Temp Gauge has me Hot!!

[MarkmyWords89]

Morning all! I have an issue that's buggin me. I have a 1989 GMC C1500 5.7 TBI. Lately, I can get in the truck and head to work in the morning and within 5 mins the temp is reading 210 and says check guages! My job is about 15-20 mins away. It might back off once or twice but generally will stay there. But sometimes the gauge will read normal.

The truck isn't running like it's hot, but I could be wrong. But when I reach work I will hear coolant overflowing into the reservoir. I have changed the water pump, thermostat, fan clutch, both temp sensors & radiator. Had to flush the entire system a few times because of rust.

I don't know if there's air in the system, if the gauge is on the way out or what the issue is? I was thinking about just running a gauge to monitor the accurate temp. And changing the thermostat again.

At my wits end with this. have a feeling it's something simple and i'm just overthinking it. Any foolproof way of making sure all air is out the coolant system?

Thanks!

 

[Swaggerwagon]

if you hear coolant bubbling into the overflow tank, then you are most definitely over heating....

Sounds like maybe some large air pockets are in the system....(Do this only when the truck has sat overnight..it must be completely cooled off)...park the truck on a steep incline/hill...nose first...remove the rad cap...fill up the rad to capacity..start the truck..let the truck run while you are constantly keeping the rad filled up with coolant...you should see air pockets bubbling their way out of the cooling system while it's running...if possible, have a helper rev the engine to around 2000/3000 rpm and hold it there, while you are keeping the radiator topped off with coolant...be careful to not get burned by hot coolant while the system is burping out the air pockets...continue to do this until you no longer see air pockets bubbling out of the rad...just a steady stream of coolant...

good luck..

 

[MarkmyWords89]

I will give that a try. Thanks a lot, I appreciate it!

 

[silverado13]

id check your therostat or the temp sensor

 

[MarkmyWords89]

I've changed the thermostat twice! Down to 160 then back to 195. And I've changed both sensors. Just this morning on the way to work the same thing. Temp shoots over to 210 in about 5 mins, and panel says check gauges! Sometimes the coolant overflows into reservoir sometimes not. Don't know what to do next??? A buddy of mine says try spill proof funnel. If its not air in the system then its the heads.

 

[silverado13]

that just odd, i think i have the opposite problem. i live in louisiana and is always over 100 degrees and it take being on the road for 30 minutes just to get it to 140ish

 

[DRAGGIN95]

I also suggest you get a infared temp gun so that you can see what temp your motor actually is, and there great for all kind's of things.

 

[MarkmyWords89]

Silverado13, mine used to do the same(barely get past 140, I thought Miami was hot til I went to Louisiana once!) until I replaced the water pump. I double checked it is the correct rotation. Draggin, i'll look into the temp gun. This weekend i'm gonna change the plugs & oil and flush the system one more time. I'm gonna use the no spill funnel to make sure all the air gets out this time!

 

[dagen_1]

my DD does that.. as soon as i start it, within a few minutes it's showing "hot" but it really isn't. it only does it once in a while on my car so i don't worry much about it. If it were my Cheyenne, i'd worry until it was fixed..hehe

 

[MarkmyWords89]

This is my DD so I have to stay on top of it. It did run hot a couple times so i'm getting ready to change the oil now and the spark plugs. Gonna flush it too make sure I get ALL the air out of the system and just run a seperate water temp gauge to moniter.