Water temperature gauge spikes to impossible high #s then goes quickly to 180°

[66chargerpat]

Just wondering where the new air is coming from ?

 

[biomedtechguy]

the mixing hole under the thermostat

The "mixing hole" under the thermostat?

 

[CHARGERSTEVEN]

Does your rad have a vent tube,try loosening the rad cap n checking to see if air or coolant is passing thru,it could be a faulty rad cap

 

[65Fury440]

Yea,under the thermostat is a hole that allows a small amount of water to bypass when the stat is closed.
Some housings are threaded so a guy can plug them, forcing all the water out of the engine, and into the radiator.

 

[biomedtechguy]

Does your rad have a vent tube,try loosening the rad cap n checking to see if air or coolant is passing thru,it could be a faulty rad cap

It's a new Cold Case radiator and their cap. I have an overflow tube that goes to a generic auto parts store white plastic container.
I posted that "right after I removed the thermostat, I let the engine come up in temperature and it spiked". I shut the engine off, let it sit about 10 minutes, and with it still off, I squeezed the top radiator hose and heater hoses. I discovered that the top half or 2/3rds of the radiator was hot, as expected at 180° but the bottom half or 1/3rd of the aluminum radiator was barely warm.
I sat in the car then, to monitor the temperature gauge with the engine still off, and I heard a "GLUG-GLUG" sound. I went back outside and found the radiator was now completely uniformly hot like it should be, and the temp gauge was around 180° I think that may be after I started it, but the "GLUG GLUG" sound was a major event in how it uniformly distributed the heat.

 

[biomedtechguy]

Yea,under the thermostat is a hole that allows a small amount of water to bypass when the stat is closed.
Some housings are threaded so a guy can plug them, forcing all the water out of the engine, and into the radiator.

Yeah, I don't know if my very nice looking, well made, well engineered, high quality materials impeller vanes and aluminum high volume water pump from Wraptor has one ah dem...

 

[65Fury440]

Yeah, I don't know if my very nice looking, well made, well engineered, high quality materials impeller vanes and aluminum high volume water pump from Wraptor has one ah dem...

It would actually be in the water pump housing, what kind do you have?
Just pop the stat out, look underneath.

 

[CHARGERSTEVEN]

It's a new Cold Case radiator and their cap. I have an overflow tube that goes to a generic auto parts store white plastic container.
I posted that "right after I removed the thermostat, I let the engine come up in temperature and it spiked". I shut the engine off, let it sit about 10 minutes, and with it still off, I squeezed the top radiator hose and heater hoses. I discovered that the top half or 2/3rds of the radiator was hot, as expected at 180° but the bottom half or 1/3rd of the aluminum radiator was barely warm.
I sat in the car then, to monitor the temperature gauge with the engine still off, and I heard a "GLUG-GLUG" sound. I went back outside and found the radiator was now completely uniformly hot like it should be, and the temp gauge was around 180° I think that may be after I started it, but the "GLUG GLUG" sound was a major event in how it uniformly distributed the heat.

Thats why i said the rad cap as they are spring loaded,n if stuck or to strong they will not open n allow steam or excess coolant to flow into resivour,if you loosen it you should here or see it pushing fluid out or see the steam

 

[biomedtechguy]

Thats why i said the rad cap as they are spring loaded,n if stuck or to strong they will not open n allow steam or excess coolant to flow into resivour,if you loosen it you should here or see it pushing fluid out or see the steam

I think they provide a 14 or 16 pound cap. When I turned it 1/2 turn open, while "hot", nothing came out. As I turned it the last half, as if to remove it, with me pushing down on it some, a bit of coolant came out and I immediately closed it so as to not introduce air into the radiator.
If I'm missing what you are saying or suggesting, I'm sorry.

 

[biomedtechguy]

It would actually be in the water pump housing, what kind do you have?
Just pop the stat out, look underneath.

The water pump is a high volume aluminum pump supplied by CVF for the Wraptor serpentine belt and accessories system. It's a high quality item.

 

[CHARGERSTEVEN]

if your hearing the glug glug,that cap may be to strong as its not opening to allow steam out,try another cap with less pressure,what you got to lose

 

[4406bbl]

As far as thermostats go the robershaw style flow the most, Evans, Mr gasket and others sell them, I use original nos military 180 ones that were cheap, and drill the 1/8 hole in the outer ring of the stat. I doubt the cap is the problem. If it was at 200 or more you would never get the cap off only losing a few ounces. It would be a geyser. The best item I have found to put your mind at ease for temp is a restuarant dial type thermometer in the radiator. I wonder if the pump/pulley combo puts out too much flow for the size of holes in the head gaskets....later gaskets have about 50%smaller slots than originals, maybe the pump sucks it into a vacuum causing an air pocket, then superheating around cylinders, then steam gurgling. Maybe slow the pump down... just brainstorming how it could do that with no thermostat. The head gasket slots, plugged block, or some kind of restriction is all I could come up with. I have also seen 440 blocks with part of the upper 2 thermostat housing holes cast over, I grind them out to full round.

 

[diesel_lv]

Yes, please, let's NOT...
Let's not debate the relative functions of a thermostat.
Does anyone have a Mopar 180° thermostat that is the BEST and why?
I'm most interested in highest quality materials and DESIGNED TO HELP PREVENT AIR POCKETS.
I'm going to be cooling THIS, and aluminum heads, and I absolutely do NOT want to overheat!
View attachment 1094773

I use the Robert Shaw style Mr. Gasket 180° t-stat in my 496 stroker in Fort Mohave AZ. My summers get up to 125+. Using a 26" 2 rows of true 1.25" core radiator. Last summer I had electric fans n metal shroud, would get too hot on the interstate. Put on mechanical fan n factory shroud and so far on a 104° day, so far at speeds 45 up to 80 it stayed at 186°. At a long idle, 15 minutes, it was at 195°. So this setup seems to work really well. That's w a/c on and vent temps never go above 39° even during the long idle.

 

[biomedtechguy]

As far as thermostats go the robershaw style flow the most, Evans, Mr gasket and others sell them, I use original nos military 180 ones that were cheap, and drill the 1/8 hole in the outer ring of the stat. I doubt the cap is the problem. If it was at 200 or more you would never get the cap off only losing a few ounces. It would be a geyser. The best item I have found to put your mind at ease for temp is a restuarant dial type thermometer in the radiator. I wonder if the pump/pulley combo puts out too much flow for the size of holes in the head gaskets....later gaskets have about 50%smaller slots than originals, maybe the pump sucks it into a vacuum causing an air pocket, then superheating around cylinders, then steam gurgling. Maybe slow the pump down... just brainstorming how it could do that with no thermostat. The head gasket slots, plugged block, or some kind of restriction is all I could come up with. I have also seen 440 blocks with part of the upper 2 thermostat housing holes cast over, I grind them out to full round.

Again, all replies are appreciated.
BUT
You have to think about this:
Driving around, all good, and once the initial spike happens, that seems to be just about the only, or majority of the time it happens, like the car has to be moving or the engine revving above idle speed to "move the hot pocket" away from the temperature probe.
NO exhibition of ANY factors telling me that anything but a tiny spot of (really hot something) is anywhere but by the temp probe.
The radiator top half hot/bottom half barely warm scenario, until the "GLUG-GLUG", and then INSTANTLY the whole radiator was a uniform hot temperature, hot as in 180°, that makes me think something was insulating or blocking the circulation.
I do have one of those flex rubber hoses at the bottom of my radiator that the shop put in, but ZERO indication of it collapsing, it's actually pretty stiff, like there's a spring all the way through it.

 

[4406bbl]

You have a weird one there for sure.

 

[Hemi 354]

Is it possible (just spit-ballin') that the radiator itself may be the problem?

 

[4406bbl]

Or a piece of packing material, foam or something was in it and got in the block? I doubt it is the lower flex hose at idle.

 

[biomedtechguy]

Is it possible (just spit-ballin') that the radiator itself may be the problem?

The Cold Case radiator is a well designed piece. I was careful not to get ANY foreign particles in the coolant as I transferred it to and from a rectangular, translucent plastic container. The issue did happen "suddenly" after about a half dozen drain/remove/replace/refill cycles as I was struggling with a POS electric fan, that I finally gave up on and switched to an 18" flex plus 2x 10" SPAL fans. I am about to add a factory shroud that looks like it will fit nicely.
I had my car idling in the mild heat around the end of October, hood open, and AC on and charging to top it off w/refrigerant, and I didn't have ANY temperature problems.
I'm convinced it's a weird air pocket, but I won't know until I know. I'm going to get a fill/funnel/fitting system and put the front up on jackstands to raise the radiator higher, and see what happens.
I'll say this: I do NOT regret putting the Wraptor serpentine belt and accessories system and Cold Case radiators on the Roadrunner and the GTO, but BOTH cars are giving me cooling system issues. I put just enough of the front edge of the factory Pontiac clutch "fins" of the clutch fan into its Cold Case radiator, at the end of a test drive, that started with a 1/2" of clearance but apparently the clutch on the Pontiac must expand forward when hot, and yeah, now that aluminum radiator is "wall art" and I put the factory radiator in until I can buy another Cold Case for the GTO.
Changing so much at once is challenging!

 

[Ironbuilt]

As to not start a big debate, do a quick search on why not to remove the thermostat. Allowing coolant in or keeping coolant from leaving are different views of the same result.

Not trying to debate anyone, but reading your above statement either you didn't explain yourself clearly or you don't understand how a thermostat works.

Thermostat keeps the water out of the engine long enough for the radiator to cool what is in it. "No thermostat" does not allow the engine to cool off after an overheating problem.

A thermostat, present or not, does not cool water or the engine afteroverheating. It allows warming up and regulating temperature above a set point.
No thermostat allows free flow of coolant which can benefit a race car but is terrible in a street car. I did it when I was a teenager because A) I didn't know any better and B) I didn't have a lot of money and thought a thermostat was a waste.
Please don't take my post as argumentative, it's not meant that way.

 

[6872n73]

Have you tried a different gauge?