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Discussion Starter · #1 ·
I'll try to make this story as short as possible.

Last winter my truck started to not warm up completely, it would run around 170 or which may be okay but wasn't normal for my truck. Mind you I live in southeast Louisiana so I use the term winter loosely. I figured the the thermostat was stuck open so I bought a replacement from Autozone, it was not a GM part. I noticed the O-ring was different when I installed but didn't think much of it. After installation the truck still wouldn't warm all the way up until the warmer months but the thermostat housing itself had a small leak along with a new problem. At idle and cruising around town the truck runs at 210 like it has from day 1 but now when I'm cruising along 70 the temperature will randomly get 5 to 10 degrees warmer then go back to 210. Also under hard acceleration like merging on to the interstate the truck will stay at 210 but when I let off the accelerator the truck will momentarily get 10 to 15 degrees warmer then go back down.

The steps I've taken to remedy the issue:
- Purchased a new gm thermostat and housing, leak stopped but other issues have persisted.
- I've done my best to burp the system, when I squeeze the coolant hoses the coolant level moves up and down immediately.
- I've checked to make sure the tensioner is reactive. It seems to be okay but I guess the only way to know is change it?
- I recently ordered a new reservoir cap to make sure it's holding pressure but the current one seems to be.

My next steps are to change the pump, the tensioner, and the belt but wanted to look for answers before just spending money and time.

The truck is a 2018 Silverado 1500 LT 4x4 with the 5.3 motor. It has 124,000 cared for miles.

Any insight or leads would be greatly appreciated.

Thank you.
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