Sucking oil trough PCV valve..

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Havran
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Sucking oil trough PCV valve..

Post by Havran » Mon Apr 25, 2016 5:05 am

Hello Guys,

I have recently rebuilt the engine and after few miles of driving it starts to suck oil from the valves trough the PCV valve and smokes like hell.. In higher rpm it stops or smoke less as the PCV closes. I have tried 3 different (used) valves, but same problem, when I disconnect it, or clog it with something then its ok, but then the engine goes rough.. Oil level is normal, oil pressure too.. Has anyone similar experience?

thanks a lot
Jan


Rickf
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Re: Sucking oil trough PCV valve..

Post by Rickf » Mon Apr 25, 2016 3:11 pm

Does it have a fording valve and is it in a partially closed position? That will cause that. Could also cause a rear main seal leak. If no valve or it is open then take the oil fill cap off at idle and see how much blowby you have with the PCV hooked up. Should be none. If there is blowby then you have stuck or broken rings or you got the ring gaps lined up instead of offsetting them.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Havran
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Re: Sucking oil trough PCV valve..

Post by Havran » Mon Apr 25, 2016 10:31 pm

Rickf wrote:Does it have a fording valve and is it in a partially closed position? That will cause that. Could also cause a rear main seal leak. If no valve or it is open then take the oil fill cap off at idle and see how much blowby you have with the PCV hooked up. Should be none. If there is blowby then you have stuck or broken rings or you got the ring gaps lined up instead of offsetting them.
Hi Rick,

It does not have a fording valve. It is not leaking oil from anywhere..yet. I checked blowby manytimes and there is none. Rings were assembled correctly offset. It has nice idle, but when you accelerate it is just noisy and rough and acceleration is little poor. When pcv is hooked up, its much better, but sucks oil in certain rpm.. Iam trying to get new one at this time..

regards Jan

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Re: Sucking oil trough PCV valve..

Post by Rickf » Tue Apr 26, 2016 1:46 pm

Do you have both the supply and return tubes hooked up on the ocker arm? I am a little perplexed since the highest vacuum is at idle so even if it was wide open I could see problems with oil ingestion at idle but where is the oil coming from? Are you sure it is coming thought he PCV line? If one of the oil lines is off or if the seal for the supply line came loose there would be a lot of oil in the valve area. I can't picture enough to get into the PCV though. Have you done a compression and leak down tests?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Havran
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Re: Sucking oil trough PCV valve..

Post by Havran » Wed Apr 27, 2016 2:42 am

Rickf wrote:Do you have both the supply and return tubes hooked up on the ocker arm? I am a little perplexed since the highest vacuum is at idle so even if it was wide open I could see problems with oil ingestion at idle but where is the oil coming from? Are you sure it is coming thought he PCV line? If one of the oil lines is off or if the seal for the supply line came loose there would be a lot of oil in the valve area. I can't picture enough to get into the PCV though. Have you done a compression and leak down tests?
Both oil lines for rocker arm are hooked up, supply one has a new o-ring and looks ok. Well when i disconnect the J tube from valve cover to PCV, oil consumption will cease. Compression is 9 bar in all cylinders, unfortunately I do not have a leak-down tester.. I also discovered that the rubber caps which are on the valves, has moved up from the seat and were stuck on valves. But it probably happened after the first start of the engine, so they were probably in this postition for the whole time so I guess it is not the main problem.. pff.. Iam really tired of this engine already :D

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Re: Sucking oil trough PCV valve..

Post by Havran » Wed Apr 27, 2016 9:07 am

little update.. I found another PCV valve, cleaned it and installed, I moved the rubber boots back to its position and valve cover cap was not very tight, so I replaced with another tight one.. It is much better now. Just a little oil smoke in lower rpm from time to time..

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Re: Sucking oil trough PCV valve..

Post by Rickf » Wed Apr 27, 2016 9:53 am

It is sounding a lot like bad valve seals.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

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Havran
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Re: Sucking oil trough PCV valve..

Post by Havran » Wed Apr 27, 2016 10:23 pm

Well I put the new ones.. they are maybe too tight on valve neck and then they travel up by a movement of a valves.. :roll:

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Re: Sucking oil trough PCV valve..

Post by Rickf » Thu Apr 28, 2016 2:15 pm

That is what they are supposed to do, How were the valve guides?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone


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