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No coolant flow LT1

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Old 07-10-2018, 12:36 PM
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No coolant flow LT1

Hi.
My engine overheats and build pressure. I have this engine in a Hot Rod and i hope someone have a solution for me.
It seems like the water pump is not flowing. The pump is new, and the thermostat is new. I have bled the coolant system and I am pretty sure there are no airpockets anywhere.
I removed the front of the waterpump to check that it turns, and it does. I have removed one of the heater hoses to see if the water flows, but no flow. So I am really stuck here.

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Old 07-10-2018, 02:55 PM
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Re: No coolant flow LT1

Any chance you bought a reverse flow pump by accident?
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Old 07-10-2018, 03:42 PM
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Re: No coolant flow LT1

Any chance the radiator is old/blocked?

Are you sure the thermostat is opening?
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Old 07-10-2018, 04:03 PM
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Re: No coolant flow LT1

Did you check the water pump driveshaft coupling?

http://shbox.com/ci/water_pump.jpg


Is the thermostat the correct one for an LT1 engine:

http://shbox.com/1/tstat.jpg

Thanks to Shoebox for the graphics.
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Old 07-11-2018, 02:18 AM
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Re: No coolant flow LT1

Originally Posted by Shadyredeyes View Post
Any chance you bought a reverse flow pump by accident?
The pump is for a LT1 Corvette 93-97 so the pump should be the correct one.
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Old 07-11-2018, 02:19 AM
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Re: No coolant flow LT1

Originally Posted by BIG SHAFE View Post
Any chance the radiator is old/blocked?

Are you sure the thermostat is opening?
The radiattor is open and flowing good, and i have tested the thermostat in boiling water.
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Old 07-11-2018, 02:25 AM
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Re: No coolant flow LT1

Originally Posted by Injuneer View Post
Did you check the water pump driveshaft coupling?

http://shbox.com/ci/water_pump.jpg


Is the thermostat the correct one for an LT1 engine:

http://shbox.com/1/tstat.jpg

Thanks to Shoebox for the graphics.
The coupler fits on the shafts on both sides. I have removed the front cover on the water pump and turned the engine, and the water pump is turning.
But still no flow when put together and filled up with water.
Also tried to disconnect a heater hose to see if I have flow there, but nothing..... It's a real mystery
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Old 07-11-2018, 08:45 AM
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Re: No coolant flow LT1

Originally Posted by Oysteinbno View Post
I have removed one of the heater hoses to see if the water flows, but no flow. So I am really stuck here.
Originally Posted by Oysteinbno View Post
The radiattor is open and flowing good, and i have tested the thermostat in boiling water.
I'm confused, so which lines are flowing and which ones aren't?

Last edited by BIG SHAFE; 07-11-2018 at 08:48 AM.
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Old 07-11-2018, 11:18 AM
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Re: No coolant flow LT1

A little more info is needed, motor year, type of radiator, how the heater hoses and steam line are connected. Some ports will need plugged.
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Old 07-11-2018, 03:32 PM
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Re: No coolant flow LT1

The engine is from a 1995 Corvette, so it's a LT1.
The steam line is connected to the hose from the top of the waterpump up to the radiator. The lower heater outlet on the waterpump is connected to the line with the heater regulator an the top are connected to the return line from the heater.
I use a 3-row aluminum radiator that fits the body of the car (1936 chevrolet ). Inlet on top left, and outlet at the lower right.
I believe that it should be flowing trough the steam line all the time, but I have abolutely no flow. The heater hoses become hot, and from the waterpump to the radiator. The lower part of the radiator is cold. After a while the water starts boiling..
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Old 07-11-2018, 07:16 PM
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Re: No coolant flow LT1

The Corvette coolant system is significantly different than the F-Body (Camaro/Firebird), particularly with regard to bleeding the air out of the system. The Corvette system “self bleeds”, the F-Body system needs to be manually bled.

Here's the way a 95 F-Body (Camaro/Firebird) should be connected, with arrows showing flow directions. The flow from the back of the heads (steam pipe) should pass through the throttle body, then enter the liquid/vapor separator in the radiator. You appear to have it entering the pump suction (feed line) from the radiator to the water pump. Putting hot coolant and vapor bubbles into the pump suction may promote cavitation.

http://shbox.com/1/95-97_hoses.jpg

The Corvette water pump is also slightly different than the F-Body pump, mainly with regard to orientation of the connections. The functions are still the same.

http://shbox.com/1/lt1_water_pumps.jpg

Do you have a heater, utilizing the connections on the water pump? Do you have a flow restrictor in the supply line (part #13 in this diagram):

http://shbox.com/1/heater_hoses.jpg

Do you have an oil cooler?

Graphics courtesy of Shoebox.
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Old 07-12-2018, 02:02 AM
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Re: No coolant flow LT1

Originally Posted by Injuneer View Post
The Corvette coolant system is significantly different than the F-Body (Camaro/Firebird), particularly with regard to bleeding the air out of the system. The Corvette system “self bleeds”, the F-Body system needs to be manually bled.

Here's the way a 95 F-Body (Camaro/Firebird) should be connected, with arrows showing flow directions. The flow from the back of the heads (steam pipe) should pass through the throttle body, then enter the liquid/vapor separator in the radiator. You appear to have it entering the pump suction (feed line) from the radiator to the water pump. Putting hot coolant and vapor bubbles into the pump suction may promote cavitation.

http://shbox.com/1/95-97_hoses.jpg

The Corvette water pump is also slightly different than the F-Body pump, mainly with regard to orientation of the connections. The functions are still the same.

http://shbox.com/1/lt1_water_pumps.jpg

Do you have a heater, utilizing the connections on the water pump? Do you have a flow restrictor in the supply line (part #13 in this diagram):

http://shbox.com/1/heater_hoses.jpg

Do you have an oil cooler?

Graphics courtesy of Shoebox.

The steam line is connected at the pump feed line, so that should be right.
I don't have a flow restrctor. This is only used to prevent to much cooling when cold outside. This is not a problem since I use the car in the summer.
No, I don't have an oil cooler.
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Old 07-12-2018, 11:36 AM
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Re: No coolant flow LT1

Since you appear to totally reject my analysis, and feel you have a full understanding of the purpose of the flow restrictor, I'll drop out at this point.

Good luck.
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Old 07-13-2018, 02:30 AM
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Re: No coolant flow LT1

I have a shutoff valve in my heater system, so I don’t need this restrictor valve
And I ’m sorry that you think this way. Thank you for your tips/questions so far
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Old 07-16-2018, 09:06 AM
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Re: No coolant flow LT1

https://www.camaroz28.com/forums/lt1...outing-881977/ Look at post 6 for the diagram and post 10 for the routing. If your filler neck is the highest point you should not have to bleed the system, just use a standard overflow tank.
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