dave1123

No this wouldn't effect oil pump pressure, only air pressure in the crankcase. If you blocked off the vent pipe to the air filter box and the CCV valve, it would blow out gaskets eventually.

Back in the 50's, cars had "road draft tubes" where this pressure was vented underneath the car. In 1962, they started using Positive Crankcase Ventilation valves that returned this vapor to the intake system to be burned in the engine. The CCV and PVC valves are the same thing by a different name. If you've got lots of blow-by, I'll bet your intake manifold is soaked with oil and your valves are carboned up.

cherokee4.096

I didn't check the valves but the manifold is coated pretty well. It has 180,000 without any rebuilds, needs an oil pump, transmission slips every so often and if the rings are done than I think I'm going to retire this old beast and part it out/ scrap it and find a me a new toy.

SHELBYGT NSM

I would keep it. Jeeps are fun to learn, they can also be expenisve when repairing. My jeep had over 300,000 miles, but i had to replace the engine. Guessing you have the 4.0, when push comes to shove buy another engine. I bought mine at a junkyard, $300, also was given a 3 month waranty, and now i have alot of spare parts. And if that new engine screws up after the 3 months of warranty, your actually not out that much at all compared to buying another car, truck or jeep. Thats what i would do, but it's all up to you. Hope you the best.

cherokee4.096

Couldnt I check for that air in the crankcase by pulling the dipstick while its running and cover it with my hand?

dave1123

Not unless you block the CCV because it's still pulling air.

cherokee4.096

Well I'm going to try and borrow a compression test kit from my dads job and check the compression in each cylinder when he gets home with it. What's acceptable? And what's good? Im really having trouble believing its rings, I just towed a 4 ton deer camp trailer around my property with ease yesterday. Not far but still it climbed my decent sized hill with ease. And I haven't seen any new oil in the intake.

dave1123

It's entirely possible that oil came from your short flight and the oil sloshing that occurred during your rebound. The crank can throw oil everywhere when it dips into the oil.

The compression in a good engine should be between 120 and 150 psi. That's with all plugs removed and the throttle wide open. A large jump on the first stroke shows good rings and tight valves. If your readings are low, squirt some oil into the cylinders and redo the test. This will seal the rings. If the readings don't improve, the valves are leaking. A worn engine may show as low as 90 psi and still run well.

The Haynes manual shows the proper procedures for a compression check and what each test means. I only went 4 strokes in a test, they say 7. Pull the ASD relay when you do the test.

cherokee4.096

I don't have the manual. how do I make sure the engine only does 7 strokes? Also where is the ASD relay located?

dave1123

The ASD relay is in the fuse/relay box under the hood and called the Power Distribution Center. This is to keep the fuel pump and spark isolated.

The number of stokes isn't important. You can stop when the compression guage doesn't go any higher. It's important to block the throttle wide open to allow unrestricted air to fill the cylinder. As I said, a big jump on the first stoke shows good rings and tight sealing valves. A slow buildup of pressure shows a leak somewhere. Putting oil in the cylinder seals the rings. If it still builds up slow, it shows valves that aren't sealing. This may show quite a difference between cylinders, usually caused by burnt exhaust valves or ones with a lot of deposits on them. One very weak cylinder or a pair adjacent to each other usually shows a blown head gasket or a cracked head. Let's not go there. A broken compression ring will usually show by a lot of oil smoke in the exhaust.

Speaking about oil smoke, if you use oil to seal the rings for the test, don't be alarmed by the large puff of smoke on restart.

A compression test will give you a clue of your engine's general condition so you can plan for the future, ie; engine replacement/rebuild or vehicle replacement.