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Discussion Starter · #1 · (Edited)
Just wondering if some of you could let me know how much oil you go through at a lapping event?

I've got a fully built 3.4 with a T67 and I'm going through about 1 quart a day. Just want to compare to some others out there.

Thanks,
Bjorn
 

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Discussion Starter · #4 ·
I can't figure out why I'm using up so much oil. I did a compression test and it came out between 175-185. Leakdown was approxiamtely 11%.
 

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I always had insignificant oil consumption at track days...barely noticeable level change. Since I'm now seeing a puff of oily smoke right after cold startup, if my valve stem seals are getting marginal my consumption might become noticeable...will check at next track day later this season.
 

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Discussion Starter · #8 ·
Have you replaced your valve-stem seals?
No I haven't. This is a completely new motor with only 3K miles so I wouldn't expect any issues, but you never know I guess. I purchased a borescope which I'll have next week so I can check out what's happening in the combustion chamber, valves etc.

I'm beginning to suspect my turbo as it's the oldest link in the chain. My breather runs through a catch can which is picking up a bit of oil as seen through the site glass. I checked the intake pipe and only a small amount of oil mist. It's a bit of a mystery, but I'm sure something will show itself the more I dig into it.
 

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Discussion Starter · #9 ·
I thought you wanted your leakdown to be less than 6%? I could be wrong.

Compression seems fine. Valve stems need replacement?
6% leak down would be very good numbers, but not common with production motors from what i have read online. Anything up to 20% is considered ok and up to 10% is very good. I've spoken to a couple of reputable Supra shops and they stated 10-12% is pretty common for a completely rebuilt motor.
 

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Blow by would show up on the Leak down numbers. I redid my engine 2 years ago and have about 2000kms on it now I do see oil in the catch can as well and only have a 5% leak down and 170 comp.

The turbo going out would not have any effect on the oil in the catch can.
 

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I havent read this through. Just a thought but what you are describing sounds like faulty or improperly installed valve stem seals..
The comp #'s are good. Leak down is also good. Turbo smoking would be evident at start up. Oil being consumed by the engine with no leaks externally. Almost leaves the valve stem seals as the likely culprit.
Eric
 

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Discussion Starter · #15 · (Edited)
Thanks guys for your input. I purchased a borescope and checked out cylinder 1 which had the dark spark plug. Turns out its been burning a fair bit of oil as the intake valves are covered in burnt oil and the top of the piston is also covered in burnt oil and it's even wet with unburnt oil. The valve stems are clean as well as the top of the valves so I've ruled out valve stem seals. What I did find was a 3/4" scored area all the way down the cylinder which I'm now 99% certain is causing the oil consumption. They're not hair line score marks. It's pretty much a consistent 3/4" score all the way down. What I find strange is that compression and the leak down were good. I think what's happening is that the cylinder is not blowing by under normal driving as I don't burn any oil on the street, but when I get into a high stress situation such as the track is when I notice the puffs of blue smoke out the back.

All the other cylinders looked fine. Cylinder walls look good and no evidence of oil being burnt at all.

Motor is coming out in a couple of weeks. I'm suspecting that cylinder may have run a little hot, but I'll see once I pull the head off.
 

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Discussion Starter · #17 ·
It sucks alright. I put a lot of effort into making sure everything was done right so I'm very surprised to see this happen. I'll post pics as soon as I've got it apart.
 

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Discussion Starter · #18 · (Edited)
For those interested. Here are a couple of pics of the internal parts on cylinder #1. All other cylinders are fine. Motor is going back together this week with a bunch of new parts. All cylinders were oval which I still don't understand why...





See valve relief. detonation
 

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Discussion Starter · #20 ·
woa, what would cause something like this?

glad to see you found the source of the problem and thank you for sharing with the community :).
I'm suspecting lack of race fuel at the race track caused the cylinder to run too hot hence the detonation on the valve relief. My tune is suppose to be fine for 94 octane, but I think a bit of race fuel may have avoided this problem. Secondly, I think there may have been a bit of dirt in the oil as there was a bit of premature wear on the bearings. We've polished the wear out and replaced all the bearings. It's possible that since the block was new there may have been a bit of machining material left in the oil ports and as soon as I fired up the car the bearings got the worst of it.

We're still investigating the injectors and a couple of other details so something new might still turn up...
 
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