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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15133
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a 1995 Chevy truck K1500 4x4 4.3L. The temp guage

Customer Question

I have a 1995 Chevy truck K1500 4x4 4.3L . The temp guage heats up to 150 degrees and won't go any higher. I have changed the Thermostat, Temp sending unit, and grounded guage to make sure it was working. Nothing has repaired the low temp. Help !!!!
JA: Have you checked the coolant level? Has there been any leaking from the hoses?
Customer: Yes the coolant level is good, I repaired the heater hose quick connect in the intake manifold , it was leaking.
JA: What is the model of your '95 Chevy?
Customer: Cheyenne
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: I have changed the thermostat, Temp sending unit, and grounded cluster guage to make sure it was working
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 1 month ago.
Category: Chevy
Expert:  K. Wiggins replied 1 month ago.

Hello, if you unplug the coolant sensor does the gauge fall to cold or go to hot?

Customer: replied 1 month ago.

when I unplug the coolant sending unit the gauge falls to cold

Expert:  K. Wiggins replied 1 month ago.

Thanks, ***** ***** no short in the wiring. Now if you would blace a piece of wire or paper clip in the connector part and ground it. The gauge should swing full hot, let me know what you find.

Customer: replied 1 month ago.

I already did that and the gauge pegged all the way hot.

Expert:  K. Wiggins replied 1 month ago.

Alright that means cluster and wiring are good. I see you also replaced the sensor.

Another thing that can make it run cool is the fan clutch staying engaged. Do you hear the roar of the fan all the time when driving?

Customer: replied 1 month ago.

I can't answer that for sure, should I go start it up and see ?

Expert:  K. Wiggins replied 1 month ago.

Yes, when you first start it the clutch should stay engaged for around 3-5 minutes and then the roaring should stop. If it doesn't the clutch is bad.

Customer: replied 1 month ago.

Ok I will start it up and see what happens. hold tight and I will let you know.

Expert:  K. Wiggins replied 1 month ago.

Sounds good

Customer: replied 1 month ago.

It appears that the clutch fan shut down after about 4 minutes. The coolant hoses are very hot to the touch and I have good heat in the cabin via the heater.

Expert:  K. Wiggins replied 1 month ago.

Alright, one last test to make sure they gave you the proper sending unit. This works best if you have a small saucepan and a candy thermometor for it. You'll need an ohm meter

Temperature Gauge: Testing and Inspection
Gauge Reads Low
1. Ensure terminals are clean and connections are tight.
2. Remove lead at sensor, measure resistance using an ohmmeter.
3. At 104 degrees F resistance should be approximately 1200-1350 ohms, and at 125 degrees F resistance should be approximately 53-55 ohms.
4. If resistance is not within specifications, replace sensor.

The GM part number for the right sending unit is 25037332

Customer: replied 1 month ago.

I already done this check after installing the sensor and temp was the same . We tested at aprox. 120 degrees and the ohms resistance was about 1200. It doesn't appear you can help me . I thought maybe you knew something that I was missing.

Expert:  K. Wiggins replied 1 month ago.

It should be around 50-55 at 120. I'll open this up to other experts to see if anyone else has any thoughts on this. Someone should be with you shortly.

Customer: replied 1 month ago.

The PN# ***** replaced with was ACDELCO 25037332 which is the correct one.

Customer: replied 1 month ago.

It is approaching an hour since our last chat. Is anybody helping me on my problem ?

Expert:  Tim's Auto Repair replied 1 month ago.

Hi, My name is ***** ***** for the delay.

I will do my best to assist you.

Expert:  Tim's Auto Repair replied 1 month ago.

lets try this again..

does the heater get hot as it should?

Expert:  Tim's Auto Repair replied 1 month ago.

does the truck run well?

Customer: replied 1 month ago.

Hi Tim, I hope you can help me. The heater gets hot as it should and the truck runs very well with 104,194 miles on it.

Expert:  Tim's Auto Repair replied 1 month ago.

ok..enlighten me here..

what is the problem?

Expert:  Tim's Auto Repair replied 1 month ago.

is there some reason you need it to run hotter?

Customer: replied 1 month ago.

Tim , this was my wife's father's truck and he has passed on. My wife loves driving this truck and I want to make sure it is safe for her to drive. If for some reason the truck would start to overheat , while she was driving she would never know acording to the gauge. We put a thermo on the coolant and it was reading 200 degrees when fully running.

Expert:  Tim's Auto Repair replied 1 month ago.

where did you get the 200deg reading?

Expert:  Tim's Auto Repair replied 1 month ago.

what part of the engine?

Expert:  Tim's Auto Repair replied 1 month ago.

sorry for the delay,i had internet trouble