Thermostats

[Rolderhawk]

My truck has the same specs as yours, and does exactly as you describe- cold start, runs up to about 215, then settles back to 160/165 for as long as I run it. Seemed odd, but is consistent, so I’ve lived with it. Had the truck two years, haven’t changed the T-stat.

 

[Crookedaxle]

Does anyone ever drill a small hole in their thermostats? I have in the past on other vehicles. I also run cardboard in front of my radiator when the temp drops. Beer case cardboard seems to work the best for whatever reason.

 

[Supercharged111]

Does anyone ever drill a small hole in their thermostats? I have in the past on other vehicles. I also run cardboard in front of my radiator when the temp drops. Beer case cardboard seems to work the best for whatever reason.

No need. The Vortecs already have a bypass and my trucks have always gotten up to temperature in the winter.

 

[Supercharged111]

WHAT VEHICLE? Rear heater?

Common for the temp sensor in the head to read 10--20 degrees higher than the coolant sensor in the intake. The sensor in the head seems to pick up heat from the exhaust.

Any modification to water pump or the coolant bypass system? Heater deleted?

The front of the driver's head (stock sensor location) runs cooler than the back of the passenger's head on my Camaro too.

 

[Schurkey]

Thermostats don't come from the manufacturer with bigass holes drilled into them, because it's damaging at worst, un-needed at best.

It slows engine warm-up, maybe even preventing warm-up if the hole(s) are big enough.

The only exception to this is when the OEM coolant bypass system has been defeated. With no other "cold engine" coolant circulation, a hole in the thermostat could be useful.

There are thermostat companies that stamp a TINY air-vent into the 'stat; and others that use a jiggle-valve which could vent air when the engine is off, but closes with water-pump pressure.

Photo 1. Robertshaw thermostat with air-vent, compared to # 73 drill bit, and 1/8" drill bit. http://hbassociates.us/Robertshaw_Vent_01.jpg

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Photo 2 Robertshaw thermostat--different angle, and 1/8" drill bit.
http://hbassociates.us/Robertshaw_Vent_02.jpg

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[Crookedaxle]

No need. The Vortecs already have a bypass and my trucks have always gotten up to temperature in the winter.

I've always done it in case an air pocket develops right under the thermostat keeping it from opening.

 

[Crookedaxle]

Thermostats don't come from the manufacturer with bigass holes drilled into them, because it's damaging at worst, un-needed at best.

It slows engine warm-up, maybe even preventing warm-up if the hole(s) are big enough.

The only exception to this is when the OEM coolant bypass system has been defeated. With no other "cold engine" coolant circulation, a hole in the thermostat could be useful.

There are thermostat companies that stamp a TINY air-vent into the 'stat; and others that use a jiggle-valve which could vent air when the engine is off, but closes with water-pump pressure.

Photo 1. Robertshaw thermostat with air-vent, compared to # 73 drill bit, and 1/8" drill bit. http://hbassociates.us/Robertshaw_Vent_01.jpg

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Photo 2 Robertshaw thermostat--different angle, and 1/8" drill bit.
http://hbassociates.us/Robertshaw_Vent_02.jpg

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Nowhere in my post did I use the technical term "bigass". .030" max.

 

[thinger2]

I would look at your grounds first.
Usually an air pocket will not stabilize.
An air pocket is basically a bubble that gets trapped in a hard corner or some other place where it can form.
Think of a sinking boat. It floats bow up because that air is trapped.
When you start the engine, the water pump pulls that air out of its space and it "cavitates" across the impeller.
Basically turns your big bubbles into foam.
Once you reach "steaming point"
Those bubbles are constantly getting trapped and released and reforming.
You would normally see ongoing and random temp problems if it was trapped air
That said, I would burp it anyway and at least pressure test the radiator.
A cold start temp spike means your gauge is lying to you.
After all, it cant possibly be that hot right?
I also really dont recommend drilling a hole in the T stat.
Coolant moving through that hole can erode it away pretty quick and if you forget about, you end up with a big damn hole or even a cracked thermostat

 

[454cid]

My guess is the thermostat is opening late and then staying open too much, due to defect. I'd replace it as you dont want it to finally stop opening at all and cause a real overheating situation.

 

[Coveman]

My 99 burb came with a 185 thermostat, when I changed it (manifold gasket leak) I put a 195 in and it ran hotter (duh) and the temp moved back and forth quite a bit. Switched back to a 185 and when it warmed up it stayed put without all the back and forth.