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Just replaced the vacuum hoses and pcv diaphragm on my 67 mgb-gt, and am now producing steady and really impressive clouds of grey smoke from the exhaust. i mean smoke like that produced by battleships in the movie. the smoke doesn't go away, but seem to get worse as i drive. i've only driven it about five miles since i noticed this problem, so i can't tell if there's sigificantly less oil in the sump than before i had this problem. the plugs are covered in black goo, and some goo backfired out of the forward carb. please tell me that this is simply a matter of adjusting the air-fuel mix and not a blown head gasket or worn piston rings.
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clouds of grey smoke
- Thread starter kevinl
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What was the situation before you replaced parts? AND what else did you do while you were under the hood? Normally replacing one part on a vehicle doesn't make another one go bad... but if it was not running before and you got it running after part of the problem was solved then it would be different.
the car was running well (for a '67 mg) before i replaced the diaphragm and hoses, although it sometimes was unable to hold an idle, which is why i investigated the hoses and pcv valve to begin with. once, upon accelerating some weeks ago, i noticed a puff of whitish smoke, but thought nothing of it. otherwise, the only thing i've done to it recently was to change the oil and put in a new steering wheel.
tony barnhill
Great Pumpkin - R.I.P
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A puff of whitish smoke is no big deal....sounds like you might have enriched your mixture some way...are all your vacuum lines/hoses in the same setup? Is the PVC clear & breathing as well as the front side cover?
The puff of white smoke was only the beginning. Next time out, I smoked like a 60s paper mill for the entire 20 minute drive.
It's possible that the PCV is not seated correctly; would it make that much difference? How can I tell whether it's in correctly and not, say, upside down? Would this cause black goo on the plugs, or could this be because the vacuum is no longer leaking, and the fuel-air is now much, much richer?
It's possible that the PCV is not seated correctly; would it make that much difference? How can I tell whether it's in correctly and not, say, upside down? Would this cause black goo on the plugs, or could this be because the vacuum is no longer leaking, and the fuel-air is now much, much richer?
aeronca65t
Great Pumpkin
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Kevin:
Have you reassembled the PCV valve incorrectly (perhaps with the spring on the wrong side)? If the device is stuck in the "open" postion all the time, it will allow oil to be sucked into the intake manifold continously. I've seen a similar thing happen when mechanics install PCV valves in American cars backwards.
...and Alec may be onto something too....it might be sucking brake fluid.
[ 04-13-2004: Message edited by: aeronca65t ]</p>
Have you reassembled the PCV valve incorrectly (perhaps with the spring on the wrong side)? If the device is stuck in the "open" postion all the time, it will allow oil to be sucked into the intake manifold continously. I've seen a similar thing happen when mechanics install PCV valves in American cars backwards.
...and Alec may be onto something too....it might be sucking brake fluid.
[ 04-13-2004: Message edited by: aeronca65t ]</p>
tony barnhill
Great Pumpkin - R.I.P
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Or, possibly the filter in the front side cover is stopped up...
Start by removing the PCV Valve from the intake manifold. If there is oil in the hose leading from the PCV valve into the manifold then you have found the cause of your problem. The smoke is from oil in the intake. There are only three ways to get oil inside the intake on a 67 B. The PCV valve is one and bad rings or bad valve seals is the other. I would start with what you changed first. Recheck the PCV valve.
Many thanks for the continuing help.
I popped the lid off the PCV valve last night, and found loads of oil inside, leading me increasingly to the conclusion that the valve's the problem, not the head or head gasket.
My PCV valve consists (in order from top to bottom) of a clip, cover, diaphragm, metal plate/plug, spring, and valve body. I can't see any other way these components would fit to make the valve non-functional. Is there a piece missing? What stops the oil from being sucked up from the crankcase in a normally-functioning system?
I popped the lid off the PCV valve last night, and found loads of oil inside, leading me increasingly to the conclusion that the valve's the problem, not the head or head gasket.
My PCV valve consists (in order from top to bottom) of a clip, cover, diaphragm, metal plate/plug, spring, and valve body. I can't see any other way these components would fit to make the valve non-functional. Is there a piece missing? What stops the oil from being sucked up from the crankcase in a normally-functioning system?