OcalaXJ

I just had my motor rebuilt by a local machine shop about 2k miles ago. The motor was a victim of the 0331 head problem. The crankshaft was turned and he reused my rods. Everything else is new inside. Down to the camshaft bearings. The head had a valve job with new rocker arms, pivits, and push rods.

The motor sounds great on a cold start and runs quietly until it gets good and hot. You have to drive it for about 30 minutes before it has this light tap to it at idle. You dont notice it at all accelerating or decelerating or anything above idle.

I have listened and had another guy i know listen to it. Its in the top of the motor. Its not a rod knock or anything like that. The guy i had listen to it suggested a lazy lifter. I did pinpoint it down to the 5 cylinder.

I broke had the camshaft break in done by a local shop and i ran the zinc additive in my oil for 1k miles. Then changed the oil twice since.

My oil pressure isn't as good as i would expect with a rebuilt motor. I know the low spec for oil pressure is 13psi idle. In this florida heat with the a/c and a long trip is see oil pressure at like 11 psi idle.

Kalali

Why would you a rebuild a cracked 0331 head? And they rebuilt the motor and did not put in new lifters? I must question the judgement of the shop that did the engine rebuild.

OcalaXJ

The guy who sold me the jeep had replaced the head before he sold it to me. I saw where he had put a new temp sensor and waterpump. He didn't mention that when he sold it to me.
It still is a 0331 head just not a cracked one. I found out it had the cracked head after i changed my oil for the first time. I realized that i had zero oil pressure with 10w30 on a hot day. He had been putting thick oil in it to hide the problem.That's when the research started.
The lifters were replaced. Everything in the motor is new. Other than rods and turned crank. I've heard something about rockers maybe needing to be adjusted after a build. I dont know if that's something.

bigbadon

Lifter bores,lifter bores,lifter bores. They are the most overlooked and worn lifter bores have the greatest effect on oil pressure!

OcalaXJ

So, the clearance of that hole the lifters go in? That makes sense. But, I had never even heard of such.

OcalaXJ

My oil pressure is not good for a fresh motor either. My tap doesn't happen until the oil gets good, hot, and thin it seems. Maybe i can put some thicker oil in it and have better results. I shouldn't have to but it helped out with my oil pressure before i had it rebuilt.

bigbadon

When the 0331 head cracks the fully concentrated coolant seeps into the top of the head where it flows DIRECTLY into the lifter bores.

OcalaXJ

So how do you fix the lifter bores?

bigbadon

Most engine re-builders will just scrap the block, but they can be sleeved by a good machine shop.