AMC 360 break in question - exhaust smoke!!!

[grampsbutler]

I have a 1990 Grand Wagoneer with the AMC 360 and 727 transmission. About a year ago I pulled the engine, transmission and transfer case and rebuild the whole lot. I did the transmission myself and had the engine done be a reputable local machine shop. The engine got a rebore, hone, magnaflux, surfacing and inspection, valve job, new bearings, new cam shaft and new pistons and rings. I installed an aftermarket Edelbrock intake, and a Holley 4BBL carb. Exhaust original, except for plugged air injection ports.

I just got the install finished, and fired it up this weekend. I primed the oil pump, checked for oil pressure. I used Lucas zinc aditive in 10-30W conventional oil. Fired it up and ran it for 10 minutes at ~2000 rpms. Shut it off, then checked the timing (had to run it for a few minutes at high idle to do this). I then ran it at ~2500 for an additional 5-10 minutes, as recommended by the engine rebuilder, and others on this forum.

I now have blue smoke at higher rpms. It runs clean at lower rpms. When I first fired it up, there was no smoke (apart from exhaust burn off). How worried should I be? I have not yet done a compression test, because the rebuilder did that. Could this be the rings seating? The engine sounds great.
Any suggestions would be greatly appreciated.

Engine was not smoking when I pulled it, but it was tired with about 150k on it.

[wiley-moeracing]

Finish the break in before you worry, may be the rings need to seat still, hopefully you did not use synthetic oil?

[grampsbutler]

Thanks for the reassurance. I called the engine rebuilder, and he suggested that I disconnect and plug the PCV. I did this and smoke is greatly reduced, so I am hoping that this + ring seating is the issue.

Any idea why the pcv might be sucking oil? Any suggestions on how to fix?

[grampsbutler]

I forgot to mention. I used regular 10-30 oil with Lucas zinc additive.

[SOLSAKS]

sounds good, I bet you are going to be o.k.

now we are ready to see the GW.

if you see Rick and AJ Simon in the red Z28 or the Power Wagon around S.D.
( or ron burgandy ).......tell them hello.

good luck with the engine. most of us have been where you are at,....

I am now finding myself there once again with my project.

dave in NC

[7350life]

PCV = Positive Crankcase Ventilation.

If the rings aren't seated yet, there will be excessive combustion blow-by past the rings into the crankcase. That excessive positive crankcase pressure is vented resulting in pushing combustion gases and oil vapors out the PCV port.

[MysticRob]

PCV = Positive Crankcase Ventilation.

If the rings aren't seated yet, there will be excessive combustion blow-by past the rings into the crankcase. That excessive positive crankcase pressure is vented resulting in pushing combustion gases and oil vapors out the PCV port.

Excellent post.
OP, just wait a bit for final break-in and you should be okay if all things were done correctly by the shop.

[babywag]

Stock intake manifold?

Some folks install an aftermarket without the heatshield/oil baffle installed and some have had pcv issues with sucking up oil from valley.

[grampsbutler]

Thank you all for the tips. I will post back once it is broken in to let you know how it resolved.

It does have an aftermarket intake manifold with no oil baffle, which could be the problem. I read up on this before reassembly, and made sure to use a one piece intake gasket to separate the intake from the valley. That is what it had on before, and I never had a problem, but with the rebuild and non-seated rings it could be pushing more air and oil through the pcv.

Thanks everyone! Your collective knowledge is amazing!

[Ristow]

lets see the plugs. you should be rolling smoke on a fresh motor.

[grampsbutler]

Thanks everyone for all the advice. It turns out most of you were right....the smoke cleared up after 3-400 miles. I must be an overanxious FSJ dad!

My guess is that the rings took some time to seat. I disconnected the PCV valve am considering using an oil filler cap/breather with an integrated PCV. Does anyone have any experience with this?

[rocklaurence]

Stock intake manifold?

Some folks install an aftermarket without the heatshield/oil baffle installed and some have had pcv issues with sucking up oil from valley.

This is my guess also.