Over Heating

[1992blazeredgs]

I have a 93 rs that is over heating. Well the gauge says its over heating, but i dont believe so. The water pump is practically new and circulating coolant. There is currently no thermostat installed in the car. I just installed a new coolant temp sending unit. I started the car today after it sitting for a month in sub freezing weather and within 3 minutes of idling the gauge was up to the middle where it is at operating temperature. Mind you its about 20 degrees outside and there is no thermostat, so freezing cold coolant is circulating. I took the car for a drive and at idle the gauge will shoot up to the H. But while the car is driving with the heat on the gauge reads operating temperature. As soon as i idle the gauge will go right back up to the H in a matter of seconds. Both radiator hoses are hot but not scalding like they should be and the radiator cap is still cold after running the car for about 10 min. Does anybody have any suggestions? Faulty wiring? Clogg somewhere so coolant is not circulating very well?? I need some help on this one cause i am stumped.

Nate

[shameem]

For the SOHC there are 3 coolant temp sensors - one for the fan, one for the gauge and one for the ECU - which one did you replace?

[1992blazeredgs]

I replaced the coolant temp gauge sending unit, that screws into the front of the head. The sensor for the fan, the pervious owner has cut the connector and spliced on a toggle switch so the fan is no ran off a switch and not the sensor. If that makes any difference.

Here is a picture of what i replaced today.
http://info.rockauto.com/BeckArnley/Det ... 011220.jpg

Nate

[shameem]

Maybe get a rad flush to see if there is any blockage.....
Then maybe look into replacing the gauge cluster ....

[Cpl_Bryant]

There is no thermostat? How is that possible? You just plugged the hole? So it is circulating maximum all the time?

[TREVO123]

you just have to pull the thermostat toss teh hosing back on and it will be a constant flow and should be hard er to make the car even hit operatin temps.

[1992blazeredgs]

I understand that not having a thermostat will circulate coolant from initial start up thus making it harder to get to operating temperature. the previous owner took the thermostat out to check it and didnt put it back in. I have been to lazy to put it back since i am trying to find out why the gauge is malfunctioning.

Nate

[SuperK]

My advice would be, stop being lazy.
Put the darned thermostat back in, would you? Jeez...

[umcamara]

Takes all of about 10 minutes to change a thermostat on a B6.

[1992blazeredgs]

thanks for the criticism and not offering any help. I know how to change a thermostat and how long it takes. Unless you are explaining how not having a thermostat installed relates to a malfunctioning temp gauge or offering other advice concerning my problem please keep your comments to yourself.

Nate

[SuperK]

We just offered freakin' useful advice. Our advice can possibly solve your current situation AND give you heat in your car. it's possible, yes it's possible that it's because you have no thermostat. My roomie's MX-3's temp gauge wouldn't function because the thermostat was stuck open. I replaced it for him and voila! Works like a charm.

Now stop being an ungrateful lout and do what you KNOW needs to be done, THEN come back to the forums.

[1992blazeredgs]

Please explain to me how no thermostat or a stuck open thermostat will have an effect on the temp gauge? How does circulating coolant before operating temperature make my temp gauge go to hot after only 1 minute of running? I am not saying you are wrong, I want an explaination. I will put the thermostat back in as its the only thing left not fixed from the previous owner. But i do not see the correlation between this and my current problem. Also I do not respond well to being called lazy, or an ungrateful lout. So again keep your comments to yourself. NO need for name calling, it only causes more problems.

Nate

[95 rs]

dude you even stated that your too lazy to put in the thermostat. maybe you should just listen to everyone else for once and look back on what you said previously. and yes not having a thermostat in will mess up your cooling system. we are all trying to help but you look at everything so negatively. it may also be you waterpump that can cause it to over heat so fast and i am NOT trying to be sarcastic here but do you have coolant in the system?

[1992blazeredgs]

Haha, I am not some numb here. Yes there is coolant, the water pump was pulled and is practically brand new. Both radiator hoses get hot so it is circulating coolant. There is no problem with the car besides the gauge reading an incorrect temp. I had forgotten that i wrote I was to lazy to put it back. So its my bad on that one, and i do apologize. But I ask again, can you explain the reasoning behind thinking not having a thermostat causes the temp gauge to read hot when the motor is still cold and i can put my hand on the valve cover?

Nate

[SuperK]

The temp sensor a variable-resistance sensor. To check the coolant-temperature sensor yourself, digital volt/ohm meter is used to check the resistance of the meter to verify that it is working.
With the ohm scale on the meter set to 20k, the black lead is connected to ground and the red is brought into contact with the terminal on the sensor. ANY resistance means the temp sensor is working, so have at it.

Here are a few other reasons
Poor grounding of upper coolant hose flange (clean and degrease everything to ensure correct ground)
Faulty temperature sender in that flange
Thermostat sticking open or opening at too low of a temperature (that's what happened to my roommates car)
Faulty gauge
Faulty voltage regulator driving gauge.

Clean it up, test the temp gauge and throw the thermostat in there. Come back to the forums and let us know if it worked. The best explanation I can give you about the thermostat is
1. It's 10 dollars
2. You need it
3. If it fixes your problem, great
4. If it doesn't fix your problem, you still need it.
5. The best explanation is "worked for me"