mmasse

I just finish the rebuil and started the engine ( '97 993 ) following the procedure on Wayne's book

The plan was to let it idle at 2000RPM for 20 min, but there is a LOT of white smoke coming of the exhaust, so I turned it off after 5 min

Ok, I let it run for 20 min, and I had the impression the amount of white smoke had gone down significantly. So I changed the oil and got ready to go for the first drive, as per Waynes book instructions. But, the engine started throwing a lot of white smoke again. I run it a couple of blocks and back home. Let it idle at 2000RPM for 5 more minutes and the white smoke would not stop.

I took the exhaust and headers out and it looks that Cyl 6 is the one throwing oil. So, I decided to perform a leak down test.
I tested the three cylinders on bank 2 (cyl 4-6). I got pretty consistent leak numbers. 18% on cyl 1; 15% on Cyl 5 and 19% on Cyl 6. On all of them you can hear a bit of air going to the crankcase. No noise on the intake of exhaust sides.*
I was surprised to see such high numbers on an engine with new rings, but I thought it might be that the rings are not seated yet.*
What confussed me is that Cyl 6 which is the one which seems to be throwing oil (wet exhaust oulet and manifold) did not show any difference with the other cylinders.

Can anyone suggest how to go from here, before the obvious "take everything apart again!!" ?

thanks in advance

mmasse

here you can see a video of the engine running. You will notice at there is no smoke coming initialy, but after 25-30 second is starts coming out.

http://youtu.be/j2IGW0uM-T0

Let me know what you think

Thanks
__________________

JackOlsen

It's not an answer to your question, but here's an improved link to the video:

www.youtube.com/watch?v=j2IGW0uM-T0

mmasse

Thanks Jack...I had posted a wring link :-)

this one works, as well as yours

http://youtu.be/j2IGW0uM-T0

Saml01

Doesn't have to be the rings, it could be the valve guides. Did you touch the heads?

Otherwise I don't know if I would even call that oil smoke, its too white. Looks almost like coolant but that's not possible.

Condensation in the exhaust maybe? Have you smelled it?

Did you deck the heads and block, did you torque properly? It could be oil passing between the head and deck if its warped. Metal gets hot and expands which causes oil to weep passed. Motor cools and contracts and your compression test is normal.

mmasse

yes. it is definetly oil smoke.

Valve guides were replaced.

theiceman

Would appear based on ur troubleshooting you broke a ring on startup. That leakdown is huge for a rebuilt engine so sometbing is wrong

mmasse

But, then i woul have broken the ring on all three cylinders, since all gave consisten leak numbers. It tha really too high for an angine with not seated rings? I have no clue about what right numbers should be in this condition.

Saml01

You really should ask what the numbers are on a broken in engine and a fresh rebuild.

According to Pete Zimmermans book, 10% is the factory maximum. However, the fact that you have consistency across cylinders makes me scratch my head. Either you are performing the test wrong, your equipment has a high margin of error, or its something else.

Did you use new head studs?

Whats the procedure for torquing the heads on these motors? Did you follow them to the letter? I know some engines are fairly complicated. Torque all to 25 ftlbs, then torque to 40ftlbs, then back off a quarter turn while working from the inside out. Crazy stuff like that.

Ed Hughes

I'm not sure your rings are fully seated yet. How much oil did you put in it?

mmasse

I put 10 qrts.