Coolant temp fluctuating up and down

[Courchained]

Hey guys so I have a 98k2500 5.7 ecsb. I can watch my coolant temp guage on the cluster from a cold start slowly rise to 195ish then drop to 160ish within seconds. It then slowly rises back up to 195ish then drops. I can't seem to get this figured out. Truck has a new delco wp and tstat. Also new heater core radiator and fan clutch w/hoses and cap. I've used multiple methods for bleeding the coolant multiple times and still no luck. Any thoughts?

 

[Courchained]

By the way I have used an temp gun on the engine/cooling components and have confirmed this temp fluctuation is happening

 

[Frank Enstein]

Try one of these.

FlowKooler 330-195 FlowKooler Robertshaw Series High Performance Thermostats | Summit Racing

Free Shipping - FlowKooler Robertshaw Series High Performance Thermostats with qualifying orders of $109. Shop Thermostats, Mechanical at Summit Racing.

www.summitracing.com

 

[eran tomer]

mine is going from cold upto 210 then goes down to 195 and stays there steady.

 

[Courchained]

I'll try out the kooler

Try one of these.

FlowKooler 330-195 FlowKooler Robertshaw Series High Performance Thermostats | Summit Racing

Free Shipping - FlowKooler Robertshaw Series High Performance Thermostats with qualifying orders of $109. Shop Thermostats, Mechanical at Summit Racing.

www.summitracing.com

I'll try this one. Fingers crossed.
I tested the 195 stant and found that to open at 198 and close at 184. My guess is the 195 delco (currently in the truck) is doing the same thing.

 

[Erik the Awful]

Use this for filling and bleeding your coolant. Also, try jacking the front of your truck about a foot while filling and bleeding.
www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY/

 

[Devon 11]

I just leave the cap off radiator and start it and fill as needed for about 30 minutes

 

[Supercharged111]

Try one of these.

FlowKooler 330-195 FlowKooler Robertshaw Series High Performance Thermostats | Summit Racing

Free Shipping - FlowKooler Robertshaw Series High Performance Thermostats with qualifying orders of $109. Shop Thermostats, Mechanical at Summit Racing.

www.summitracing.com

This lacks the bypass thingy the Vortecs use. This will work just fine on a TBI motor.

 

[454cid]

This lacks the bypass thingy the Vortecs use. This will work just fine on a TBI motor.

Bypass thingy?

 

[Supercharged111]

Bypass thingy?

The Vortec stats are taller than the old school ones and have a plunger on the bottom.

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