Pete is right. I was thinking coolant because of the VP leak. If the head gasket leak is only between cylinders i don't know if they make a sealant for that. Thermagasket not Thermaseal. RXAUTO.com is the site. Contact them and see what they say.

Pete, I didn't know that about testing with WOT. Good to know.

When testing the compressions I took the fuel pump fuse out. Removed all the plugs so I could get a bench mark uniform turn over speed. Took each pot in turn with the accellorator peddle depressed I let the engine do ten ful revolutions on each test. I am not sure that that will open the throtle, does it?! Or to do this would I have to manually prop it open.
Anyway the results from doing that were the ones I posted. What diffrence would it make if just the individual plug being tested was the only one removed?
Genuine question as I don't know! I can see that cranking speed may be slower and if you have a blow across the pots it may raise the comp. in the pot being tested. What am I missing Pete?
I know you know your stuff mate not doubting that in any way shape or form. Just what to know.
Has anyone else used a gasket liquid fix? I would be interested to here from you. Eddie the eagle watch out 👀

When testing the compressions I took the fuel pump fuse out. Removed all the plugs so I could get a bench mark uniform turn over speed. Took each pot in turn with the accellorator peddle depressed I let the engine do ten ful revolutions on each test. I am not sure that that will open the throtle, does it?! Or to do this would I have to manually prop it open.
Anyway the results from doing that were the ones I posted. What diffrence would it make if just the individual plug being tested was the only one removed?
Genuine question as I don't know! I can see that cranking speed may be slower and if you have a blow across the pots it may raise the comp. in the pot being tested. What am I missing Pete?
I know you know your stuff mate not doubting that in any way shape or form. Just what to know.
Has anyone else used a gasket liquid fix? I would be interested to here from you. As the coolant has been pressurising its self. Eddie the eagle watch out 👀

Last edited by Pepi on 5th Apr 2016 3:29pm. Edited 1 time in total

Hi Pepi, I'm in the middle of doing my valley pan seal.
For the purpose of others, I will detail my method later, (I have some pictures) however, when you lift off the valley pan, you find (normally) the original rubber gasket, it's a real rubber seal, and can come off in one piece. It appears, that this gasket fails, and weeps coolant, and the valley between each side, fills and drains down the back of the engine block, with coolant. Possible from alloy corrosion creeping under, like old alloy wheels, going porous. The original gasket is not available, and should you search for a replacement, you end up buying a whole 'valley pan cover' with a bead of set RTV to reseal it. So, the repair is to clean and reseal the original cover, with some RTV. I have done this, and after you refit the knock sensors, and the water pipes, and (in my case) the rear coolant manifold, your water circuit, can now be pressure tested. (With coolant pipes refitted), BEFORE you go ahead and refit the intake manifold. My first attempt, was very leaky, so, have recleaned, and fitted a continuous bead, and let it go tacky, placed the cover on, and now waiting for it to semi seal, before tightening. There are limits cast into the cover, to stop you over tightening all the RTV to smithereens.

Did you get success Pepi, as this job is a pig, and my hands are in tatters, any tips welcome.

Let the tea drinking/ setting time commence!

All other tips welcome.

update....
my resealing of the valley pan, has since failed. i believe it was because the distance between both pieces, ie the pan cover, and the block, is not completely 'together' -more, it is on a step, that you tighten to. so the thickness of the RTV is about 1-2mm, which, it would seem, is too much, for typical RTV to bridge for any length of time. my solution, is what i would now recommend, namely to buy the whole valley pan, either pattern part at £35 or about double for an LR original. (LCW00010) it comes with a very hard already applied bead of sealant.., which is obviouly different to the self applied soft,(even when 'gone off' and dry and therefore, much more squidgy)... and therefore not up to high pressures. my reseal lasted about a month, but i replaced the pan this week, and all is good, i will update in another month.

note, replace the 2 rear water jacket y piece green gaskets...and all four water pipe o rings, and if needed, the inlet manifold four orange 'binocular' gaskets.
water pump can be left alone, if doing this job. -when attacked from above/rear, and with pollen filter assembly removed.
and... with inlet manifold off, attend to the horrid torx bolts that hold the PCV on. these are really tight, so easily stripped when removing the PCV, and can be substituted at this point for regular hex head bolts.

Pepi wrote:

Did anyone come up with a sources of the "Green" valley pan gasket. Or a part number.

Does anybody have the part numbers for all the pipes at the back? Also the gaskets for the coolant manifold? I'm going to change these on mine while I'm doing the valley pan. 2004 RR 4.4 V8 Autobiography

Unnecessary quote removed

I might of missed it but did you let the RTV partially cure before setting torque?

When I first did my repair, I did let the RTV go off overnight. It was 'hard' and did not burst or squish soft unhardened RTV out at all. I carefully placed it and tightened it down. It did hold for about 3 weeks.
I had the urge to briefly thrash it nuts off, for about 10-15 seconds...one evening, just to tell it that I was driving it. It failed on way home, with quite a big leak. So, I guess it didn't handle a sort of high pressure test. When I removed it I could see the RTV had indeed split and let through water etc. I immediately ordered a whole cover, and it came with a very thin, and very much harder unsquashable bead. It's been on for about a week or so. I still have to replace my 'water' with some decent coolant. And then, maybe give it the beans once more, and report back here.

As earlier, I would , for £35 delivered, get at least, the pattern part, new cover, and fit that.
Will as promised add a few pictures too.

The PO on mine used a Permatex Gray. It has been holding. I know it is not the same pressures but on my BMW 325 valve cover I had a of a time getting it to not leak. This last time I was sure to clean everything off the head side and wiped it down with acetone. I also cleaned up the inner valve cover surface and wiped it down with acetone. I applied the black RTV in a very thin layer with my finger to both surfaces and let sit about 2 hours before adding the gasket and setting torque. Let it set 24 hours. No more leak.
Now on the VP it must not have been bent or warped. It's gone if it is.

johnboyairey wrote:

As earlier, I would , for £35 delivered, get at least, the pattern part, new cover, and fit that.
Will as promised add a few pictures too.

Hi folks
Just an up date. I went to the trouble of stripping and rebuilding the VP Gasket to no avail. Even though I took the belt and braces approach to doing the job the thing blew again.
I took the car over to Duckworths in Market Rasen Dan got one of the lads in the workshop to look it over. He brought my attention to the very slight and barely noticeable uneven cranking speed on start up.
He also said that he was sure there was a lot more going off which was causing the VP to go. He also said get a compression test done and a leak down plus a pressure test on the cooling system. All of which made a lot of sence and a logical approach and advice for us all with VP problems.
My heads were both leaking badly.
Not really noticeable to me as I think they had been going from the day I bought the car and had no idea of what to expect from the RR after driving a Disco 300tdi for years.
So if you are having VP problems before you start stripping the car get the tests done and take it from their results what to repair.
Hope you head my tail. Or should that be heed my tail!

Ouch! Great pics and info though. Are you starting a Gofundme page?

This is the same as what I used. Either search online for LCW000010 or use a link like this...
https://www.ebay.co.uk/itm/391324327393
Remember, the old original gasket, was thick rubber, and was sandwiched between the cover and the block. There are stepped edges to all the bolt holes. This stops over tightening the old rubber gasket. When you replace the thick rubber gasket, with just RTV you have the same stepped gap to make up, with just RTV. So it has to be something better. (Than regular RTV, which is for thinner 'gaps')
This part (above) comes with a thin, but very hard applied bead, ready to bolt to the block, once you have cleaned off old material, and no doubt all the oil/grease on either side.

That job should be sorted now I hope.
Ha John, Just followed your link and I

johnboyairey wrote:

This is the same as what I used. Either search online for LCW000010 or use a link like this...
https://www.ebay.co.uk/itm/391324327393
Remember, the old original gasket, was thick rubber, and was sandwiched between the cover and the block. There are stepped edges to all the bolt holes. This stops over tightening the old rubber gasket. When you replace the thick rubber gasket, with just RTV you have the same stepped gap to make up, with just RTV. So it has to be something better. (Than regular RTV, which is for thinner 'gaps')
This part (above) comes with a thin, but very hard applied bead, ready to bolt to the block, once you have cleaned off old material, and no doubt all the oil/grease on either side.