Hi there,

Before I book into my local Jag dealer I thought I'd see if there's anything obvious I can check for prior.

I'm not a mechanic but I'm not shy of taking on basic auto maintenance tasks (and have done in the past) but, as Dirty Harry says, a man's got to know his limits :-)

...anyway...

My 2001 XJR has never got hot...always creeps up to the gauge mid-point and stays there.

However...today I notice it sitting way up at the red-line, now I know not much faith can be put in the gauge reading but suspect it still means something is wrong somewhere.

At about the same time I noticed the temp gauge I also noticed the AC seemed to have switched off as the car seemed to get humid (it's been very hot in Sydney at the moment, so when the AC stops the car gets stuffy very quickly).

The fans were on [I think full blast] when I stopped the car temporarily prior to noticing the overheating.

I checked the coolant level and noted it was sitting about 3-4 cms below the kneck, but still plenty in there.

Is there anything else [simple] that I can check before I book it in to be looked at?

Thanks for any advice or help.

Regards,
Troy.

 

This may be a no-brainer, but too much antifreeze/coolant in the water can cause overheating. The coolant really isn't a heat transfer medium but more of a system conditioner. It's the WATER in the system that actually promotes the cooling. There are inexpensive test kits for the correct ratio.

 

Erm, it does still have a serpentine belt? It hasn't snapped?

 

I'll check that as soon as I get the chance.

I've also noticed that the fans don't seem to be working consistently, they were on but when I stopped my car with the gauge in the red the fans weren't on.

...and the AC seems to be barely working :-(

 

Thermostat?
Coolant leak?
Bad fans?
Bad water pump?

Those are the ones I would investigate first - my XJRs over/under heating issues all happened in that order, but not all a the same time

 

Hmmm, I wonder if it's safe to drive to the mechanic in this state, providing the temp doesn't hit red again?

 

To add to previous good advice I wonder if you have a small leak resulting in an air lock. A bit risky driving if it goes into the red !

 

Fans should be blowing hard long before overheat. Fans will also run with AC on. On our VDP, one of the fans got intermittent and it would run hotter than normal. Fortunately the wife was pretty observant and didn't do any other damage.

I ended up repairing the fan motor by changing the brushes. The originals were very worn out. Oddly enough, the other fan was just fine. In hot weather both are needed to control temps if the car is not moving.

The AC will not work without the fans.

-Mike

 

Compare the cost of a tow versus the cost of a new engine.

Your coolant level should be just under the bottom of the filler neck.

 

It is NOT a good idea to drive the car anywhere with an obviously compromised coolant system.

If the fans do not come on when the AC is on it is a fan system problem. If they do come on then the thermostat is the most likely villain, then water pump.

 

Easy test ...

if the AC is turned on, the fans should be on. That's the way it's designed.

If the fan does not come on with AC on after a cold start get it towed unless
you can fix the problem.

 

For those who have had a "low coolant " warning light that was hard to remove try this.
Unplug the electrical connection {its a wire clip retainer} Pull out the sensor and clean the tube with fine sand paper.
Take dental pick type tube and gently rotate the white circular float {that contains pin like magnet to ensure its not jammed in! Clean contactor , join plug and re insert the sensor. Fishing for magnet gives wrong impression for fix . Its loosen the float containing the magnet . 10 miute fix to a 3 month irritation !!

 

Just for clarification . . .

The removable reed switch tube is isolated from the coolant by the tube integral to the tank that the switch is inserted in and that the magnetic float rides on. Cleaning the reed switch tube is not going to have any affect on the float. The point is that moving the float around on the tube that is part of the tank cleans some of the 15 years of junk off and allows it to float again.

 

Thanks to everyone for their advice. I've not driven the car but found a mechanic that's quite close (5mins) so I'll drive it to them rather than risking the 30min drive to the Jaguar dealer/service centre.

Based on everyone's input, here's what I'm guessing:

1. No coolant loss, not a leak/hoses
2. No fans on when the cars hit the red-line

Most likely:

1. Fans
..then...
2. Thermostat
3. Waterpump

I'll report back just in case anyone's curious

 

Post of the resolution results is the cost of the free advice.

 

Go Back to Basics , take a flashlight at night shine it from the engine compartment with a helper and see if your Radiator or most likely the AC condenser is Plugged up with Bugs causing an air flow problem :-) car should cool at speed regardless of fans unless you have a airflow blockage or a coolant blockage in your radiator

 

TXE36, do you have the info on were you brought the brushes from? Part numbers and such. Was it hard to replace the brushes?

 

AFAIK, there are no direct replacements and I don't think the motor was built to be serviceable. You have to bend metal tabs to get it apart and make your own set of brushes by modifying a standard set. I used these .31" x .31" x .55" BRUSH 33L . The motor has 4 brushes. I paid ~$27 with shipping.

The brushes need to be filed down to fit, a messy (graphite goes everywhere), but fairly straightforward process. Then the leads have to be soldered, whereas the originals are welded.

I would consider it a fairly advanced project to re-brush one of these motors, but not something impossible if you understand electric motors have decent mechanical skills. I would have preferred to replace the motor, but I couldn't find any at a reasonable price. I also would have preferred a better fitting brush, but the 33L was the best I could find.

Make sure the bearings are good before messing with the brushes. If the motor doesn't turn freely, brush replacement won't really fix anything.

-Mike

 

Update!

It appears that the top fan has "burnt out". The mechanic has said that the bracket holding the fan was broken resulting in the fan collapsing on itself and subsequently burning out. He said it was very odd, as if some impact had damaged the bracket.

Apparently I need to replace the whole dual fan unit which in Australia costs $1,350 (US$ 1,054) and another 4 hours labour to replace it.

...apparently I should be grateful because I managed to get the last unit in Australia - although the looming $1,800 bill has put a dent in that gratefulness

Troy.

 

Anyone know the part number for the dual fan assembly for an 2001 XJR?

From my googling it looks like it's: W0133-1597400

Troy.