This is originally a Canadian car (Vanden Plas), does anyone have accurate vacuum diagrams for this model? I can find a world of info on the L6's, but I can't even seem to find a V12 diagram in the Jaguar factory manual (Series III Service Manual)

I also seem to be have full vacuum being pulled into the air temp port (I assume, little hole directly above the glove box)

Should it really be pulling in there so strong? It's loud enough to hear in the car with the engine running.

When I disconnect the vacuum pipe going to the dash off the manifold in the engine bay & suck on it I can feel no resistance (my quick & dirty vacuum line test lol) This also seems wrong.

Any ideas?

Cheers

Nick

 

I've never found one, either.

XJS vacuum diagrams are pretty darn close in most instances, though.

No.

That hole above the glove box in an inlet to cabin air to the cabin temp sensor, as you say. There's a small boot after the hole which holds the sensor...which is tube-shaped. From the sensor is a metal tube was terminates at on of the large rubber ducts coming out of the heating/air conditioning case. As air flows thru the duct it creates a low pressure which draws air thru the tube and thru hole above the glove box... and thru the sensor.

It should not be outwardly 'sucking' to the point where you can hear the air flow.

I don't have an immediate explanation other than the remote chance that someone was rooting around in there and hooked it up wrong....but I'm at a loss as to how they would've gone wrong.

Might be wrong. I'm not sure.

There are two vac hoses thru the firewall as I recall. One to operate the heater valve and one to supply the climate control system with vacuum. The attachment might help IF you have the Delanair MkII climate control. If you have the Mk III system a lot of things with be different. Your car probably has has the MkIII system. You might need a later manual, Edition 5 rather than Edition 3. Or go a later XJS manual.

Cheers
DD

 

Yes, although, the only jaguar I've ever messed with is my 83 SJ. As to the Climate control, I suspect all are much alike in the applications. And, a bit alike under the bonnet. But, the engines differ.


In my LHD car, there are two vacuum spigots and hoses directly under the battery. Never actually or mebbe on a rare occasion, seen by me. Felt, yes to attach hoses. Which hose to which spigot??? In my car, a slight difference in size. A lot of fiddling in sparse space, but doable....




Removing the battery might have been when and If I ever saw them. But, it would make the access a bit better.


Carl

 

Forgot to mention that the easiest way to tell which system you have is the MKIII has a "pull for manual control" feature on the temp control knob

Cheers
DD

 

Thanks for all the info! That was just what I was looking for

Looks like I have a MkII as it isn't pull to manual.

We took it all apart after work on Friday & it looks like someone had been messing around in there. The two normal vacuum pipes were there, the larger tested out fine, the smaller (hot water) didn't hold air at the solenoid, but I have no idea if that one is NC or NO so doesn't mean much.

But what we did find was an extra pipe going through the hole that normally has a blanking grommet on the corner of the battery tray, this was connected to a S2 Jag metal fuel filter & then up to the cabin temp sensor.

On the engine side, it was connected to the manifold on the port that normally has a rubber blank.

For the moment, I have replaced the blank on the manifold & put that all back to match our 87 XJS's

The 'extra' pipe I have left disconnected on the engine side, I would like to put it all back stock, we do have an 87 XJ6 parts car that I could take the correct parts from, I just need to get further up in there & see where they joined the Heath Robinson style addition into :/

With the extra pipe disconnected, it does suck very gently through the hole, so I am hoping they have put a T in rather than destroyed anything.

They dash is already out of the XJ6 parts car so I can't check the exact routing on that as all the bits are now in boxes, and the other two XJ12's we have are S2... :/

Cheers

N

 

Good grief! There should be severe punishment legislated for people who mess around with systems they do not understand ( I am referring to the person who altered the systems on your car). And the Canadian-market 1987 V12 VDP did in fact have the Delanaire Mk III system, so your car has been further altered if it does not have manual temperature override (the left hand knob should be labelled "pull- Man" or similar. Perhaps your car was manufactured in 1986? - The V12 VDP did not conform to the normal model year changes - they were made in very small numbers, about 420 +- for that year. There are no factory records for model years for this model. The only records are for the number of V12 cars sold to Jaguar Canada in a given CALENDAR year!).

 

Sorry... I am an idiot, it is a MKIII

The 'pull' lettering has worn off & it didn't pull out on Friday when I tried it... It did today, it was just stuck with decades of crud ��