Break In Oil Consumption ????'s

patkeefe · 06-04-2007, 04:34 AM

To make a long story relatively short, I rebuilt my 3.0 last year , and added an old BAE turbo kit to it. Had lots of compression loss; turns out I stupidly used the wrong oil rings...I put in later 3.0 oil rings, and should have used the early. I pulled the engine back apart after realizing something wasn't right, and refitted it with the correct rings, and yes, this time I checked the side clearances.

So, now, I have the car drivable again, have maybe 100 miles on it, plus 1/2 hour initial run at 2500 RPM. It is using a bit of oil, as in burning. The tailpipe is black, some of it carbon from tweaking my mixture to get the AFR OK, but it's oily, and I do notice some additional blue smoke also. I am going to check the oil tank vent, which I feed back to the air filter to make sure I'm not puking oil back into the air inlet.

However, I am concerned that I'm leaking past the rings. How long does it take to seat the rings? I figure I'll give it a bit more run time before I look for the razor to drag across my wrist.

TIA

Pat

304065 · 06-04-2007, 07:11 AM

Pat,

What does a leakdown test say?

The same thing happened to the prior owner of my airplane: he didn't break in the engine properly so the rings didn't seat before the hatch was worn off they cylinders: the result was a permanent blowby condition that required a teardown and deglaze.

What procedure did you follow to deglaze the cylinders the first and second times?

Never despair: it's only time and money at stake.

patkeefe · 06-04-2007, 07:38 AM

John:
Didn't do a leakdown yet. I'm giving it a chance to heal itself first. Probably going to do that next weekend, as soon as I can borrow a leakdown tester again. The last year rebuild had the cylinders and pistons checked by a machine shop, they did the recon of the cylinders, which are Nikasil, and the original Mahle CIS pistons. This time around, I simply washed them out with Simple Green and a Scotch Brite. My ring gaps and side clearances were all within acceptable limits. However, I do think the cylinders are getting to the upper end of the bore limitations, although they were within specs. They were also still round, according to my dial bore gauge.

Time and money...

Thanks!
Pat

patkeefe · 06-05-2007, 04:28 AM

Update:
I looked at my plugs; they were good. Did a compression test on two cylinders; they were at 150 warm. I then contemplated the problem some more over ice cream.

Then, I put a valve in the feed line for the turbo, and turned the idle oil pressure down at the turbo to 5 PSI, and it was getting about 40 PSI at revs, which is about 1/2 the pressure my system has normally. It seems to have abated the smoking and oil use! It's a miracle! Evidently, the old Rajay doesn't like to see a high pressure large volume of oil; perhaps it was overwhelming the seals.

Pat