Problem with Blow-by and low oil pressure

First of all I would like to thank you all for your great forums you guys have here. The time you regular poster's (if that's a word) spend here answering questions is great. Specifically your posts help me pin point my cps causing start problems in the past.

Car :
1988 jeep Comanche 200 K 4liter inline 6 (really grown to love it)

Now for my problem which i think i have pinned just hoping to glean some experience from you all.

got a blow by problem (causing oil on my air filter) so took the rocker cover off to clean the breather's (already cleaned the hoses etc ) to help slow the oil problem and replace the valve seals. Decided to run the engine to which cycl's were really bad. Discovered the valve seals are doing there job, but the exhaust is coming from around the connecting rods.

so I’m thinking the head gasket has partially gone. I cannot think of any other way for exhaust to get there. But I have not taken apart this engine (or any other) and am not 100% sure. Trying to avoid unnecessary work.

second
i have a low oil pressure problem. when the engine is cold things are cool.
when the engine is warm my oil pressure light comes on at idle but not totally on it pulses with the engines rpm's (as if the pressure was quickly rising and falling below the threshold) if the engine is hot the light is solid
on. tired different weight’s of oil no diff, different filters, etc. looked in valve cover to inspect the conn rods and associated gear to see if something was worn out up there and all looks good. I have not removed the oil pan yet but i plan to.

so do you all think there is likely somewhere else that is worn out? should i get a new oil pump? how does one tell if the oil pump is worn out?



Thanks again guys

Check you're vacuume that conects you're intake manifold and the rear of the valve cover and the grommet going into the valve cover, that solved my problem. also check as many of the vacuume lines as you can trace and the vacuume cannister inside the right side of the front bumper. Make sure you have a good seal on the valve cover too. Good Luck.

Blowby is caused buy bad rings, cleaning the valve cover and vacuum lines helps but is not the root cause of the problem.

I know cleaning the breathers and the lines does not solve the problems. what i need to know is how exhaust is getting into the connecting rod area.
if it is the head gastket or something else

thieu said:

I know cleaning the breathers and the lines does not solve the problems. what i need to know is how exhaust is getting into the connecting rod area.
if it is the head gastket or something else

Click to expand...

It blows by the pistion rings, into the crankcase and up the pushrods, that's why it's called blowby.

so the exhaust is going past the lifters as well as the camshaft??
how does the exhaust get into the camshaft area?? it's sealed off by itself it it not??

thieu said:

so the exhaust is going past the lifters as well as the camshaft??
how does the exhaust get into the camshaft area?? it's sealed off by itself it it not??

Click to expand...

No it is not.
Think about this, if it were not open back to the crankcase like you think, it would be full of oil would it not?

so your saying the exhaust is comming from the crank case up through the cam shaft, past the lifters, then up the conn rods?? would you say this is exxcessive blow by or is there another path the exhaust that blows by the piston rings is supposed to take?

any suggestions on the oil problem??

thanks in advance for your paitence

thieu said:

so your saying the exhaust is comming from the crank case up through the cam shaft, past the lifters, then up the conn rods?? would you say this is exxcessive blow by or is there another path the exhaust that blows by the piston rings is supposed to take?

any suggestions on the oil problem??

thanks in advance for your paitence

Click to expand...

You ready for a rebuild.

thieu said:

any suggestions on the oil problem??

Click to expand...

Langer 1 is most likely right on the rebuild, but before a rebuild,
Replace the vac lines running from the valve cover to the intake manifold, and to the airbox. to see if yours is working, unplug the line from the valve cover to the airbox when the engine is running. you should be able to feel a slight vacuum. as stated before, a clogged rear line will screw up the ccv and cause even normal blow by to soak the air filter.

thieu said:

so do you all think there is likely somewhere else that is worn out? should i get a new oil pump? how does one tell if the oil pump is worn out?

Click to expand...

Simply put, your 200k mile old engine is knackered.
What you're experiencing is a classic case of blowby, where combustion gases are "blowing by" worn piston rings into the crankcase, which is the reason why your crankcase pressure is high and your air filter is soaked in oil.
The next problem that you have is low oil pressure at idle, especially when the engine's hot, and the reason for that is worn rod/main bearings.
The only cure for your engine's ills is, as Langer said, a complete rebuild. You could try replacing all the crankcase ventilation hoses and try 20W-50 engine oil to bump up the oil pressure a bit, but these are merely bandaids for a broken leg so a rebuild is inevitable. Don't wait for the bottom end of the engine to start knocking because that might be too late.

Before you tear down your engine get a compression tester and see what your compression readings are.

The connecting rods are not visible with the valve cover off. They're in the bottom of the engine. With the valve cover off you're looking at rockers and pushrods, valve tops and valve springs.

It's completely normal for an oil mist to be present inside the engine. It's a combination of blowby vapors and oil draining down through the engine hitting all the rotating parts. However your oil pressure light flickering is not normal. I'd verify with a mechanical gauge. If the oil pressure is indeed below spec, it could be the pump, main/rod/cam bearings, or a combination of both.

Yeah knackered thats the word I was looking for. :laugh3:

cool and thanks for all your time guys