OleBlue

its very possible to crack the 0630 head, just like any other head, if you drive it overheated like your wife did, something is bound to break

cherokee_99

Today we flushed the radiator. After doing so and running the jeep a minute we noticed the head crack was larger and the oil in the dipstick was now milky. This is the first time the oil has been milky in the dipstick. Think the flush cleared debris in the crack making it flow more?

With the oil now milky what are the chances the block is bad? Just wondering if it's worth the cost of a head or if the block is shot

Turbo X_J

If the oil pressure is still good don't run the engine anymore. I think the next step should be a compression test, see where you are after that. If you add 1 qt. of G.M. top engine cleaner you may be able to slow down the damage done by having coolant in the oil.

cherokee_99

I found a 7120 head and saw that it would work in place of the 0630. Are there any mods i need to make? I've never switched head models like this so as much info as possible is appreciated. Thanks everyone!



Btw....only went with the 7120 because it's what I found

Kalali

I didn't want to be presumptuous but it was almost certain that the head had cracked when you reported the 0.017" warping. My theory is that he 4.0 heads are fairly long as compared to most V6/V8 engines and that combined with the iron material don't respond well to the slightest warping. Fortunately you don't have to worry about the coil pack placement on the head and that will provide you with more options. Just need to make sure the replacement head matches the intake/exhaust manifold ports.