Autopsy of a WUR 0 438 140 001

prebordao · 02:41 AM

The heating element on my car's WUR wasn't heating... so I decided to open it.
As it is the -001 (the earliest one) I think some interest exist on the differences between it and all the other ones.

As you can see the differences are quite visible. The biggest one is that the cover appears to have some kind of thermical switch that cuts power to the bimet strip after a while. I don't think that any of the others has it.

Turns out this was the ruined bit (seized and a contact is broken). The resistance heats and has the correct ohm value (+-16) so I think I will connect it permanently to 12V.

As for the "myth" that the -001 is not rebuildable, I think it's debatable...

thumbdoctor · thumbdoctor's Garage

Just thinking out loud, is it possible that this regulator is designed to operate without an engine mounted thermo switch. That would explain the internal contacts. It appears to have some adjustability in the sense of the Bi metal post being pressed into the housing and the pintle pre load spring having an adjustment on the bottom. I would first check for any restriction in the control valve assembly. The filter screen are known to become blocked. This problem is quite common here (Quebec) due to the Ethanol in our petrol. The stuff manages to scrub the years of accumulated varnish from the reservoir and carry it through the fuel filter to the fuel distributor and ultimately the WUR. My experience with cleaning them is making the bi metal post adjustable helps with cold control pressure problems and replacing the diaphragm o-ring (newer Viton) or stacking extra diaphragm discs helps with low control pressure issues when CIS system pressure is correct "dead heading" the delivery pump.

T77911S · 08-24-2013, 04:56 PM

WOW! that IS and old one.
i think the ones in the 80's went back to that thermal switch inside.
interesting hose fittings.
i remember reading something about the early WUR and having to "update" to a newer style when they go bad. if part of that mod includes updating the fittings that could be a big benefit, not only safety as far as fuel leaks but pressure gauge connection.
rebuildable also depends on parts that are available.

donlan · donlan's Garage

I sent a reply but it seems to have disappeared into cyber space? Anyway thanks for showing this.It made me go and have a look at mine and where it mounts on the inlet pipe is the same shape as the bottom of yours and the wire has been changed to a two wire fitting with one wire earthed to one of the mounting bolts and the fuel lines have been altered.The present wur ends in129. Car seems to be early73 and motor late 72. [I am trying to waken it after a long sleep.]Michael.

E Sully · E Sully's Garage

The 0 438 140 129 is the later replacement for the original 1973 cis wur.

donlan · donlan's Garage

Ed.I just read on another thread that that [0438 140 129] is for a '75 US model and vacuum operated???Michael.

prebordao · 08-27-2013, 01:34 AM

As the internal switch was "dead", I had to wire an external ground connection...

E Sully · E Sully's Garage

The '73 001, and the 008 which was for the early 2.7's, are both considered non rebuildable. From my research they seem to be the only wur's that cannot be rebuilt.
The 0 438 140 129 is the correct replacement unit. It has no vacuum connection.

Here is a link to the inside of a WUR.
http://jtresto.com/e21/WURServicing.pdf