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MK 10 Mystery

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JustV12 Avatar
JustV12 Duane Grady
Toronto, ON, Canada   CAN
Greetings all, and to note this is my first post on the forum.
I was referred here by a Brit car friend who is not a Jag guy.
I had never head of you until now and I signed up immediately so I could have a new audience to whine to. winking smiley
I feel welcome already smileys with beer

OK, so on with the whining,
I have a strange problem with my 62 MK 10. Although I grant that all Jaguar problems are strange, and this one is no exception.
After years of flawless operation, I had the brakes attended to and their is a slow leak onto the drivers floor panel. driving the car leaves your shoes soaked with brake fluid.
After that the car developed an electrical issue very suddenly after a high speed trip. I was doing a registered 90 MPH so it was likely 75MPH in reality, and I doubt there is a "connection" (hey good pun) but I went the next day to start the car and the brake lights came on full, as if the pedal is being pushed.
When the brake pedal IS in fact pushed there is a dim attempt at the other filaments coming on but you have to be paying attention.

Second, when I turn on the headlamps all of the running lights come on as they should with no change to the taillights but nothing from the headlamps at all.
When I hit the high beam switch the low beams come on and it looks like its running OK.

Any ideas?

PS:
I am going to leave this post but as I wrote it out for the first time I realized I may have an issue with the dimmer switch, so I will check that.
Perhaps I can answer my own post.


Cheers
DG



When working under your Jaguar be certain to secure it well.
While there is a measure of prestige involved in being crushed to death by a Jaguar, especially a V12, bear in mind the results are rather permanent.

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JustV12 Avatar
JustV12 Duane Grady
Toronto, ON, Canada   CAN
Its not the dimmer switch....confused smiley



When working under your Jaguar be certain to secure it well.
While there is a measure of prestige involved in being crushed to death by a Jaguar, especially a V12, bear in mind the results are rather permanent.

ahaugland Avatar
ahaugland Silver Member Alex Haugland
Eugene, OR, USA   USA
First off, I don't own a Mk10 but own just about every contemporary Jaguar to it so hopefully I can be of some aid. The leaking brake fluid must be coming from the master cylinders, of which, I believe, your car has two, one for the front brakes and one for the rear. I'm assuming as your chassis number ends in BW that you still have the automatic transmission in the car, so don't have a clutch, so you won't have a leaking clutch master cylinder to contend with as well. You may be able to rebuild your existing cylinders, honing them and replacing all the rubber seals if not too badly pitted, or or getting them sleeved with brass or stainless steel. New replacements (not exactly like the original) are available from SNG Barratt and probably others as part number C19968. Don't drive a car that leaks brake fluid. The fluid leaking out hurts brake performance, but even worse is the air that likely can leak in.

The brake light switch in your car is also part of the hydraulic system and relies on pressure in the brake line to actuate, With the leak, the brake lights may not operate properly until proper braking is restored. If the switch is stuck in the on position, it may also need to be replaced, but I'd fix the master cylinders first and see if the problem goes away after rebleeding the system.

The first thing to check on the headlights is the fuses. I believe that the Mk10 has a separate fuse for the high and low beam, though I could be wrong. Try replacing the fuse even if it looks OK, especially if they're old. The fuses for British cars are not the more commonly available ones from the American parts suppliers as they use a different scale for rating them (Rating for one system is what amperage the fuse will hold at while the other is what amperage it will blow at), so use proper British fuses (readily available from any British parts supplier). Does your dash main beam warning light come on as you toggle the dip switch on and off? It's on the same circuit as the high beam light. If it works but the headlights don't then it may be a corroded connection in wiring to the headlamps or even both high beams being burned out on your lamps.

As far as the brake light issues, Make sure that you have a good and solid ground to each of the brake lamps. It isn't uncommon for a poor ground issue to cause current to flow through the lamps in odd ways as it tries to find the easiest ground, lighting up bulbs that shouldn't illuminate. You can potentially test this by providing a good ground to the lamps by running a wire from a good metal contact on the chassis and touching it to the lamp base (which is used for the ground circuit) and see if the lights sort themselves out.

Hopefully this helps!

--Alex Haugland
Eugene, Oregon
USA

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Curmudgeon Dave C
somewhere, USA   USA
1950 Ford Custom
1950 Ford F-1 "The Ugly Truckling"
1964 Jaguar Mark 2 "Elizabeth"
A clue is "After years of flawless operation, I had the brakes attended to and their is a slow leak onto the drivers floor panel. driving the car leaves your shoes soaked with brake fluid. "

WHO attended to the brakes?
WHAT kind of brake fluid did they put in?
Wrong stuff (or a mix of massively different types) can cause the rubber bits to perish real, real fast, leaks, holding pressure (brake lights on), etc.
Find out what was IN the car, find out what was put in, plan on a full-on rebuild of the hydraulics and flush of the steel pipes.

May not be that bad, just be prepared.

Master first, new fluid, bleed down to the calipers to prevent and possible bad stuff from pumping back into the master.

JustV12 Avatar
JustV12 Duane Grady
Toronto, ON, Canada   CAN
Gee there has been action here and I missed it!
Sorry for the absence, but typically with multiple cars when one acts up its not a stress to get it dealt with.
I was dealing with Daimler stuf, and the XJ-12 and XJ-6 colling systems... (YES, both cars...)
Just to be clear, the brake issues are the easiest issues in the world for me and I'm not really worried about that.
My real concern is how possibly the leaking brake fluid may have leaked down and affected the electrics.
What is under the dash between the master cylinder and the floor that may mess with the wiring?
There is a lot there believe me. I don't live in a car friendly place (even though we have 13 parking spots) we are not really allowed to work on cars here.
I will do it anyway but I need some clues. I think the ground wires are a good place to start and Ive done that at the lights themselves.
No luck there so I am back to under the dash or the panel beside the foot well again.
I spent some time looking but the need to put it all back together whether you've fixed it or not is a frustration and a major time consumption.
I need to have a target idea, get in and check it, hopefully fix it and get out again befor security taps me on the fender ans says "Whats up?" which requires him to write a report to the management office etc etc, you may know the drill if you live in a similar situation.

So if anyone knows of a connection under the brake cylinder anywhere under that drivers side of the dash that could be affected by the brake fluid leak please let me know.

And BTW, Curmudgeon, are you that guy that put a Jag engine into a Chevrolet sedan just to get even with the "lump" guys?
Whoever that was I love it!

Cheers

DG



When working under your Jaguar be certain to secure it well.
While there is a measure of prestige involved in being crushed to death by a Jaguar, especially a V12, bear in mind the results are rather permanent.

Curmudgeon Dave C
somewhere, USA   USA
1950 Ford Custom
1950 Ford F-1 "The Ugly Truckling"
1964 Jaguar Mark 2 "Elizabeth"
Nah. I might have put one in a Ford, but never, ever a General Misunderstanding.
Now, a Flathead Ford V-8 in a MK2....hmmmm...have one of each.....

As far as wiring, been a while since I looked under a MK10, but there should be nothing of consequence straight down (gravity) from the master other than the pedal and floor.

ahaugland Avatar
ahaugland Silver Member Alex Haugland
Eugene, OR, USA   USA
I would still suspect that your brake light problems are almost certainly related to your hydraulic brake switch rather than a wiring connection. Does the Mark X have a floor mounted dimmer switch? That could potentially be contaminated by brake fluid and possibly shorted, causing your headlight problems. That switch is pretty robust but have been known the fail. They are readily available new.

--Alex Haugland
Eugene, Oregon
USA

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lbconfire David De (Disabled)
Disabled Account, Antarctica   ATA
SO what is the problem here, its a bit hard to read. Fluid leaked down and thats the problem? Or is the brake pedal not right, or? What work did you have "tended to" with the brakes?

MKJag Avatar
MKJag Pat Ruster
East Tawas, MI, USA   USA
I'm sure you have resolved by now; however, my guess it the master is rusted out and a pin hole leak is draining into you foot well. It is also located in a position that could allow the fluid to get into you wire harness and cause damage.

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