smokes at idle (oil i think)

[toolguy874.1]

i am working on 85 gn with hybrid 87 swap. swap includes stock exhaust manifold for 85. 85 turbo location but uses intake and turbo from 87 and front mount intercooler. problem i have is car smokes at idle. seems to bee find driving car even under full boost 17 pounds for now. engine is from jasper engines with 3500 miles on it. i have had engine out of car. engine got heads checked out guides are still tight got new valve seals and valve grind. cometic mls head gaskets . 212/206 comp hydro roller all comp beehive springs comp pushrods. i removed crank and measured rods and crank and checked all bearings all in good shape and in spec. i did NOT remove pistons from cylinders. cross hatch in cylinders looked new with no signs of wear or scratches. car is running and engine looks good but smokes at idle soon as i started adding boost. i have compression tested it 145-150 #s in all cylinders. then i did a leak down test resulting in 9-12%in all cylinders. i have remove pvc vale and still smokes. pvc is now re installed. i do get oil dripping out of driver side breather but just couple drips. all plugs are off colored white with no residue at all. if any one has any ideas or a good place to take it to please help. i am located near cleveland ohio will post pictures to better describe what i am working on. thanks brandon

 

[earlbrown]

Best case, you need a hone job and new rings.

Less than best case, it's time for an overbore, a hone job and new rings.

 

[toolguy874.1]

It has been bored .030 over and bore is round and within spec the turbo is a band new ball bearing precision 5557 and i spent it back and had it checked again sent back with good bill of health. Ring should be seated after 3500 miles. Thank you for response. Can oil rings be bad and compression rings still be good? Didn't smoke til after I started putting boost to it. Not when first started after swap.

 

[earlbrown]

You've losing 9~12% of your cylinder pressure with only 100PSI in the chamber.... Imagine how many CFM's you're losing when cylinder pressure is in the thousands.

Without removing your pistons you have no way of knowing if you have limp, broken or pinched rings. A few passes with a cylinder plateau brush would have been nice while you had the heads off.

 

[Buick Mark]

Do the heads have valve seals on the exhaust valves? Alot of shops that rebuild Buick V6 and V8 heads DO NOT install seals on the exhaust valves, because Buick DID NOT USE SEALS ON THE EXHAUST VALVES. Buicks reasoning for not using seals on the exhaust valves was theres no vacuum on the exhaust side like there is on the intake valve. Thats fine, BUT, you can still have oil running down the guide and INTO THE EXHAUST! Yes, the oil never makes it into the intake tract, thats why the plugs look clean, but smokes out the exhaust

 

[toolguy874.1]

 

[toolguy874.1]

This is how it smokes at idle. I put new viton positive seal valve seals on both intake and exhaust valves. I am not arguing but if ring was broken pinched or stuck would you get scratches in cylinder walls. I don't know just my thoughts. Thanks for help.

 

[ek02]

Were the exhaust guides cut down far enough so the retainers do not crush the seals? The symptoms sound just like oil going down the exhaust guides like Buick Mark said.

 

[toolguy874.1]

I was doing research on internet. It said 10% on race engines and 20% on street engine for leak down. Does that seem reasonable?

 

[toolguy874.1]

Heads look to have had new cast iron guides installed by jasper engine. Before I had valves ground I set head up and machine guides down to clear new retainers from comp and new higher lift cam. There is .060 between top of seal and retainer. That has comps recommendations.

 

[ek02]

.060 retainer to seal clearance at full lift is plenty. Intake gaskets seem to be OK? If Jasper set the ring end gaps too tight, it may have damaged the rings under boost?

 

[toolguy874.1]

Replaced intake gasket with felpro gaskets not the valley pan kind. First one was valley pan style. I weld half of a pie under PVC valve so it won't draw oil from turbo oil return pipe. No change.

 

[dr_frankenstein]

do you see any oil in the intake track or up pipe from the intercooler?

i see you have converted it to the 86/87 style of intake and computer... normally on the HA engine the turbo is carbon sealed since it experiances vacuum, i dont think precision makes any carbon sealed units...... not to say it is here.... but it could be a possibility to look at.

 

[toolguy874.1]

Replaced intake gasket with felpro gaskets not the valley pan kind. First one was valley pan style. I weld half of a pie under PVC valve so it won't draw oil from turbo oil return pipe. No change.

 

[howdies86]

Where is ur oil return line from the turbo going to? U can't have any kinks or restrictions or oil will build up in turbo center section and run past the turbo exhaust seal. Personal experience!!

 

[toolguy874.1]

Well thanks guys for the help. I have found the problem. I installed beehive springs and viton seal made sure I had clearance between retainer and top of seal what I failed to check was clearance between seal and small inside diameter of beehive spring. All the valve.seals are stuck up by spring retainer. So that why it smokes at idle. Now to.try to fix them without pulling heads.

 

[earlbrown]

Go ahead and buy another set of seals for your heads. That way if you have the wrong ones on your car, you won't have to leave it apart while you're sourcing parts.

 

[Buick Mark]

Cool, you found the problem And Thank you for letting us know

 

[toolguy874.1]

Got all seals changed and driver side put back together. The 2 rear springs by a/c weren't fun but made a compressor. And got it done. Seal on the right are the new ones.

 

[ek02]

I assume your exhaust valves have smooth stems, with no step like a stock valve?