Zero10

Okie dokie, I have no idea how many of you were following my oil burning saga, but it apppears that there is a significant chance the problem was owner caused

Here are the latest pics from my disassembly




Notice how there is a clean spot in roughly the 7'oclock position on pistons #3 and #2? That's how it is all around #4.... I presume the clean spot is from the gap in the top compression ring, and that a tiny bit of oil is allowed through at that point, cleaning that small area on the piston. I can't imagine a significant amount of oil gets through in that fashion. However, that same cleanness is present all the way around the piston on cylinder #4, and it extends much farther inwards than it does on the others.
So, either I forgot the oil ring, or I have an upside-down ring. That sucks.
What I've observed to be important at this point,
The entire cylinder appeared to be nicely cleaned, LOTS of buildup on the #4 exhaust valve, and inside of the exhaust port, which I think tells me that there is a lot of carbon and such in the exhaust, and that the EGT's are very low on that cylinder. My first impression was head gasket failure, but I don't go through any coolant at all, and I can't find any spots where the HG could have failed. Go widefire! I ran 23psi of boost with unknown chips, and a few other problems to boot, and the head gasket held. That's impressive.

What do you guys think? Am I correct in judging it as a ring problem?

The turbo does blow a little bit of oil, and it would appear that it will be in need of replacement soon, but it's nothing extreme. The intercooler pipes have oil residue throughout, however there is very little pooling of oil. The #4 intake port shows signs of a small amount of oil passing through it. The others don't really.

I haven't yet ruled out a valve seal, but I just can't imagine it pumping THAT much oil into the cylinder, and wouldn't I see some kind of distribution pattern on the piston crown if the oil was coming in through a valve?

On the upside, all of the cylinder walls look perfect. Hardly a mark on them. The marks on #4 are from the assembly, and you can't feel them with a fingernail at all. I guess that's good news....

Mighty Shilling

I say rebuild the turbo... you can get a rebuild kit for cheap. it does sound to me like it could be a ring problem, but I'm no expert.

Also, while the head is off, if you can afford it, get it rebuilt and resealed. then you'll have peace of mind that it's not the valve seals.

I was going through a MASSIVE oil burning spree about 1000 miles before I spun a bearing. Good luck!

Zero10

In my case, the head was gone-over about 6000 miles ago. It was milled top and bottom, valve seats were ground at 3 angles, valve guides and seals were replaced.
I had a suspicion that perhaps a valve seal had come loose from the head, but it does not appear to be so with the pattern on the piston crown.

The DareDevil

I love pictures.

TRWright

You know it is going to be a depressing post when the first picture with the head off shows a used but VERY recent head gasket. . .

Best of luck, pal!

Zero10

Haha, I guess you think I'm Féd too, eh?

It's sad, most of the gaskets came off clean, and I actually thought to myself 'Hmm, I could re-use this...'
I have a new headgasket to replace that one, although it won't be a widefire, but I don't plan to ever go over 15psi of boost, most likely keeping it at stock levels (~11psi), so I'm not worried there.

I have this bad feeling that it's upside down rings...
If I had them upside down, do I need to replace them, even though it's only been 6000 miles?
And, if I do, won't I have to stick to conventional oils until they break in, that is IF they break in? Since the walls have now started to glaze, I don't think new rings will seat against them... gah, now I'm starting to worry!

Porschephile, I doubt you burnt as much oil as me I went through over 6L in less than 30 minutes on the track, and have gone through (seriously) about 1L/100km, more on hot days.

I think I'll take some carb cleaner to the pistons and inside of the head, pull the oil pan, flip the rings over, and hope for the best.

brad-cam

Zero10, I wouldn't rule out a valve seal that's come loose just based on the pics. I had a couple of seals that were floating on the valve and had the same oil contamination as you. Take a good look inside the valve springs and make sure those seals are tightly installed on the valve guides before you you tear into the bottom end to replace rings...

Zero10

brad-cam, you mean somebody else has actually had that problem?!
Most fascinating.
Everybody I've talked to has told me I'm insane for even considering that as a possibility. But honestly, if the valve seal stuck on the valve, and came loose from the head itself, it would act like a tiny oil pump, pumping oil inside of the valve guide right into the intake port. It seemed pretty possible to me.
I'll be pulling the valve springs off the next time I'm working on it.
I'm going to have to modify my valve spring compressor, but it's no biggie. Unless I just put the head in my hydraulic press... Hmm

brad-cam

Yup, I had 2 or 3 guides floating. The tell-tale sign is if the valves are coated with oil on the backside of the valve - especially the exhaust valves as it will burn and coke on the valve.

I've changed valve springs on two heads so far and they are a bear with normal valve compressor tools because of the tight clearance in there, and the fact that there are two springs - inner and outer. I ended up making a tool with a 2"x7"x 1/4" steel plate that I bolt to the head. Too hard to explain...PM if you want more detail...

Rip It

why are the only water jackets that are open on the block at cylinder # 4, is that correct or is it the picture ? Do all the rings have a top and bottom, I am thinking only the compression ring does ?

hosrom_951

Zero,
Could you get more pics? i am sure Chris White would identify the problem, he is an expert after all

Try e-mailing him with some pics, look for a professional opinion.

Zero10

The water jacket spaces are perforated on all but the outsides of #1 and #4. I am not sure why this is, but that's how the head gasket I took off was when I rebuilt the engine, so I'm not worried about it.

I haven't examined the valve stems yet, I was in a terrible mood by the time I finally got it apart, as I had some obligations for the day, and the disassembly took so long I was about 2 hours behind on everything. I will be looking at it all tonight though.

I am hoping I can use some kind of U shaped piece of steel and a hydraulic press to compress the valve springs, then just remove the retainer clips (however they come off, I'm not sure), and let it all come off. It's so difficult to see through the springs what the condition of the valve seals is, so I'll just remove the springs.

If I'm really lucky, then it will be valve seals, but I doubt it. Luck has never been my strong suit

cruise98

I have not been following your saga so I am not sure what all you have done before tearing into it. What were the compression and leak down numbers? I would have the head looked at before tearing the bottom end apart again if the numbers were good.

If the turbo was bad, all of your plugs would be oil fouled and since #4 is the only one that appears fouled the turbo is not currently a suspect to me.

Looks like rings or valve seals to me.

The rings are installed with the writing towards the top. How did you do it? If you change them, use new ones. Why take a short cut considering the difficulty of getting these cars apart.

Zero10

No writing on the rings, they are custom 101mm pistons, so re-ringing is not a cheap option, not to mention, the cylinder walls have now set up, and new rings will not seat properly against them.
The rings just had dots on them, which IIRC I was told to put facing down. Which I thought I followed on all 4 cylinders, apparently I only followed it on 3.

Compression was superb, 150psi+, and considering my altitude, that is amazing. Leakdown was all 2% or less, great as well.

However, an upside-down ring would give me good compression, and good leakdown, yet terrible oil burning.

I will be checking the valve seals, but I do suspect that the problem is rings

500

Hey Zero,

Don't mean to swing things too far off track, but it sounds like you had the cylinder walls prepped with the Sunnen machine during your rebuild? I'm curious as this is one of those things where it is really hard to get a good answer on. Half the time the advice seems to be to just leave the walls as they are and run the rings through a typical run-in using dino oil... but I'm still not 100% sure on this.

I will be facing this question when my engine goes back together. I'm curious as to what you've heard and learned.

It is an interesting theory you have regarding the rings, but I can't understand why the excess oil would leave a cleaner area around the periphery of the piston.