My 98 Blazer 4x4 dash analog temp. gauge never gets above what appears to be 160*F or so. No way near the 210*F as marked on gauge.

I have replaced the thermostat twice with the proper rating that was verified by parts counter. Heater pumps out heat no problem.

Radiator is new heavy-duty. The car has always showed 160*F when fully warmed up any time of year, hot or cold weather.

The gauge had shown just above 220*F or so when the old radiator was partially blocked and it was hot Summer with a/c blasting.

Is this just the normal fully warmed up temp?

My gas mileage is really bad (14mpg highway) so I was wondering if the engine computer never gets into full warmed up mode.

I suppose I could add a separate temp gauge to compare but really do not want to go that added expense.

 

Normal operating temp should be ~210F (gauge needle ~straight up) with a 195F thermostat. I'd say you either still have air in the system that is trapped around the gauge sensor or possibly have a bad sensor. I can't remember exactly when they made the change from two sensors to one. If the sensor located in the driver side cylinder head is a single wire sensor, then that is the gauge sensor and you will have another sensor near the thermostat that is for the PCM. If it is a multi wire sensor in the driver side head, then that is the only temp sensor for the cooling system and is used by both the PCM & the cluster.

 

Wouldn't air cause the temp to rise due to a hot spot?

Anyway, for the life of the vehicle the gauge has read approx 160*F. System is quite full of water/coolant. Last flush was 3 Summers ago. I think all the air is out by now.

Anyone else can chime in with where their temp gauge reads?

 

See below for my gauge reading. I just swapped out the el cheapo thermostat that the previous owner put in for a Stant 195 SuperStat and that is my reading at hot idle, sitting at a stop light, after burping and everything.

Edit: get a thermometer and boil some water...drop your current thermostat in and see when it actually opens up to confirm it is a 195* unit. Only other thing I can think of is a faulty engine coolant temperature sensor.

I have a '98 Jimmy and I have the one sensor in the driver side cylinder head (two wire). The other location in the thermostat housing has a plug in it and no sensor.

 

This is where my temp gauge always reads when fully warmed up, where I drew an arrow. Just about 160*F.

 

What brand/part number did you use each time? You really shouldn't go cheap on them. The best one to get would be a Stant Superstat, they are less than $10 at most FLAPS and very reputable.

I would consider buying a new coolant temperature sensor and swapping it with the old one just to compare readings. Have a wide pan underneath, you're gonna lose a ton of coolant. If it shows the same reading on the gauge, put the old one back in and take the other one back just to save yourself the money. At that point, I would probably think there was something with the gauge itself. Try to borrow an infrared thermometer and get a temperature reading off the metal water outlet. It's the metal pipe that goes over the thermostat, and that the top radiator hose connects to on the engine. Compare to your gauge.

Edit: actually, if I'm reading correctly, you say you started getting 160* temps after the HD radiator installation? Can you post a link of this radiator. I think the standard duty/OEM radiator is a single row, and the one you put in might have been a multi row which could provide extra cooling/lower temps...not sure though, not a cooling system pro.

 

Wasn't Superstat, just the regular Stant.

It could be that the sensor is bad considering I have such poor gas mileage. The computer thinks the engine is not warm yet and runs in rich mode.

 

If you could get a hold of a scanner with live data I think you can actually see what temperature the sensor is reporting and it will also tell you if it's in open or closed loop. Chances are you can find a shop in the area that does free engine diagnostics/code retrieval, they can show you that info.

 

Like at Advance Auto? Do their scanners show that detail?

 

Some might, but most just use the standard Actron scanner with no live data...I think it's better to just go to a repair shop that offers free computer scans. It takes all of 10 seconds to get into live data mode and pull up the info you need to see.