foggdog

Ok, Im new to the forum and posting on behalf of my cousin...He's got a 2000 grand cherokee laredo with the 4.0 Inline 6 with 106k on it. His problem is the coolant keeps gettin low with no apparent leaks and says oil looks fine (no milky look). Runs great he says, but has taken it to shop and their trying to get him to buy a new/rebuilt motor . So thought I would get on here and hope someone could tell me whats goin on or what to look for.
Thanks ahead of time, Foggdog..

97xjCrow

Ive had that problem on both of my xjs, a good flushing helps . Most likely the coolant is boiling and therefore evaporating.

foggdog

Thanks Crow I'll let him know. Much appreciated.

97xjCrow

Yep, i would also install a lower degree thermostat to keep the boiling temp down. I have a 160 in mine and it still runs about 180

foggdog

Was thinkin about that, will do. Thanks again.

Firestorm500

unlikely

Cherockee

well, all of you might want to think again....

First off, dissapearing coolant in the model 2000 4.0L motor is a sign that you might have a cracked head. A block test can be preformed by a mechanic which will almost tell you for sure. It sounds like this may already have been done if he has someone telling him to replace/rebuild the motor. They may have not been far off the mark.

Aside from that, running a lower temp t-stat will usually cause poor proformance and gas mileage and is strongly not recommended by most professionals. If anything people who do this are band-aiding another problem that they are too lazy to diagnose.

Firestorm500

won't help.

Firestorm500

Unexplained coolant loss is a real good indication of a cracked head and/or blown head gasket.

Lack of milky oil is not proof that the head or gasket is not bad.

2000 XJ with the flawed 0331 head. The mechanic shop is probably right. Just because someone tells you something you don't want to hear does not mean they are trying to rip you off. Don't blame the messenger.

97xjCrow

k

foggdog

Hows come he cannot find no signs of leak then ? just askin, when he first told me about it I thought head or gasket, but wheres the coolant goin then if there is no sign of leak anywhere. Just tryin to help my cous and save him some money if possible. This 0331 head is known to be faulty ?

97xjCrow

So you said because their is no water in the oil it could still be a bad head/ gasket? So where is the coolant going ? Outerspace? Comeon. water seperates from oil, change your oil its easy to tell if it has water in it. If the head or gasket has been damaged, and there is no leaks. YOU WOULD HAVE COOLANT IN YOUR OIL. there is no denying that. All the 4.0s i have owned have always ran on the high side or just at 210 and thats just one measurement of temp from one location. When you turn your car off, the temp actually goes up 13 to 14 degrease because there is no circulation. This takes place the first 15 minutes after you shut it off. If he is running at 210 or near there, there is a good chance when he shuts it off the water temp goes up to around 230. During that short period of time, the water can boil and cause some coolant to evaporate. a 160 degree thermostat is not a bandaid and i get 19 mpg with it, and would hardly say it suffers performance loss. And a coolant flushing is recommended anytime when adding any coolant to a system if you want to get technical about it.

zombie jeep101

Yes, well known.

O.p. Are you running coolant or just water?

Firestorm500

It's blown into the cylinder(s), where the coolant is being burned.

Yes, the 0331 head is infamous in Jeepdom. You won't have to search far on these forums to find us talking about it.

Unless your cousin is married to his Jeep, or is willing to sink a fair amount of money into it to fix it, he might be better off selling it.

While he still can.

Firestorm500

Quote: "Comeon. water seperates from oil,..."

Actually, when thoroughly mixed together in an engine, they form an emulsion.

It ends up looking like chocolate milk.

Has about the same lubricating properties also.