Quick question regarding coolant temp sensor.

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Dec 26, 2003 | 09:26 PM

zelement

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Melting Slicks

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From: Carlsbad, CA CA

Quick question regarding coolant temp sensor.

I am running AFR competition heads, they do not have a place where the coolant temp sensor can plug into, so my mechanic made some type of fitting in order to fit the sensor on to the head.

The first time I drove my car I noticed that my water temp gauge inside the car doesn't move at all. It just stays at the 100 mark. The first time I drove my car in traffic, I overheating the motor and the coolant was boiling over at the overfill tank. I noticed that the fan never came on.

Luckily I have a manual fan switch so right now I am just leaving on everytime I drive.

My question is, Does the coolant temp sensor provide water tempurature for both the water temp gauge inside the car and the computer? Is that why the fan is not turning on?

If anyone is running the AFR comp. heads, could you please chime in and let me know where is a good place to tap in the coolant temp sensor?

Thanks,

Paul

Dec 26, 2003 | 09:43 PM

jfb

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From: Cincinnati, Oh USA

Re: Quick question regarding coolant temp sensor. (zelement)

The ECM turns on the fans via info from the coolant sensor that is under the MAF. The cluster temp is provided by the sensor between cylinders 6 and 8.
I think your gauge sender (between 6 & 8) is defective because if the sensor or the wire to it is open circuit the dash will read, "Lo" and if shorted it will read , "299". A reading of 100 indicates neither open or short circuited, therefore the sender must be defective.

Dec 26, 2003 | 10:31 PM

zelement

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From: Carlsbad, CA CA

Re: Quick question regarding coolant temp sensor. (jfb)

Thanks for the reply.

MY car is a 91 so it doesn't have a MAF. Is it still in the general area? Can you tell me where it plugs into?

A 91 doesn't have a digital read out for water temp, that is why I said it is at 100 degrees, because the needle doesn't move.

So what you are saying is that the dash gauge and the computer reads off two different sensors?

If that is true, then can you think of why the Fan is not turning on?

Thanks,

Paul

Dec 26, 2003 | 10:51 PM

scorp508

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From: Boston, MA

Re: Quick question regarding coolant temp sensor. (zelement)

Zel,

You should have 2 coolant temp sensors. One is on the front of the intake manifold (although you've got a miniram right? so i could be totally wrong here) and is a 2 wire weatherpack connector. This one is for the ECM. The one between 6&8 is for the display and is a single wire blade connector.

Dec 26, 2003 | 11:36 PM

JAKE

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From: Kempner Texas

Re: Quick question regarding coolant temp sensor. (scorp508)

Quote:

Yep, I think that's right. You should have two, one that the ECM gets info from and the other one is for the dash gauge.

I don't know about where they are located on your year Vette because GM just loves to change things.

On my 86 the gauge sending unit is in the passenger side head between 6 and 8 and the fan switch is in the driver's head between 1 and 3.

Guess you'll have to refer to your manual to get the correct location of yours, unless someone posts where they are.

Jake

Dec 26, 2003 | 11:46 PM

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From: Phila., PA burbs

Re: Quick question regarding coolant temp sensor. (scorp508)

Quote:

I don't believe this is the case (at least for 91s). My car had no sensor in between the 6 and 8 plugs when I bought it and my display worked fine. I later removed the plug that was in this hole and added an aftermarket fan switch to bring the fans on at an earlier temp. I think (at least on 91s) that this outlet was for an auxiallary fan, which I obviously didn't have.

Dec 27, 2003 | 12:59 AM

zelement

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From: Carlsbad, CA CA

Re: Quick question regarding coolant temp sensor. (TA)

Thanks for the response guys.

So the one in front on the intake manifold is what the computer reads and it is the one that turns on the fan...Right?

If this sensor is bad can the car overheat? Even with the fan running? How do I check to see if the thermostat is working?

Paul

Dec 27, 2003 | 04:54 PM

NoWorries

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From: Enter Post Count Here

Re: Quick question regarding coolant temp sensor. (zelement)

Just a thought, but the block has a hole for the knock sensor, since on difference cars, the knock sensor may be on either side, whatever side the knock sensor isn't on, there will be a plug. On an L98 I *think* the knock sensor is on the right. Maybe there is a temp sensor made to fit in the unused knock-sensor hole.

This is risky because that temp is STRAIGHT out of the radiator and is going to be at least 15 degree's cooler than the head temperature, so plan accordingly.

Good luck.