Blue Smoke After New Cylinder Heads
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Amateur
Joined: Dec 2012
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Blue Smoke After New Cylinder Heads
So I replaced the cylinder heads on my 1989 non-magnum 3.9L 1989. The originals were cracked and I had coolant mixing with the oil. The new heads cured that problem for sure but now I've noticed that when I start the truck, it starts to blow blue smoke out of the tail pipe after it's been running for about 5 minutes. For the first few minutes when cold there's no smoke at all. The truck runs very well. Here's what I have done about it so far:
-Talked with the head rebuilder, he assures me they are good as new. He is a very reputable builder.
-Verified my PCV system is functional. I found it was blocked at the throttle body. Cleaned and vacuum is good now.
-Changed oil to 20W50.
-Done compression test. Dry test shows all cylinders at 130PSI. Didn't do a wet test.
-Removed spark plugs and saw oil fouling on some of them. Didn't make a note of which ones so I'll need to double check.
-Removed the oil cap with the engine running to check for blow-by. No obvious pressure detected from oil fill hole.
I have the truck stripped for paint right now and so I can't take it for a good run under load. Have only run it on my driveway for a few hours after I did the heads in hope that it will get better.
Am I looking at worn rings? Or could I have goofed something up when I reassembled it? Maybe intake gaskets or torque? I followed the FSM carefully though. It smoked a bit before the new heads from what I thought was just water vapor due to the cracks. It didn't seem as blue to me back then. It also passed the emissions test before I redid the heads. LOL.
Any help would be appreciated. Otherwise I'll have a great looking truck soon that can also double as a smoke machine!
-Talked with the head rebuilder, he assures me they are good as new. He is a very reputable builder.
-Verified my PCV system is functional. I found it was blocked at the throttle body. Cleaned and vacuum is good now.
-Changed oil to 20W50.
-Done compression test. Dry test shows all cylinders at 130PSI. Didn't do a wet test.
-Removed spark plugs and saw oil fouling on some of them. Didn't make a note of which ones so I'll need to double check.
-Removed the oil cap with the engine running to check for blow-by. No obvious pressure detected from oil fill hole.
I have the truck stripped for paint right now and so I can't take it for a good run under load. Have only run it on my driveway for a few hours after I did the heads in hope that it will get better.
Am I looking at worn rings? Or could I have goofed something up when I reassembled it? Maybe intake gaskets or torque? I followed the FSM carefully though. It smoked a bit before the new heads from what I thought was just water vapor due to the cracks. It didn't seem as blue to me back then. It also passed the emissions test before I redid the heads. LOL.
Any help would be appreciated. Otherwise I'll have a great looking truck soon that can also double as a smoke machine!
Record Breaker
Joined: Aug 2013
Posts: 1,033
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So I replaced the cylinder heads on my 1989 non-magnum 3.9L 1989. The originals were cracked and I had coolant mixing with the oil. The new heads cured that problem for sure but now I've noticed that when I start the truck, it starts to blow blue smoke out of the tail pipe after it's been running for about 5 minutes. For the first few minutes when cold there's no smoke at all. The truck runs very well. Here's what I have done about it so far:
-Talked with the head rebuilder, he assures me they are good as new. He is a very reputable builder.
-Verified my PCV system is functional. I found it was blocked at the throttle body. Cleaned and vacuum is good now.
-Changed oil to 20W50.
-Done compression test. Dry test shows all cylinders at 130PSI. Didn't do a wet test.
-Removed spark plugs and saw oil fouling on some of them. Didn't make a note of which ones so I'll need to double check.
-Removed the oil cap with the engine running to check for blow-by. No obvious pressure detected from oil fill hole.
I have the truck stripped for paint right now and so I can't take it for a good run under load. Have only run it on my driveway for a few hours after I did the heads in hope that it will get better.
Am I looking at worn rings? Or could I have goofed something up when I reassembled it? Maybe intake gaskets or torque? I followed the FSM carefully though. It smoked a bit before the new heads from what I thought was just water vapor due to the cracks. It didn't seem as blue to me back then. It also passed the emissions test before I redid the heads. LOL.
Any help would be appreciated. Otherwise I'll have a great looking truck soon that can also double as a smoke machine!
-Talked with the head rebuilder, he assures me they are good as new. He is a very reputable builder.
-Verified my PCV system is functional. I found it was blocked at the throttle body. Cleaned and vacuum is good now.
-Changed oil to 20W50.
-Done compression test. Dry test shows all cylinders at 130PSI. Didn't do a wet test.
-Removed spark plugs and saw oil fouling on some of them. Didn't make a note of which ones so I'll need to double check.
-Removed the oil cap with the engine running to check for blow-by. No obvious pressure detected from oil fill hole.
I have the truck stripped for paint right now and so I can't take it for a good run under load. Have only run it on my driveway for a few hours after I did the heads in hope that it will get better.
Am I looking at worn rings? Or could I have goofed something up when I reassembled it? Maybe intake gaskets or torque? I followed the FSM carefully though. It smoked a bit before the new heads from what I thought was just water vapor due to the cracks. It didn't seem as blue to me back then. It also passed the emissions test before I redid the heads. LOL.
Any help would be appreciated. Otherwise I'll have a great looking truck soon that can also double as a smoke machine!
Registered User
Joined: Jun 2017
Posts: 15
Likes: 0
From: Brookings Oregon
Sounds like he didn't do a full rebuild just the heads
Did the heads come to you assembled? The valve guide seals might not be seated all the way, and when the valve covers fill up with oil might be leaking. It could verry well be the rings though.
Did the heads come to you assembled? The valve guide seals might not be seated all the way, and when the valve covers fill up with oil might be leaking. It could verry well be the rings though.
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Amateur
Joined: Dec 2012
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Right, I just replaced the heads and did not do a full rebuild. The heads were fully assembled by Charlie's cylinder heads in AL. I bought a refurbished set of OEM heads for it. I may go ahead and try replacing the valve seals anyway as it could be a possibility that I could find one missing or not installed correctly.
Record Breaker
Joined: Jan 2014
Posts: 1,852
Likes: 109
From: Va
It likely is rings. I doubt the seals. Usually they smoke on start up and then clear out. FWIW if it was my truck, I would wait until you can drive it. If its rust in the cylinder-rings, it may clean up. But again, more then likely rings IMO