Coolant system question

frog7151 · Aug 8, 2021

The last couple of times I drove my car made me suspect I have a coolant issue. The car has never overheated but it the temp has risen to 222 will idling in heavy traffic. I also noticed the temp would be higher in overdrive than in 4th gear with higher rpms.

I am thinking I might have trapped air so I “burped” the coolant system using one of those no spill funnels. I jacked the car up and turned the heat on. Some air came out but I still have the same symptoms.

I used the port on the radiator below the top hose for the steam line, but it is lower than the steam ports on the heads. Is this an issue?

dhutton · Aug 8, 2021

I have used that steam port configuration without issue on several builds. It sounds like insufficient fan air flow. What fans and shroud are you running? Have you blocked off gaps around the radiator? Do your fans go to high speed when idling?

Don

copo9560 · Aug 8, 2021

On my Gen 4 car, the cooling (steam) line from the heads runs in under the cap where you can see it. When refilling the system it can take a while to establish solid flow with no bubbles. Also it will not clear at idle speed, more rpms are needed.

frog7151 · Aug 8, 2021

dhutton said:
I have used that steam port configuration without issue on several builds. It sounds like insufficient fan air flow. What fans and shroud are you running? Have you blocked off gaps around the radiator? Do your fans go to high speed when idling?

Don

I am using the shrouds that came withe fans.

Superior radiator - Camaro

I used the dual spal fans.

Have not blocked off any gaps.The fans to go to high while idling.

Vega$69 · Aug 8, 2021

frog7151 said:
I am using the shrouds that came withe fans.

Superior radiator - Camaro
I used the dual spal fans.

Have not blocked off any gaps.The fans to go to high while idling.

I have used the same radiator and fans on several builds with AC. No cooling issues in Vegas heat.

frog7151 · Aug 8, 2021

I think I just found out one issue. Just ran the car to 205 and the thermostat did not open up. I am pretty sure the GMPP LS3 came with a 187 thermostat.

Vega$69 · Aug 8, 2021

Possible coolannt is not reaching T-stat due to air.

With the engine running squeeze the top hose, slowly pumping. Hose should feel firm. If not keep pumping slowly. This will draw the air out and hopefully get the stat to open.

Wear a glove. Lol

Shannon4570 · Aug 8, 2021

frog7151 said:
I think I just found out one issue. Just ran the car to 205 and the thermostat did not open up. I am pretty sure the GMPP LS3 came with a 187 thermostat.

I had the same issue. When it warms up reach down and see if there is any flow in the lower radiator hose. If there isn't jack up the front end, open the radiator cap and squeeze that upper hose until your hands hurt. I believe I had a pocket of air trapped at the rear of the cylinder head which finally burped out allowing coolant to reach the thermostat and open it up.

frog7151 · Aug 8, 2021

Shannon4570 said:
I had the same issue. When it warms up reach down and see if there is any flow in the lower radiator hose. If there isn't jack up the front end, open the radiator cap and squeeze that upper hose until your hands hurt. I believe I had a pocket of air trapped at the rear of the cylinder head which finally burped out allowing coolant to reach the thermostat and open it up.

Tim, when you say until your hand hurts do you mean from being tired. Did you does this with the engine running? Thanks

frog7151 · Aug 8, 2021

Vega$69 said:
Possible coolannt is not reaching T-stat due to air.

With the engine running squeeze the top hose, slowly pumping. Hose should feel firm. If not keep pumping slowly. This will draw the air out and hopefully get the stat to open.

Wear a glove. Lol

How firm should the hose be? I know that is subjective, but should you be able to collapse it all the way?

57vette · Aug 8, 2021

Shawn... You might want to look at an EMP/Stewart thermostat. With the three holes they have in the center section, its supposed to allow any air in the system to escape, plus if their thermostat gets stuck, it always allows some coolant flow.

"Manufactured by Robert Shaw and modified by Stewart, these custom thermostats feature a balanced sleeve design and are constructed for high flow, high RPM applications. Strongly recommended for any performance application - must be used with Stewart Stage 2, 3 or 4 water pumps. Our Stage 2,3 and 4 Small Block Chevy water pumps do not have the factory bypass hole, therefore we put three 3/16” hole in our modified high flow thermostats, this moves the bypass to thermostat. This also allows air to escape on initial system fill making bleeding the cooling system much easier."

frog7151 · Aug 8, 2021

57vette said:
Shawn... You might want to look at an EMP/Stewart thermostat. With the three holes they have in the center section, its supposed to allow any air in the system to escape, plus if their thermostat gets stuck, it always allows some coolant flow.

"Manufactured by Robert Shaw and modified by Stewart, these custom thermostats feature a balanced sleeve design and are constructed for high flow, high RPM applications. Strongly recommended for any performance application - must be used with Stewart Stage 2, 3 or 4 water pumps. Our Stage 2,3 and 4 Small Block Chevy water pumps do not have the factory bypass hole, therefore we put three 3/16” hole in our modified high flow thermostats, this moves the bypass to thermostat. This also allows air to escape on initial system fill making bleeding the cooling system much easier."

View attachment 279739

Thanks Mike. It looks like you have to use their water pump as well.

Shannon4570 · Aug 8, 2021

frog7151 said:
Tim, when you say until your hand hurts do you mean from being tired. Did you does this with the engine running? Thanks

Yes, essentially from getting tired. It wasn't that difficult and you can tell when it works and yes, with the engine running. Like John says, you are trying to pump or draw the air out of the system. I also saw a significant drop in the coolant level when the thermostat finally opened.

frog7151 · Aug 8, 2021

Shannon4570 said:
Yes, essentially from getting tired. It wasn't that difficult and you can tell when it works and yes, with the engine running. Like John says, you are trying to pump or draw the air out of the system. I also saw a significant drop in the coolant level when the thermostat finally opened.

Thanks. I will give it a try. I pumped it but maybe only 10 times.

Shannon4570 · Aug 8, 2021

frog7151 said:
Thanks. I will give it a try. I pumped it but maybe only 10 times.

My advice is do it until you can feel liquid in the bottom hose - that's the indicator it's open (also the liquid level in your radiator).

frog7151 · Aug 8, 2021

Well both hands are tired and the thermostat still did not open. I filled the no spill funnel about an inch past the neck and the coolant only expanded. The bottom hose eventually got hot but again no drop in coolant. The car never got above 205. My low fan kicked off and on.

Picture is after coolant expansion.

Brettallen59 · Aug 8, 2021

Shawn, it looks like your upper radiator hose is lower than the back of the block. I don't see how you will get the air out if it is in the back of the engine. I have a radiator pressure fill kit. I also have the Lisle coolant "Burb" kit, but this kit uses pressure to force out the air and replace it with coolant. It works amazingly! If your upper hose is lower I don't see any other way to get that air out. Mastercool Vacuum purge and refill kit .

I wonder if you run it without a thermostat (simulating and open thermostat), it will have a better chance of getting the air out from the back of the engine and up to the radiator. Then, you can add the T/S.

Brett.....

frog7151 · Aug 8, 2021

Brettallen59 said:
Shawn, it looks like your upper radiator hose is lower than the back of the block. I don't see how you will get the air out if it is in the back of the engine. I have a radiator pressure fill kit. I also have the Lisle coolant "Burb" kit, but this kit uses pressure to force out the air and replace it with coolant. It works amazingly! If your upper hose is lower I don't see any other way to get that air out. Mastercool Vacuum purge and refill kit .
Brett.....

Thanks Brett. The picture is a little deceiving. The hose is higher than the back of the block, maybe not the very top of the rear of the heads.
I was thinking about one of those vacuum purge tools, but at this point I am not sure if an air pocket is actually my problem. I guess I could use one if I replace my thermostat.

after cool down.

Brettallen59 · Aug 8, 2021

Well yes, those kits are pretty expensive so I would not recommend getting one if you aren't sure that is what it is. Now, if you want to try one without spending the $$, I will send you mine and you can try it. If you decide you want to try one let me know and I'll send it your way.
Brett....

frog7151 · Aug 8, 2021

Brettallen59 said:
Well yes, those kits are pretty expensive so I would not recommend getting one if you aren't sure that is what it is. Now, if you want to try one without spending the $$, I will send you mine and you can try it. If you decide you want to try one let me know and I'll send it your way.
Brett....

Thanks Brett. That is a very generous offer. If I decide I need one I will pick one up. It will help build my tool collection. Plus, it will still be cheaper than paying someone to fix it.

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Coolant system question

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