Greetings Folks,

I read more on here than I post. I expected to be a frequent poster/contributor when we bought our XK8. Just because it was 15 years old and, well, a Jaguar. To our great and welcome surprise the car has been very trouble free. Other than a fuel pump last winter, I have only had to do regular maintenance. Until now...

My wife and I took the car on a bout an hour trip to a local winery, went in for a tasting and were in there about 45 minutes. When we came out and started the car the "low coolant light" was on. I had seen it a couple times before and knew from reading here that the sensor can have issues and I had parked on a pretty good incline. It was on my to do list but had never noticed any loss of coolant so it wasn't at the top of my list. Well, being an hour from home the warning bothered me so a few miles down the road I pulled over just to have a look-see. Mind you, the Temp "gauge" never wavered from the middle position.

I popped the hood and jumped out of the car and immediately smelled coolant. Lifting the hood I find that the upper radiator hose has decided to part ways with the Thermostat housing - original plastic version. It just came off. The clamp was still on the hose. Huh. I have never seen this before. I am able to fit the hose back on the tower with no problems. No splits in the hose, the collar on the housing looks fine. So... I put the hose back on (moved the clamp a little for a fresh bite on the hose), topped it off with some water, and drove it home. Since then, I have had the car up to Operating Temp several times and driven it around with no problems.

So now I am in the process of collecting parts and trying to find time to redo the hoses and thermostat housing, etc. Should I do anything else "while I am in there"? But my real question is what would cause it to just blow off like that? Or was it just normal pressure and bad (plastic) design? I need to restore my wife's confidence in the car as this is her "fun car".

For the record - 2002 Conv, ~33K miles, original hoses and clamps (so it appears), plastic "tower", temps that day were in the mid-50s, easy driving that day - mostly interstate @ 70-75.

I did a few searches here but did not find any such event. Lots of postings about thermostats and hoses and for that I thank those that went be fore me!

Thanks in advance for any thoughts and comments.

Curtis

 

Maybe the water pump. It's right there, cheap and easy. The serpentine belt as well. You have low low miles but every rubber bit succmbs to age, not just miles.

 

When the light had come on after starting the car, I would have switched off and checked the coolant level. You know the sensor has a reputation for unreliablility.

Water pump is definitely a possible cause as is a sticking thermostat.

I would also take a very critical look at all the plastic and rubber components in the cooling system and consider replacing anything doubtful.

Graham

 

Thanks for the quick responses guys. Yes, I had almost convinced myself to do the water pump and you guys pushed me over the edge.

GGG - I agree and normally I would have done just that. It is just that we had seen that message a few times already in the preceeding weeks and I did just that to find nothing wrong. Just glad that I didn't ignore it for the entire trip home - or until the engine seized! I have already planned on replacing hoses and plastic bits - oh, and the sensor/reservoir. Plastic pieces under that much heat exposure after now 16 years are all suspect.

 

Good call on the belt. Added to the list!

 

the water pump is a easy job.

 

A couple of times a year I read about the hose coming off. The crossover pipe lip erodes a little and the hose pops off. It's another plastic part and should be replaced. All of the cooling system parts should be replaced, but that doesn't always happen.

 

The things I would concentrate on are the thermostat/thermostat housing and coolant outlet pipe.

The housings are resin composite and deteriorate. The thermostat can stick CLOSED.

The engine coolant pump is likely not at fault if the impeller is intact.

bob

 

Happened to me a year ago. Luckily I was stopped at a Burger King, er, "winery" drive through. The upper hose has insufficient grab on the serrated plastic housing so I added two pop-rivets to the housing to provide grip for the hose and clamp. Been fine ever since. Strange that it would hold for all the turnpike driving and then pop off at idle speed. Two pop rivets versus $500.00 in parts and labor.

 

The Expansion Tank comes complete with Sensor and Filler Cap.

In addition to the Sensor sticking and giving incorrect fluid level warnings, the tanks are known to develop pinholing. I had a mysterious coolant smell on my 2001 XK8 which took ages to find. It was occasional drops of coolant from tiny holes in the tank base falling on the hot exhaust manifold where it would immediately boil off leaving no trace other than the smell.

Aftermarket aluminium Thermostat Housings are also a great improvement on the OE plastic ones.

Graham

 

Make sure the cooling fans are coming on. I had the rad hose blow off on me a couple of times on my XJ8 and I came to find out the fuse for the electric fans was blown.

 

Fans operate fine but thanks for mentioning.

 

What are your favorite parts houses for such items? I am finding that some have some parts but not all. Any suggestion for a reasonably priced one stop shop? I am not cheap and looking for bargain basement prices (and quality). I do value my time and would prefer not to piecemeal from three different vendors. Anyone market an entire "kit"?

 

I recently redid the thermostat housing (tower), thermostat, heater hoses, and upper coolant hoses.

I used URO brand aluminum thermostat housing and hoses from Amazon - nice quality parts IMHO, and ... I don't remember who the thermostat was from, but it was via partsgeek.com I believe

I also don't put cheap parts in my cars - I was pleased in the past with URO so that's how I went this time.

I also recently replaced the coolant expansion tank with that brand - worked a treat and seemed a little more substantial than the factory part it replaced.

 

I have used RockAuto & SNG Barratt to source parts.

 

While we're all colluding on emptying your bank account, consider changing the valley hoses and the tee piece (NNE3944BA - about $3) 'while you're in there'.

It is extra work as the inlet manifold has to come off, but they will fail eventually and it makes the tstat tower job much easier. I replaced mine at around 30K due to a pinhiole leak - age rather usage is the key here.

And, yeah - the OEM temp. idiot gauge gives three readings:

-- --and

 

I would replace the thermostat and housing as well as the clamps. Thermostat probably stuck closed briefly, this will blow the hose off quick. A 2002 with 33k miles is sitting a lot, this will let things deteriorate just as if it had miles on it, especially things sitting in coolant. I would be sure the coolant is getting changed on time.

 

Thanks for all the suggestions and help folks! Parts begin arriving tomorrow and I now have a weekend project. So far I am doing the following:

Thermostat and housing (aluminum)
Upper and Lower Rad hoses
Coolant Outlet pipe
Reservoir Serpentine belt

Once I get into it I may do a few more hoses. And of course I will check everything else out in the area "while I am in there".

@michaelh - your comments about the heater hoses and "making the T-stat job easier" has me intrigued. I will look over the job this week and make that call. I have the time and the parts are not expensive and with my luck, if I don't...

Curtis