4.0l XJ Overheating

[eksjay]

What does it mean, if the top large hose coming from the radiator leading to the front of the engine (I assume the water pump) has expanded in places?

Does it mean that the water pump is on the way out or has died?

There is no sign of a leak so far.

I opened the bonnet after experiencing a 115 deg C climb which came back down to 100 deg C when the aircon was switched on - a departure from the regular 95 - 105 deg C range.

Is there a blockage somewhere that is causing this expansion?

I haven't really noticed the expansion of the hose before but only did so when I hadn't switched the aircon on and the car was still hot.

The radiator was changed about 7 years ago, not that it needed changing back then, but the stealer could not find the source of a coolant leak - it wasn't the radiator.

What is the typical cost of an XJ waterpump and thermostat and labour?

[eksjay]

Originally Posted by eksjay

What does it mean, if the top large hose coming from the radiator leading to the front of the engine (I assume the water pump) has expanded in places?

Does it mean that the water pump is on the way out or has died?

There is no sign of a leak so far.

I opened the bonnet after experiencing a 115 deg C climb which came back down to 100 deg C when the aircon was switched on - a departure from the regular 95 - 105 deg C range.

Is there a blockage somewhere that is causing this expansion?

I haven't really noticed the expansion of the hose before but only did so when I hadn't switched the aircon on and the car was still hot.

The radiator was changed about 7 years ago, not that it needed changing back then, but the stealer could not find the source of a coolant leak - it wasn't the radiator.

What is the typical cost of an XJ waterpump and thermostat and labour?

To clarify - the hose had expanded between the sleeve protecting it from the pulley and the water pump. The rest of the hose was its regular size. I had another look at it now that the engine temp is cooler and the area of expansion went back to normal size.

At the time I stopped the engine running, I could smell a disc brake type smell coming from the wheel area but it could have been the disc brakes.

[bruggz351]

I'd be replacing that hose man. Sounds to me as though it's gone soft.
Did it blow up, like a balloon?
Was it the top hose or bottom hose?
Does the overflow work? Perhaps the radiator cap isn't releasing pressure.?

[eksjay]

Originally Posted by bruggz351

I'd be replacing that hose man. Sreplacements to me aTelco. ugh it's gone soft.
Did it blow up, like a balloon?
Was it the top hose or bottom hose?
Does the overflow work? Perhaps the radiator cap isn't releasing pressure.?

Its gone soft between the pulley and the engine. I bought A new top hose from repco but have not installed. Yes, the existing hose blows up like a balloon when hot, and deflates when cool, but remains soft in that section after deflation, while the rest of the hose is firm. I am guessing the bottom hose might have same issues. Will get a thorough cooling system check done.

[bruggz351]

Originally Posted by eksjay

Its gone soft between the pulley and the engine. I bought A new top hose from repco but have not installed. Yes, the existing hose blows up like a balloon when hot, and deflates when cool, but remains soft in that section after deflation, while the rest of the hose is firm. I am guessing the bottom hose might have same issues. Will get a thorough cooling system check done.

Hey eksjay, how did ya go with this mate??

[bruggz351]

Hey peoples, just thinking out loud so tell me to shut up if this seems silly

I was reading an article in Autospeed recently about under trays and engine bay air pressures etc, and the effects on air flow and temperatures.

I can't remember, and I'll be stuffed if I'm going to re-read this thread, if anyone has mentioned any differences or effects upon removing the front bash plate!!

I'm going to replace mine to see if I get any change in highway temps... I shall report back here...

cheers

[rastus2571]

Originally Posted by bruggz351

Hey peoples, just thinking out loud so tell me to shut up if this seems silly

I was reading an article in Autospeed recently about under trays and engine bay air pressures etc, and the effects on air flow and temperatures.

I can't remember, and I'll be stuffed if I'm going to re-read this thread, if anyone has mentioned any differences or effects upon removing the front bash plate!!

I'm going to replace mine to see if I get any change in highway temps... I shall report back here...

cheers

Bruggz, Very interesting you made this suggestion. That has merit. However there is no need to remove the bash plate as you suggested. These Aussie XJ's are devils for overheating. Mine doesn't since I rebuilt the cooling system, right coolant mix. Go Jeeps hose restrictor and a new a/c condenser and raised bonnet at the rear. I was involved many moons ago in class 7 off road racing and I know a select amount of people that we have all followed from the years and they have all branched out into various forms of motor sport all over the world. Peter, who worked for Richard Petty, Nascar champ who actually now works next to to me as a matter of great karma, builds street rods and drag races himself reckons we have got it all wrong with our raised bonnets and vents. He said that has merit to a degree with what we do but jeep stuffed up with our aussie models. Pete and I had a good talk a few months ago. He said airflow from underneath is the most important towards upward vents such as a bonnet effect. Ramflow effect for a road vehicle. Drilling 1/2 holes in the standard bashplate on the XJ at 3 inch spacing from each hole will give a great upward draught effect. Now I follow this theory as I posted a long time on here ago about a rear mounted tranny cooler that would keep mud and crap out with scoops but allow upward reverse downward flow dropping the crap out on a splashplate but let air in. Here was his solution and I am seriously considering it due to Pete taking airflow into consideration and the off road environment. Drill the bashplate as described, drop the bonnet back down, install rear bonnet vents on the last 1/3 of the bonnet from the centre fold to the edge fold. These are the Bunnings cheap vents to use. Both vents in both inner guards with vent upwards just behind rear shock tower. 86mm holesaw through inner guard then pop rivet vent to inner guard. This will keep crap and water out of the engine bay and allow hot air up and out from the rear vents and the fan will back blow it out through the inner guard vents. I'm going to give it a go. I have seen the machines Pete has built over the years and I cannot fault them. Might be hard for some, but easy for others. Bypassing the auto cooler out of the rad to an external cooler creates stable temps too. I run a Derale cooler with a 10 inch fan for my auto totally cutting the rad cooler out and it is great. Sand, mud, low range, idling. 70-80 does not move with a/c on offroad or traffic jams. I have a manual over ride for the a/c thermo if needed. Mine in normal running sits on just on or above 70. And m.temp gauge is not faulty.

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