Temperature gauge fluctuating

[Jerryred94silvy]

The heater temp is consistent. It’s consistently lukewarm but it doesn’t rise and fall with the alleged engine temperature.

 

[Jerryred94silvy]

Ended up bleeding it in a parking lot on the way home after it got to 260 and wouldn’t cool back off. Took the cap off, revved the motor up, watched the coolant go down and topped off with coolant in my toolbox then put the cap back on. Ran at 1-2 lines above 100 the whole way home after that.

 

[alpinecrick]

Probably unrelated, but has anyone noticed as these trucks age, the gauge on the dash reads lower? This is something that has bugged me for years, and has been noted on several trucks.

The temp gauge on my 96 reads very low, I even sent my gauge cluster off to be "refreshed" and the guy emailed me and said the gauges were within spec, but he would work on vibrating needle on the oil gauge, and he did reduce the movement a lot.

My 97 has low miles, and the temp gauge reads higher.

Both trucks read 195 on my scanner when fully warmed up.

Both trucks have new AC Delco sending units for temp and oil pressure--it made no difference.......

When I install a pillar pod I might go with 3 gauges and include a coolant temp gauge even though it would be redundant with the factory gauge.

 

[Erik the Awful]

Wildly fluctuating coolant temperature makes me think air pockets.

This is one of the most "Worth it!" tools I own:
https://www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY

 

[HotWheelsBurban]

Yes I used to have a 96 Dodge Intrepid 3.5 V6 and it was very sensitive to air pockets in the cooling system. Apparently these vehicles are notorious for this because they have a bleeder screw on the thermostat housing. But our trucks are somewhat sensitive to this problem. If mine gets very low on the radiator level, it burps when it's filled up. I have a snap in plastic funnel that prestone used to make, if the funnel is loose in the radiator neck it probably burps the air out around it. Just my guess anyway, hope this helps

 

[HotWheelsBurban]

When my truck overheated, it was in January and it was in the high 30s. That's cold for Houston! Especially standing outside in the wind putting water in the radiator cause it's almost empty cause I forgot to check it that evening. The gauge went up so fast I could watch it and usually it doesn't move much unless we're in traffic. Scary!

 

[Erik the Awful]

Yes I used to have a 96 Dodge Intrepid 3.5 V6 and it was very sensitive to air pockets in the cooling system.

'90s era Nissans were also bad about air pockets. They had a bleed screw on the manifold, but it wasn't reliable for getting all the air out. The trick was to raise the front of the car at least a foot in the air and use the funnel above. I've used that trick on a good number of other cars.