Brembomaster

hello,
I have started the new assembled and run it in idling. But it issue a white smoke when the engine hot. but never see the situation when engine is cold.
Somebody told me that a normal with the new assemble engine because there a some oil in the exhaust system. but i am confusing is that a oil burning in the engine?
how do i know what the issue is that?
That why there are no white smoke when cold?
i am confusing is it the valve stem seal problem. because i remove the exhaust header, i see the exhaust port get wet but i dun what that is it, it does not like oil.

NVturbo

That's not normal. The sleeves on the motor may have a hairline cracks.

Brembomaster

Thank you,
That's why no smoke when engine first start and cold?there are new bore cylinder and rings.
what can i check the reason from the piston or cylinder sleeve or valve stem seal?

NVturbo

You should have checked the cylinder walls prior to the rebuild. On mine, I added water into the block to make sure no leaks. My block was a reman, bored to 75.5mm. I did this for reassurance.

Brembomaster

Thanks,
otherwise, i want to ask if the crankcase pressure is high, that will cause the oil leakage from the oil pan gasket? because i have the same situation in same time.
but i really dun understand why just happen in hot engine.
I think i need to check any oil on the piston head or compression leak down firstly.

NVturbo

if you're still using the "black box" on the back of the block, make sure the PCV valve isn't clogged. I didn't use one in mine. I added a 10AN fitting and ran it into a catch can.

Brembomaster

the black box is open by the hose, there are no pcv

Brembomaster

I have a new idea i think that is a oil leakage from the valve guide, because of if there are leakage from the piston ring, that must be white smoke when cold, but it just smoke when hot, i think there are burning oil when exhaust manifold is hot.
Am i right,,,,HAHA

night

I'm assuming this is from exhaust..
White = water
​​​Blue = oil (takes practice to tell)
Black = fuel

You haven't said how much run time it has total​​​, but some water/moisture burn off from the exhaust is normal. Valve seals are more likely to show oil on first start up and wot.

Jumping to cracked sleeve is craz​​y.

Brembomaster

It's about 15mins run in ilding , I checked the piston also get wet and did the compression test average 165psi , i think it is too low to the rebuilt engine. I think the some of pistons are blow up.

night

165 is not a problem, assuming you don't have high compression pistons. Even then the rings aren't seated yet.
​​​​You need to find someone that understands this stuff to help you in person.

Brembomaster

that are YCP high compression piston. what the mean of " rings are not seated'?

TomCat39

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

He means you haven't broken in the engine to seat the rings. First run rebuilds will burn oil and smoke until the rings are seated. To do this, the engine needs to be broken in.

Brembomaster

In your experience, how much compression will built up after the rings seated?

Brembomaster

Hello ,,anybody?

K7-1Ktrevor

I don't know if any one can give you concrete answers as often compression testers read differently. They are correct though. You need to drive the car. Start with light throttle pulls and work your way up to half throttle then 3/4 throttle. The rings need the cylinder pressure to press against the hone on the sleeves so they can wear in correctly. Do an oil change after about the first 40 min of run time. I wouldn't sweat it too much, my motor smokes pretty bad on initial start up and after some pulls it cleared out.