Why Do SW Gauges Suck?

blykins · #1 (**permalink**) 10-12-2003, 03:02 PM

Alright...I have to vent. I ordered yet another oil pressure sending unit for my SW gauge set....and I still can't get a valid reading. I can thread an Auto Meter sending unit in, plug in an Auto Meter oil pressure gauge, and it will hit the mark between 50 and 75 psi idling. I plug the SW sending unit in, plug the SW gauge in, and the thing barely moves up to 25 psi.

I have had so much trouble with this gauge...out of all of them, this is the only one that doesn't work. Using the previous sending unit, the gauge wouldn't read anything...so at the advice of others, I grounded the sending unit straight to the block....when I did that, the gauge started sweeping upwards...and it would have pegged if I hadn't taken the wire off.

With that test, I thought the gauge was working fine...and the sending unit was bad...so I ordered a new sending unit. Now I'm getting this problem. I'm getting so ticked with this...any more ideas guys?

aumoore · #2 (**permalink**) 10-12-2003, 03:35 PM

50 to 75psi at Idle seams a little high are you sure the Autometer is correct? Maybe the SW is the correct one?

Have you contacted SW?

My SW reads about 25psi at idle and only gets to about 45 to 50 underway. When it reads 0 then I will get concerned.

CJ428CJ · #3 (**permalink**) 10-12-2003, 04:53 PM

I never have liked the electrical oil pressure gauge. You might want to consider switching to a mechanical pressure gauge instead.

Art Burtt · #4 (**permalink**) 10-12-2003, 05:06 PM

Mine said assembled in Mexico----- Maybe that's the problem!!
Thanks NAFTA

blykins · #5 (**permalink**) 10-12-2003, 05:24 PM

aumoore,

The Auto Meter is correct...that's what the oil pressure gauge at the dyno shop was reading too. It idles at about 60psi...

I really don't know what else to try. The gauge works...and has to be wired correctly...because the gauges are in series and the rest of the gauges work.

I can ground the sending unit itself to the battery, and the gauge will sweep all the way up....but when I put a jumper from the stud part of the sending unit to the block...nothing happens.

Maybe I will switch to a mechanical gauge. This is really getting on my nerves.

427sharpe · #6 (**permalink**) 10-12-2003, 07:14 PM

Of all the gauges to be off, this has to be the worst! If I were you,I would take a look at the Autometer look-a-like. I have them in now, and they are excellent.

ccomt · #7 (**permalink**) 10-12-2003, 08:08 PM

"I can ground the sending unit itself to the battery, and the gauge will sweep all the way up....but when I put a jumper from the stud part of the sending unit to the block...nothing happens. "

This sounds like it could be a grounding issue. Since the gauge will read at max when you ground the sending unit to the battery, the gauge should read at max when you run the jumper to the sending unit stud if you had a proper ground. Are you using a lof of teflon tape on the sending unit?

Just my $.02

Jack21 · #8 (**permalink**) 10-12-2003, 08:50 PM

My Windsor oil pressure (Autometer gauges) goes up to ~50# when first started, and the oil is cold. When the engine warms up, oil pressure runs ~20# - 25# at idle, then goes back to ~50# cruising/highway.

The suggestion made to check all grounds is a good one. You have to have metal to metal contact on the threads on at least part of your sending unit or you won't complete the ground. Same for the block to frame to battery ground. Don't use teflon tape for automotive use. Use teflon compound out of a tube, and only for water. In fact, Locktite blue, or plain old Permatex will work fine. Do a trial assembly, then apply sealant to the upper half of the threads to get metal to metal contact, and a good electrical ground on the bottom half.

Another way to test things is on the bench before you put it in the car. Hook it all up with a battery charger and alligator clip leads.

The thing we "Assume" is going to work, even brand new, DOESN'T! The assumption I made was that my fuel tank sender would work as advertized. Hah, Murphy strikes again! Second time, it all got bench tested before installing.

John-Tucson · #9 (**permalink**) 10-12-2003, 11:45 PM

The S.W. company is not the quality manufacturer of the 50's and 60's !!! I have a full set , seven guages, in my FFR with an EFI 302 AND I spent over two hundred dollars trying to get the water temp. guage to work. Calls to S.W. were answered and I followed all of the instuctions. After three replacement sending units the local S.W. dealer refused to give me a new one. After three new gauges the same dealer refused to give me a new one - so much for the S. W. warrantee ! It is fixed now and it cost me another new sending unit out of my pocket. Out of the seven guages, the odometer doesn't roll over properly, the fuel quantity gauge does not indicate a full tank, the volt meter and the tack. both fog up when there is moisture in the air, and the water temp. cost me two big ones to finally fix ( yea, if I was smarter I'd of junked it at the start ), the oil temp. gauge normally reads about 230 degrees in the winter and 240 + in the summer. As a previous owner mentioned THE S.W. GAUGES ARE MADE IN MEXICO. Please don't waste any money on trying to get these poorly made instruments to work. John

750hp · #10 (**permalink**) 10-13-2003, 03:25 AM

I'm disappointed to say that my Autometer Ultralights aren't any better than the luck you're having with SW.

My water temp gauge fluctuates from 160 - 240 and back within 1 second.
My fuel pressure gauges is 5psi out.
My oil pressure is 12psi out.
My fuel level fluctuates wildly (probably sender location - my fault)
My boost pressure is out 2 psi.
Tach works a treat !
Speedo hasn't been hooked up yet

It's so bad that I take no notice of the gauges anymore. I have an aftermarket engine management system that I've programmed to activate a warning light if any engine parameters go out of my preset ranges.

Pretty sad when I have a dash full of gauges that are useless....

Wild Thing · #11 (**permalink**) 10-13-2003, 05:24 AM

I'm pretty happy with my SW gear. They are over 20 years old, and they work fine. Ok, these are no gauges, but a 38 special and a 357 magnum....

BB427 · #12 (**permalink**) 10-13-2003, 07:05 AM

I prefer. a mech oil pressure gauge, I just feel more comfortable with the reading Im looking at.Too many things can mess with an electric sending unit. ground,wire,connector,thread tape,etc

I had the same issues as 750hp with my AM Ultralite stuff in our racecar. I guess to keep em light they left out some parts.

blykins · #13 (**permalink**) 10-13-2003, 03:15 PM

Well for those of you who are interested...here's what I found out:

I called SW tech support...and BTW, they are pretty helpful and patient.

He told me to take an ohmmeter and measure across the sending unit to see if it was bad...it's kinda like a fuel sending unit...this particular one should read 240ohms at 0psi...and 80ohms (I think that's what he said) at 80 psi. So...

I came home, got my handy multimeter and measured the resistance. Sure enough....it made 239.8 with nothing running through it. I got a shot of brilliance and fabbed a quick connect for my air compressor, turned it down to 80psi and hooked it up...sure enough... 80 ohms. So the sending unit (both of them now) are good.

I screwed the sending unit back in the block and hooked up the gauge...even without turning the key on, I checked the resistance again, and it read 80...hmmm....It should ready 80 at 80 psi....not when the engine is dead. I took the gauge out and hooked it by itself to the battery...this time the ohmmeter wouldn't read crap...which means that it was an open circuit.

The tech guy also told me that if I hooked the gauge up to the battery and grounded the sending unit post out...the gauge should sweep all the way up.....each time I did that, it would do something different...sometimes it would go to 100psi....sometimes it would go to 70 and stop....other times it would go down instead of up. So by this means of testing, I consider my gauge......(what would the Butcher call it...) a turd-sucker.

I'll order another one.