Another overheating thread

[disco_nex]

Yes, I know it has been slaughtered to death on overheating. Got to love XJ's and overheating. If possible, I would like some experience to solve this problem.

The facts: Radiator was replaced less than 2000 km ago. The thermostat is now brand new (and has not fixed the issue), Water pump was replaced approx 25000 km ago. I can guarantee the temperature gauge is working correctly. I have a manual override switch for the A/C fan in case I want to personally turned it on (a great modification)

History: I have replaced the radiator less than 2000 km personally. It was refilled with a less than perfect 60/40 glycol water mixture, and it warmed up quicker than usual, but held the temperature as usual, with nowhere near any overheating. The XJ ran a solid 100-110 km/h trip out west for 1000 km before coming home for its usual trips to and from work.

I went for a fishing trip and it ran perfectly fine up to the location. The trip home is when the issues started to occur. It started overheating (close to redline) all the way home. The load was two persons and light camping gear. I got home and could not fine any issues. I ran it to and from work for a month with the manual overridden A/C fan on and the gauge always read between 75-105. Without the extra fan, it would run higher, closer to overheating.

Recent issues: After running the XJ with one person without issues, I picked up a mate and his camping gear for a fishing trip. With an extra approx 150 kg load, the XJ ran higher temps throughout the whole trip. The faster it went (60 km/h compared to 100 km/h), the higher then cooling temperature. When I hit the sand, that's when the temperature when to past overheat (overflow bottle was spitting water (ended up loosing 5L.). That was home time, where it drove as before the sand experience.

Question: I believe it's a water supply issue (blockage or water pump/impeller), while my father thinks it may be the catalytic converter (as it seems to be weeping a bit of water (1 drip per 15 sec at idle and parked). Lord knows how the catalytic converter can stuff around with the cooling system to me.

I'm looking for some ideas. I appreciate the time. Thanks!

[Big Dave]

Have you checked the fan clutch?

[anthonygubbin]

Are you losing coolant?

regards A

[tazwegion]

Originally Posted by disco_nex

my father thinks it may be the catalytic converter

A damaged (ie. broken or clogged) catalytic converter causes additional strain on the engine thereby altering it's running temperature, additionally MPG gets worse (this happened to my last XJ)


Did you flush out the cooling system when you performed the radiator and/or water pump swap?

+1 on checking out the clutch fan operation too!

[ruffy01]

Water in the exhaust? surely that implies a head gasket.

[Doctor W]

Originally Posted by ruffy01

Water in the exhaust? surely that implies a head gasket.

You always have a bit of water in the exhaust.....for every gallon of petrol you'll also have a gallon of water (exactly how much depends on humidity, water in the atmosphere) going thru the engine and as part of combustion process - that's why engines run better in higher humidity and colder air. Most engines will have light pinging in dry, hot air if timed optimally for "normal" temps and humidity.

A third vote for checking your fan clutch!

But it shouldn't make a difference at speed, so this could be something else or more than one cause......maybe fan clutch AND a disintegrating/ed Cat ???

[tassiecj6]

pull the water pump of and check the impeller blades .
they have been known to disintergrate in harsh water .my 95 did .
does it have addative in it ?