Stewart Warner Sending Unit Problems

blykins · #1 (**permalink**) 10-04-2003, 08:02 AM

Has anyone ever had an electrical sending unit be bad from the factory? I ordered a whole set of SW Deluxe gauges and received them last night. After 3-4 hours of wiring, I plugged everything in and started the engine. All gauges worked except the oil pressure gauge. (I had an Auto Meter gauge previously, so I know I have oil pressure...) The gauges are wired in series, and the oil pressure gauge is almost first in line, so I know it's getting power...as a matter of fact I grounded the sending unit wire, and the gauge slowly went up...so I'm pretty sure the gauge is fine. Could I just have a bad sending unit? Is there anything special you have to do with a SW sending unit that you don't have to do with the others? I'm hoping there's maybe a few tricks of the trade I can try before sending this one back.

Thanks,

Brent

Bob Putnam · #2 (**permalink**) 10-04-2003, 08:30 AM

Check that the sender is properly grounded to the block. Do not use teflon tape on the threads. A small amount of gasket sealer is OK.

blykins · #3 (**permalink**) 10-04-2003, 10:30 AM

Bob,

The sending unit itself does not have teflon tape on the threads...but I had to use a nipple and a 45 to get the sending unit out of the way....on those I put teflon tape. Is that a bad thing?

blykins · #4 (**permalink**) 10-04-2003, 12:19 PM

A good friend of mine here told me that I could jumper from the sending unit body to the engine block...that would be a significant enough ground to see if the gauge worked. I tried that...and to no avail.

Bob Putnam · #5 (**permalink**) 10-04-2003, 12:20 PM

Quote:

Originally posted by blykins

Bob,

The sending unit itself does not have teflon tape on the threads...but I had to use a nipple and a 45 to get the sending unit out of the way....on those I put teflon tape. Is that a bad thing?

If it interferes with the sender's electrical connection to the block!

If you have jumper cables, use one between the sender and battery or chassis ground. If the gage works then, the problem is the tape.

blykins · #6 (**permalink**) 10-04-2003, 12:50 PM

Ok.....

When I went back outside, the gauge was at 50psi. When I turned the key on, it went down. I took a piece of 18 gauge wire, attached an alligator clip on each end, and put one end on the sending unit post along with the sending unit wire...and the other end on the negative terminal of the battery. When I started the engine, the gauge kept increasing...and was on its way to pegging the gauge.

I'm way confused.

The gauge is a SW Deluxe....SW82305. The sender is SW279B-F.

If anyone has any clues, please let me know. I have already ordered another sending unit, but I would love to know if there's just something else amiss before it gets here.

Bob Putnam · #7 (**permalink**) 10-04-2003, 03:26 PM

Sorry - I should have been more specific. Don't ground the terminal. Ground the base of the sending unit.

ENTDOC · #8 (**permalink**) 10-04-2003, 03:37 PM

Brent,I have fought with my oil pressure gauge and water temp gauge for the past 3 weeks.The problem is almost for sure the sender.I changed my water temp sender and it worked right away,the oil pressure gauge still does funny things so I have another one ordered.SW gauges are very poor quaility in my opinion. chuck