This is for my girlfriend's 85 2.8 v6 camaro that we just bought from the junkyard. The thing runs and drives good, I've been using it for around the town errands and stuff the last few days and it seems to be fine, but the gauges have some issues.
1) oil pressure gauge, its the small one mounted in the tach. When we first got the car the gauge was pointed straight up and wouldn't budge, after a few days it moved down with the car idling, but if you just BARELY rev it the thing points straight up again. I doubt my oil pressure is skyrocketing like that from a tap on the gas pedal. Is this a common problem? My first guess is that maybe inside the gauge there was a counterweight or something to dampen the movement of the needle and that fell off or broke. Any opinions?
2) Coolant gauge spends most of the time stuck at the bottom like its stone cold, sometimes if I drive for awhile and then sit idling it starts to come up slowly but will go down again real quick when i start to drive again, any ideas here?
Also this isn't gauge related but so far the radiator fan has never come on far as I can tell, is it one of those deals that only comes on if the car gets really hot, like 240 degrees? It won't come on when I turn on the AC either, but the AC is discharged which I think has something to do with that. Thanks in advance for the ideas.

 

Oil pressure sounds fine. It's going to stay high until the motor warms up. Then it will drop to around 20-40psi at idle and up around 60-80 off idle.

Then fan doesn't come on until about 228*F. If it doesn't come on try giving it 12V straight from the batt. Also, if your A/C is discharged the low pressure switch will keep the compressor off and the fan will NOT come on.

How high is the temp gauge going? It's possible that the thermostat is stuck open and the engine can't heat up. This would also explain the fan not coming on.

 

1)Thanks for the info so far, I should have described the oil pressure part better. When I say the needle is straight up I mean past 80psi all the way up as far as it can go, and it will be up there with the car off, and stays there most of the time with the car on. sometimes after driving around and then coming to a stoplight it comes down to a normal level for a car idling in gear, but if i tap the gas slightly while holding the brake, say to up the RPM by like 200rpm according to the tach the needle goes all the way up again as far as it can go. Thats why I'm thinking its probably the gauge at fault but I would rather be sure so that I don't replace it and then find out its the sender.
2) Temp gauge, well I drove it some to run errands after my first post and this time the gauge didnt stay at the coolest position, it came up almost a quarter, just a bit under the first line. I checked earlier for a stuck open thermmostat, had the motor running for awhile with the rad cap off, and it looks like the thermo isn't stuck open as there was no movement of the water unless I revved the motor a bit. Once the car was running for awhile then the water started to circulate some, I didnt leave the cap off until the car was fully warm tho. I do plan to replace the thermo one way or another once we are done with all the registration crap to see whats up in there, and can't hurt to change a cheap part in a car that has been abused some. Isn't there some wire I can ground or something coming from the back of the AC compressor to make the electric fan come on?
Anyway keep the ideas coming!

 

The oil gauge is probably not at fault. The sending unit's go bad fairly often. I'd start with that...it's not an expensive part but it does require a large wrench around 22mm.

If you jumper terminals A and B in the diagnostic connector with the KEY ON/ENGINE OFF the fan should come on. If you don't know where the connector is, read Vader's post in this thread:

https://www.thirdgen.org/techbb2/sho...highlight=aldl

 

Ok I'll give that a shot tomorrow, thanks.

 

So its normal for the oil pressure gauge to rest pointing all the way up with the car switched off?

 

Cali..you mean you can force the fan on by connecting terminals A & B? Does it work when the engine is ON? Hope it does..that'd be useful as hell!

 

I have an '87 RS, my oil guage jumps when i hit the gas also, I think it's prety common, it also points straight up when the car is turned off. My car has tattle-tail intruments, but it doens't seem to effect the oil guage. You should have the sending unit replaced for the temp. guage, because with out an oil guage AND a temp guage you could royally screw over the car. Just be careful is my suggestion, and fix the temp, don't worry too much about the oil guage, just check your oil often!

 

Yeh I'll either fix the temp gauge or put an aftermarket one, I always try to make sure I have a real working temp gauge in all the cars. The oil pressure gauge doesn't really worry me that much, I just think it would be nice to have it work properly.

 

The oil pressure guage in my 84 used to jump around a lot too. I replaced the sending unit and it worked fine agian. My sending unit went totally bad on me and started leaking oil like crazy.

 

How much is an oil sending unit. . . my oil gauge is crazy.

 

The temp gauge seems to be more active now for some reason, still runs really cool according to it tho. I tried putting a paper clip in the diagnostic plug and the fan did work when I did that, so it is operational.

 

The aftermarket one that I bought was under $40....maybe under $30..... I forgot the actual price.

 

yea, the oil pressure sending unit will cost you about 25.00. its location is in the same proximity as the oil filter. easy change, and i've seen it happen in three 3rd gens including mine. g/l