Faulty gauges ir what ???'s

[dickeymoore]

I have a 1988 Monte Carlo SS with 107K original miles that runs and drives great ,but the temp gauge goes up and down from like 190 to 260 and the oil gauge goes to zero when at a stop but shoots up to 40 psi as soon as the gas is pressed and I'm driving, could this be BAD gauges or what?Thanks

 

[UC645]

For the temp gauge, it’s either the gauge, sensor, or an air pocket.
The oil pressure however, is a sign of bad cam bearings if it’s dropping at idle. If you’ve got a mechanical oil pressure gauge, tap that in and get the car warm and have someone watch it when you put it in gear. If it drops, you’ve got smoked bearings. If it stays stable, gauge or sensor’s shot or the sensor screen is clogged from trash.

 

[79 USA 1]

Do they seem to happen at the same time? When the temp rises to 260 does the oil pressure see the drop?
I would start with checking first the coolant level and the condition of the oil, 305 blocks in the late 80's were prone to cracking across the lifter galley. The 88 SS I currently own had in the previous owners repairs slips from the dealer the description as you mention and after pressure testing the coolant system the found the crack in the block.
I've also had an 86 El Camino that had the fan clutch go out. Temp gauge was fluctuating to 260 while moving under load but would cool slightly while at low speed. found it to be free wheeling at higher temps.
Just a suggestion on where to look.

 

[dickeymoore]

when temp rises oil pressure is good as long as im driving

 

[79 USA 1]

when temp rises oil pressure is good as long as im driving

The higher temp could cause the lower oil pressure at idle due to the oil losing viscosity at the high temp. Personally I'd look first at the cooling issue, When the temp gets to 260 degrees, shut off the engine and check for the fan to free wheel. You should have resistance when you attempt to turn the blades. If it turns very easy, good chance it is defective. Also look for fluid streaks down the fan blades which may indicate the viscous fluid in the clutch has leaked out.

 

[dickeymoore]

ok will check the fan clutch