1991 Trans Am GTA 5.7l TPI
 

I have an overheating and oil pressure issue. There is about 130000 miles on my motor. It all starts up perfectly and runs smooth warming up and once its warmed up it still runs smooth. Oil pressure is around 45 or so when it is warming up. Once it is warmed up the oil pressure drops down alot. The lowest I have seen it drop is around 5 or 10 PSI. I have seen some things that says it could be the cam bearings causing the oil pressure to drop. Is this correct? I also have an issue with the car over heating very bad. The other day I was driving and saw some smoke come out under the hood, pulled over and the over flow tank was about 3/4 full and boiling....Not good at all... Could these issues be related or will they more than likely be unrelated issues? Any help and ideas for these issues is appreaciated!

They're unrelated. The oil pressure could be a non issue. The gauges aren't necessarily accurate. Sending unit or gauge itself maybe wrong. Use a mechanical oil pressure tester to find out for sure.
Overheating you treat like any other overheating vehicle. Is the thermostat opening? Fans kicking on? Water pump ok? ....or is its bearings good? Coolant leaks?

Re: 1991 Trans Am GTA 5.7l TPI
 

I have had issues with the fans kicking the on before and thought that was fixed. I'm going to check those out again. I replaced the water pump already, and I loosened a hose to see if water was moving though while running and there was. My temp gauge inside isn't registering a temperature on it. When I start the car the gauge moves but it doesn't go up at the temp does. Could that be a temp sensor issue?

The temp gauge not reading in the car could be the temp sensor for the gauge. (There are 2, one for the computer, one for the gauge.) But you can't rule out a bad wire or the off chance of a bad gauge.

Re: 1991 Trans Am GTA 5.7l TPI
 

Where is the temp sensor for the gauge located? If I change that and I'm still not getting anything would it be easier to run it to an aftermarket gauge or would that require extra wiring and such? I think the overheating issue is going to just be my thermostat, like I said earlier, I have replaced the water pump, and I have also replaced the radiator and see no signs of a coolant leak.

Re: 1991 Trans Am GTA 5.7l TPI
 

in regaurds to the oil pressure issue, what is the procedure for testing it with an external gauge? Is it possible the drop in oil pressure could be due to the cam bearings being worn out?

Re: 1991 Trans Am GTA 5.7l TPI
 

Easiest option to test oil pressure is to pull the sending unit out that is above the oil filter and connect a normal craftsman/snapon/mac/parts store rental gauge to it. I don't think worn cam bearings would make any change as it gets hot. I would believe it to be a constant problem if bearings are a problem. But trust me...these gauges are wrong frequently.


What makes you think the cam bearings are bad? Even at 130,000 mi it wouldn't be high on my list of suspects.

Re: 1991 Trans Am GTA 5.7l TPI
 

I don't know if they are bad or not. I was reading some posts on a different site and read that that could be a potential cause for the oil pressure loss. I have had this car for about 8 years now. I bought it with about 127,000 miles on it, so as you can see i haven't driven it much at all. I have spent most of my time working on it cause there is always a new problem when i want to drive it. I will rent a tester and test the oil pressure and see what its like. How difficult is it to run an external gauge to keep track of the oil pressure?

Re: 1991 Trans Am GTA 5.7l TPI
 

Depending on the gauge, you may be able set it up to see it while driving but I doubt it. Personally, I'd hook it up, keep it away from the exhaust, and let it run. If you have to drive it, find a place for the gauge to hang happily. Park and check it again when the engine should be hot.

Re: 1991 Trans Am GTA 5.7l TPI
 

Sounds good. After talking with you, it sounds like I shouldn't have any MAJOR problems. Just a few things to sort through and check. Thanks for your help. I am going to PM you if I have any more questions or need some more help. Thanks!!