Oil Pressure
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
Oil Pressure
78 vette oil pressure will only read up to 20 psi. I have applied up to 60 psi air pressure on sending unit and still only get 20psi indicated. Both old and new gauge react the same. I have two sending units and they act both the same way. I replaced the mylar circuit panel with no change. The resistence on the sending unit wire when dissconnected is 0 ohms. The only thing I can think of is the sending units I have are not compatable with the gauge resistance wise. Anyone ever run into this problem. Thanks Dave
Pro
Joined: Dec 2005
Posts: 596
Likes: 1
Dave, Not that you need to spend more money, but I have always converted my vehicles to mechanical oil pressure gauges, and always Auto Meter at that. I like to know. If you have the ability to turn a wrench, it's really an easy job and oil pressure gauges are readily available in a wide price range. I simply removed the electric sender above the oil filter and screwed in the compression fitting provided, ran the tube to the dash and gauge and wired in a light. The less wiring (especially resistance type) in a fiberglass car, the better. My .02
Steve
Steve
Burning Brakes
Joined: Jul 2003
Posts: 868
Likes: 5
well sounds like you've checked everything ...sending unit and gauge.
What about the resistor thats on the back of the gauge? It helps calibrate the guage..Did you reuse the same one or did the new gauge come with a new one?
Also are you putting alot of sealer on the sending unit where it screws in,maybe messing with the ground?
Jason
VetteInstruments@aol.com
What about the resistor thats on the back of the gauge? It helps calibrate the guage..Did you reuse the same one or did the new gauge come with a new one?
Also are you putting alot of sealer on the sending unit where it screws in,maybe messing with the ground?
Jason
VetteInstruments@aol.com
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
This 78 is near the end of a body off project that has lasted about a year so far. This is the last gremlin left right now. When you put in the direct reading gauge did you have to do and grinding of the panel to make it fit. Would like to see picture if not to much trouble. Thanks ED
Pro
Joined: Dec 2005
Posts: 596
Likes: 1
Sorry, I don't have a digital camera,- yet. It seems that I'm going to need one to really make good use of this forum. As for my gauge installation, I fabricated a new center panel for the dash from aluminum stock and mounted five gauges in it. I have my old stock panel here, and looking at it I would say that your best bet would be a 2 1/16" gauge. I like the Auto Meter sport-comp series. You would have to do some careful cutting of the stamped steel stock panel. I would probably tend to mount the gauge in a remote location and leave the original in place. If you're doing a factory correct restoration you know what I'm talking about. If, like me, you're saving a non-collectable late 70's car from the scrap heap, you do the practical, functional things. I kept the original sender. The wire is coiled up, along with the little boot, and tied off on the firewall. Anyway, I didn't like the looks of the factory gauge from a quality and dependability standpoint. It appears to me to be about a $12 item. You're welcome to have mine if you want it. That goes for the whole cluster as well. I don't think any of them worked when I bought the car.
Got to run,
Steve
Got to run,
Steve
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
Well i know its been too long to fix this but have been busy. I set up a test bench trying to duplicate problem. The gauge will stay at 20 psi no matter what pressure applied. The gauge works fine on bench but if you remove resister the gauge will only read 20psi. So I now know what is causing problem. So I remove center instrument panel again and test resister, Resister tests fine. I look futher and discover the circuit is not even making contact with resister. The mylar is not letting the circuit contact the resister. So I put a small jumper from under mylar to the top of mylar under the nut, and guess what problem solved. Oil pressure gauge works great now and so do all the other gauges. yeeeeeeeea 
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Racer
Joined: Aug 2005
Posts: 255
Likes: 0
From: Mason MI 82-93-04CE
Originally Posted by Dave Witman
The mylar is not letting the circuit contact the resister. So I put a small jumper from under mylar to the top of mylar under the nut, and guess what problem solved. Oil pressure gauge works great now and so do all the other gauges. yeeeeeeeea
My oil pressure has never read above 20 psi on my 82, and takes forever to get there. I'll pull it out (easier said than done) and see if it is having the same contact problem. If it's my sending unit, it's going to be a job, since it is somewhere behind the dizzy on the upper rear block. The hole by the oil filter is taken by an oil temperature sensor.mkflanagan: About the Fram filters. I dunno. I have been using Fram off and on for about forever and have never once had a failure of filter or filtration or pressure - well over 200K on a number of engines, and still going. I've read odds and ends people have written about them, but haven't been convinced they are that much worse (or better) than other brands. If so they were, they would have been gone long ago - but that's for another thread.
