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Sooooo... Smoking after new rebuild...

N

nate halter

New member
Hey guys I have a 97 cavalier with the l67 swapped in and the engine is rebuild as well with better internals. So I have about 1000 miles on it and noticed that I was letting out a puff of smoke after running it good a couple times. When I rev it up it smokes just a little. I pulled all the plugs out and #5 was totally fouled/black and smoke was coming out of the spark plug hole. I switched injectors and re-did the lower intake gasket just in case it was pulling oil through some how or had an injector leaking. After all that its still smoking. I did a compression test hot and cold and its the same as the other front cylinders. Im really at a loss on this one. There is no drivability issues at all. Any advise would be awesome!
 


when you say rebuilt, who rebuilt it? and was there any machine work done? if not its gonna let go on ya. aka blow up. aka 200 mile engine.
 
Stock bottom end would have handled 500hp no problem.


Either the oil is going past the piston rings or the valve seal is letting all the oil in. Seems a small chance that the PCV system would be causing just one cylinder consume oil.
 
The engine has the powder Forged fods and Keith black pistons. Valve job with new stem seals. I already pulled the valve cover and looked at the seals checked valve side play as well. And I built the engine.
 


I understand where you're coming from asking the questions that you are, thinking that I'm stupid or inexperienced. But the reality of it is is that I had machine work done on the Block and heads about $1,500 worth, and have been an auto technician for over ten years with GM so feel free to spare me from the unproductive comments. Moving on. I'm at a loss on this because I don't see anything that is bad and wanted to get ideas. The back of the intake valve has a light coat of oil on it when I look through fuel injector hole after I shut the car off I thought it could be the valve seal myself also but it doesn't look bad they're brand new.
 
If it was really burning alot of oil the smoke would be more blue so if it's mostly black it makes me think it's all fuel.

Or there is a chance the rings are no longer offset correctly and allowing blow by.
 
sorry if i insulted you in any way, but these questions need to be asked, ( we dont know you personally yet) guys go and rebuild these engines and they fail asap on them, then they learn about the machine shop work needed.

when done right, as you already know your dumping up to 2500 into the rebuild, and stock internals will hold 500 hp from a turbo. why we most here will opt for a used engine.

being we now know your are a mechanic now, id think maybe a leak down test might shed some light on things. if a valve seal didnt not push off, we've seen a few guys lately that had a seal pop off for no good reason.

could also be a stuck open injector fouling out the plug.

or maybe even a bad icm or coil. you got the little crank harness ground bolted on the coil bracket right?

have you tried a crank relearn yet? sounds like you must have a tuner on hand or at least a tech 2. if you changed pcm's or the bin file for the pcm even if its not showing a code for the crank relearn it can still help.
 


Thanks for all the suggestions. Using a leak down tester is only done with there is a compression problem to tell you weather its rings or valves. I ordered another set of valve stem seals just to try it. I switched the injector with another cylinder just to try that and the problem still remains. Ive ran this car hard after break in. Had it dynoed and had it down the track a few times with no smoking problems. I will try to post a video of it so you can get a better idea of the issue.
 
Update. Replaced valve stem seals and it still smokes. Removed head and had machine shop look at it and the lower intake for cracks. None found. So Im assuming now that the rings did not seat in right upon break-in. I will be removing the piston and rod for inspection, replace rings and rehone cylinder. Very strange in my opinion. Has anyone else ever experienced improper ring break-in?
 
I have seen bad ring seal/seating when an engine was ran very rich after a rebuild.

This was on a carb'ed engine.

Good luck and hope you find your issue.
 
I have seen where a 65' Chevy L6 (230c.i.) smoked oil badly, turned out someone installed the second piston ring on all six cylinders upside down.
 


When you break it in you need to break it in hard. Thats the best way to seat the rings. Nothing else needs break in.
 
Hey Localish OP. How is the Tune, I see a 3.4 and a Downpipe, but no mention of a Tune. Valve stem Seals are not all created equal. the ZZP are the same as the Fel-pro. The Viton ones from Intense-Racing are the preferred.

Let me know if you want some help looking at this thing.
 
check the LIM flanges, if its got 3m roloc marks, toss it in the trash.
ive had one that was a heavy hand that would have needed rtv around the intake port Oring to seal it.

clean, new single edge razor blades, changed often, the only good way to prep, no need to clean off the "stains" as those are in the metals pores and not above/measurable via a roughness gauge.

3m rolocs are like adding millions of leak paths in 1 second....

if it was ring seal the leakdown would have been notably different from the rest
 
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