'93 GXE with "cold" engine indication

I have a 93 GXE with about 60K miles. On cold winter mornings I start the car and let it warm up for about 10 minutes. The engine coolant temperature gauge is half way between cold and hot ( a little more to cold actually) as usual. The engine idles at about 800 rpm. I drive onto the highway. If I leave the heat off then the engine coolant gauge level remains the same. If I turn on the heat then the gauge slowly goes to cold - mind you I am driving at a constant 65-75mph and the engine operates normally. Is the cooling system working off the engine heat? I thought that the heat was electrically generated. Could this be a problem for me latter? Is there a way to fix it. I have a mechanic but do not trust him completely because of a test I ran by him and he failed.

Bob

Change the thermostat AND the engine temp sensor from the Nissan parts dealer. Don't mess with finding a PepBoys or Autozone part for these. I had the same problem w/ my 90 GXE and replacing the temp sensor took care of it. These little temp sensors, for some reason, slowly fail. Your water pump should be ok w/ 60K miles.

If you don't trust your mechanic, why is he still your mechanic???!!!

Chris

During the hot summer I was running the AC at 4 (max) .The brake pedal got really soft so I took the car to this mech. He explained that the vacuum pump that powered the AC also provided the resistance in the brake pedal..then he turned around and charged $100 to replace front disk pads.This was less than 1000 miles after I had bought the car from a dealer and it had passwd inspection!

Bob

Well .... Yeah.... The A/C controls are vacuum actuated (but not the A/C itself). It uses vacuum to move the little doors that direct the air. And the power brake booster is vacuum actuated. If the problem was vacuum, he should have fixed the vacuum leak which was probably a 10 cent piece of hose. But the symptom would have been a brake pedal that got really hard to push, not soft.

I agree with the previous poster - why is this guy still your mechanic?

I just got the nearest mech I could find. So now I am thinking that the front brake pads were worn since the pedal pressure returned after he worked on it. Is he an idiot savant maybe? I also need to have the AC system charged because it only keeps cold for about half an hour..Any idea about how much this would cost?

Bob

Sounds like it just needed pads. That vacuum business was sort of off the wall, though.

Cold for a half hour is a strange symptom. If it stops cooling because it freezes up in a half hour, then you probably do need just a charge. Otherwise its probably something else.

When did Nissan change over to R-134? Does the '93 still use R-12? If its R-12 they are going to be proud of it. These days, they don't just charge them up, they have to figure out where the last charge went and fix it first.

Maybe you could post where you are located and see if anybody can recommend an honest A/C shop.

Hi, I have a similar problem, which Temperature Sensor did you change? there are 3 sensors 1- coolent sensor, 2- normal sensor 3- EGR Sensor?

It's called the engine temperature sensor in the manual. It is above the thermostat housing and is in the rearward position. The sensor in the front position is the cooling temperature sending unit that goes to the temperature gauge in the dash. Replace the engine temp sensor!!!! If it's the original sensor that came w/ the car, chances are it's sending a bad signal to the computer which in turn does strange things to your fuel mixture, like enrichening it cuz it thinks the engines's still cold. Also, it will make the fans stay on if it sends a false high temperature signal. This can also cause low coolant temp when you come to a stop cuz the fans will still be running. Let me know if you need more help. BTW, I'm changing out my stat this week for the 3rd time in my 90 GXE (150k miles) cuz it's heater is starting to blow cool air sometimes. The Nissan stat is ~$10.

Chris