does not use seals, and the valve stem clearance is the seal. Flywheel seal leaks should be noticeable as a puddle when sitting, under the motor on the skidpan. the drain for the flywheel /torque converter area is similar to the manual transmission drain point. For the most part, I find that ATF feels much thinner at any given temperature than dino motor oils, since my only synthetic experience is with turbine oils.
Good suggestions - thanks. I don't know where I'd find that type of scope but maybe a good mechanic would have one. Worn valve guides is one thing I hadn't thought of but now you mention it I'll have to check that out.

I originally had a suspicion re the head gasket so I still need to find my compression tester and check what results it gives.

What I'm going to do tomorrow is a total coolant flush as I noticed the fans kicking in the other day when the accurate temp gauge was saying the temp at the back of the head (where the thermocouple bolts on) was only about 83 and the fan switch is an 89 C switch-on type. I've found some coolant boilover has been occuring out the coolant tank cap but just minor and I don't know if it's related though this might lend more weight to the HG suspicion..

I keep looking for obvious areas where fresh oil leaks from and haven't seen anything but there is some oil around the timing cover though it might just be residual.

When I did the reluctor to hall ignition conversion I did see a fair bit of oil leakage from the distributor but I wouldn't expect that to be a big leak.

The engine definitely has an oil issue as I put half a litre two days ago to top it up and even with that, when the car points downhill to any significant amount and I brake, the oil pressure goes down below 0.5 bar or lower (with the oil warning light coming on). It goes right up to about 4 bar under lots of throttle, and when rolling without much acceleration or braking the pressure sits at around 1.5 to 2.5 bar.

This might be a bit daft, but I wonder if the oil pick up tube has become blocked? Only way to check that would be seperating engine and trans so unless I do an auto to manual trans swap I don't really want to pull the engine. However it's also the only way to check the front crankshaft seal (while the car has it's auto trans).

Craig.
 

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- front oil seal. This one would require full engine/trans removal as with an auto trans that seal is not accessible until the engine and trans are separated.

Short of pulling engine to actually get at the front seal....
I don't really want to pull the engine. However it's also the only way to check the front crankshaft seal (while the car has it's auto trans).
I don't know where you get that idea.
The Seal/Oil Pump replacement procedure is the same, regardless of the Transmission type.
 

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If you are leaking oil past valves compression test then squirt a teaspoon of oil through plug holes and compression test again will tell you.

Rear engine seal: you can check and replace it. If you need I do have the factory tool and am willing to loan it; it has already visited Spain and New Zealand.

Turbo: check the compresso outlet for oil.
 

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I don't know where you get that idea.
The Seal/Oil Pump replacement procedure is the same, regardless of the Transmission type.
Jim, I believe he is referring to the flywheel seal. I can remove the clutch on a manual transmission, but have to remove the whole trans on an auto to reach that seal.
 

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Ahh! The Rear Seal, that's a horse of a different color.

A compression test will tell you a lot about compression, but very little about oil consumption. If you're burning that much oil. you should see an oily/burnt residue on the Plugs and in the exhaust.
 

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Discussion Starter #15
Ahh! The Rear Seal, that's a horse of a different color.

A compression test will tell you a lot about compression, but very little about oil consumption. If you're burning that much oil. you should see an oily/burnt residue on the Plugs and in the exhaust.
One thing I did notice yesterday late in the afternoon after getting the car back together from doing the water pump was that when the engine is running, out of the oil filler pipe I was seeing pulses of what I could only call steam similar to what I get out of the exhaust when the engine is cold and/or humidity has been high.

Possible indication of a HG issue perhaps? Car runs fine and apart from noise from the timing chain (it's quite rattly - dug out my timing chain kit for it yesterday), alternator and PS pump (these two both sound very worn), there isn't much else to go on. The coolant tank does show signs of blowing out the safety valve on the cap though I haven't identified any coolant bubbling.

I'll have a better look at the gasket interface between the top of the trans and the bottom of the engine when I have a chance as it could be that. Might check all the bolts in that area too.

Craig.
 

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It could also be an indication of worn/cracked rings. There will be some blowby of combustion gases, which is why there are crankcase ventilation systems. The AMOUNT of blowby is what you have to determine. Might not be a HG, and didn't catch how many miles are on the engine.
 

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Occasionally, some pre-APC turbos used to get carbon-fouled Rings, resulting in a lot of blowby and high oil consumption.
They often responded well to lightweight 100% synthetic Oil within 3000 miles. It seemed to free up the Rings in many cases.
 

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Discussion Starter #18
Occasionally, some pre-APC turbos used to get carbon-fouled Rings, resulting in a lot of blowby and high oil consumption.
They often responded well to lightweight 100% synthetic Oil within 3000 miles. It seemed to free up the Rings in many cases.
Just today I noticed a bit of oil in the coolant tank when I got home from work. Hmm. Have to monitor that very closely. One thing I have not considered is whether the head could benefit from being re-torqued. I haven't done it at all in the four years I've owned the car. If I end up needing to renew the HG, I do already have a new one (Elring brand

I just recently changed the oil I was using to a thicker type of full-synth oil (Shell HX7-K) in order to better-combat engine wear.

Craig.
 

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Discussion Starter #19
Ok I have been monitoring what has been going on and the oil loss is still fairly constant but it's not super-critical. Suggestions of worn rings and perhaps worn valve stems both seem possible given how much the oil drops and also how much oil is ending up in the air intake system via the crankcase breather (possibly turbo seals leaking to exhaust too but turbo works 100 percent as far as I can tell and it was a fully-reco'd one fitted when the last owner had the car).

Just this morning when I got home from work (nice 11.25 hr shift!) I topped up some of the fluids including the ATF and the engine oil, and I observed a lot of 'steam' coming out of the oil filler pipe. I've captured a couple of pics and hopefully they're useful to illustrate what I mean:



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I'm convinced the engine needs to come out so it can be pulled apart, along with give me an excuse to start fitting the G45706 manual trans I've saved from another car. Just need to get the car out of being a daily-driver (another few weeks before that can happen) so it needs to keep in good order until it can be 'rested'.

Craig.
 

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What was your temp when you did that? Outside? And, do you do distance to work, or is it a short commute? If cool enough (60F would work) "steam" would appear from the the heat/cool interface.
 
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