Thanks for your prompt reply, have my fingers and toes crossed it reveals the leak! Have a horrid feeling it will be the valley, looking at everyone's comments.

 

If the system does lose pressure, check around the back of the engine to gearbox mating area with a torch to see if there is any evidence of coolant.

I have often seen leaks from the side expansion tanks on the radiator; check there if you haven't done so already.

 

17.4 psi ?

 

On Monday evening, I had a similar problem. Coolant low warning came on, pulled over as soon as I could. Nothing in the expansion tank so topped it up (there was a bit of pressure). Managed to get the car home just as the low coolant warning came on again and notice the temp had increased slightly. Waited until it had cooled and went to investigate. As I was pouring more coolant into the expansion tank, it began pouring out of the bottom of the radiator. Luckily I had tie to check it out during the day on Tuesday. Punctured radiator is the cause. So new radiator ordered, old one removed (I am a competent DIYer). New radiator installed, however the replacement has different unions on for the Auto transmission cooling connectors. So back to the parts dealership and new one ordered, should be here tomorrow. I'll let you know how it goes.........

 

You might have had a large bubble trapped in the cooling system as a result of the malfunctioning or improperly previously installed thermostat.

The liquid intercoolers share the same reservoir but not the same flow as the engine cooling and have their own radiator.

This is not a simple cooling system.

Keep an eye on it.

The coolant hose under the supercharger is a know issue. Pray that this is not the issue.

I lose coolant too but not very much and it all comes out along the reservoir tank's seam. I'm on my 3rd tank. Everyone of them did the same thing from new. It's a really crappy part that Jag supplies. It too is not a simple design so not easily replicated in aluminum.

 

Thanks everyone for your help, I have learnt a lot about the joy of the jaguar cooling system.

Pressure tester turned up, so today I had time to use it. Pressured it up to the pressure recommend by you guys and no signs of a leak for the first couple of hours....then it looks like it started seeping from the seam of the rad between the metal clintch and plastic.see pic. I can not see any leaks that are dropping on the seam causing it to collect on the bottom so assume I am going to have to put a new rad in.

 

Is there a recommended brand of radiator, I notice there are some budget brands doing radiators, as well as the likes of Hella? Wondering if other brands will be ok, or is it best to stick to a jaguar original rad? Thanks

 

A lot are wrong - make sure whatever you get actually is compatible.

 

+1

This not a simplistic radiator and it wouldn't surprise me if it we're STR and Vin # specific. Any time they changed even the slightest thing in the STR compartment adjustments had to be made.

This isn't just a Jaguar issue either. Audi's are even more horrific!

I've decided I'm going to quit beading a dead horse, I'll revive it and ride it insteed! LOL

 

The radiators are VIN-specific as the earlier cars had a separate cooler for the gearbox. You may also need to remove the air conditioning condenser whilst replacing the radiator.

Seepage from the radiator side tanks is quite common given the age of most of these vehicles.

If it hasn't been done lately, I would also recommend replacing the DCCV unit at the same time as access is much easier with the radiator and associated parts removed.

 

To add now would be a great time to swap out as many cooling hoses as possible with the access you'll have, especially the hoses associated with the DCCV and intercooler hoses going to the pump.

 

+1 to both of those.

Another to check before you take any other steps is to have your cooling system sniffed for hydrocarbons with a tail pipe tester. That's what blew out the radiator in my Suburban. The worse news is that's caused by deteriorating head gaskets.

In the really odd department my 84 Maserati Biturbo which I've had since new and has 70K+ mile son it still has the original radiator and that's an aluminum core with crimped on plastic plastic tanks too.

 

Have me worried now, think I have a hydrocarbon tester and fluid in garage from when my Audi blew it's gasget. Will give it a check tomorrow, as does seem a little steamy from exhaust but hopefully that's just because the weather has turned cold.

Thanks all for the advise, didn't think of changing the hoses, but think that's a great idea while I'm there!

 

I've not had great luck using the fluid that's supposed to change color
as a test. Two cars tested OK with that but the tail pipe sniffer found the problem. Neither were putting coolant into the combustion chambers just exhaust gases into the coolant. My suburban is still running decently with this issue. I just run an unsealed system and it pushes some coolant into the recovery tank and then draws it back in when it cools down. I do lose some coolant this way but not much so once a month I add. some. That's an old vehicle and a new set of heads and everything else just isn't worth it.

Don't fret and worry just check it out. If it fails then you can curse me ... LOL

Yeah I did a lot but not all of the hoses and the DCCV because it's a bitch to change and they do fail early. There's a Ford part substitute for that one.
I also did the belt idler bearings and belt. I figured I might not be back in that way for a long time. Ha! Looks like my new oil cooler hoses have failed again after only 2 years. I'll be busy in the spring.

 

Finally got the correct radiator on Thursday (the first one had been wrongly packaged and listed as my part number. So Friday evening I fitted the new radiator and finished the job yesterday. All done and working well. I have a Foxwell NT510 diagnostic set. This came up with one fault (MAF sensor) so I disconnected it and reconnected it after clearing the fault from the list and it's all fine. For the hose clips that secure the cooling hoses in place, I used a pair of plumbers pliers to release them. Once the hoses were clear and the radiator was off, I once again squeezed the clips and put a tie wrap round the clip to hold it open, this makes it easy to reconnect the hoses, then a snip of the tie wrap and it springs back into place. With regard to brands of radiator, I had the choce between Hella and EIS. There was only a small difference in price and both brands were almost identical. I ended up with an EIS

 

For removing the constant tension hose clamps, you can order pliers to hold them open for £24.80 from eBay:

Mobea or Constant Tension Hose Clamp Plier with Extended Jaws SES860L Brand New! | eBay