1980 XJ6 4.3L US model.

My PWDA is rooted!
I have found similar looking ones for Triumphs, and XKE's
Does anyone know if there is an acceptable replacement?
I am not worried about the light working. I just want the connections to fit, and it not to leak.

I Checked with Barrett and they suggested to ask you guys.
Thanks
Bobmo
Merry Christmas

 

What is a PDWA?

 

I've never seen a 4.3 Liter engine. much less a PDWA.

 

Pressure Differential Warning Assembly. Or something like that.

The brake fluid goes into the cylinder. If there's a leak in the system, the pressure differential moves a shuttle valve which in turn contacts the switch, closing the circuit, and causing the'brake' warning lamp on the dash to glow.

It can be seen roughly in the center of this illustration:



Series III cars had'em until '83 or so.

Sometime they can be opened up and cleaned, and new seals/o-rings installed, to return to good operating condition. I've never researched a substitute but wouldn't be surprised if MG, Triumph, Rover, etc used the same part

This video, although for a Mercury Cougar, will give you a feel for how it's done. Skip to 15:07 to see the shuttle valve/piston. Not sure if any repair parts are available for the PDWA used on Brit cars


Cheers
DD

 

Land Rover Defenders use the same part (AAU1700) for the switch. As for the whole assembly, I'm not sure.

https://rovahfarm.com/seriesbrakespage2.htm

 

whoops,
I guess a 4.3l would be a worn out 4.2l
It is 40 years old ya know. I know my volume has increased over the years.
Bobmo

 

You might try Moss Motors, they have two of them listed: here. I used to buy from Moss back when I was in college in the 60's and I had a $250 MGA. I like there web site because you can search for a part across all British car brands at the same time. This week I needed a temperature guage sending unit for one of my series IIIs and it turns out that sensor was used in MGs, Triumphs, etc for years. Plus their price was much less than the Jaguar parts suppliers. They bought out XJs Unlimited in San Luis Obispo last year and they now ship Jaguar parts from both California and their facility in Virginia. Plus they will send you a free paper parts catalog and they send out a quarterly magazine. I highly recommend them.

Jeff

 

Thanks Jeff
I saw Moss's PDWA at $500
So I moved on.
I can get a TR5 version for less than $100 thats why I'm asking around to see if anyone else has tried a different variant.
I'm not out to win a Concours, just want to have brakes and stop the leaking
Bob

 

Hi.
No use replacing the sender unit if it is leaking. The owners manual states the actual valve mechanism is not serviceable but it is only a couple of O rings on a shaft. Mine is leaking but the shaft moves freely so I'm thinking I'll seal up the screw in sender unit somehow.

 

Thanks Leon.
So I solved my leaking problem.
My sending unit had been smashed and all that was left was the bronze bit that looked like a shraeder valve sticking up.
My leak was, I thought, around the seal and I did everything to stop the leak. Finally my son stopped in for a visit and had him pump the brakes while I watched what happened.
It appears that fluid was leaking through the sending unit.
I pulled it out and soldered both sides shut and the leak is no more.

I also tried to fix the orings but never could find the correct size.
Most of the oring kits dont match up well for necessary id/od. and since its just there to alert the signal switch, which is now permanently non functional, I've reduced the PDWA to an empty manifold.
Simplify!
Bobmo

 

Thanks Bobmo,
I was considering soldering mine as well but wasn't sure if this was the way to go. I managed to find some O rings with a square profile that fit well but I will solder mine as well as I don't want any leaks on my newly painted engine bay.
Thanks again.
Leon