94 Sonoma running hot

[djm1951]

Hi all, I am new here. Just traded for a 94 Sonoma the other day. It has the 4.3 Vortec. I noticed that it is running hot. On the gauge I would estimate that it is running about the 240 degree mark. Any ideas on what to check for? I just got it a couple of days ago so haven't had a chance to do anything to the truck. Thanks.

 

[lmleck]

First see if the radiator is full of coolant. (check when cold!!) Look in the radiator for anything other than antifreeze.
Next replace the thermostat, (see below) the cheapest test/repair you can do.
With the thermostat out, bolt the thermostat housing together, fill with water and run the engine with the radiator cap is off. Look for coolant/water mix flowing and check the temp gauge. If you drive it, put on the cap loosely and check the temp gauge often. Don't go for a loooong drive, just enough to heat it up good.
If all looks ok, drain the water, put in the new thermostat and add 1/2 gallon pure antifreeze and fill remainder with 50% antifreeze mix.
If you still gets hot, probably needs new radiator.
If it still gets hot and fills the overflow bottle, could be a head gasket(s).

 

[djm1951]

Thank you. I will check it out tomorrow. I have class tonight.

 

[Molson02536]

Hi all, I am new here. Just traded for a 94 Sonoma the other day. It has the 4.3 Vortec. I noticed that it is running hot. On the gauge I would estimate that it is running about the 240 degree mark. Any ideas on what to check for? I just got it a couple of days ago so haven't had a chance to do anything to the truck. Thanks.

Start with the simple and replace the Thermostat and coolant with a 50/50 mix of Dex-Cool and water. You may also want to use Preston Radiator flush before servicing your cooling system.

Good luck and keep us posted.

 

[djm1951]

Thanks. I have been thinking about it all day. I am still leaning towards a bad thermostat. I was at class tonight and before I left I loosened the radiator cap and it still got hot so this is telling me that the thermostat is not allowing the water to flow to be cooled. Planning on replacing it tomorrow. Thanks for the response.

 

[djm1951]

Okay. I replaced the thermostat and that didn't help so I went ahead and replace the water pump and that did not help either. The only thing that I can think of is the radiator. Either it is bad or needs a super good flushing like at a radiator shop. What ya all think?

 

[Molson02536]

Okay. I replaced the thermostat and that didn't help so I went ahead and replace the water pump and that did not help either. The only thing that I can think of is the radiator. Either it is bad or needs a super good flushing like at a radiator shop. What ya all think?

Preston radiator flush, just follow the instructions and keep us posted, also keep in mind the temp sensor may have gone bad also.

 

[lmleck]

If it is aluminum radiator, seriously consider replacement as the plastic tank(s) may be nearing their end of life. The plastic tank will begin to bulge near the input from the motor where the hot water rushes against it.
I R&R radiator on 95 Buick last year, bulged and cracking.
If it is a brass tank and radiator, get it fixed.

 

[bigmac]

i would just replace parts just because its a waist of money. you should figure out why its hot first then replace the right part instead of changing a bunch of parts

 

[djm1951]

Thank you all for your inputs. I did get it fixed. It was the gauge sending unit that was faulty and showing it running hot. It was not actually hot but just the gauge. Thanks