Engine Engine oil from breather.

[ram137]

I have an 85 with the AMC 258 i6 / 4.2l . 84k actual miles. The jeep sat for many years. It runs well now, but at high RPMs engine oil is blowing out of the breather and gasket around the pcv. I’m thinking I need to replace the valve stem seals. Does this sound right?

 

[CJ]

Sounds like a lot of blowby, most likely caused by a stuck ring because it has been sitting for a long time.
Bad valve seals would show as alot of blue smoke in your exhaust because of oil getting in the cylinder. They do not control blowby.
A quick solution that might work could be soaking the cylinders in some Marvel Mystery Oil to try to free up the ring BUT first run a compression check to see if this is your problem.
It's unlikely but the valve guides may be an issue.
First thing to do is a compression AND leak down check .

 

[Manic Mechanic]

Exactly what he said. It's blow by. Besides marvel, kriol works well also. Either one will work into the rings and help. But don't be alarmed by the amount of blue smoke at start up as you are putting oil directly into the cylinder.

 

[ram137]

Sounds like a lot of blowby, most likely caused by a stuck ring because it has been sitting for a long time.
Bad valve seals would show as alot of blue smoke in your exhaust because of oil getting in the cylinder. They do not control blowby.
A quick solution that might work could be soaking the cylinders in some Marvel Mystery Oil to try to free up the ring BUT first run a compression check to see if this is your problem.
It's unlikely but the valve guides may be an issue.
First thing to do is a compression AND leak down check .

Would I add the marvel to the fuel like the instructions say, or would I add the marvel to the cylinders through the spark plug holes and let it sit for a while before starting?

 

[CJ]

Would I add the marvel to the fuel like the instructions say, or would I add the marvel to the cylinders through the spark plug holes and let it sit for a while before starting?

First, how did the compression/ leak down test come out?
Add a few ounces through the spark plug hole then let it soak for as long as you can. The longer the better.
Once your ready to start up, turn the engine over with out the spark plugs in for a bit to.blow the majority of the oil out of the holes then reassemble.
That will decrease the chance of fouling the plugs. Then drive for a while.
Next pull the plugs and inspect, clean or replace them if needed.

 

[ram137]

First, how did the compression/ leak down test come out?
Add a few ounces through the spark plug hole then let it soak for as long as you can. The longer the better.
Once your ready to start up, turn the engine over with out the spark plugs in for a bit to.blow the majority of the oil out of the holes then reassemble.
That will decrease the chance of fouling the plugs. Then drive for a while.
Next pull the plugs and inspect, clean or replace them if needed.

Thank you. I haven’t been able to do the compression test yet. The tester will be here tomorrow. As soon as it’s done, I’ll post the results.

 

[CJ]

Thank you. I haven’t been able to do the compression test yet. The tester will be here tomorrow. As soon as it’s done, I’ll post the results.

One more great tool to add to a Jeepers ever expanding tool box!

 

[ram137]

One more great tool to add to a Jeepers ever expanding tool box!

Just finished the compression test. Looks like #1 is the culprit, and #5 is on the way. From what I’ve been seeing, the numbers I’m getting for the other cylinders seem high though.

 

[CJ]

150psi and up is considered very good. 120 is not real bad but since your engine is in really good shape the more than 20 psi between cylinders is a problem.
I would definitely soak #1 for a day or so. Next drive it for a while and recheck.

 

[ram137]

150psi and up is considered very good. 120 is not real bad but since your engine is in really good shape the more than 20 psi between cylinders is a problem.
I would definitely soak #1 for a day or so. Next drive it for a while and recheck.

Will do! Thanks for the help!