Smoky motor after top end
 

I have a 3.6L here are the details of the build.

Stock bottom end. (one race year fresh)

993 cylinders

964 J&E High comp pistons - Piston rings are not stock Porsche. The ring grooves were not stock sizes, so based on J&E's recomendations I bought Hastings rings.

early 964 heads rebuilt and machined flat to match the cylinders.


The problem is that the engine will not seal up. It runs great, but a lot of oil in the exhaust. Plenty of time on the motor to burn out the cylinder oil.

Performed a leakdown and I have 2% or less across the board. Even left the pressure on a cylinder overnight to make sure I was not getting a wet leakdown number. Never moved from the 2%.

So much oil that you can get your hand wet with oil by wiping the end of the tailpipe.

Any advice or experience would be appreciated.

Thanks

Ed

Just thinking out loud here.... If you are running a porsche intake plenum, is your oil tank too full and overflowing through the engine? I would think with 2% leak down, that the oil is somehow coming in through the valves. Obviously if you are running ITB's you may not be putting an oil overflow into the intake system. Maybe the valve guides were not machined properly? Also from experience if you get liquid oil into the headers and muffler, it takes a LONG time to burn off. Even on an empty muffler can. I would also wager a guess that for enough oil to pass the rings and go out the exhaust in liquid form, the engine would not run well, if it would at all. How much time have you put on it? Where are you in Ohio, and who did your work (from the way you wrote the post it sounds like you build it yourself, but who did the machining?) What do your spark plugs look like? Any one pair of plugs look more suspect than the others?

Are you running Teflon valve seals by any chance, if so I have seen these work off the guide because of the large amount of drag on the valve stems then they act as pumps rather than seals.

I have a front engine dry sump tank. I have drainded the oil from the crankcase after running to be sure that I do not have a large amount of oil in the engine case. I am satisfied that the oil is returning and I can see in the dry sump tank that the level is normal for my car.

I am running the 964 plastic intake plenum. I do not have any vacumme lines set up for crankcase evacuation. I am using a beather instead.

I am in Cleveland. Gellner did the machining work on the motor.

All of the spark plugs look simmilar.

My exhaust is independant, so I can see left vs right. My left bank smokes much more than the right, but the right still smokes.

It seems like the more I run it, the more oil in the exaust pipe I get.

I do not know what valve seals I have. More than one must have come off to have the smoke on both sides.

To give you an idea of how much smoke, I took it to my works parking lot to run it a bit and got kicked out.

I ended up taking it to the lot where I store my trailer so no one would be around for miles to notice.

Thanks

Ed

That sounds like a lot of smoke! Just shooting from the hip, If it was me I would pop the lower valve covers off, and take a look to see if any of the seals seem to be obviously askew. I would also concider taking the left header off to have a look at the valves to look for any evidence of problems. Maybe use your fingers to check an open exhaust valve for an excessively loose guide. I'm not a race engine building expert, but those are probably the first two things I would check due to their relative ease, and limited expense. I really feel like the problem has to be in the heads since the leak down is so good, but it could always be from somewhere else. I would call Gellner, tell them what is happening, and ask if they have any advice.
I am from the Columbus ohio area, which is why I asked where you were located. It seems like everyone with interesting cars are from the cleveland or cincinnati area. Not much happening in the central area.

Sounds like the Hastings rings you used are probably chrome and/or too high of tension. Probably a problem with the oil control rings.

Just curious.

Were the cylinders de-glazed, honed, or prepared in any way? If so what procedure was used?