This started after the car stood for three weeks whilst I was abroad. Upon starting uo there were no issues but shortly after the temperature reached about one third the low coolant warning light came on but the temp went to normal and stayed there. I parked the car up for 12 hours and when I opened the header tank there was very loud gurgling from the LH side of the radiator and an 18 inch geezer of coolant from the header tank. Subsequently I note the engine runs perfectly at all times, no water in oil or vice versa no smoke from exhaust. When hot the hoses are very tight almost as if they want to blow up. If the car is driven very steadily for up to one hour or more there is no low level warning light and then after stopping the engine you can open the cap with just a little sound from the rad and no geezer. Also no water loss is apparent either. However, if you use the car at pace using the superchargers the low light comes on quite quickly and remains so. You dare not open the cap for at least 12 hours after stopping the engine. Latest event was today when the the centre hose fitting to the back of the thermostat split under the pressure and the temp meter started to climb rapidly. After letting cool down engine starts and runs perfectly but of course cannot be used. Many have said head gasket but somehow it doesn't fully add up. To me it as if the supercharger is pumping up the cooling system. Is that possible, any ideas ?

 

You can't rely on the temperature gauge. The engine can be way overheated before the gauge will move from the normal position.

First thoughts on the symptoms you describe are to check for sticking thermostat. A known issue on the V8.

Graham

 

There is definitely a blockage somewhere in the cooling system. The water pump is pushing against this blockage which is over pressurising the system.

You need to get the whole thing flushed out, and don't drive it around like this. The temp might be fine where the sensor is located, but other parts red-hot.

Take the thermostat out completely, and try again.

 

A non-functioning water pump would be a problem, but a water pump would never be able to create the kind of residual pressure that has been described. Certainly not when the engine has been off for some time and not rotating.

 

I have read the other comments and have one of my own. I do believe that you have an over pressurization situation due to a crack in either the head gasket or in the combustion chamber. Before you say Well I don't have oil in the water and visa versa. Consider the fact that crack has just started and has not opened up enough allow the leakage back and forth.

The test for this is a engine block leak detector. It looks like a hydrometer. It has 2 chambers and you fill it with a reactive blue solution.

Run the engine with the recovery tank open, you may need to lower the fluid level a bit so you dont get antifreeze in the tester. Allow it to run for a good while, then plug the hole in the tank with the tester. Give it a couple of good pump so it can draw the residual air in the tank into the test. If CO2 is detected it will turn the fluid yellow.

I hope I'm wrong, but I have found many a bad gasket or cracked head that doesn't exhibit any of the classic signs of a defect using this tool.

 

Thanks guys for the replies. Actually I forgot to mention that before I went for the slow 1 (2000rpm max average speed 50 to 80kph) I had in fact removed the thermostat. Unfortunately I thought I had hit the nail on the head. Have to admit that head gasket would appear to be the most likely. As no one has accused the supercharger of having a hand to play in this I assume that was just wishful thinking...
The post mortem will commence on Monday and I will keep you posted as to my findings as I fumble my way around the JTIS.............

 

Do youself a favor and either take it to someone that has a tester or buy one. You can get them as low as 39.00 if you look around. It will be money well spent either way.

 

I am going with your advice Mr. Ooootis and have orderd a Uview unit on E-Bay. After waking up this morning what you say makes far more sense. So, the beast will have to sit tight for about 7 days whilst I await delivery.

Will advise the result once the test has been completed.

Many thanks to all who have responded. Have a great weeekend...........

 

Very good. BTW that was a very broad brush I used to describe the use of the tool. If the tank is closed when you get the tooling you may be able to just sniff it with out running. I don't know how long CO2 takes to dissipate. I wouldn't run the engine to the point of over heating though.

Take samples as it warms up it won't take much CO2 to get a reaction. Even the slight change in color is a positive. The included instruction (hopefully)may have specific details I have left out!

Good luck!

 

Ok, well after a two week sabatical I am back. The delay is due to the manufacturers of the tester you recommended. I gave up with them, too stupid for words, and bought one from Wurth Malaysia. I stumbled on it by pure chance when their rep called round on the off chance he could find a new customer. So I followed all the instructions and conclusively no C02 is present. Actually I did it three times.
Since then we have removed numerous hoses including a really bizarre arrangement to do with the heater water supply. I note that all hoses and pipes are crusted with a pure white hardened powder which has to be scraped off. Never seen anything like this before, orange from rust etc, yes, but not this. Also all the hoses under the powder look as if they have been sandblasted. The inner surfaces feel like a cat's tongue. I have found the electric water pump below the header tank is seized solid but have yet to work out if this is for the heater system or supercharger intercooler.
I am looking forward to any ideas you guys may have regarding some of my comments.............. and findings.

 

Sounds like the forensic examination has found the culprit - the crust sounds like a leak-stop additive.

The pump under the header tank is for the heater circuit. It could be the bottleneck, but as these cars have a lot of pipework, each part needs checking.

The pump for the intercooler circuit is located on the lower front lhs chassis leg, and should be heard with key in posII - I'd check all parts and go for a coolant flush additive with fresh water.

Have you fitted a new thermostat? - drive the car with the flush additive and water for 50 miles and let it break down the crud, then replace with the orange coolant, a 50/50 mix with water.

Another item to inspect is the waterpump - earlier versions had black plastic impellers that broke, the newer version again plastic has white impellers that are fine. There's also an aftermarket version with metal, but I'm not a fan - lower flow rate compared to the white version from Jaguar.

Let us know how you get on.

 

I'm glad you didn't find Co2. Sean's comments are spot on for the next round of trouble shooting. I would like to suggest testing the radiator for flow @ a radiator shop before taking to large of a step in to the motor. If indeed the crust is stop leak it was added for a reason.

My intercooler pump is located on the right hand side of the car in front of all of the heat exchangers. Access to it is from the bottom after you remove the lower plastic cover. Yours may be located on the other side if your a rh steer.

As far as the Aux water pump, its fused with 10 amp fuse located in the trunk. My fuse blew but somehow blew in a way that still allowed the circuit to remain active. Look at this

My intercooler pump was also locked up. If the pump fails it will set a reduced performance notification, amber light, and set a code. So unless you have seen this I feel that pump is most likely ok.

Like Sean said let us know how you make out.

 

In addition to listening for the running pump, if the ignition is turned on while the fill plug on top of the SC is open, the level will drop visibly. On one of the models, the fill procedure involves letting the pump run for a full minute to drop the level, then topping and capping while the pump is still running.

 

I had a similar problem (rock hard hoses, loosing coolant from recovery tank, white residue on hoses and thermostat housing, no coolant gasses AT FIRST CHECK). Entire radiator was flushed and thermostat was changed...clearly some clown put stop leak in there....those things did not resolve the issue. Sounds like the head gasket. I would test for exhaust fumes in your coolant after high rpm or a brisk drive....eventually, I got the color change after a hard drive. Expensive job. No leaks since. See my old posts. It took me months to figure out.

 

This saga continues. The heater circuit pump is jammed. have decided to by pass heater circuit altogether (after all it doesn't get below 25c around here at any time during the year).I have all new hoses but one which arrives tomorrow. Rad and intercooler has been to the rad shop, cleaned, checked and tested for leaks or blockage. Have decided to clean everything up,refill with fresh water and cooling system flush and run for 50 miles or so and then wash all of that out. Also will be changing the coolant level sensor as that talks utter rubbish most of the time and a new expansion tank for good measure. Yup, I agree some "CLOWN" has indeed put stop leak or whatever in here, but guess what guys, over here they do that as a matter of routine whether or not there is a problem. I suspect that is what nailed the heater circuit pump, probably glued together with rad weld. WELL DONE DORK THE CLOWN. If all this fails to solve the problem then it will have to be a mamoth pull down to expose the head gaskets. A trifle boring as only 3 moths ago all the timing gear was replaced and judging by the book (JTIS) all that gonna be out one more time. Quelle Joy! Well, let's be positive and see where the clean up takes us. Will let you know......................... and thanks for all the response.

 

Standing by............

 

Ok, so finally after fitting all the new spaghetti and cleaning the whole cooling system out we have a result. There is no pressure in the system other than a slight hiss when the top is removed after engine been off for an hour or so. The a/c is much cooler now that the heater water has been diverted. The low coolant light has not poked it's ugly little head above the hedge and the car runs beautifully. WELL, that was for 300 miles after which, very suddenly when pulling up at some traffic lights the engine was idling very roughly with the needle on the rev counter fluctuating from 400 to 600. it was like sitting in a jelly. Once moving everything is as normal. There are no fairy lights on the dash, no starting problems and the coolant level has remained static. I am thinking this is either yet another new issue or related to fitting back throttle housing possibly. Also the alarm system appears to have thrown in the towel and so locking etc is manually done with the key. Actually preferable to me but in the light of experiences with my series 2 Range Rover alarm system an issue that can lead to many a headache. I see some strong resemblances between the two vehicles, something which is of great concern.

 

Had exactly the same problem 3 months ago. After a full modification, including tensioners AND waterpump plus new metal thermostate all was peachy again.

 

For this, I would check the TB, and all vacum hoses. There is a vacum leak somewhere after all the work performed (disconnected hose, rupured hose, or something of that nature).

 

Hello Sean B, I have this problem of high pressure in the cooling system whereby the level drops in overflow vessel soon after starting engine end is under some considerable pressure. It returns to normal level when engine cools down. There is also signs of steam mixed in the exhaust gases but no loss of coolant nor oil in same. Any ideas!! Oh, by the way I'm in Southport as well.