So just to clarify, it is unlikely that it is the actual thermostat at this point? Air in the system is most likely what is causing it to heat up that hot initially? I could just buy a gallon of coolant myself and bleed the system. As long as it is a universal coolant I should be fine?
Temp gauge fluctuating after coolant change...
- Thread starter derekjl
- Start date
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So just to clarify, it is unlikely that it is the actual thermostat at this point? Air in the system is most likely what is causing it to heat up that hot initially? I could just buy a gallon of coolant myself and bleed the system. As long as it is a universal coolant I should be fine?
east302
Full Access Member
You can use a scanner to read the Engine Coolant Temperature (ECT) sensor output. This is the one by the thermostat and is the sensor that reports the temperature for the computer’s use. The gauge sender is on the driver side block. I’d trust the ECT sensor reading over the gauge, and this would help verify if the temperature is really fluctuating or if the gauge (or sender) itself is just flaky.
I would try bleeding it again, though. Just match whatever coolant you have in there (orange dexcool or just regular green). A store brand is fine.
Minimum heater temperature specs are below...
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I would try bleeding it again, though. Just match whatever coolant you have in there (orange dexcool or just regular green). A store brand is fine.
Minimum heater temperature specs are below...
Sent from my iPhone using Tapatalk
Just for reference, this is where the gauge usually sits as of right now. An observation I made tonight was that I drove about 4 miles and the gauge was up to 210 degrees. The thermostat opened right around 215, just one tick above the 210 mark. It dropped to about 160 and then rose to and stayed where it is in the picture. The other night I drove the truck straight onto the highway from cold and the gauge rose much higher before the thermostat opened. Tonight it seemed to work as intended and I have very very hot air coming out of the vents, almost painfully hot like I would get sick if I didn’t lower the temp. The most the gauge moves from where it is in the pic once the truck is warm is maybe 1-2 ticks at most. Does outside temperature have an impact on the coolant temp and where it sits? It is currently 25 degrees where I am. I’ve now been sitting in a parking lot for 15 minutes and the gauge has not moved...hmm.
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looks like it is sitting at about 180 which is where it should be, but it should stay there regardless of outside temperature, only time you might normally see it move is if you were pushing it at high altitude or pulling something heavy and pushing it hardJust for reference, this is where the gauge usually sits as of right now. An observation I made tonight was that I drove about 4 miles and the gauge was up to 210 degrees. The thermostat opened right around 215, just one tick above the 210 mark. It dropped to about 160 and then rose to and stayed where it is in the picture. The other night I drove the truck straight onto the highway from cold and the gauge rose much higher before the thermostat opened. Tonight it seemed to work as intended and I have very very hot air coming out of the vents, almost painfully hot like I would get sick if I didn’t lower the temp. The most the gauge moves from where it is in the pic once the truck is warm is maybe 1-2 ticks at most. Does outside temperature have an impact on the coolant temp and where it sits? It is currently 25 degrees where I am. I’ve now been sitting in a parking lot for 15 minutes and the gauge has not moved...hmm.
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That makes me feel a bit better, but keep in mind this is not the Vortec motor. I know those tend to sit at a lower temp. I was always under the impression that it should sit at 200-210 constantly, which is where I thought it was before the work was done.
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you can look up what temp thermostat it calls for at most autoparts websites just plug in your year/make/model/engine size, etc.
iamdub
Full Access Member
A scanner is only gonna tell you what the coolant temp sensor is reading. If an air pocket/bubble in the system is at the sensor, then it's not gonna read accurately. The bubble passes and the sensor is suddenly immersed in coolant again and reading the temperature of it. This can cause the sudden and relatively drastic temperature swings.
With that said, where should a 350 TBI be running at in terms of coolant temp? 180 degrees seems low compared to everyone else I’ve heard saying it should be 200-210 degrees. Gauge is probably not 100% accurate.
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iamdub
Full Access Member
It should have either a 180 or 195 thermostat. I know the newer ("Vortec") engines were designed to run with a 195 'stat. Mind you, this is thermostat temperatures and not actual operating temperatures. The Vortec generation engine had a 210 operating temp with it's 195 'stat. The gauge cluster had "210" at the center so that only a quick glance was needed when checking the coolant temp. Most factory gauges are set up like this: "14" at the center of the volt gauge, "40" at the center of the oil pressure gauge to represent the average operating pressure, etc. Having said that and referring to your gauges pic you posted, I'd guess that your engine's normal operating temp is intended to be 210 which would lead me to believe it takes a 195 'stat. Too hot is definitely not good but too cool can cause problems as well.
