Hey guys. We have a set of Stewart Warner gauges in our 39. Every time I turn the key on the gauges go on, the temp goes to 180, oil to 40 and the gas goes to 7/8th. This is without the motor running, cold and 1/4 tank of gas. Dissconnected the senders, all stay at 0, ground the senders all go to full just like I expected. Checked the ground to the gauge cluster. I'm lost. If it was only one gauge I'd say it was a bad sender but all 3? Suggestions?
I have a similar issue with the gas gauge on my Apache. All new stuff, works great with the sender out of the tank, put it in, weirdness happens. Ill be watching this. Let me be the first to suggest to you and me, bad grounds, even tho we are sure it isnt.
try running a temp ground from the minus batt post right to the gauge cluster--see if it changes. Had a similar issue with a gas gauge--all grounds checked good but added another wire from tank to frame rail--problem gone.
Isolate the grounds and guages. Eliminate the possibility that one guage is providing a false ground to the others. Is this a new problem that has developed in a formally working system?
OK. Thanks for the replies. Gauges read the same when it's running. Wouldn't know if the temp will climb past 180, haven't had the car get that hot yet. 31 Vicky, new system, never worked right. Kinda hard to isolate the grounds, all 4 gauges mount into a single can. I've tried every combination of gauges (hook 1 up, other 2 disconnected, hook 2 up with the other disconnected to eliminate 1 gauge causing the problem. Can't help but think it's a ground issue but everything should be grounded well. Geez, I'm losing what little hair I have left over this.
So what could possibly common to all guages located inside a single can? The can Ok, how about disconnecting one sender at a time, that will drop out stray grounds entering the can. Or disconnect all and reintroduce them one at a time watching for all guages to move on one wire.
Think I got it. I assumed the gauges grounded thru the can. I ponied a ground wire from each ground post on each gauge to chassis ground. They all seem to be functioning correct now. Geez, I been gauges for 40+ years, I don't recall ever having to run a ground wire to each gauge unless it was in fiberglass. Still doesn't seem like I should have to on these, the gauges appear grounded to the can so ??? Oh well, long as it works. Thanks for the help guys.
The trouble I found with Stewart Warner gauges are the new ones are made in Mexico and I have had nothing but problems with them.
Your gauge might not be transferring the ground thu the dash itself. Thick enamel paint are who knows.
2-3 wraps with tape won't bother anything. The tapered treads force the tape into the voids. No grounding issues. Now ive seen wobbled out pipe threads get the sender wrapped with 1/8" of tape to seal. That's a ground problem but not from the tape! It's a operator error dabbling in nincompoopery.
Only two raps with tape, gauge did not read correctly all the time remove tape ,used tread lock , installed let set , gauge reads correctly , GROUND !!