Dynapak951

My dad's cherokee has been losing coolant for months after I changed his radiator his or Gina did have a leak. Then he started noticing his oil pressure getting lower and lower over a few weeks. I changel the oil about a month Pryor for him. Oil was clean. So after he told me this I said how bad I mean the keep has 206k so figure bearing had some where but checked oil and it looked like coffee with milk so he drove sparingly and then I pulled the head today. Can't see a Crack in it but a lot of caked rust in the water jackets?






Thats not right.



Heard of micro fractures that you can only open up once when at temperature. Like I said he caught oil pressure problem quick. Car ran great no noise hesitation etc.

Firestorm500

Pull the engine.

Replace the head with an aftermarket one.

Rebuild the lower end. Oil pressure is mainly developed in the bearings, especially the cam bearings. The damage was done before you noticed it. Today's oils have to have a whole lot of coolant in them to go milky.

It's the only way to be sure. Engine has high miles anyway.

tjwalker

I agree with Firestorm500. Rebuilding the engine and a redesigned head like from Clearwater or a used TUPY head that has been gone through at a machine shop is best option for the long run if he plans on keeping the XJ or find a replacement salvage yard engine.

Once oil pressure starts to drop, there is already significant bearing damage. I've seen a lot of guys slap a new head on and cross their fingers, but they usually end up doing the engine as well.

Cane

the crack can literally be as thin as a hair and you'll never notice it. like others have suggested, time to replace the head.

you can manage to do it with the engine still in, or do like it was said above and dig in the block.

Dynapak951

jcollege

The crack in my head was super thin, but you could see where the coolant was seeping out. Got a new one from Clearwater, in the process of installing it now.

extrashaky

I think I see where you're trying to go with this. Even if that head is not cracked, it would be a mistake to try to reuse it. Yes, you may have just had an old fashioned blown head gasket, but it would be foolish to put that crack-prone 0331 on a rebuilt engine and have it pop a few miles later when you can bulletproof that motor now with a Clearwater head. Send that one to the scrapyard.

Also, that mud you're seeing in the water jackets is probably not rust. You probably had exhaust gas getting into your coolant and boiling it. When coolant boils, it precipitates out a sticky mud that clogs up everything. If that stuff is in your coolant system, plan on a complete cooling system overhaul with the new motor. Your old water pump is probably already damaged by that crap flowing through it, so don't swap it over to the new block.

For future reference, you can't always see coolant in oil. The detergent package in the oil is designed to trap moisture from condensation inside the engine until it can be boiled off when the engine comes up to operating temp. What used to happen is that if you got coolant in your oil, it would be too much for the detergent to bond, so it would sit there in an emulsion that made the oil appear milky.

Now, however, the detergent packages have gotten so good that they can chemically bond a lot more moisture. The up side is that it takes a little longer to do damage. The down side is that you can look at some oils full of coolant and not see it. I was using Mobil 1 synthetic in mine, and it never went milky at all even though I could see the oil level rise on the dipstick. The only way to be sure whether you have coolant in your oil is to send off a sample for analysis.

Dynapak951

[QUOTE=extrashaky;3254329]I think I see where you're trying to go with this. Even if that head is not cracked, it would be a mistake to try to reuse it. Yes, you may have just had an old fashioned blown head gasket, but it would be foolish to put that crack-prone 0331 on a rebuilt engine and have it pop a few miles later when you can bulletproof that motor now with a Clearwater head. Send that one to

Thanks for the reply and info I am not going to rebuild engine but I will do lower bearings I'll order head tomorrow from clearwater and I'll pull oil pan and go from there. Does anyone have a part number for lowering bearings etc. Thanks