WUR woes and repair.

I have a WUR for 3.0 QV engine that went to hot and the electric connector burnt completly. So I'm trying to repair it and want to know more how this works. The electric element for heating up its bi-metal has 2 heating resistance (normal WUR have only 1 resistance). And there is and extra bi-metal with electric contact just under the normal bi-metal.
So my questions :
- how does this WUR works ? Like I understand, the extra resistance helps the WUR heating up more rapidly and disconnects after it reaches 90 °C (something like that). The normal resistance temperature is also 88 to 90 °C ;
- how is the setting of that little bras screw on the extra bi-metal ? It has to do with the temperature but I have no idea when it has to touch the bi-metal when its cold or when its hot.
Any ideas would be appreciated
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I tested the heating elements and they work both. I just wonder why the electric connector has burned completly.

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I think that's correct, but the 2nd heater is only used to open the electric bimetalic thermoswitch portion (not so much to change the control pressure).

I believe that's a mechanical adjustment to control when (or at what temperature) the electric thermoswitch opens (i.e., it controls how long electric current is supplied to the green encapsulated heater after +12V power is supplied). If that electric thermoswitch (wrongly) never opens that could explain things getting hot enough to melt the plastic at the connector.

This design would allow a WUR to heat-up very quickly by having a large current in the green encapsulated heater, but that current is so high that it can't always be present (i.e., the thermoswitch is needed to disconnect the green encapsulated heater). Whereas, on WURs without the thermoswitch, the (different) green encapsulated heater has to be designed to provide less heat (i.e. less current) so that current can just always be left flowing.

What is the Bosch PN of that WUR?

 

Forgot to add that, if the electrical stuff is still working (but just somewhat melted), you could compare the current used by this WUR to the WUR without the thermoswitch when +12V is applied to both.

 

Number is ending 116...for 3.0 QV Euro version. The resistance between ground and first electric winding gives me 37 Ohm, the second resistance between ground and second electric winding gives me 84 Ohm....on the green heater element is marked 47 and 35 Ohm.
As I see it, the first winding is constantly connected to power, the second winding is cut by the extra thermo switch. Image Unavailable, Please Login

As you see on this picture ground is connected to the left pin on the green heater and then to the upper connector where the external connector is put. The other black wire that comes from the external connector is going to the middle pin of the green heater. The right pin of the heater goes to the thermo switch and when closed is bridged to ground. Normal WUR is heated up until 80 degrees I have read somewhere. But this heats up to 90 degrees. I will try to release the bras screw so the thermo switch is disconnected and then turn it and see how its going to act.
Here is a better picture ;

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So is it wired/constructed in a way such that current always flows in the 35 Ohm heater, but current only flows in the 47 Ohm heater when the thermoswitch is closed? Can you draw a schematic of the wiring and components? Alternatively, if you measure the resistance between the two input terminals (when assembled as normal) is it ~20 Ohms when the switch contacts are closed and ~35 Ohms when the switch contacts are open?

 

Yes, 35 Ohm al the time, 45 Ohm when screw touches ground.

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Resistance between 1 and 3 is 0.5 Ohm when thermo switch is closed.
Resistance between 1 and 3 is 84 Ohm when thermo switch is open.

Resistance between 3 and 2 is 20,8 Ohm when thermo switch is closed.
Resistance between 3 and 2 is 36 Ohm when thermo switch is open.

Resistance between 2 and 1 is 20,8 Ohm when contact is closed
Resistance between 2 and 1 is 48,5 Ohm when contact is open

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Temperature goes within 5 minits to 92 degrees. With the screw of the thermo switch completly in (closed) temperature will rise until 102 °C and more. I started to unscrew until temperature whas fluctuating between 85 and 95 °C. I think this is the set up that is needed. Maybe a bit less.

 

Thanks -- that's perfect and great information. I can see why things melted if the switch never opened. Couple questions:

1. When you made these tests did you use +12V or, say, +14.3V that an alternator would apply?

2. Do you know the corresponding resistance of the heating coil in the more simple WUR without the switch?

 

Test with battery charger 12 V....normal WUR between 15 and 30 Ohm.
I'm glad you do learn from me this time...its always the other way around !!

 

Every different model car that use WUR have other resistance.
Intresting articles and videos.
http://forums.pelicanparts.com/porsche-911-technical-forum/385646-wur-ohms-question.html


Also : temperature can be changed by the brass setting screw and time to heat up bi-metal also can be changed by the direction of the thermo switch.
If the thermo switch is just under the heating element, thermo switch will react faster and opens more rapidly.
If the thermo switch is put more beside it will take longer to open the thermo switch, so it take longer for the bi-metal to go up and close the fuel pression valve.
I think it has to do for what region the car is produced. And I'm not sure what position it would be correct for hot regions of cold regions.

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In order to choose temperature, direction of the thermo switch first and then you can find the right working temperature with the adjustable screw.

 

I did find WUR with higher single heating element...for Saab its 35 and 40 Ohm That whas a hell of a job for the Bosch engineers to find the right set-up for each model car.

 

hi TheUni,,

if all else fails.
call,,
send to the Deloran Guy.
( i’ll have to go find the literature.
)

Porsch, Delorian, Ferrari
,, all used our bosch CIS systems.

,,
do,, you have a frequency valve,,?

I don’t.
mines euro.

good luck.
Eduardo

I have a spare,, always carry a spare.
,,

 

Thanks, this is also a spare (did get it for free) ...just in case. No need to send anywhere...I love to make/repair things myself.
With this set (not my site) and new springs and pin this WUR will be usable.
https://www.ebay.co.uk/itm/Repair-Kit-Suitable-For-Bosch-0438140116-Warm-up-Regulator-Wur-Repair-Set/184407788991?hash=item2aef8f8dbf:g:WVoAAOSwE0penBV5
I'm making a new electric connector for the moment. This is just a testmodel.
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He died in 2019 :-( I don't know if anyone is taking over his business. I got to meet him a couple times (because Lotus and Delorean share a bunch of parts), and it turned out his first wife was a distant cousin of mine.

Aaron

 

I just send mine to CIS FlowTech in Alabama and they fix them and send them back. Good on you for digging into with what and how they work.

 

I just received the repair kit with repair manual.
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There are several ways to make adjustments : How this works exactly will make some comments, first completing with the new kit.

The big cilinder with fuel lines can be beat in or out...
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The shaft where the bi-metal is put on, can be beated in or out ;
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There is a bolt mounted in the middle of the membrane lower side : this can be changed up or down Image Unavailable, Please Login

Because this bolt is inside the lower part of the Wur, you cannot reach it once installed. So there it possible to make a hole in the brass plug to reach this lower bolt.
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Before testing this repaired WUR I wanted to check the 39 year old one that is in the car (Mondial QV 82). WUR ending 116.
This are the results :
First picture : cold start with exterior temperature 16 °C = 2.3 kg/cm. A bit high....
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Cold start after 1 minit : 3.0 kg/cm

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Cold start after 3 minits : 3.65 kg/cm

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Cold start after 10 minits = 3.65 kg/cm and stays that way.

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System pression with warm engine, valve closed = 5.3 kg/cm

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Pression after shut down car after 1 minit = 2.75 kg/cm. It dropped until 2.0 kg/cm after 10 minits and stays that way for a least 40 minits.

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Lines are connected between fuel distributor (middle exit on top) and the big connector WUR. Make sure you have 4 new copper washers when you put the original lines back. They tent to leak easely.
Engine runs smooth and all cilinders have the same compression. Car has 59.600 km...
I will let the old WUR sit. Do not mess with something that works perfect !!

 

Nice write up!!
I missed this one, I had to login severall times to view it??
I'm busy doing the same thing (repairing and adjusting the WUR. I guess you are Dutch? (according your name?)
I just send my WUR to Kjetronicrevisie.nl waiting for repair now.

 

Dré ksen van Tongeren....tegen Maastricht.

 

Some more interesting video how to check/repair WUR

 

Some other videos with explaination of the fuel metering KJetronic.
This is for a VW model where the metering plate works up...on ferrari the metering plate goes down.
www.youtube.com/watch?v=Ax6O6Zhxx0E

www.youtube.com/watch?v=PuELRd3gqgk

www.youtube.com/watch?v=weE8pVCPQFA

www.youtube.com/watch?v=ynwSQJyhhiw