gauges
 

on my 72 c10 with a 509 merlin i purchased a new factory style gauge cluster.i have tried 3 new different sending units for the temp.gauge finally i found one that worked but after 30 seconds with it running the gauge is almost pegged and when shut off it stays there and the temp on motor is 115.the oil pressure gauge gets pegged all the way over and out of sight and that too stays at about 3/4 when off i tried a new oil pressure gauge today and had the same problem.any help is appreciated.i tried another oil pressure gauge and it read 60.

Re: gauges
 

Kinda sounds like a grounding issue? If it were one I'd suspect a particular gauge or sender, but with all of them acting 'weird' Sure sounds like a common electrical problem,,, which is 99% of the time GROUNDS!

GM changed the ohms required by the gauge / sending units in the mid 60's as I recall so you should be compatible with everything in the 70's I believe.

Whomever supplied the replacement cluster should be able to supply details for the sending units, ohms for full sweep of the gauge etc. If all thats compatible and correct,, sounds like a electrical issue. I'd suggest you check the grounds to and between the engine block and the cab.

BTW, Have I mentioned that grounds are a real important thing in an electrical system?

LOL Seriously. Even too much teflon tape can on the sending unit can screw up the reading as the sending unit only goes to ground.

Re: gauges
 

thanks Marv,i did test the gauge and it is ok also all the grounds are new and ok and i did not use any teflon tape on the sending unit.i will contact the co.that i purchased the cluster from.