Irritating smoke problem
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Fleet Mechanic
Joined: Aug 2001
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From: Round Rock, TX
Irritating smoke problem
I've got an irritating smoke problem that I'd like some people's thoughts on. It's on my '92 Bronco.
I never had any smoke problems with the engine. Then, I had a steaming problem, which was a head gasket, so I replaced the head gaskets and had some machine work done on the heads. Specifically, four exhaust seats were replaced, the heads were milled, two cracks were fixed, and new stem seals were installed, all at the machine shop.
I got the truck back, and the steam problem is solved. I then had an oil smoke problem, which laid down a screen a block long after startup. I noticed that all of the plugs were oil-fouled, which I traced to the shop using the wrong size stem seals (they all rode up the stems b/c they were too small to fit the tops of the guides). I replaced all of these seals, and I no longer lay down the long smoke screen.
My problem is now that I still put out a good-size oil smoke cloud on startup, but it is not nearly as large as the one I was previously expelling. Remember, before the head work, I did not have any smoke problems.
Does any body have any thoughts on what could be causing this? I will say that I'm just now starting to experience a small amount of oil on the breather filter, which I also did not have before the head work. I'm going to replace the PCV valve, but I'm not convinced this will affect anything.
I never had any smoke problems with the engine. Then, I had a steaming problem, which was a head gasket, so I replaced the head gaskets and had some machine work done on the heads. Specifically, four exhaust seats were replaced, the heads were milled, two cracks were fixed, and new stem seals were installed, all at the machine shop.
I got the truck back, and the steam problem is solved. I then had an oil smoke problem, which laid down a screen a block long after startup. I noticed that all of the plugs were oil-fouled, which I traced to the shop using the wrong size stem seals (they all rode up the stems b/c they were too small to fit the tops of the guides). I replaced all of these seals, and I no longer lay down the long smoke screen.
My problem is now that I still put out a good-size oil smoke cloud on startup, but it is not nearly as large as the one I was previously expelling. Remember, before the head work, I did not have any smoke problems.
Does any body have any thoughts on what could be causing this? I will say that I'm just now starting to experience a small amount of oil on the breather filter, which I also did not have before the head work. I'm going to replace the PCV valve, but I'm not convinced this will affect anything.
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Joined: Dec 2003
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From: Saskatoon, Saskatchewan
How many miles on this engine? If there is more than 100,000 + miles then it possible that with better sealing on the valves (new machine work) that there may be blowby past the original rings. This can cause the smoke you mention plus the oil on the breather.
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Joined: Sep 2003
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If it is just a puff of smoke right at start up after the truck has been sitting and then clears up right away than it is still the valve steam seals, But i would agree with Fomoko that engine blow by is your problem. Do a compression and leak down test to find out for sure. Good luck
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Fleet Mechanic
Joined: Aug 2001
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From: Round Rock, TX
Guess I should have mentioned it; it has about 80k miles on the engine. It lasts for about half a block, but isn't near as bad as it was before I replaced the stem seals.
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Fleet Mechanic
Joined: Aug 2001
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From: Round Rock, TX
Now that's it's warmed up slightly, it seems to be less apparent. When it's colder outside, it seems to be worse. Much worse. When I take off from my driveway, drivers behind me have to hang back pretty far for about a block.
I've got an external coolant leak where the lower intake meets the head at #1 that I'll fix tomorrow. Who knows what else could be wrong. It just irritates me that it didn't do this at all just a month or so ago.
I've got an external coolant leak where the lower intake meets the head at #1 that I'll fix tomorrow. Who knows what else could be wrong. It just irritates me that it didn't do this at all just a month or so ago.
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Fleet Mechanic
Joined: Aug 2001
Posts: 1,526
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From: Round Rock, TX
It turns out that, yes, it is a steam problem. I'm guessing that the crack he repaired didn't hold for very long. Assuming that the gaskets are all good, are there any other thoughts as to how I keep getting coolant in the combustion chambers? The warmer it is outside, the less steam I see at startup.
