Hey, have a 98 4.0 in my tj and am thinking it might have the notorious cracked 0331. not sure if it is an 0331 or not but it drains antifreeze mysteriously, ticks a little, has low power, and has low oil pressure to 0 at times. has anyone had this problem or similar?

 

I don't think the 0331 head came out until 99 or 2000.

 

ok then what the hell is going on with my jeep

 

A cracked head is a cracked head. The 0630's are not immune to cracking, just less likely to do so than an 0331.

Do a compression test.

 

I had that exact problem with my XJ. For me it was the notorious cracked 0331 head. I don't know if it could possibly be a cracked gasket and not full blown head, but for your sake, I hope it is just a gasket.

 

thanks! its ran like a champ for a while but in the last 2-3k its had this problem and havent came up with a conclusion. other than the symptoms i have played around and found that the back pressure from downshifting pushes the pressure back up to about 40. 1st, 2nd, and 3rd run roughly around 20-30, 4and 5th run 20 and under. and then stops and starts are 0-20.

 

Just be careful that you don't do more damage. Get it checked out soon. The kid I bought mine off of in July had overheated it once and said everything was fine after he switched a few parts. The truck ran like a champ for 3 months before I saw any issues. Now it's sitting outside collecting snow. I swapped in a new head, but the problems run deeper than that since I drove it without knowing I was doing damage. Not worth you risking it.

 

Why have you driven it this long when you knew there was a problem? You need to get this fixed before you completely destroy your engine.

 

it doesnt overheat, rides smooth at 210. also it doesnt get driven much or daily so it hasnt been a multi-thousand dollar priority