Hi from Carolina, having trouble with the gauge reading low, replaced both temperature sensors, thermostat, now Purging the air out of my heater core. Still have the problem, heat is working great. Don't know what to do. ...

 

Is the Check Engine Lite coming on with the code for low coolant temp or is it just the gauge showing a low temp?

 

The gauge has been reading 150-155 for a month now. Been hearing gurgling Sounds from the dashboard so I'm in the middle of replacing the heater core. First time for me, the codes were p0141 and p0441, checked all evap vac hoses changed gas cap and cleaned egr valve, changed HO2S12 and light went out, still is reading 150-155. I don't know where start next. Thanks in advance for any tips, Carl@gmail from NC.

 

Gurgling in the dash indicates there's an air bubble in the cooling system, (low coolant level). Most likly a coolant leak somewhere, (leaky lower intake gaskets are very common). Low coolant temp is usually caused by the thermostat not closing completely.

 

Not sure why replacing the heater core; gurgling sound is air in cooling system as Captain stated above. Only reason to replace heater core is when it is leaking.

I read where the thermostat was replaced, but no uncommon to get a defective one. Did you use RTV/silicon around the housing? Not needed, just use the supplied flat gasket as silicon beads can prevent thermostat closing.

The low temp gauge reading is likely due to trapped air as the gauge is reading the air temp, not the coolant temp...or the gauge itself has failed...not common though.

Either there is a leak that is letting air in/coolant out or when the thermostat was changed, the air was never purged.

Could always try parking nose on an incline to try to get air to come to top of radiator.

 

No silicon used, found evidence of stained carpet. parked on hill and purged heater core of air and seen a small drip, decided to change heater core, man what a job, been taking my time, have the dash back in but still have to install radio, heat/air controls, four wheel drive controls etc...... should have it back running tomorrow. Hope this fixes the problem.

 

I know what you mean about not being a fun job....replaced the heater core on a '95 Blazer I had....took good part of a weekend to do the job start to finish. Also found one of the vacuum acutator was shot as well causing AC to blow on feet only.

Let us know how it turns-out.