Oil pressure guage replacement

[clazar]

My oil pressure guage ( 70 Ralley dash ) has been going wonky lately. While driving it sometimes goes to zero pressure & then reads appx 20-30 lbs of pressure. We've tested the engine with a mechanical guage & it reads appx 75-80. We replaced the sending unit. It showed appx 60 lbs. Now today the guage went back down to zero again & then back up. i'm thinking bad guage. If my suspicions are correct, do I need to pull the ralley dash. Or can it be replace from behind the dash.

 

[pnora]

It has to come out the front side so bezel, and lens needs to come off. Two nuts and it will come out. Sounds easier than it is. I would drive it with a mechanical gauge first. Most of the time these gauges are not intermittent.

 

[clazar]

It has to come out the front side so bezel, and lens needs to come off. Two nuts and it will come out. Sounds easier than it is. I would drive it with a mechanical gauge first. Most of the time these gauges are not intermittent.

Could something be loose somewhere thats causing it.

 

[pnora]

Could something be loose somewhere thats causing it

Possibly. Check the two nuts to be sure they are tight and clean the wires at the bulkhead. Also check the bulkhead wires for fitting tight.

 

[steve340]

Check or replace the gauges voltage regulator is also a possibility.
That would probably also affect the temperature gauge.
Loose connection on the feed side of the oil gauge as mentioned.

 

[pnora]

Check or replace the gauges voltage regulator is also a possibility.
That would probably also affect the temperature gauge.
Loose connection on the feed side of the oil gauge as mentioned.

It the voltage limiter was suspect the fuel and temperature gauge would act in unison with the oil pressure gauge.

 

[clazar]

It the voltage limiter was suspect the fuel and temperature gauge would act in unison with the oil pressure gauge.

The volt limiter has been replace wth the solid state version (RTE ).

 

[RJRENTON]

The volt limiter has been replace wth the solid state version (RTE ).

The fuel level gauge, temperature gauge and oil pressure gauge are thermal type instruments. It is possible that the gauges' internal thermal element in the oil pressure instrument, along the other instruments are merely volt meters, with a 0-5 volt range, calibrated to read a specific value, fuel level, temperature or oil pressure. They're thermal design to be deliberately slow to respond to dampen out fluctuations. Since you've already replaced the instrument panel voltage regulator with the RT design, the problem is: a poor gauge connection to the circuit board, the circuit board connector or the instrument itself. Just my opinion of course......
BOB RENTON

 

[Plumcrazy]

My oil pressure guage ( 70 Ralley dash ) has been going wonky lately. While driving it sometimes goes to zero pressure & then reads appx 20-30 lbs of pressure. We've tested the engine with a mechanical guage & it reads appx 75-80. We replaced the sending unit. It showed appx 60 lbs. Now today the guage went back down to zero again & then back up. i'm thinking bad guage. If my suspicions are correct, do I need to pull the ralley dash. Or can it be replace from behind the dash.

Dash needs to come out. But before that I would make sure you have a good connection at the bulkhead connector.

 

[clazar]

Could the oil pump intermittently go bad to cause the loss of pressure on the guage ???

 

[pnora]

Could the oil pump intermittently go bad to cause the loss of pressure on the guage ???

Read post 2

 

[clazar]

Update. I installed a mechanical guage. It reads 80 lbs. Still nothing on the factory guage. So at least I know i'm getting oil. I had just installed a new sending unit only a month ago. I decided to replace the sending unit again just to see if it was a bad one out of the box. It now reads 50 lbs. How common is it to have bad new sending units. And is it common for the factory gauge to read appx 30 lbs low ?? Or is the gauge going bad ??