WUR at 10.5 ohms?

[Barenecessity]

I don't know much about electrical work but I went by the instructions on these boards. I took out my WUR and unhooked all of its connections. I then tested the contacts points with a multimeter set on ohms. First the meter read between 9 and 10 ohms. When I reversed the test leads the meter read 10.5 but sometimes up to 13. Are these readings adequate? I know the ideal readings should be 30 ohms. . .

[mark houghton]

Is there a reason you're concerned and felt that testing the resistance was a "barenecessity"

Benny and I were just kicking this around the other day WUR Ohms, 89 930
I'm just going to guess and surmise that different model number WUR's may have different internal resistance to the heating coil, which would govern how quickly the coil heats up and how quickly it affects the control pressure moving from cold to warm settings. In the two WUR's that I have on hand (both different models numbers) I've got readings from 39 ohms on one to the low 20's (don't remember exactly) on the other.

Logic would say that really low readings could be the result of the windings insulation breaking down and allowing a short somewhere partway through the coil, or corosion creating an electrical pathway where one shouldn't be (a short, basically). The more windings, the higher the resistance. Conversely, if there were no coil at all then of course you would see 0.0 ohms reistance. A complete break in the coil would read infinite resistance (no meter reading whatsoever).

What's it all mean? As long as your WUR warms up enough to produce the correct warm control pressure then all is well. Do a search, somewhere someone posted WUR teardown procedures as well as re-winding the coil.

[Benny771]

+1
My reading was different than Mark's reading...... so........
Are having an issue that made you test the wur?
When did you test it ? was the car cold (dont know if this matters). My tests were.
PS. my adjustable wur is working out great Mark. Thx.

[Barenecessity]

Thank you for the info. The WUR was cold when I tested it but the problem began this winter when the temps here dropped into the 20s. On those cold days the car would not start. When it got a little warmer the car started but with backfires. The p/o had installed the pop off valve backwards and one of the backfires destroyed the air box.

I anticipated the damaged air box and had been purchasing parts to tackle installation of a new CIS. As part of this process I decided to replaced all of the rubber hoses, sealing rings, cold start valve, etc while I had access to that part of the car. I did not anticipate a bad WUR but after reading some posts on this forum I decided to test it and that's when I got the 10.5 ohms reading.

I sent the WUR to a place in Texas that will send me a refurbished one for $230. I will test that one when it comes in. Will keep you posted.

Cheers
BN

[mark houghton]

Originally Posted by Barenecessity

Thank you for the info. The WUR was cold when I tested it but the problem began this winter when the temps here dropped into the 20s. On those cold days the car would not start. When it got a little warmer the car started but with backfires. BN

A bad or shorted out heating coil will have zero impact whether or not your car starts or how it idles after initial cold start. If your WUR is working correctly, the mixture will be rich when cold and the car should idle with high rpms until the heating coil heats up a bimetalic strip inside the WUR - which will change the control pressure (raising it as it heats up) and leaning out the mixture. With a non-functioning heating coil, your WUR would be stuck in warmup mode (rich mixture).
Hopefully your new/rebuilt WUR will solve your problems.