What I'd look for FIRST is that there not be a big variance of more than, say, 10% from highest to lowest.

OK - checking my 1988 FSM, it's a minimum of 100psi, with no more than 25psi variance highest to lowest.

Your 1991 is also an LA motor, so I'd think it'd be the same.

RwP

 

alright. Thank you. I'll get a tester and check it this weekend.

 

I have the 94 and the PCV valve (Small plastic with 90 bend) comes out of the passenger side. PCV = Positive Crankcase Ventilation. The driver side valve cover has a vent in (this is what I am calling the crankcase vent) it goes into a large hole maybe 1.5" and has large hose connection off the top there is a hose from it to the air cleaner. Oil blows by it on my motor so it is a possible source of oil to the Plenum if your air cleaner is not the exact right size to seal the top and bottom of the air cleaner pan. Oil out the tail pipe aint no fun. Just in case the rings might be stuck you might try some Risolone in the motor. A quart should loosen the rings if they are stuck. Don't overfill the oil. You may have to do an oil change to get the right level but if its coming out other places it might be low enough to take a quart. Oh yea when I saw the oil on the plenum after I had done the kit more than a year prior I used a rag a paint stir stick and some carb cleaner to wipe up as much as I could. Shrug

 

i have some marvels mystery oil on hand. Would that do anything? And the crank vent has no oil residue that I can find, and the air filter seals nice and tight and is clean as a whistle.

 

I was told to use Risolone by a mechanic. It is supposed to break up deposits and loosen the rings. IDK if MMO would work. I can't remember ever using it.
There is another way many would advise against and if your motor is going bad???
An Aussie told me how he does oil changes on all of his vehicles from the get go. Warm it up. Drain the oil. Remove the filter and drain it then put the dirty filter back on. Add 1/2 the recommended amount of new oil and 1/2 quart of diesel fuel. Drive it as normal for a day or two if you don't drive much. When its warm drain the oil and replace the filter with a new one and add the right amount of new oil.
This is supposed to clean valve seals and do other things. I did it on my dak and drove it on the highway for 100+ miles with the diesel in the oil then changed it out. Seems to have helped with valve/lifter noise
Here is a link that shows the filters I added to see if the oil was coming from the PCV or the other breather. I hope it helps. That oil was only able to get by because I had a cheap air filter in and it did not seal top and bottom of the canister.
https://dodgeforum.com/forum/1st-gen...ml#post3312292

 

it hasn't been registered in about two years now so I can't put any highway hours on it. I changed the oil before the idle got messed up when cold, so that kinda worries me. The oil pressure is good however.

 

Around town for 30 miles or so should be fine. You want to drive it like you normally would for a day if you do that diesel thing.

 

heh I dont even have my license yet. And recently the only driving it's been doing is pulling a trailer around the farm. Usually a couple round bales, so I guess I've been a little hard on it... But I imagine I can get away with taking it down a couple county roads and not get in trouble.

 

Don't be doing anything illegal because I suggested it. I figured you were old enough and had a license. Most people on here will be making that same assumption.

 

I've been driving for a year now and have had no issues. Just not this truck, but I do need to get my license. And I understand most of y'all will be making the assumption I have my license.