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Jaguar XK8 Problems: Cooling system & Suspension

Maintenance/Repairs
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#1

Hello,
My 1998 Jaguar XK8 Convertible has several problems I can’t get to the bottom of:

Problem 1: The cooling fans seem to stop working, and I’ve replaced the cooling fan relay, which fixed the problem, but I noticed the cooling fans don’t kick on anymore. I sense the car gets hot, but the temp gauge doesn’t really show fluctuation unless the temps get really bad, which it doesn’t show. The car absorbs coolant somewhere slowly, about 1/3rd of a quart per month. (I had the engine replaced after similar trouble already). One other detail to point out, when I turn on the vents to bring in outside air, it comes in hot even though it’s cooler outside, and if I kick on the a/c, then the air drops to room temperature. I have done a lot of work to this car, including replacing the engine with a used one, changing the water pump, thermostat, upper and lower radiator hoses, “octopus hose”, among many other parts. I’ve had the car at Jaguar dealers and independent Jag specialists that are really stumped. It’s been at a indy Jag guy for a week now with no diagnosis.

Problem 2: The driver front tire is high and rubs the tire well when I hit bumps. The suspension was never lowered. I was originally told it was a ball joint. I had that plus the control arm changed (they come together). When that didn’t solve the problem, I was told it was the shocks, which I changed, it did slightly improve the problem, but the tire still rubs. I am now being told it could be the coil springs. Should I change the coil spring on the left only (where the problem is) or both sides? Is this the right solution? I have seen coil spring extenders that expand sagging coil springs, should I try this first? The tire size is appropriate for the car and hasn’t been changed.

#2

How did the relay “fix” things if the fans still are not coming on ?

What makes you believe the car is getting hot if the gauge doesn’t show it ?

The wheel and tire are not “high” unless you have replaced them with larger ones. They are still sitting on the ground where they belong,

You need a good mechanic,which you haven’t found yet. You don’t need someone who tell you that it is the ball joint, it is the shock and it is the coil spring. Don’t just run from one place to another throwing money at the car, get references from friends, relatives and co-workers.

Get the cooling system pressure tested to find out if there is a leak that is making you lose coolant. It may have to be pressure tested hot if it doesn;t lose pressure cold/

#3

Berum:

oldtimer 11 asked two excellent questions pointing out how your description is puzzling. If you clarify your description with responses to his questions, that will help people understand what is really happening with your Jaguar and give you some advice on the cooling system.

Problem 2: The driver front tire is high and rubs the tire well

Unless you have a deformed inner fender liner, or mismatched tires or wheels, then it sounds like you have a problem with the suspension. Does the car lean to one side or the other? Look at it carefully from a distance in a very flat parking lot. If you can’t see anything, then start comparing measurements left and right. Forget the Jag specialists, look for a local independent shop specializing in suspension and alignment.

#4

Old springs can sag, so you might need new ones. Also the mount(s) that holds the springs should be checked to make sure they are sound.

#5

Thanks for the responses…

I when the mechanic changed the cooling fan relay, the fans started working again… I could hear them. They have since stopped (after several months of use)

These cars have a dummy gauge for coolant temps. It shows the heat rising, up to halfway, where it stops and stays there, not showing a certain amount of fluctuation unless it gets really bad and starts to overheat where it’ll move up. I have confirmed this fact independently. I feel the car getting hot from the heat it throws off, much hotter than normal. At the same time I will get a low coolant warning, and add to that the vent lines throwing in hot air when set to cool outside air.

I do have matching tires/wheels that are correct for that car. The gap between the top of the left tire and the fender is like a quarter of an inch, which is visibly higher than the right side which is like 2 inches. The rears are both even.

I hope this information helps with the diagnosis. Thanks again.

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#6

Don’t think about the tire being higher, but rather the body, or at least the fender well, being LOWER, perhaps as a result of a spring problem as Uncle Turbo has mentioned. What you are seeing is a difference in clearance between tire and fender well.

Prove this to yourself by measuring the distance been the top of each tire and the ground. Are these measurements all the same? Did you measure the distance from specific places on the body, left and right? This comparison will be instructive. It seems highly unlikely, but maybe you have a defective tire with a severe deformity.

#7

I don’t have a deformed tire, they are sized evenly, I think we are having trouble communicating.

Would the coil spring be the right avenue of pursuit? If so, like I asked in my original statement, should I change just the one or both?

Also does anyone have ideas for problem 1?

#8

You should change both springs, and make sure all the suspension mounts are sound. If the car has been expwsed to winter roads and salt then you could have a rust/corrosion problem.

#9

I have exactly the same problems. I had overheating problems which was blamed on a head gasket so I had the gaskets replaced but they over skimmed the heads so that the cam covers fouled the timing chain cover and leaked oil so I bought a replacement engine but it still overheats. I have replaced all the hoses, the radiator, the water pump and the header tank to no avail. It only overheats in traffic which is obviously a cooling issue so I am considering replacing the fans but, reading what has been said, I don’t want to waste the money if it’s not the cause. There didn’t seem to be a solution in amongst the advice given.

I also had hot air coming in if I set the AC to outside air so disconnected the heater matrix (never gets cool enough here to require a heater) but that made no difference. I only get cool when the engine is cool or the outside temperature is cooler.

Surprisingly, I bought a new set of Pirelli P Zero tyres, 245/50 17 for 17 inch wheels and they foul the inside of the wing on big bumps. I have new shock absorbers and top mounts plus all new suspension joints and bushes but not springs.

This the first second hand Jaguar I have had since 1976, everything being new after that except an XK150 3.8s DHC (genuine matching numbers) so I have been on a long uphill learning curve with no specialist for more than a thousand of miles.

#10

I’ve seen this temperature issue before with my '97 XK8 Convi- the culprit is a corroded or damaged thermostat, which could cause many of these issues. Did you source the replacement thermostat? Or did your mechanic/dealer “indicate” one was replaced? No need to distrust- but one should always verify :slight_smile:. No guarantee that the thermostat was the only root cause of the problem, but it was for me- and after that swap it started running much better once again.

Problem 2 Solution: I have also had this, and seen this problem in many a unit and rarely if ever is it diagnosed correctly. You’ve got a bad set of wheel bearings and swivel pins, from the sound of it. The ball joint is nearby, by the pin being worn, bent, or out of place would affect the toe angle on the tire, and then could create the fender rub you’re describing.

**Never modify the suspension parts without doing them all at once- if you get too drastic, it’ll tear itself apart driving down the road.

Since the shop you’re using has already stuck you for shocks, ball joints, and now coil over springs- have they checked the shock tops/coil mounts? These are the upper metal plates under the bonnet which provide a top surface for the springs and shocks to push against and maintain top ride height. the issue is, they’re thin. If you’ve got new suspension gear, and still seeing slouch- it’s time to advance your train of thought from buying springs to making sure the vehicle is fully maintained.

In short, I shouldn’t do so much thinking about how you believe these things should be fixed. There are real, live Jaguar mechanics out there who- believe it or not- have made it their business to resolve issues exactly like this. If you ever find yourself wondering whether you should do a 'half replacement of coil over springs to fix ride height", as yourself this question- who knows more about cars, yourself or Jaguar?

A: Jaguar. Time to take it to a professional- guess and check isn’t cutting it for you, unfortunately.

#11

The issue is the repair necessary here requires effort. Like, real effort. think 10 book hours of shop time effort- for only a little thermostat. Your issue is also a thermostat issue. There are two, and the other being in the bank of the block makes it difficult to access, as a result, lesser mechanics don’t feel they ought waste the time to address it. If I’m paying for the service, it will be addressed, in my opinion :slight_smile:

Issue 2: Those Pirrelis probably look amazing, but given those measurements (245/50 17) you bought them 5 too tall on the side wall. Stocks on the 17’s are 45, not 50, and the wheel wells are tapered accordingly. Also- who are you that you would buy the WHOLE tire suspension without the Spring that allows the kit to work?

#12

Agreed- but don’t forget to replace the Shock Top Mounts at the same time- or the whole refurb will have been for naught.

#13

So glad you guys revived an eight year old post about cars that are best traded in when the 36/36000 warranty expires.

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