WUR test

[Blue83Cab]

Hello, how do you test a WUR to see if it is bad. I am basically looking to measure the ohms but can not find anything when I search on how to perform the test.

Thanks.

[Bob Kontak]

What resistance reading did you obtain? I have searched and found your post from earlier this year. No one really answered your question specifically.

Do you not know how to perform the test at all or do you need the specific resistance? Do you have an ohm meter?

From a couple of old posts I saw it will be around 15-25 ohms - there is a specific value for your WUR.

Fill us in on what you don't know.

[Blue83Cab]

Thanks Bob, I need to know how to do the actual test. THE WUR is still in my car but if needed I can pull it out to complete the test but if i pull it out of the car i assume that it would not get any power to measure. I do own an ohm meter. Thanks for the helps.

[Gunter]

Originally Posted by Blue83Cab

Thanks Bob, I need to know how to do the actual test. THE WUR is still in my car but if needed I can pull it out to complete the test but if i pull it out of the car i assume that it would not get any power to measure. I do own an ohm meter. Thanks for the helps.

No need to pull it out.

Carefully disconnect the wire clip and disconnect the plug on the WUR. It's a little tricky, use a tiny screwdriver.

Set your OHM meter to a low scale OHM reading and carefully touch each probe to the 2 pins inside the plug connection. It doesn't matter which way the probes go on the 2 pins. The internal battery in the meter sends a current through the WUR to check resistance of the inner winding.

You may want to check calibration on your meter first by letting the probes touch each other and using the adjusting feature to calibrate to zero.

Hope it's a digital meter and not analog? With a fresh battery?

Let us know how many OHMS you find.

Even if the range is good, it doesn't mean proper function of the WUR. For that, use CIS pressure gauges like John says.

[john walker's workshop]

you're basically checking for an open circuit. install the proper cis pressure gauges and see if the pressures are in spec. control pressure starts out low and gets higher after a couple of minutes. that means the heater is working. 3.4-3.8bar warm. check the screen under the large fitting for debris.

[Bob Kontak]

Originally Posted by john walker's workshop

you're basically checking for an open circuit.

Nice write up Gunter. Open circuit means the element that you are going to be tested is broken and no juice can flow through in case this is your first electrical test ever.

My old WUR read 31.1 with an "error" of .2 ohms when I touched the probes together. So that trues up to 30.9. The pictured regulator number is Bosch 0 438 140 089 so that WUR number can be cross checked to the factory manual to see if it resistance is appropriate.

[56 nomad]

hello,
i would like to check mine as well.....which reading is considered good 31 or the lower reading of 15 to 25....where could i get the info/specs on my 83 sc.as my warm up (high, does not keep idle up) rpm is sometimes to short to keep the car from running correctly (drops off too quickly) when cold and i suspect the wur may be the culprit. no vac leaks with carb cleaner
regards, Ben

still too many projects

[Blue83Cab]

OK, so i tested the WUR this morning. The car was cold, left overnight in a non heated garage. The Reading on my digital Ohm was 26.1. The contacts were slightly corroded where the plug inserts so i cleaned them with a small file. Any thoughts.

[Gunter]

Sounds like the winding is good.
Because of corrosion, I use dielectric grease (Or Vaseline) on ALL electrical connections, especially the 6 and 14 pin connectors.

Next I'd do what John suggested. Carefully open the line on top of the WUR using 2 wrenches, one to counter-hold the nipple and one to open the cap-nut.
Check the small screen inside for dirt/debris.

That's all you can do without using CIS pressure gauges.

What problems/symptoms do you have?
Cold-start?
Hot-start?

[Blue83Cab]

Just cold start, Once the car is warm and or in the summer time it starts fine.

[Gunter]

Originally Posted by 56 nomad

hello,
i would like to check mine as well.....which reading is considered good 31 or the lower reading of 15 to 25....where could i get the info/specs on my 83 sc.as my warm up (high, does not keep idle up) rpm is sometimes to short to keep the car from running correctly (drops off too quickly) when cold and i suspect the wur may be the culprit. no vac leaks with carb cleaner
regards, Ben

Get the Bentley SC Repair Manual, the info is in there and more.

Carb cleaner is NOT good for the vac leak test, even Propane would be better, IMHO.

[Gunter]

Originally Posted by Blue83Cab

Just cold start, Once the car is warm and or in the summer time it starts fine.

Checking/cleaning the tiny screen in the WUR isn't going to hurt.

For cold-start problems, I'd do a quick check underneath to make sure that 2 yellow wires are connected to the starter Solenoid, one yellow is from the ignition switch to energize the Solenoid and the 2nd yellow wire goes to the cold start injector (CSV). Make sure both are connected and not corroded.

Next, I'd check the AAR located on the right side of the engine between 5-6 intake runner.
It's the item that has a small electric plug and a large vacuum hose connected to it.
Open the clamp holding the outside-hose.
Pry it off with the screwdriver just enough to get it out of the way so you can see into the opening.
Don’t worry about the Alu pipe; it’ll move enough.
With the help of a small mirror and a light, peek inside the AAR.
When COLD, you should see an opening in the slide shaped like a half-moon.
Re-connect the hose, start the engine and let it get real hot.
Stop engine, remove the vac hose again, check the opening again.
When HOT, the opening should be completely closed.
If it isn't closed, the AAR is either kaput, out of adjustment or doesn't get any power.
You can spray some WD-40 into the valve in case it is just sticky.
To check the power, carefully open the tiny clip on the plug with a very small screwdriver and pull it off.
The wire clip is tricky but necessary; don't yank it off.
Start the engine and check the plug for 12 V. (Careful of the fan/belt!)
Just ignition ON will not get power to AAR or WUR; engine has to run.
(One wire is power, the other (brown) is ground)
With power to the AAR, it should close after about 5 minutes.
If all is well, replace the hose and clamp securely.

[56 nomad]

Originally Posted by Gunter

Get the Bentley SC Repair Manual, the info is in there and more.

Carb cleaner is NOT good for the vac leak test, even Propane would be better, IMHO.

will it give specs for the various wurs? thanks , ben

[Gunter]

Yes