At first I thought I had a coolant leak but it was blowing out of the cap .
I am hoping I am wrong but am getting bubbles through a tester when I run the cold engine so it sounds like a head gasket sending fumes into the coolant.
Has anyone done a HG replacement on a V6 or had one done at a garage?
Would it be worth retorquing the head bolts? The rest of the car is good and it runs fine so I reckon its worth doing.

 

I believe you need to purchase new head bolts, simply put they are the stretch bolts that are only good for a 1 time torque. If you choose not to replace head bolts, the torque will be off!

 

Please run the proper test first!! Any parts store will have a tester to check the coolant for combustion gases. The V-6 is not known for head gasket leaks and is pretty rare.
So;
First test the coolant
Second if combustion gases are present then re-torque the heads in hope that will fix it.

In my experience if you do have a head gasket problem the gasket will already be burned beyond use and no amount of re-torqueing will fix it!

Please post back with your results.
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If you mean just trying to torque the bolts on the existing gasket, it's not going to work!

 

I did the test as advised above and it failed the fluid went yellow showing combustion gases. So I am still hoping that replacing one bad head gasket will be ok .
The testing kit suggests running it on one bank at a time to see which one or both leaks. I am guessing that a compression test on all the cylinders would tell me the same .
I would do it myself if other members think its sensible or pay a good mechanic I know (not a jaguar specialist), Any further hints or tips?

 

I found a jaguar specialist -not an official one- and he is now half way through replacing the head gaskets. One point he made was that skimming V6 heads leads to the cover not fitting after so it leaks oil. Luckily mine did not need skimming.

 

Is the shop working on your vehicle inspecting the head(s) for leaks through the casting since the head(s) are not warped? There is always a reason for a head gasket to fail, which may not always be readily apparent when looking at the head or block without further tests.

NBCat

 

Surfacing the heads is always a good idea when changing head gaskets!! In fact I consider it mandatory but it's your choice.

I am a bit worried about his statement that this will somehow affect the cover gasket?? It has nothing to do with how the gasket fits. If you cut too much it will affect how the intake manifold seals to the heads but if you cut just the minimum to remove the warping it's usually OK. Usually a .005" to .01" cut is all that's required. Any more than that I would consider replacing the head.

I have to agree with NBCat here. Did the car over heat? These V-6 engines do not have head gasket problems at all so something caused it. If it did overheat you will be VERY lucky to not have a warped head.

Can you explain the test kits recommendation about "running one bank" at a time?? The test kit was checking the engine coolant correct? That type of test cannot tell you which gasket is leaking.

I never change just one head gasket. If it got hot enough to blow one side the other side was also was exposed to the same high heat. So you are taking a chance that you will need to go back in and change the other one at a later date. Are you selling the car or keeping it?
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They are replacing both gaskets and hopefully have checked for warping and found it was straight. The problem was likely from coolant loss as the previous owner had replaced a heater valve and the top up tank. I will know more tomorrow as it should be finished then and I will report back. I hope to keep the car a few years as I recently bought. Now I know why it was cheap and being sold by auction!

 

There's some chance it'll be OK as the CHT (cyl head temp) sensors let the PCM back off the power and even shut down cyls on the 3.0 (unlike on the STR, for example). Fingers crossed!

 

Gaskets now replaced as well as power steering long belt, water pump and plugs and its running fine. The job cost £1100 which is a lot to me but I did have faith in the mechanic and had had a higher quote.
Thanks for the advice, it was really helpful.