Well, two good choices, one- the oil analysis is still a good idea; two- the compression test is fairly easy and cheap. The only way to tell if the damage goes any deeper is to tear the motor down significantly.

I still stand by my recommendation to stop driving the vehicle if you have something else you can drive.

My experience with this is really only from the prospective of my brother having this problem. He described what was happening (loosing coolant and not seeing where it was going) and I told him the same thing- dont' drive it. Well he didn't listen to his little brother and he drove it around for another six months, just kept putting more coolant in, and eventually he starting loosing oil pressure. He took his Jeep to a service shop to have it checked out. The shop found the crack, took it apart to change the head and discovered the bearings were bad too. $3000 later and two engine builds (because they did it wrong the first time) and he's now got a Jeep with a good reliable motor in it. And we used a 0630 head, not a 0331.

 

yes and no........ the cracked 0331 head results in coolant going into the oil which in turn wears out the bearings causing excessive clearance and loss of oil pressure.
Water is not a good lubricant and it doesnt take long for it to do its damage.

When most people hear "cracked head" they automatically think running rough and white smoke coming out the exhaust. Thats the result of a crack or blown head gasket in the combustion chamber. Thats not what the 0331 head does.

I agree with the previous poster who said stop driving it if at all possible and get a head put on it.....

Fair warning on buying a remaned head locally...... if it doesnt have TUPY cast into it , it is not the updated casting sold by alabama cyl head or clearwater and all you will be getting is the same head as you have now with a casting flaw just waiting to happen.

The TUPY heads came out on the 02 models and newer.
You can find one in the JY and have it worked also... which was under $275 for mine including used head from JY, machine work, and gasket set

 

Alright, tomorrow after work im ordering a head from clearwater. What else do i need to purchase before i take it to be replaced? Bearings? if so, which ones specifically? New Bolts? Where can i get some?

 

Need a gasket set (head set)... i like fel pro... and a new quality thermostat.
You dont need any bearings unless you are going to have the motor pulled and the lower end rebuilt. If the engine runs good and ya got over I3 psi oil pressure when at operating temp I wouldnt go in the lower end.

Clearwater may have the gasket set and new head bolts also.... Ive seen some people getting them from the dealer. I reused mine, but it cant hurt to get new ones.

 

Recommendations for a thermostat? should i get a new housing or gasket for it as well?

 

I've been following this thread because I have a mysterious loss of coolant too (although I don't notice it in my oil). Can anyone post a picture or a link to a picture of what a cracked 0331 head looks like when it's still on the Jeep? I'd like to see how to diagnose it when I take off the oil cap or valve cover. Any other pics would be good too, but it's hard for me to visualize what I should be seeing, because I haven't seen it before. Thanks a lot.

 

Like i said, i cant post pics, but after about 10 min of driving (to get to normal temp) look in the oil fill hole. I Had to use a small flashlight, but i saw bubbling and a small green pool of antifreeze. I cant see anything once the engine has cooled though man.

 

Thanks for the quick reply, Truck. That does help.

 

Do you leave the engine running or turn it off when you check for bubbles under the oil cap? I'm wondering if taking the cap off with the engine running would create an oily mess.

 

Sometimes you can see it under the filler cap, sometimes you can't. Another good technique is to pull the valve cover and perform the inspection. They always crack between cylinders 3-4; that is where the casting defect is.

Here is a link to a thread on the 0331 that contains some pics.

http://www.jeepsunlimited.com/forums...d.php?t=391831

 

I didn't want to take us too far into left field with my own questions-- so I thought I should point everyone back to the OP's latest.

 

So i have started getting estimates on the labor for replacing the head, and i just got one for $1000!! Just for labor!!! Am i cheap, or is that on the high side? Mind you, this is ONLY for labor as i anticipate providing most/all of the parts. The other estimates were around $400-$500

 

It's not a fun job, but a properly equiped shop should be able to handle this in an afternoon, so $400-$500 sounds about right for me.

 

Ok, thanks for the confirmation of my sanity. But I think i would have fun helping out and learning how. Experience can be a cruel teacher though.....

 

If the oil pressure is low as a result of the bearings being bad, why do some say a rebuild is necessary while some say just replace the affected bearings?