mikesignal

I've been reading some posts on the 0331 head. I came accross one where someone suspected a cracked head but they could not see the crack. they did an oil analysis and found antifreeze in the oil. sounds pretty simple. I saw kits online for around $20. has anyone used one of these kits and have any feedback? thanks.

belvedere

Yes, a UOA is a good idea. Which lab were you looking at?

mikesignal

I was looking at a DIY kit, and I was looking at blackstone labs

belvedere

Though I haven't used Blackstone, they are a well-known lab. I'm sure they would do a good job.

bigbadon

The spot test on blotter paper works well but you have to know what to look for. The sizzle test is easy, just pull the dipstick after engine warms up and dribble some oil on the hot exhaust manifold. If it sizzles it has water in it. If you can't see the crack and coolant is getting in your oil it could also be a head gasket problem. A simple test to rule this out is to drop a bars stop leak pellet in the radiator. The stop leak pellet will usually (not always) stop MINOR head gasket leaks but it will not stop leaks from a cracked head.

mikesignal

thanks for the replies. I was looking in the oil fill cap last night and notice some discoloration on the head. It's very small, maybe the size of a nickel. I almost want to say there looks like a small crack starting right next to that, but it's hard to see. I will try using a magnifying glass. it seems easier to see in there at night with a flashlight than in the daytime. I might just invest the $25 and get the analysis done by blackstone. I'm going to go see what they have at the local auto parts store too.

bigbadon

How much coolant are you losing? How often? Does your oil turn black soon after you change it? I have a 2004 GC with a salvage 2000 4.0 in it. Do not know history but suspect cracked head because of low oil pressure. I cannot see any crack and head looks extremely clean. I was losing a very small amount of coolant like a pint every couple of months so I used the blotter test to verify I had coolant in the oil. I put Bars pellet stop leak in radiator and the coolant is no longer disappearing. After 3 regular oil changes the blot test is coming up clean.

mikesignal

I just noticed the resovior is a little lower than it was a few weeks ago, not by much. I don't really use the jeep much, it's a spare vehicle, so it's hard for me to tell. Right now it's sitting in my driveway with the evaporator and heater core housing out of it. Hopefully I'll have that done by the weekend. I've been working on it little by little the last 2 days after work. After I get it back together I'll do one of the oil tests. Oil pressure is good on it also.
I did read in a thread somewhere that someone used a sealant on the head itself to seal it up. I don't remember what he used, but it was purchased a a local parts store.

bigbadon

USE CAUTION with block sealers because their main ingredient is silicates (water glass) which will destroy an engine if it gets in the oil.
Head cracks on the 0331 head are impossible to seal because the crack size constantly changes with engine temperature. Block sealers have been known to seize engines....this is the same stuff that was poured into the oil to destroy "cash-for-clunkers" vehicles.

mikesignal

you used Bars pellet stop leak. is there any downside to using that?

bigbadon

Not unless you use more than the recommended amount. IT WILL NOT stop a cracked head from leaking but it will usually seal a LEAKING (not blown)head gasket. OEM have used this stuff on new vehicles for years to guarantee against gasket leaks.

Radi

Yep. I believe GM's shipped with 2 of the pellets installed (Certain Cadillac motors had 6 IIRC) up until a couple of years ago. It's made of ground ginger root. It's absolutely harmless and does work on minor leaks.