Hello:

I have suddenly started loosing coolant in my '04 Vanden Plas. It's not a whole lot, but enough for the warning light to come on. It happens whether I drive it or let the car sit. I haven't really investigated it yet, but from the top, I see no signs of a broken pipe/hose. I see nothing under the car either.

Any thoughts/ideas on what I should look for? I'm planning to hunt down the cause this weekend between World Cup games.

Thanks

 

jeropon,

I've moved your question from Jaguar Forums Advice / Feedback & Suggestion Center to X350 forum. The Advice / Feedback & Suggestion Center is for posts about the forum and not for technical questions.

Members here with the same model will be able to help.

Graham

 

It would be helpful to track how much you're losing over a certain period of time. Could be weeping from coolant reservoir, thermostat housing, or water pump. The thermostat housings are known to crack over time. Mine had a crack right along the seam that was very hard to detect.

 

A couple of thoughts:


- Things that leak always make a wet spot somewhere. Fill reservoir to the top and wait. Repeat until the wet spot shows itself.
- Things that are soft and leak (e.g. hoses) prefer pressure in order to leak. They may not leak when there is no pressure. If it leaks when cold, think something hard is leaking.
- Most auto parts stores have a pressure test kit on their tool rental shelf. You might not find exactly the fitting you need, but putting 10 pounds of pressure into the system will speed up the search.


Hope this helps.

 

My apologies for posting to the wrong place.

 

I have a 2004 VDP with the same problem. She looses about a pint every two weeks and it has me quite cross. There's no evidence of a leak at all. The coolant either has to leak out or leak in. If it's leaking in, it's leaking into the engine (very not good) or elsewhere...also not good. I can't trace it, nor can our mechanic. A pressure test is a good idea. Next service we'll have that done. Our VDP has 74000 miles on it. Odd that there's no performance degradation to show it has a leak into the engine.

 

Have a look round the engine bay in the dark with a torch. If there are beads of coolant there, you'll see a glint in the torchlight. This works because the human eye adjusts to the dark, it's no good in daylight when the torch light is overwhelmed and the eye is adjusted to daylight.

It's worked for me on two occasions now. Last time it allowed me to identify a leaking water rail connection on my X350.

 

Just last month I found and repaired what MAY (or may not...) be a player here. As with yours, the source of the leak was masked. Doubly-masked as it turned out.

The coolant was being lost at such a low rate that it was being 'distributed' by gravity, the fan air-flow, and adhesion to surfaces so as to make finding a trustworthy back-trail difficult.

By fortuitous accident, pressure on the small hose from under the engine's vanity cover to the top of the header tank caused coolant to slowly fill the rebated well in the header tank around the recessed fitting. 'Smoking Gun'.

Research here on the forum revealed that these tanks are known for failure, and quite often at that very fitting.

A new tank was ordered, and a temporary patch begun.

I did say 'doubly' masked...

The existing tank and that fitting proved to be without blame. No cracks.

The hose with seventy-leben pre-formed angles had deteriorated at the end - under the clamp.

Hose, of a higher US-made grade, was cut from coil-stock and laid to a new routing that required ZERO angles - just a wide loop of a length 'just so' that created no air-traps. Took three tries of shortening just a smidge to nail that.

Motor's plastic vanity cover was modified to accommodate exit-point for that routing, and a wear-sleeve of larger diameter hose fitted to insure there would be no cut-through from vibration or such.

Problem solved.

Hopefully in a more enduring manner than the over-clevered OEM choice had done.

And I ended up with a spare tank put by. Flawed design as well, so it WILL fail in due course.

 

It turned out to be a bad thermostat. The leak was so slow that the coolant left no trace. I gave up trying to find it and went to get a pressure test done. When I opened the hood to explain what I wanted done, the leak was noticeable to the naked eye...of course . A new thermostat assembly, which the dealer says Jaguar does not sell anymore, has fixed the problem.

Thanks for the suggestions, everyone

 

Rockauto doesn't list it, either. There is one for the Lincoln Town Car at about eleven US$ that might be a drop-in, though.

As it is bleepin' plastic, if mine ever goes, I'll just fab a proper metal one.