Intermittent Coolant Temp Issues

[colorado.dmax]

The other morning fired up the truck and started fine. Was only 32* out so I kicked the high idle on for a few minutes. Truck was over 130* when I left my place. Jumped on the highway shortly after and temp started to drop, dropped all the way down to 80* and held there for a few minutes. Then all of a sudden temp starts climbing fast up above 200* and then drops back down to the 170* it usually sits at.

Went out this morning and started the truck up. High idle on for a few minutes, come out to leave and the truck was only at 60*. Take it nice and slow and the temp dropped down to 57*, keep driving for a few miles and nothing, still sitting at 57*. Then all of a sudden it starts climbing real fast, shoots up to 232* then settles back down at the usual 170* and is fine the rest of the day.

Reading ECT with both dash and edge CTS, also the air temp varies with the coolant temp, blowing cold when it plummets and hot when it rises.

 

[Stancedlb7]

Did your heater blow cold when your gauge shows low temp?

 

[Chevy1925]

sounds like thermostats

 

[SSchmi5519]

sounds like thermostats

seconded, one or both of them.

 

[chevyburnout1]

Thermostats or low coolant. The temp sensor reads coolant a lot better than air lol.

 

[Dozerboy]

Odd that the hvac fallows the ect swings that are that big. I wouldn't think it was low on coolant.


Sent from my iPhone digging a ditch near you.

 

[colorado.dmax]

Did your heater blow cold when your gauge shows low temp?

My heater did blow cold when it dropped and heated back up when the temp came back up. But that appears to have stopped.

Driving home from work, temp rose to 230* and never came down and heater was blowing cold. Temp was just 220-246* the whole ride home and it's maybe 32* outside.

When the temp spikes at the warmest it is followed by a "low coolant level" message. When I got home the degas tank was full and squeezed right up to the cap.

 

[Chevy1925]

You have some sticking thermostats. They generally fail safe to open from factory and it sounds like they are not fully opening like they should giving you hotter than normal temps.

For shits and giggles, there is a bolt on top of the thermostat housing that lets you bleed air from the system. Pull it and see if a decent amount of air comes out or just water

 

[colorado.dmax]

You have some sticking thermostats. They generally fail safe to open from factory and it sounds like they are not fully opening like they should giving you hotter than normal temps.

For shits and giggles, there is a bolt on top of the thermostat housing that lets you bleed air from the system. Pull it and see if a decent amount of air comes out or just water

When would be the ideal time to pull the bleeder? Let the truck sit overnight? Let it warm up a bit first?

 

[DBUSHLB7]

Thermostats are an easy fix!:thumb:

 

[mlp27esplin]

Thermostats

 

[Dukcaln]

I vote for starting with the thermostats as well