3SGTE / CT26 Oil Leak through Exhaust - ideas? (pics)

[RobST162]

Hey guys,

Interesting problem here, but someone more educated will probably be able to answer it right quick.

Been noticing a bit of oil coming out the old exhaust of late and it's just got way worse recently to the point where I can't really drive the car anymore.

The problem is most evident when coming to an stop, say at some traffic lights, and after about 15 seconds a big cloud starts coming out the back of the exhaust, persists for about 10 seconds and then resumes it's normal medium smokiness.

I got up under the car yesterday and took this photo of the underside of the compressor housing.



Now given that there's a lot of oil coming out the exhaust and it's worst at idle after i've been driving (even conservatively) I'm not sure what to make of it.

I could imagine if it was an oil->exhaust side seal, but if it's oil -> compressor seal, I'd expect it way worse on boost for instance.

Anyway, the basic problem is, leaky turbo, super evident after idle for about 10-20 seconds.

Turbo has to come off now *cry* anyway, as it's undriveable and just wondering what your thoughts might be.

thx

rob

[af300e]

The fact that it gets worse at idle could suggest valve stem seals perhaps in conjunction with shot turbo seals.

I know the Gen 3's have an oil catch can above the cam cover that drains back into the side of an oil gallery on the block. Does yours have this system? Perhaps the return is blocked and overflowing oil into the intake?

Turbo oil return line clear?

The bottom of your turbo is definitely too wet for comfort. The oil appears to be leaking from the compressor housing as the oil return tube looks dry. I'd say the turbo seals are sure to be at least part of the prob.

Perhaps get the turbo checked/rebuilt if required and see if the issue persists.

[RobST162]

thanks for the reply mate +rep

I did a very dry compression test about 4 days ago (hadn't started the car for like 3 days) and ran 185+ psi on all 4 cylinders (the engine has about 150k on it) Id be surprised if it was stem seals. Also, if it was a stem seal wouldn't I get a little bit of oil through the system on cold starts as oil would have seeped down the stems? There's nothing of this kind. (edit: problem really starts once the car gets warm).

I don't have the catch can (gen 2 sadly) but I have disconnected the oil return line from the cam covers (for this reason) into an atmospherically vented catch can (for testing this issue) and it hasn't made any improvement.

yes the oil lines themselves are dry and none of the pipes look bent or damaged so I don't think we've got a pressure build up in the oil cooling gallery area in the turbo either

[af300e]

Stem seals won't show up on a compression test as they are outside the chamber, but yes, they would leak-down and show up when you first start the car cold.

[RobST162]

yeah sorry I know the stem seals wouldn't show up in a comp test sorry I should have said that

it just gave me an overall idea of where the engine's at and the leak-down doesn't show anything

so i'm leaning more all turbo.. (or maybe that's my paranoid brain hoping)

[wilbo666]

The seal on the turbo compressor needs to seal in two states..

Vac, and boost.

Perhaps your turbo isn't doing such a good job of sealing in the vac state?

I'd pull the intake pipe off and have a look...!

Cheers
Wilbo

[RobST162]

The seal on the turbo compressor needs to seal in two states..

Vac, and boost.

Perhaps your turbo isn't doing such a good job of sealing in the vac state?

I'd pull the intake pipe off and have a look...!

Cheers
Wilbo

thanks wilbo, how to I evaluate the vac state status after I pull the pipe off?

I've done that recently doing some work on the i/c and there's some oil around the lower lip of the intake 'trumpet' of the turbo.. but that could have been attributed to the recirc blow by vapours, as I hadn't redirected that line at the time

[RobST162]

Interesting update on this issue guys.

Pulled the i/c off today to find no oily residue on the inside of the cooler, which I would have expected given (assuming the leak was drawing oil through into the intake at vacuum)

So I'm wondering just what is going on!

[af300e]

Very badly ratted out stem seals?

[RobST162]

this problem here is essentially my problem too

http://www.toymods.net/forums/showthread.php?t=35695

lol crazy gt-fours...

[YGT04A]

you learn to love it Rob one problem after another

I might have a spare set of stem seals soon as I will be getting a set with the rebuild kit and I have just recently done the head so it probably wont need redoing

[RobST162]

OK, just pulled the turbo etc etc off and as I went to under the oil -> turbo lines I discovered the nuts were relatively loose, and I thought 'huh', and then when the turbo came off I found that the silastic used to seal the two was damaged and the oil you see in the picture up there is oil that's leaked from the mating surface between the oil feeder lines and the turbo housing.

that means my smoke at idle is most likely stem seals I guess.. I can only conclude

the turbo seems fantastic, with NO back and forward play and very small amount of up/down as expected

[RobST162]

quick update for posterity

have been advised that it could also be the oil rings.. anyone with 3S experience tell me what's more likely? seals or rings?

naturally a worn oil ring wouldn't show up in a comp test and couldn't really be diagnosed very easily

[big_zop]

A worn oil ring may show up in a dry vs wet compression test - details are out there on the web but if you cant find any then i have a magazine at home with some details, including the different aspects that can be diagnosed with the full test.

While its obvious that replacing the rings is a fairly hefty job, how much are you able to do your self and would you be looking at rebuilding the entire motor with the kms/issues it has? That said, can you live with it long enough to save up to get it done and what are your 'intentions' with the car?

[RobST162]

hey zop your second paragraph is where it's at

I can do almost everything myself, just without a hoist on the 'four' it's hard work!

Also a question of time (and a few more tools I'd have to buy).

The engine has done approx 140k and did a fantastic job on dyno day (140.8atwkw on 11psi) and from the history (prev owner) has never been cooked etc

If the engine's kaput it's time for Gen 3

But that's a lot of money I don't have

I would love it if there was a way I could diagnose the head before setting off with trying to diagnose the bottom end.

Perhaps I'll bite the bullet and take the cams/buckets etc out and inspect the seals - if it's not them, then it's the bottom end.. at which point I should probably remove the engine..so I guess it makes sense doing it in that order

[sw20r]

my motor recently had this issue..

blowing white smoke out the turbo once it was warmed up like no tomorrow.
its at the shop now having the main and engine bearings done as there was some metal pieces found upon dumping the oil.

the issue was the motor was built loosely thus piston to bore clerance wasnt spot on

[big_zop]

From your thread i was under the impression that it had done 300k (well i know the chassis had - wasnt sure that the engine had been replaced previously).

While i dont know too much bout different gen 3S motors, would it be better in the long run to rebuild the engine stronger (if thats your goal - what i tried to ask first but didnt quite word it right)? from what i remember, the Gen 3 is a MUCH better base and has more differences than cams, ect that would be changed later, negating the swap.

And while an engine rebuild may be out of your league (both skill and cost wise), i guess changing an engine isnt so thats another important factor.

If you cant find anything on the dry/wet compression test ill post up the magazine article later tonight (probably after top gear )

[RobST162]

I have a gen 2 in there now with circa 120k on it.. my chassis, yes 300k

if I could get some diagnosis I'd be better informed about the move to a Gen 3 or work with this one I guess...

I'm going to have to read more on these wet/dry test

after top gear

[Keith ST204]

I am not familiar with these turbos but it sounds to me as though the oil might be leaking from the exhaust side of the turbo and then being burnt in the turbo/exhaust pipe by the hot exhaust gases. I don't see how the valve stem seals could leak that much oil even if they were not there.

[af300e]

I am not familiar with these turbos but it sounds to me as though the oil might be leaking from the exhaust side of the turbo and then being burnt in the turbo/exhaust pipe by the hot exhaust gases. I don't see how the valve stem seals could leak that much oil even if they were not there.

Doesn't do it under load, most prevalent at states of high vacuum eg cruising and idle. Points to stem seals. If you've ever seen an early magna idling at lights you'll know just how much oil can get past stem seals, Then, once the ports clear on take off, no more smoke.

Roughly how much oil does it use?