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Old August 26th, 2017, 08:43
chilipepprflea's Avatar
chilipepprflea chilipepprflea is offline
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'00 XJ Overheated again

The only major problem I've had with my 2000 XJ 4.0 is overheating. It seems to occur once a year and for different reasons, according to the mechanics.

In the last few years, I've replaced the water pump, t-stat (twice), hoses, radiator, head gasket, and of course coolant.

The other day, I drove for about 20 mins on a 92 degree day, then parked and let it run for 5-10 mins with the A/C running. The check gauges light came on and I saw the water temp was high so I immediately shut off the engine. I opened the hood, checked under the car, and no coolant had overflowed. The coolant was at a normal level in the reservoir. There was some liquid on the ground, but I believe it was condensation from running the A/C while sitting.

After letting the engine cool off for 15 mins, I tried starting it again (I was curbside at the Departures area at the airport and was getting hassled about sitting there). The started cranked, but the engine wouldn't turn over because it was still too hot.

I waited longer, started it up, and away I went with the temp gauge dropping to normal levels for the hour drive home. I haven't had a problem since, though I haven't let it sit and idle for too long.

My question is, what could have gone wrong and why would coolant not be dumped if it overheated?

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Old August 26th, 2017, 09:16
RCP Phx RCP Phx is offline
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Re: '00 XJ Overheated again

That's what my 2k did for a year leading up to complete failure! A good chance that combustion gases are getting into your cooling system creating air bubbles within the cylinder head. There was no loss of water until towards the end. Remember the cooling system only get up to about 15psi whereas the combustion pressure reach over 100 psi! I suggest you start with a sniffer test of the coolant!
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Old August 26th, 2017, 10:16
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Tim_MN Tim_MN is offline
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Re: '00 XJ Overheated again

A low cost DIY test kit can determine if there are combustion by-products in the coolant.

The cranking and not starting is very likely heat soak, a common issue with the 2000-01 4.0L.

Originally Posted by chilipepprflea View Post
... drove for about 20 mins on a 92 degree day, then parked and let it run for 5-10 mins with the A/C running. The check gauges light came on and I saw the water temp was high ...
With the symptoms described, I would suspect a weak mechanical fan clutch. Is the electric fan operational, and turning ON when indicated temperatures are about 218* ?

Originally Posted by bimmerjeeper

Blanket caught in the rear liftgate latch. Now I can't open.

Last edited by Tim_MN; August 26th, 2017 at 10:21.
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Old August 26th, 2017, 12:47
md21722 md21722 is offline
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Re: '00 XJ Overheated again

Based on sitting idling with the A/C on, I too would suspect the fan clutch. If it's original just change it. They can pass every test you'll ever read about, but still not push the air they're supposed to.
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