F600 gauges- different oil sending unit???

[fomocoguy]

Well, my F600 gauges work quite well except for one problem. The fuel reads correct as well as the temp, but the oil pressure acts funny. I had a light in my old gauges, so I bought a sending unit for a 69 360 with a gauge. Now when I start it the oil pressure gauge doesn't move until I rev the engine a bit, at which point it pegs out and stays there. Any ideas? Do I need a sending unit from an F600? How can I test my gauge and/or new sending unit? Thanks!

[Thunderfoot]

Sounds like a bad sending unit, there is no difference in it for this gauge. To test the gauge if you touch the sending wire to ground it should read full pressure and from the sounds of your gauge reading full it is working, so would suspect a bad sending unit from your description.

[fomocoguy]

Great! Thanks for the info. I've got an old one from my 300 I tore down and it looks the same; I'll swap it in and see what happens.

[fomocoguy]

Well, no such luck. I put the other sending unit in that I have and got the same results. There must be an issue either with the wiring or the gauge. I don't think it's the wiring because the gauge doesn't move until I rev it up, like a spike of voltage is sending the needle all the way to the right. I'll have to pull the bezel and check the wiring so I can rule out a wiring mistake.

[Thunderfoot]

Double check that the White/red striped wire is connected to its mate on the instrument panel connector. Check that the needle on the gauge is not bent dragging on the face or something.

[fomocoguy]

Ok, well here's some more info. Yesterday I actually drove her around a bit and at stop lights it drops down to nothing. As soon as I pull away it pegs. So it seems that the gauge is working properly except for the fact that it swings wildly from left to right. I think the gauge itself may have a resistance problem or is just plain worn out. I suppose a 42 year old dump truck gauge has the right to be a little worn out...