Finally got around to figuring out where the infinitesimally small leak was in my cooling system (loss of about a cup over ~2 months or so). Smells vaguely like coolant from the vents after a bit of driving (have been using recirc to get rid of this, so probably not the heater core). Nothing on the garage floor. Pressure test drops about 1 psi starting at 15 psi over about an hour. Valley hoses/octopus appear to be newish and unsullied. Thermostat housing is aluminum.

Anyway, finally found this orange stalactite at the bottom of this hose. Hopefully this is the issue, it certainly is some issue.


Orange stalactite, poorly focused cell phone picture


It's the one towards the centerline of the car of the pair coming out of the firewall (not the one that appears to have the check valve). Two questions in case anyone happens to know. 1) Is the part number MJB6720AC? The diagram is not particularly clear. 2. How hard is this to replace by removing the coolant reservoir but not the throttle? Do I need my daughter's hands for this?


This one is MJB6720AC?

 

I just had all of this apart while I was working on my car. It is quite easy to remove the intake, throttle body, and the coolant reservoir to get a lot of space to work on this hose.

If you want to try to do it without removing the intake and throttle body, then it may be more difficult to get space to work on this, I am not incredibly sure. Although I likely am going to have to do the same here in the next few days to repair a leak i made while replacing all of my heater hoses. If you want me to do some recon i can for you.

 

Hi Dale,
Probably not what you want to hear - the inner hose of the pair at the firewall routes to the side of the water pump 'Water pump to heater hose' MJA6721AG.

Unless your daughter is a magician you will need to remove the assembly somehow. RaceDiagnostics went from the top:
https://www.jaguarforums.com/forum/x...41/#post752880

..and Gus from underneath:
JagRepair.com - Jaguar Repair Information Resource

I've just done this, and it wasn't particularly painful. Just the usual lots of obstructions to undo, and I cut the hoses away from the firewall.
Worth checking the pump brushes 'while you're in there'

 

Appreciate it Michael. So, no, her magic largely consists of making currency disappear.

Thanks for the pointer to the thread, just what I needed, fantastic with copious pictures.

 

I would say start by cleaning this up and see if it comes back. Removing the expansion tank and bracket gives a lot of room for not that much effort. Aggressive use of a turkey baster will let you get a lot of fluid out without much spilling (put the baster end as low in the tank as it will go, then use it again in the bottom hose once the tank is off, no need to drain the whole system). Keep your mind open. The tank sometimes cracks. Those hoses are not generally problematic, to my knowledge. There are a couple of EGR hoses in the general area, too, if you have EGR.

Best of luck, keep us posted.

 

Thanks and appreciate the advice, suspected the tank originally, but no evidence anywhere around it. As you note, many things remain to be seen when I remove it and start rooting around under it.

More quick investigation today, appears to be 'blowing by' (dripping by?) the firewall joint on the underside of that hose, tiny rivulet leading down to the 'stalactite' that cannot be seen without twisting the hose. Literally as if it was a stalactite from repeated tiny drips over a fairly long time. No one has that hose locally (i.e. all 5 dealers within a couple of hours) which also gave me the idea it wasn't a particularly common failure, the dealers have generally had the other hoses that found themselves to be inadequate in my cars.

I thought about just reseating the offending end for about 30 seconds before I went ahead and ordered the hose.

 

Finished this evening.

This job would have been relatively easy if
1. I had the same strength arms/hands while having longer arms and much smaller diameter arms and hands, like very small toddler diameter.
2. I had more joints in my arms/hands
3. I had xray vision.

I couldn't see the lower connection from the bottom or the top, and I couldn't feel down the hose from the top to the connection with the coolant tank off. I was also afraid of breaking the connection to the pump with vigourous explorations.

So, choices
A. There was not enough room to put my hand anywhere near the pump from below, so remove left cat (possible?) and hope I could reach up to where I would need to remove the pump, then remove the pump and turn it sideways to get at the hose you can't see from the bottom or reach since I don't have 1 or 2 above.
B. Remove heater valve from above and hope I could reach down to the hose and also hope I could see or feel the lower connection to the pump it once the valve was gone.
C. Cut the top end of the hose off, repair it with a right angled barbed piece (5/8" OD)/hose and hose clamps adding two more joints into the system.

I chose C, the minimal wishful thinking option. If I ever have the heater valve or the cat off some day, or the pump dies, it will be fixed with one hose. Until then two hoses and a fitting.

Good luck for me, though. The coolant tank level sensor started malfunctioning last week. Replaced the coolant tank at the same time.


Inelegant but fixed,