Hi all,
We just got my '75 w200 5.9l runnin. I looked at the instrument cluster and the only gauge that seems to be working is the ammeter gauge. No oil pressure, no temp, no fuel. The only one that concerns me right now is the oil pressure, the other two I can live without for a while. What should I be looking for to get the oil pressure gauge working right? Is it a fuse, or a sending unit? Or do I really have 0 oil pressure?

 

There is a voltage regulator that plugs into the back of the instrument panel. It powers every thing except the ammeter.

 

There is a voltage regulator that plugs into the back of the instrument panel. It powers all the gauges except the ammeter.

 

Charlie is probably right about the regulator but if you are really worried about the oil pressure pull the oil pressure sending unit and screw in a mechanical gauge.

 

Thanks for the replies. If it isn't a bad voltage regulator where is the sending unit located on these trucks?

 

Sending unit for oil pressure is at the back of engine on the passenger side of distributor.
Temp. S. unit should be in intake manifold near thermostat housing.
Fuel S. unit in gas tank.

 

I just had the same problem with my '89 D100. Since there was no valve noise or other indications of problems with the engine I assumed it was the sending unit. I replaced it with a lighted mechanical oil pressure gauge for about $25 at Schucks and it shows an accurate reading.
It's kind of tough to get at on the top of the engine next to the firewall and distributor but is worth it as now I know I have sufficient oil pressure.