Hi everyone-
I was on a roadtrip today when my 98 vdp began to run hot. I pulled over and let it cool down, then drove off again. From this time on (20 or so miles driven) the car temp read normal, but now I just noticed coolant leaking from underneath. Any ideas as to the cause? Any common occurences like this? A busted hose? Could it already be the radiator, even though the car is mint and has only 66000 miles? Thanks for your time---

 

From what I've read I think the thermostat housing is plastic on the XJs and has a tendancy to crack as it ages. Plastic and flexing from the engine to the radiator is never a good idea long term. Apparently the XJR has a metal one which fits fine and most upgrade to this. I'm guessing it is leaking up front as you're thinking radiator. Honestly, a radiator life is about 10 years or so before it starts to give issues... esp. if the fluid hasn't been attended to somewhere durning that time. I know its a pretty old school thought but most modern radiators tend to go before 15 years as well.

 

Also, I just noticed that the coolant leak only happened after the car was shut off...any ideas? Where can I check the coolant fluid level? Thanks in advance!

 

Are you sure or was it burning off when running? Where is it dripping from?

 

HI,
Well, i noticed it dripping immediatly after I parked. It seemed to be coming from the left to middle of the drivers side....also coming from what I think is the brake cooling duct for the drivers front wheel. It happened in a parking garage, so I went back to where I stopped to get the ticket, and there was no leak there or leading up to where i parked. Somehow I doubt that much coolant could have burned off without me noticing a smell or smoke coming from the engine. Additionally, when i drove off the car was running at normal temp until i hit traffic. Then, it seemed as if the temp needle would rise and fall according to the stop and go of the car (like hot for a few seconds and then back to normal in a quick time span).
Two questions in addition to above: Where can i check the coolant level? and Are these temp concerns most likely indicative of a faulty termostat?
Thanks again for your time--

 

These cars have a history of several common leak points which can be brought on by a case of overheating. Some only leak after the engine cools off. To your questions; there is a coolant reservoir at the left rear of the engine. Remove the cap only when cool.

Common leak points:

Thermostat housing cracked - plastic, replace with an aftermarket aluminum one which is not the XJR/XKR version.

Water pump - they all wear out sooner or later and yours has a history of shedding its plastic impeller blades causing overheating.

Coolant reservoir - again plastic. Besides leaks the plastic pressure cap can fail pumping coolant directly into the overflow container, never to be returned.

Climate control hose connectors - again plastic

Use a pressure tester with the engine cool to easily find leaks. Completely resolving a cooling problem is imperative as overheating the aluminum engine can result in damage that will economically kill the car. I would add that the temperature 'gauge' is really an idiot gauge. If it is moving off mid point it is screaming 'help me'.

Without a history documenting repairs I would replace the water pump, the thermostat, the thermostat housing and the upper and lower radiator hoses. They will now be 13 years old.

 

Thanks for the input,
When the mechanic did the upper tensioner fix, he also replaced some plastic piece with metal related to the waterpump,not sure what it was...I've driven the car today and no more leaks, but the temp gauge is still going crazy in stop and go situations.....

Is this the thermostat?
Where do I check the coolant level ????
Thanks again---

 

It is likely a thermostat problem but there are a couple other issues that could cause the problem:

coolant level, fan fuse, fan relay, fan, etc.

Remove the coolant reservoir cap when not hot. Fill there. Do not remove the cap when hot . . . you will regret it a lot if you do.

This needs to be resolved immediately! Aluminum heads are very expensive.

 

Ive removed the cap just after shutting down the car, with no hiss or apparent pressure escaping. When I look in there, I can still see fluid, even touch it if I stick my finger down the hole. Where should I fill it up to? Any chance of overfilling?
Thanks

 

Like Test Point said, the coolant reservoir is under the hood, left rear. It has a black plastic cap on it that says 'Do not remove when hot' or something to that effect. Not to be confused with the brake fluid reservoir which is further left and blue (I think). Look down in there and see if you can see light reflecting off the coolant. The water pumps in these cars fail - period. They have plastic impellors or vanes that disintegrate. The first thing I did when I got my car was replace the water pump with one that has an aluminum impellor and replace the thermostat. It sounds like your temp guage has issues. Do not trust it. Mine goes weird every so often, as it will not "park" correctly and it will start off in the middle and end up at the top, but I know what's going on. Then it will "park" itself after a drive and be fine for months. It's the only guage that is a little flakey - sometimes.

 

Also, the fan seems to come on every time the car is shut off for about a minute or more, and this was happening before any symptoms arose with the temp or leaking fluid. So, the fan works, but maybe not correctly?

 

Just fill the reservoir to the top ring. Overflow will only go into the overflow container without any issues. If you removed the reservoir cap on a hot car and did not get a hot bath the cap itself may be bad. It should retain about 15 lbs of pressure and should boil over when removed hot. If it is not retaining pressure it will simply pump coolant into the overflow container leaving the system dryer and dryer.

 

Hi everyone,
Just wanted to say thanks to everyone for their input and also give you guys an update....
I drove from Charleston to Hilton Head today, about 80 miles, and the car temp read normal the whole way with one exception: stopping for more than a few seconds or going only 1-5mph, the needle would rise into the red, only to fall again a second later when back on the move. Quick check upon arrival of the cooling system showed no leaks, and the coolant level was where it had been when I topped it off before the 80 mile trip. This whole issue is kinda weird to me... Do you think it is most likely the water pump? The coolant cap? All the hoses look good, and the car hasn't leaked since the other day, which I have pretty much narrowed down thanks to you guys as being from the overflow resevoir. The fan does still comes on for 1-2 minutes after the car is shut off however, but it was doing this a while before the temp issue ever surfaced....
Part of the fun of this car is that it keeps me guessing....maybe you guys can help me with answers....
thanks again--