The JTIS indicates there is are two (2) tanks: A header tank and a recovery tank. AFAIK the "header tank" is what we commonly refer to as the coolant reservoir.

When I use a pressure tester on the system, I removed the pressure cap [from the header tank], install the Stant tester adapter; and then attach the pressure system tester.

But, unless I pinch off the single line leading to the recovery tank the system will not hold pressure.

I was my understanding that the complete system was closed, eg. not open to the atmosphere. The last time I tested the cooling system, I used the bleeder cap above the T-Stat housing. Obviously the header tank cap was in place.

I was wondering if this is the proper testing technique, or should I be looking further for a leaking downstream of the line connecting to the recovery tank?

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I have attached the JTIS text for this part of the XK8 cooling system.

The header tank is made from glass-filled nylon and provides the cooling system-fill point. It also carries the coolant-level sensor and the correct level is to the bottom of the filler neck. A fitted 1.0 bar pressure cap allows controlled release of coolant to recovery tank during normal operation.The recovery tank is made from polypropylene and accommodates the expansion of the system coolant during normal operation. Upon engine cool-down, the coolant contracts and is returned back to the main system.If the engine overheats, a controlled-spill occurs onto the ground, just behind the left-front wheel. This spillage also occurs if the vehicle repeatedly has the coolant-level checked whilst hot.

 

If I'm reading this right, whenever there's more than 1 bar (~14.5 psi) pressure in the header tank, the cap will open and vent to the recovery tank. That second tank, I think, would be open to the atmosphere.

So now I'm focused on the Stant Tester Adapter. Could the problem be that it does not extend down into the filer neck properly and seal off the overflow tube from the pressure tank, as the normal cap must be doing to hold stuff in when it doesn't see > 1 bar pressure?

 

Yes on all counts. I was thinking that the recovery tank system would need to be sealed in order for it to suck the overflow coolant from the header tank into the recovery tank. However, if it were not vented, then the coolant could not flow freely between the recovery tank and the header tank [and the rest of the engine/radiator cooling system].

And yes, the Stant adapter has no center section designed to seal off the recovery vent line until 1 bar pushed opened the cap vent. As noted earlier, the last time I pressure tested, I used the bleeder cap above the T-stat housing with the header tank pressure cap in place. The cap closed off the port leading to the recovery tank line.

I can still pinch off the recovery tank line with a pair of needle nose vice grips which effectively seals the header tank and closes off the rest of the system. This post began after I bought the Stant system and I simply wanted to do some preventive maintenance/ testing.

I would however, still like to follow the overflow tube down into the recovery tank. Do you know where it is? I was going to simply follow the hard line, but that falls out of sight into the 'octopus'. JTIS doesn't illustrate its location, so I guess I just have to get the car up and follow the line from underneath. thx. gordo

 

I rented a pressure test kit with 21 adapters and none fit the Jaguar reservoir except for the universal adapter. The reason was exactly what you found; none of the adapters was set up for the two level pressure system used by the Jaguar pressure cap.

 

You're quite welcome. I owe you a few from the tensioner replacement project.

No clue where the recovery tank is, I'm afraid.

 

Recovery Tank is in the RH front wing space behind the black liner:



This shows the black feed and vent pipes.

Graham

 

The Stant Adapter PH 12023 ($48 from Amazon) is the correct part to replace the header tank pressure cap. It screws onto the header tank like the pressure cap. However, as noted above, it does not have the same internal design as the pressure cap, which means it can not seal off the side passage opening into the recovery tank line

Consequently, in order to perform a pressure test; either the header tank outlet needs to be capped off; or the line leading to the recovery tank needs to be pinched close. I used a pair of needle nose vice grips on the short section of rubber connecting the tank to the hard line to effectively eliminate this part of the system. After that, it is an easy test.

 

Sorry to revive an old thread, I'm a newbie when it comes to coolant pressure testing. Can someone tell me or send me a pic with which line needs to be pinched off? I'm not sure if it makes a difference but it's a 00 XKR...

Thanks!

 

I had the same issue with the Stant adaptor not holding pressure. I found out from the forum you need to clamp the left hand hose coming from the header tank (facing the bulkhead). I did and the tester worked fine.


Regards,
Karl

 

Hey Karl,

Thanks for the help! Is that the correct hose clamped in the attached picture? It's clamped off but I can't get any pressure.

I'm not using the Stant adaptor, instead I rented a OEM Tools for Professionals Radiator & Cap Adapter Set 27118 and a MotoRad Pressure Tester MT-300. Maybe that's the problem...

Thanks
--Ryan

 

Most pressure test kits have an universal fitting that is simply a tapered plug inflated by the pressure applied to the cooling system. It seals the opening to the tank eliminating the need for pinching the recovery bottle hose.

 

Ryan,
I clamped off the opposite hose that runs under the windshield/ bulkhead and it worked for me.


Regards,
Karl

 

Karl,

Pressure!! Well it works for a few seconds anyway, then the pressure comes out. Although no coolant is coming out probably because the pressure is to low (large leak). I think I feel air coming out of the reservoir where the plastic is sealed in the middle. Which is ridiculous because I just replaced this reservoir about a year ago... Probably just out of warranty.

Cheers
--Ryan

 

Ryan,
Make sure you have the hose clamped off tight.


Regards,
Karl

 

It's clamped off tight. Another closer look and I think it's leaking out the bottom of the adapter.... Maybe this is the wrong adapter.... it sure went on and felt secure

 

Coolant pressure tester, $90 at Harbor Freight. The green cap fit the Jag perfectly and no need to clamp off hoses. Helped me change a colander back into a Jaguar

 

Thanks Jeff! I didn't want to have to buy it, but it looks like I'm going to have to go that route, as this adapter just isn't working.... Time to take a trip to Harbor Freight!

Cheers
--Ryan

 

The correct tool makes such a big difference! The build quality seems far superior to the Autozone rental and you don't have to clamp the hose. It's $89.99 at Harbor Freight but if you have one of those 25% off coupons they send out it's only $71.54 after tax.

Unfortunately the part that's leaking doesn't look very easy to get to (see photos).

 

I used a Ford/Lincoln expansion tank cap and epoxy'd an air fitting to it so I can use my compressor. I also epoxy'd a schrader valve to an air fitting so I can put a pressure gauge on my compressor line and adjust the air pressure appropriately. Seems to work fine and cost about $12.

 

How to turn a small leak into a gusher? Pressurize the system way above the release pressure on the cap. I'd limit test pressure to 14/16 PSI.