Actually, the pressure Evans has is very near zero, or otherwise 'ambient'. At full operating temperature you really can remove the coolant cap with no bad things happening. I do that on my P/S Mustang to freak people out.

 

This is the mess of coolant residue inside the bellhousing. The torque converter side is exactly the same. It must the concentrate from litres of evaporated coolant.



The gearbox was extremely difficult to separate from the engine as Jaguar decided to use "external" locating dowels high on either side in an inaccessible place rather than the "internal" dowels I've found on every other gearbox I've ever removed. Steel dowels open to the atmosphere in an aluminium casting was never going to be a good idea!

The biggest problem is that removing the gearbox turned out to be a waste of time, apart from the fact that I've been able to snip the end off the duckbill with a pair of scissors.

When I looked into those three open holes in the casting at the very top above the core plugs and oil gallery bung with a torch, it's obvious that the coolant is leaking into the bottom of the V between the cylinder banks and the running out of the lowest point of the two holes on either side and then running down over the core plugs before accumulating in the bottom of the bellhousing and then being splashed around the entire space by the starter ring gear. When I first saw the pink core plugs I thought that the issue was as I believed, but cleaning them up before I took the photo showed no sign of any leakage.

My new theory is that a coolant line in the valley must be leaking. I know these are a likely leak spot on these car but everything I have read and seen suggests that coolant leaks in the valley run down over the outside of the bellhousing and are easily visible at the back / front of the engine when you look down inside the engine bay. My car has no coolant leaks visible from above. The only way to observe the leak is the remove the rubber bungs in the bottom of the bellhousing and witness the lake of coolant in there.

Until I remove the intake manifold, I won't be able to understand why my XK leaks its coolant into the bellhousing rather than down the outside. Presumable there is a lower plate across the valley which is supposed to be sealed but in my car is allowing coolant to pass through and down into the very bottom of the valley. I can't understand why this is not a lot more common but I seem to have fallen victim to being the first to record this particular fault. ☹

Any thoughts on this turn of events would be most welcome. I'll report back once I have the inlet manifold off.

Richard

 

Hi Richard,

I am following your progress with great interest!

Regarding the locating dowels, the 6HP gearboxes used on BMWs are set up the same way, so I think we have to blame ZF rather than Jaguar. I clean them up and wipe a little aluminum-based anti-seize compound on them before reassembly to help myself or the next tech who has to pull the transmission.

Regarding your coolant leak, looking at the parts diagram it must be the "Engine Cover" (Part 1 in the diagram), the molded plastic plug that fits into the top of the block:





I couldn't remember having seen this plug until I pulled up a photo of the block from an ebay listing, and there it is:





I'll be very curious to know what you find when you get the intake manifold off. Aside from a few fiddly fasteners, its really not a difficult job on the normally-aspirated engines. Just a lot of brittle plastic parts to deal with. I recommend replacing every seal and O-ring you can to reduce unmetered air leaks that commonly develop with age.

Cheers,

Don

 

Thanks very much Don. I assumed that the dowel design was a Jaguar feature as it seems so unusual but if BMW's are the same then I think you are correct about it being a ZF thing. If only Jaguar had used a little anti-seize on the dowels. It must have taken me two days to persuade the flange to separate and when it finally went it was like a gun going off. It's not the kind of sound that you want to hear from expensive metal parts!

Your rubber bung theory is fascinating. I wonder why Jaguar did not simply make that plate a solid part of the casting of the block? The rubber bung seems to serve no useful purpose unless there is something underneath it that needs to be accessed but I've no idea what that might be. Anyway, the fact that there is a bung there does mean that there is a way for leaking coolant to find it's way directly into the bellhousing without making any appearance on the outside of the block or bellhousing. It's just my bad fortune that it doesn't seem to have happened to anyone else. ☹

I'll update this thread with my findings. Hopefully, it could prevent someone else in future wasting a lot of time or money.

A small point to help anyone else is that the Jaguar workshop manual states that you need to remove the two securing clips holding the main loom cable which runs down the back of the engine to the gearbox port once you have started to drop the gearbox but before the cable starts to become stretched. My car had three clips so I removed the two I could actually see from underneath but missed the third one until it was almost too late!

Richard

 

My assumption is that either the recess that is covered by the rubber bung was required so the sand/clay core could extend inside the recess to form some important shape in that part of the block during casting, or the recess is there as a mass-saving measure, since these days every gram matters.

 

The results are in! The photos shown the coolant line which feeds the throttle body and the EGR valve is leaking adjacent to the plastic blanking plate. It appears to be the only coolant hose which runs in the valley so it's a pity that Jaguar did not design it so it runs outside. I haven't removed the blanking plate yet as I need to vacuum out all the crud first but that is clearly where the the coolant has entered the bellhousing.

I don't understand why the coolant has not run down to the low valleys on either side and then spilled out over the outside of the bellhousing. It seems to have followed the higher route which is not what liquids normally do but it is what it is. I'm going to try and clean everything up as much as possible and then seal the blanking plate with RTV sealant to try and prevent the bellhousing filling with coolant ever again.



I hope this thread helps someone in the future.

Richard

 

New genuine Jaguar hose is now fitted and everything cleaned up. The hose only cost £15 / $20. It's a pity that such a cheap part can cause so much trouble.

Richard

 

Just a thought, maybe the hole was for smugglers to carry their contraband? Not an easy place to search!

 

Dude, you are SO luck you don't have an /R to do that on. Just the intercooler removal takes a few painful hours. Probably down to two with some practice.