Hey guys, I need some expert opinions... 2000 Cherokee, 4.0, I have had a slow oil leak for a while now, maybe a quarter size puddle each day, not much. Figured it was a valve cover gasket because when I replaced my spark plugs 3 month ago, they had a little oil on them, plus there is a light coating of oil on both sides of the engine. I purchased a good rubber valve cover gasket but haven't had a chance to put it on yet.

I have recently noticed a drop in oil pressure, but it's random, some trips it hangs at 80 the whole time, others it will drop to 60 or 40. Once it drops it won't go back to 80 until I shut off the engine and restart it, even then it doesn't always go back up to 80. Last week I noticed it was low on coolant, I pulled a sample of what was left in the reservoir and there is obvious oil sheen. I last topped it off 3 months ago, about the same time I did the spark plugs. I've read this is probably due to the faulty 0331 head on the 2000's.

Questions:
A: Is there any way that replacing the valve cover gasket would solve this, in other words, would I be wasting my time if I replaced it?

B: If the head is cracked anyone know the success rate on putting on a new head? Or am I better off to price a jy engine? If so it's going to be really difficult justifying a new/different engine for a 13yo vehicle. Any way to retro fit a 96-99 engine into a 2000?


Thanks for any advice!

 

That's really jumping to a lot of unfounded conclusions based on internet lore. Compression test first just for yucks then check the cooling system.

 

Like Turbo XJ says, you're kinda leaping right past diagnosis to disaster here.

When the heads crack, coolant goes into the oil, not the other way around. Oil looks like a milkshake.

You could have a bad oil sender. What rand of oil filter are you using?

How much coolant did you have to add after 3 months? Have you been checking it all along?

 

Like others have said, your jumping to conclusions. The oil gauge on Jeeps is notorious for being inaccurate and was never intended to be used as a diagnostic tool.

 

You may or may not have a cracked head but the first thing I'd do is replace the oil pressure sending unit with a Mopar unit. Then fill the overflow bottle to the Full mark and check its level twice a week. And, replace the valve cover gasket.

 

Your oil pressure should never get to 80 unless you're racing with straight 60 weight in the arctic...

Replace the sensor and valve cover gasket

 

Thanks guys for the advice, I'm less worried about it now. I am in the middle of doing the valve cover gasket now, it's currently off the Jeep. In doing so, the grey PCV elbow rear broke. I'm going to advance soon to get a new one. It felt so brittle I don't see how I could have taken it off without breaking it.

Additionally the block has 99 on it, does that indicate the year the block was made? If so, is it common to see a 99 made block in a 2000 year model? It came with a 99 manual but when I look up the VIN online it says it's a 2000, and it was sold to us as a 2000. I've looked all along the block and I don't see any cracks. If it is cracked is it blatantly obvious or is it a hairline crack?

Also I think I made a stupid mistake, I sprayed the inside of the valve cover with break cleaner and let it sit for a few minutes, the puddle that collected at the bottom ate the paint away some, is this something I need to be concerned enough about to get a new valve cover? I'll attach some pics for visuals, thanks for any advice.

 

Oh and to answer some previous questions...

I use Pennzoil High Mileage oil and Purolator Gold oil filter

I had to add 1 reservoir's worth in a 3 month time frame. I've lost about an inch worth any coolant from the reservoir since I added some a few weeks ago.