Oil Pressure and PCV Issue on F134

Hi everyone, Happy New Year!!!

I have a little lengthy question and all my terminology may not be quite correct but please bare with me.

I have a 1957 CJ5 with the stock F-134 engine. I have been planning on replaced the rear main seal which is leaking but first I wanted to make sure that I dont have an oil pressure or crankcase ventilation problem. First of all, I have a relatively new oil pressure gauge in the Jeep so have no reason not to believe that it is accurate but my oil pressue seems to be way too high. I am getting 60 psi at idle and around 70 when I rev the motor so I suspect that this could be a valid reason why I am leaking out the rear seal and other locations for that matter. Granted, the Jeep it is old so leaks are a given.

First thing I wanted to do is be sure my PCV valve is operating properly so here is the story. I can post pics latter if needed. I have the PCV valve hooked up the vacume port just below the carberator and a hose that goes from the pcv to the rocker cover on the top of the engine. I checked for vacume by disconnecting this hose from the rocker cover with the engine running and have a ton of vacume at this location coming from the pcv valve. Next, correct me if I am wrong but I then have the other side of this engine ventilation with a hose that attaches to the oil dipstick tube and then goes to the bottom of the oil bath air cleaner. If I am not mistaken, this should complete my engine ventilation but if I disconnect this hose where it attaches to the air filter, I cannot feel any vacume which I assume I should feel something at this point coming from the vacume created by the PCV? Is this correct. I thought maybe my dipstick cap may not seal well so it could be pulling from there as well. Then I tried removing the dipstick, plugging the tube with the palm of my hand with it running but still cannot feel any vacume at the air cleaner hose. Then I noticed something odd. When I shut down the engine, I heard a gurgeling sound coming from the dipstick tube as if the engine was in a major vacume. This sound continued for about 10 seconds until the apparent vacume on the engine was equalized. Any opinions, thoughts or suggestions at this point would be great.

Do I have my PCV hooked up wrong and is my oil pressure too high.

Oh, one more thing I noticed odd, I notice a small amount of oil bubbling from my number 4 spark plug. I suspected the the plug was just loose which remedied by snugging up the plug a little more but what would cause oil to come from here? Bad rings maybe? I checked the plug and the probe was a fluffy light brown color and not oil soaked so I have no indication of it running too rich or lean that I can tell but the plug threads were oil soaked. All in all the Jeep runs great and does not smoke at all. I just would like to fix the rear seal leak.

Thanks for your wisdom guys,

Mike

 

Mike-- are you getting 60PSI of oil pressure after the engine has warmed up? I get high pressure (70PSI or so) when the engine (oil) is cold, but it then drops down to 20PSI or so at idle, when warm. The thick & cold oil is of course thicker, & therefore gives a higher pressure.

I am very certain that the high pressure will not cause the rear main seal to leak.

The rear main is a tricky design & kinda prone to leaking, in my experience. This has more to do with the gaskets that seal the sides of the main bearing than the seal itself. I am sure others here know of ways to make this easier.

I can't be much help with the PVC system-- my F-Head is the early design & does not have a vented upper valve cover.

 

What weight are you running for oil?
10w30, 10w40, 20w40? or if you can find it 30, or maybe 20 if it is pretty cold out?
My PCV is mounted on the side valve cover above the oil pump, and the top cover is not vented. The vent that runs to the air-cleaner comes from about half-way up the dip stick tube.

Should not be any oil bubbling past a spark plug, not sure what is going on there. Pull that plug and see if the electrode and ceramic is soaked in oil. If not make sure that plug, and all the rest, are seated correctly. You don't want any of them deciding to leave the vicinity.

Did you put in a mechanical or electric oil pressure gauge? And just cause it is new, doesn't mean it works right.

 

I am using 10W-40 motor oil. I live in Phoenix Az so cold is not much of an issue here. I have only had the Jeep a couple months now but she runs a pretty steady 60 psi oil pressure all the time, weather cold or hot. The oil pressure guage in it is a Sunpro, good or bad, not sure. I am not real concerned about the oil pressure unless somebody in here says I should be. I am just not sure if the high pressure could contribute to my oil leak/leaks.

As far as the spark plug goes, I pulled it and the electrode and ceramic are dry. There is just oil around the threads and I can see the top of the piston has black oil on top of it. Looks like a layer of thick crud that is still wet so that is why I am thinking the rings must have a compression loss. I dont have a compression guage at the moment but there is no doubt that I have some compression loss of there would not be oil present.

The PCV has be baffled because the engine appears to be running in a vacume which tells my that I must not have an even flow of air through the engine.

Mike

 

x2!


On the spark plug bubbling-- is the oil coming out of the plug hole or has it dripped down from above- past the upper valve cover seal?

I've seen these bubbles, too, after washing down the engine with water. I think VERY mild bubbling is normal. In a perfect situation, they are not there, but with anything old-- wear/nicks/pitting happen!

Oil getting there from the spark plug hole is not. If you are not seeing any oil smoke in the exhaust, then it is most likely leaking from the valve cover.

 

The oil is definately coming from the plug hole. The valve cover is dry and no oil coming from above. The oil seems to have stopped since I snugged up the plug a little more but I definately have oil leaking past a valve or ring since the top of the piston is coated in black oil. I am just amazed that she doesnt smoke.

I am just really wondering if my problems are related to poor crankcase ventilation. I would love to hear some ideas of how to improve ventilation. I am pretty sure the crankcase should not be in a vacume like it appears to be

 

A crankcase vacuum would not cause a leak but a crankcase pressure would. To get a crankcase pressure (like in the fording system of military jeeps) you have to block off all the vent tubes so the crankcase pressure would build.

If your PVC is working you should have low flow at the vent tubes at idle so yours may be bad. Still, this wouldn't cause a pressure but more like it would be hard to set the air/fuel ratio.

I thought the PVC was down next to the side valve cover like mine. If yours aftermarket?

 

agreed

 

You asked about vacuum in the tube from the oil fill tube to the air filter. There should not be vacuum there. That is a vent tube that allows blow by gasses from the engine to be vented into the air filter and be burnt off through the cylinder combustion. A few years earlier these were just vented into the atmosphere via a road draft tube.

 

Okay guys,
This makes a lot more sense now. That explains why I have a low flow at the vent tube that goes to the air filter. I was kinda thinking the same thing that a vacume should not be a big deal if not a benifit to help prevent leaks. I am not sure if my PVC is original or not but it sure looks original. There is a tap on the side of the head, just below the carb where it is attached. It has a brass T that has one vacume that runs to the pneumatic heater controls, one is capped off and the third is the tap for the PCV.
So it sounds like I do not have a pressure problem and I can proceed with the repacement to the rear main crankshaft seal. I just wanted to be sure I did not have another problem before I went forward.
I really appreciate the help.
You guys are awsome!!!!

 

One of those taps should go to your vacuum powered windshield wipers.

 

If oil was getting into the cylinder enough that it actually leaked out the plug hole . . your spark plug would sure so signs of burnt oil. I suspect that you have oil traces coming down from th e valve cover. Its going going to go up onto the cover, unless it was a lot and you drove it that way a lot as well. It will seep down and puddle at the spark plug holes.

 

Intresting on the vacume powered wipers. Mine has electric motors. They look original but I suppose they could have been change somewhere between now and the last 55 years.
And Pete, I understand what you mean about oil coming from above. It sure could be possible. I can't see any sign of the rocker cover leaking down on the plug and the oil on top of the piston had me thinking that it was coming from the cylinder but I thought the same thing that the plug should have been fouled. Hmmmmmmm...... Anyway, seems like these darn old machines are always leaking from was place or another. Everytime I fix one leak it seems like another one pops up from somewhere.
OH THE HUMANITY!!!!!!