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2000 XJ 1 Gal+ Low Coolant??

1987Comanche

NAXJA Forum User
Location
NC
One of my friends brought his 2000 XJ (4.0, 82K) over to investigate a noisy fuel pump and, while under the hood, I noticed his overflow tank was completely empty. Additionally the radiator was about 1/2 gal low. I didn't see any obvious leak points but I'm not sure how long it took for it to loose that much coolant.
I'm thinking there's a good possibility he messed the head up by running it that low (0331 casting if I'm correct). The oil looked clean so I chided him for not watching the coolant level and told him to keep an eye on everything. How long until I'd see evidence of a problem with the head??
 
The symptoms I would look for are using coolant (which you have) and look for milky residue on the bottom of the oil fill cap. This is what I also have. Mine has been this way for too long already. I have never seen any evidence of coolant in the oil like increased oil level or milky looking oil.

If you run it that way, you are highly risking catastrophic bearing failure.
 
you should know in a weeks time. If the coolant is low again in a week and no external leaks seen take it and have someone put a pressure tester on the radiator. If they find no external leaks its more than likely the head.

The key is catching it early before it wipes out the bearings. I have one now that belongs to a friend of mine im putting a engine in.
It would loose about a pint of coolant a week. The oil never showed overfull, or milky. BY the time it was brought to me it was dropping oil pressure. Oil still did not look milky at all..... pulled the valve cover and I could see a green tint on the engine parts.

Catch it early and fix it before any more damage occurs.
 
You say the oil looks good.
First ask the obvious.
Did he recently change out the coolant or flush the radiator?
If yes, Was it refilled properly?
Pressure test the cooling system, look for leaks.

Then look under the oil filler cap, is there any coolant looking residue there?
Look at the exhaust, is it very wet? Coolant could be finding its way through a cracked head into a cylinder & getting pushed out the exhaust.
 
I looked in the valve cover and the bottom of the filler cap. No residue and everything looked fairly clean. Exhaust looked ok (a bit wet but I wouldn't call it excessive). He had the cooling system flushed in October and I would hope it was refilled after that. No telling for sure, however.
I told him to keep a close eye on it and figure out how quickly it's loosing coolant. Also of note, what little was left in the rad was fairly cold considering the engine was close to normal operating temp.
 
Or it could be a 0331 head ( right number?) I'm kinda new.

Didn't the bad heads affect 2000, 2001?
 
Or it could be a 0331 head ( right number?) I'm kinda new.

Didn't the bad heads affect 2000, 2001?

Yep, sounds about right. The corrected 0331 head has "TUPY" in the casting but I'm not sure when that started getting used.
 
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