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Oil smoke after rebuild

Posted: Sun Sep 06, 2020 9:30 pm
by dodgerammit
My Jeep in sig.

So basically, I've had it back for a couple of weeks.

Broke in and initial run for about 50 miles then oil changed. The current oil has been in for about 400 miles now.

Oil is 10w30 VR1 conventional.

Have driven at varying speeds and not been babying it. Done many 30-60 pulls then let the engine slow the vehicle. Lots of mixed highway.

Still haven't gotten rid of the issue.

Upon start up, the exhaust is clean. Driving, the exhaust is clean. However, once warmed, if stopped at a light/stop sign, etc, I get the exhaust smoke. Blue in color. Not real bad, but I'd hate to be next to me with windows down.

I am running Wiseco forged 21cc pistons.

The ring spec is:
Top Ring Type: Moly-Faced Ductile Iron
Second Ring Type: Phosphate-Coated Cast Iron
Oil Ring Tension: Standard Tension

So, no chromed rings. These things should be seated/sealed by now I'd think

Reading other forums, it may be valve seal issues. I have positive seals installed.

Pulled spark plugs to look. The 2nd and 4th on passenger bank have a shine to the black on them. Nothing really bad, but have a bit of residue on them. The second one actually looks the worst with the electrode also black.

The others all look normal to me. If they have any black on them, it is a matte color with no residue.


Most plugs look like this:
Image

This is the 2nd plug passenger side (Cylinder #4):
Image

This is the 4th plug on passenger side (Cylinder #8):
Image

So, am I on the correct thought process of having the shop check out the valve stem seals on those two?

Re: Oil smoke after rebuild

Posted: Thu Sep 10, 2020 7:46 pm
by letank
bummer for the bad news... I'll take a stab at it...

With a warm engine, turn off engine, wait a few minutes and upon restart does it smoke a lot... a real foggy cloud ? That was my case until I replaced the valve seals, also called umbrella seals. The spark plugs do not outrageous, when I burnt 1 Q per 400 miles the plugs were really crusty. My motorcycle plugs are about 1 notch darker and does not burn any oil...

Re: Oil smoke after rebuild

Posted: Thu Sep 10, 2020 10:12 pm
by Stuka
Forged pistons will result in some blow by until they fully heat up, but sounds like this happens for you even after driving for some time.

Would be worth doing a compression check. Outside of valve stem seals, another cause is having the ring gaps lined up, but this normally wont result in smoke at idle, its a mid-high RPM issue.

Whats your PCV line look like? Are you pushing oil into the air intake? Admittedly I think all the plugs would be a bit darker if this was the case, but its an easy check.

Re: Oil smoke after rebuild

Posted: Fri Sep 11, 2020 6:30 am
by carnuck
We used to get the rings to seat with a mixture of Bon-Ami cleanser and water, then trickle it into the intake while running and do an oil change in less than 20 miles after. Never had a problem seating them that way. And luckily never heard of any bearing trouble after.

Re: Oil smoke after rebuild

Posted: Fri Sep 11, 2020 6:49 am
by dodgerammit
letank wrote:
Thu Sep 10, 2020 7:46 pm
bummer for the bad news... I'll take a stab at it...

With a warm engine, turn off engine, wait a few minutes and upon restart does it smoke a lot... a real foggy cloud ? That was my case until I replaced the valve seals, also called umbrella seals. The spark plugs do not outrageous, when I burnt 1 Q per 400 miles the plugs were really crusty. My motorcycle plugs are about 1 notch darker and does not burn any oil...
It does this. Valve seals are no longer umbrella. These are new positive seals. My initial guess is one or two seals are ether damaged from the spring install or coming out of hole they are installed in.

Re: Oil smoke after rebuild

Posted: Fri Sep 11, 2020 6:51 am
by dodgerammit
Stuka wrote:
Thu Sep 10, 2020 10:12 pm
Forged pistons will result in some blow by until they fully heat up, but sounds like this happens for you even after driving for some time.

Would be worth doing a compression check. Outside of valve stem seals, another cause is having the ring gaps lined up, but this normally wont result in smoke at idle, its a mid-high RPM issue.

Whats your PCV line look like? Are you pushing oil into the air intake? Admittedly I think all the plugs would be a bit darker if this was the case, but its an easy check.
There is no smoke on cold starts. Given the builder is experienced, I'd highly doubt ring gaps are lined up or rings are an issue. PCV does puff a bit, but I've already disconnected and drove it for a while with no change. The baffle is on the new intake.

Re: Oil smoke after rebuild

Posted: Fri Sep 11, 2020 6:52 am
by dodgerammit
carnuck wrote:
Fri Sep 11, 2020 6:30 am
We used to get the rings to seat with a mixture of Bon-Ami cleanser and water, then trickle it into the intake while running and do an oil change in less than 20 miles after. Never had a problem seating them that way. And luckily never heard of any bearing trouble after.
Yeah, not dumping sink cleaner into the motor..... I don't think it is the rings.

Re: Oil smoke after rebuild

Posted: Fri Sep 11, 2020 7:18 am
by tgreese
Are these new Wiseco pistons and an overbore, or new rings in an old bore? Supposedly chrome or moly will not seat in an old bore, even when honed prior.

Re: Oil smoke after rebuild

Posted: Fri Sep 11, 2020 12:09 pm
by dodgerammit
tgreese wrote:
Fri Sep 11, 2020 7:18 am
Are these new Wiseco pistons and an overbore, or new rings in an old bore? Supposedly chrome or moly will not seat in an old bore, even when honed prior.
.030 over