Got an XJ6, now I have questions.
 

Hey all,

I've just taken a dive off the deep end and purchased an 81 XJ6. Obviously a wide variety of items are not functioning and left me with a few questions I'm hoping someone here can answer.

First, the central locking works from the lock on the driver side door, but the switch in the center console doesn't seem to do anything. It has three positions, an impulse switch position when rocked forward, a middle state, and switch position it stays in when rocked backwards. What is this switch supposed to do?

Second, the position of the shifter is about a half icon off of the lit guide beside it. Is there some kind of adjustment that can be made to this guide?

Third, the fan works on high, but not low. Any suggestions?

Fourth, and most uncomfortable for me, the low brake pressure light flickers on sometime for no more than a second or so randomly while driving down the highway. The brakes feel stiff but do stop the car. I wondered if the brake servo or the pressure sensor was the issue. Any common gotchas here I should look at?

Thanks!
-Kurt

On your '81 it should also work from the front passenger door


Power antenna





The shift cable from the gearshift to the transmission is adjustable to ensure that the transmission engages the correct gear as selected ....which likely would alter the position of the gearshift relative to the icons.

The adjustment is a the rear of the gearshift assembly, under the console panel


With the selector set to 'auto', does the lowest fan speed work?



A good brake system inspection is in order as you may have a stack-up of issues.

But, often a flickering brake warning lamps comes down to the connections at the fluid level sensor at the master cylinder. Check/clean/tighten the connections and make sure the cap/wires are not getting mashed by the hood when it is closed. The clearance is very tight and the cap has to be positioned "just so" to avoid fouling against the hood

Cheers
DD

Thanks Doug,

The fan is always on high when I put it in the auto position. Right now the air conditioning doesn't work, so I wouldn't really expect it to turn the fan down as the cabin never gets any cooler. I believe the air conditioning is going to need a leak fixed and a conversion to 134a, which from my reading on this forum sounds like it's going to be a bit of an adventure.
I plan to take it to a shop and get the whole thing looked over, I'm a little nervous about the brakes, they seem to work well but being new to the car I don't know how they are supposed to feel and with the light coming on periodically it quickly makes me paranoid.

I am also having trouble with the starter. It turns over really slowly at first but gains momentum quickly and then starts easily once the engine spins fast enough. In the MGs this was usually the starter motor becoming a little weak with age. My inclination is to install a gear reduction starter rather than to rebuild the one that's there. Is there a good source for gear reduction starters for these cars? My usually sources for British car parts don't seem to have a lot for the XJ6.

Thank you so much for your advice, I feel much more relaxed about the car already knowing there is at least somewhere to go for help. Otherwise it's kind of intimidating.

On the top of this window ↑ on the right side → black menu bar> click on Vendor Directory. You will find plenty of vendors selling XJ6 parts.

Set the temp dial to provide heat and see what happens. When the cabin warms up to the set temp the fan speed should reduce to the lowest speed.

What we're trying to determine is if the system just can't give a lower fan speed (fan speed relay fault, most likely) or if the brain of the system isn't commanding a lower fan speed


Not necessarily. The *refrigeration* aspect of the system is very ordinary. The control side of the system is tricky


A rather hard pedal is normal so that's probably OK. But obviously any brake warning light merits investigation. it might well be an electrical glitch but that doesn't mean you don't have other brake issues as well.



I got mine from Coventry West but I think all the 'usual Jaguar vendors" offer them. Terry's Jaguar, SNG Barrat, etc. Just Google it



I had MGs before owning Jags as well. Quite a difference. :) But there's a ton of info on these old Jags and most work is well within "DIY" territory. Just about any fault you're likely to encounter has a documented fix.

Climate control problems can be a real bear, though.

Cheers
DD

Congratulations. These cars can challenge one. But, certainly tons of fun. Lots of help here.


Doug is one of the several acknowledged masters of them.


As to the center rocker on the console, not to contradict Doug,
but, on my car it also controls the power windows and sun roof.
Some folks jump the switch and render it inoperative???


Enjoy.


Carl

Or perhaps even the cruise control?

Kurt, what is the *exact* location of the switch?

Just aft of the gearshift would be cruise control.

On the flat surface of the console trim, near the ashtrays, would be power antenna.

On the sloping surface of the console trim would be the four window switches, a lock-out for the window switches, and a sunroof switch for cars so equipped



Cheers
DD

Doug was correct (kudos Doug), it is the power antenna. When rocked forward it causes the antenna to go up and down about 6 inches at very high speed, I am confidant this is not what it is supposed to do. Other than that, none of the other positions seem to have any effect. If anybody can tell what it is supposed to do in each position, I think that would help me figure out why it isn't doing that.

I've got most the bugs worked out, but not the fan speed thing. I am taking it to a shop tomorrow to have the air conditioning switched to 134, hopefully I'll be able to sort it out after.

Ok, I have gotten the air conditioning converted to 134a, nothing fancy but it gets plenty cold enough. However, the air conditioning controls don't work well. I have a variety of symptoms.
-When the air conditioning is on it blows through the defrost vents in addition to the dash vents.
-Only the high fan speed works, even when in auto.

I have a parts car, in which the air conditioning controls seem to work correctly. I could swap any or all of the components. Before I go that route, is there anything simple I should try first? Is there any component that I ought to replace first which might be responsible for all the faults?

Thank you all very much, you have been immensely helpful already.

K:


Two sorta easies:


1. Excercise both the temp and fan speed knobs back and forth. At times, that scuffs off minor internal corrosion and full function returns.


2. Vacum is used to do the settings inside the Delanair. Leaking lines
in the engine bay can disrupt functions. Search the archives for the diagram of the lies and where they go. Key parts are the vacuum reservoir and the one way valve.


3. There are two spigots, well hidden under the battery tray in LHC cars. Disconnected or reversed can deter good operation.


4. When my car was 4.2 powered, it's AC worked well, sorta. If I accelerated "briskly", the ac would shut down and blow hot. Clear clue of something amiss related to vacuum.


Oddly, just before the engine's demise, it was cooling really well.


Carl
o

Carl, you're awesome. Drove the car over lunch and noticed that sure enough under hard acceleration the air barely blows from the center vents and mostly through the defrost vents. It comes back as soon as I let off the throttle. I'm going to start digging through vacuum first, it sounds kind of like the baffle that switches between the defrost and front vents sits in the defrost position normally and gets pulled to switch to the dash vents when vacuum is applied. That would explain why I get some cold air coming through my defrost vents (which wouldn't be a big deal except it tends to fog up the windshield).

I was also able to get the fan into low speed by getting the temperature knob in just the right position while in auto. So low speed would seem to work, just not the low speed position on the switch. I wiggled the control switch around as you suggested, but it didn't help in this case.

I set mine on Auto and leave it there. I've not seen any reason to fiddle with the fan switch at all.
(';')

Ok, my adventure continues.
I found the check valve in the engine bay which heads back to a T, I pulled the arm of the T heading into the AC controls off and put my vacuum gauge in instead and found I get good vacuum after the check valve and it holds the vacuum even after the car is shut off. So my check valve is good. Then I reconnected the AC controls and put my vacuum gauge on the other side of the T and see a vacuum leak, not as much vacuum which goes away when I rev the engine. I then put the AC on defrost and the vacuum looks great as soon as the center vent closes off, so I put the heater on and much the same. It's only when the center vent is open that I see my vacuum leak. This is about when I started taking the interior apart. I was able to get to the vacuum line starting at the vent actuator and follow it all the way down to the servo unit and I find that it looks like the vacuum leak is somewhere past where the line head into the servo. Unfortunately at this point I cannot for the life of me figure out how to disassemble the car any further.

https://cimg3.ibsrv.net/gimg/www.jag...273584c4d2.jpg

AC control servo.

The line in question is the black vacuum line heading into the plastic box around the servo unit on the left side.

Any information on how to get deeper into this thing? I can't even get the plastic surround off the thing.

Been so many years that, for the life of me, I can't remember how the servo comes out. Others will chime in

If it helps in some small way to see what you are dealing with here's a pic of the servo and an illustration from the parts book

Air Conditioning Components - Parts For Series III Saloon | Jaguar Classic Parts UK

Cheers
DD

Here's more stuff that might help

Cheers
DD

Thanks so much Doug, that info was enormously helpful, the diagrams and picture were better than what I had. I did get the servo out, but rather than show me why I had a vacuum leak in the center vent flap actuator line, it showed me that when the AC is on it also applies a vacuum to the heater control valve. After a bit more investigation it turns out the vacuum leak is actually in the heater control valve and was the entire time. The heater control valve that is really easily accessible from the engine bay without disassembling large portions of my interior. :icon_rolleyes:

The hose going to the heater valve does not leak, the valve itself seems to be the issue. So applying a vacuum presumably shuts off the coolant to the heater core then, but in my case it doesn't do anything as my valve (or at least the vacuum actuator) appears to be shot.

I've just spent hours out in the 90 degree heat to fix my air conditioning only to discover that it was the heating system. Cruel irony.

I plugged the line going to the heater valve for now, I figure that should keep my AC going until I replace the valve. Hopefully my fathers day gift will include leaving me be long enough to replace the valve with the one from my parts car. :)

Yeah, supplying heat when not wanted is confusing.


My AC is not yet operative. Speak of procrastination, That's me.


Although the replacement plastic vacuum operated heater valve in my car works fine, I "improved" on the idea.


I installed a manual valve in the other hose. Thusly, no water goes to the heater matrix when it is in closed. I call it my summer/winter valve. getting warm, so mine is shut down..


Carl

My MG Midget has a manual valve on the head much like that, works just fine. I could just bypass the valve for now if it ends up being a pain to switch out. I have a spare though, so I might as well install it.

Interestingly, although I am confident that valve is stuck open I don't get heat when the AC is on, it would appear that air isn't pulled through the heater core at all when the air conditioning is running.

https://cimg3.ibsrv.net/gimg/www.jag...25ce3fe2e7.jpg

I zip tied the valve closed. I can always go snip it for cold weather, but I'll probably replace it eventually.


I have had a weird problem since then. When restarting the engine after it has sat for only a few minutes and is still hot it will run very poorly with the RPMs rising and falling. Hitting the gas causes backfiring and reluctant increase in RPM, after awhile of hitting the gas it cleans up and all is well. It never does this if the engine has cooled before restarting, only when I have just gone in for lunch and then headed back out. With the heat right now I wondered about vapor lock, which is common with my MGs, but I wouldn't expect that issue with a fuel injected engine. Any ideas?