oil'd faithful
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Lead Driver
Joined: Oct 1999
Posts: 6,782
Likes: 558
From: Kalispell, MT
oil'd faithful
The 351M in my 77 is tired and has given evidence of some blow-by ever since I've had it. Problem is within the past 2 weeks it has started puking oil up the dipstick tube. I found an archived msg that just mentioned it is caused by ring gaps getting aligned on a piston, but there were no responses or any more details.
This truck was parked for three years without running until 6 months ago. I took the normal precautions when I fired it up. Any ideas out there?
Could it be plugged return holes in the head, or is blow-by the most likely culprit? If the rings did rotate and the gaps lined up, will they keep rotating and close again? I know, I'm grasping at straws....
I have a 400 to rebuild and replace this motor, but I don't have time to do it right now.
Thanks for any ideas - tim
This truck was parked for three years without running until 6 months ago. I took the normal precautions when I fired it up. Any ideas out there?
Could it be plugged return holes in the head, or is blow-by the most likely culprit? If the rings did rotate and the gaps lined up, will they keep rotating and close again? I know, I'm grasping at straws....
I have a 400 to rebuild and replace this motor, but I don't have time to do it right now.
Thanks for any ideas - tim
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Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
oil'd faithful
The odds of the rings lining up and staying lined up are astronomically high. The culprit is most likely just simply age. Older engines have more blowby and at some point they simply overwhelm the ability of the PCV to handle it. By all means check the PCV valve to make sure it's good but I wouldn't worry about the piston ring gaps lining up.
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Lead Driver
Joined: Oct 1999
Posts: 6,782
Likes: 558
From: Kalispell, MT
oil'd faithful
Update on the problem and solution - spent some time under the hood and found a ventilation hose under the aircleaner had collapsed producing the same effect as a plugged pcv. Opened it back up and the geyser stopped! Now I only have to clean up the mess under the hood. Thanks for helping me think it thru.
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