LT1-LT4 Modifications 1993-97 Gen II Small Block V8

lt1 water pump

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Old Feb 4, 2010 | 08:25 PM
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Default lt1 water pump

on the water pump there is 2- 1 1/4 pips. witch one is the in and witch one is the out....
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Old Feb 4, 2010 | 11:08 PM
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The one with the Thermostat is the out I believe..

That makes me wonder aswell cause on the LS1 the one on the bottom side has the Thermo..then again it's not reverse cooled..
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Old Feb 4, 2010 | 11:46 PM
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http://shbox.com/1/95-97_hoses.jpg

http://shbox.com/1/heater_hoses.jpg
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Old Feb 5, 2010 | 12:38 AM
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This does not look right. I didn't think cooled water flowed back into the water pump throught the top of the thermo housing.
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Old Feb 5, 2010 | 04:58 AM
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Can't really argue with it..the Thermostat does regulate Coolant going into the Engine.
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Old Feb 5, 2010 | 05:12 AM
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its called reverse flow for a reason... hence REVERSE.
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Old Feb 5, 2010 | 06:41 AM
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Originally Posted by jaycenk
This does not look right. I didn't think cooled water flowed back into the water pump throught the top of the thermo housing.
#1 is called the radiator outlet hose and the thermostat housing is called the water pump inlet, so you tell me which way the water should flow.
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Old Feb 5, 2010 | 07:35 AM
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thanks guys.
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Old Feb 5, 2010 | 09:20 AM
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Originally Posted by shbox
#1 is called the radiator outlet hose and the thermostat housing is called the water pump inlet, so you tell me which way the water should flow.
I see in the GM parts PDF where it actually calls #1 the radiator outlet, and the thermostat housing is called the water pump inlet.

But in my Helm manual, it definitely calls the thermostat housing "Outlet, Water". Not to mention that just by looking at that picture, it's not possible. For coolant to even flow into the water pump via hose #1, the thermostat would already have to be open.

You can also confirm (when bleeding the cooling system), that the lower hose (#14) heats up before #1. And hose #1 only heats up AFTER the thermostat has opened.

Now, correct me if I'm wrong, but I think GM labeled those hoses wrong.
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Old Feb 5, 2010 | 10:30 AM
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Originally Posted by Spartan7
You can also confirm (when bleeding the cooling system), that the lower hose (#14) heats up before #1. And hose #1 only heats up AFTER the thermostat has opened.
Very easily explainable..Heat Transfer.

Heat isn't going to transfer through that much water sitting still in the Radiator. When the Thermostat opens..the cooler water goes into the Engine and the warmer stuff finally cycles through.

Same way with the LS1.
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Old Feb 5, 2010 | 01:00 PM
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Originally Posted by Spartan7
I see in the GM parts PDF where it actually calls #1 the radiator outlet, and the thermostat housing is called the water pump inlet.

But in my Helm manual, it definitely calls the thermostat housing "Outlet, Water". Not to mention that just by looking at that picture, it's not possible. For coolant to even flow into the water pump via hose #1, the thermostat would already have to be open.

You can also confirm (when bleeding the cooling system), that the lower hose (#14) heats up before #1. And hose #1 only heats up AFTER the thermostat has opened.

Now, correct me if I'm wrong, but I think GM labeled those hoses wrong.
Yes, the Helms does call the neck an outlet in a couple of diagrams. However, it calls the radiator tank inlet and outlet as I described above. I also have a cutaway diagram of the water flow in an LT1 pump. It is just as my arrows indicate. Cool water comes IN through the thermostat housing.

As Merv said, neither main radiator hose is going to warm up until the thermostat is open and water can flow.

If you want to call something documented "wrong", I would say it is the label on the thermostat housing that you pointed out. I think the parts book is entirely correct.

Last edited by shbox; Feb 5, 2010 at 05:20 PM.
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Old Feb 5, 2010 | 04:45 PM
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keep all the info coming...
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Old Feb 5, 2010 | 10:25 PM
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Originally Posted by shbox
Yes, the Helms does call the neck an outlet in a couple of diagrams. However, it calls the radiator tank inlet and outlet as I described above. I also have a cutaway diagram of the water flow in an LT1 pump. It is just as my arrows indicate. Cool water comes IN through the thermostat housing.

As Merv said, neither main radiator hose is going to warm up until the thermostat is open and water can flow.

If you want to call something documented "wrong", I would say it is the label on the thermostat housing that you pointed out. I think the parts book is entirely correct.
It still does not make sense. There is a bleed screew on all of the water pumps on the neck that holds the thermostat. This shows that cooled water from the radiator flows in through that water neck. You cant bleed an intake water line because it will inject air through siphen. Also why would you need a bleeder there if it flows that direction because the radiator cap is less than 8 inches away, and is a higher point.
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Old Feb 5, 2010 | 10:31 PM
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Originally Posted by kmracer
its called reverse flow for a reason... hence REVERSE.
REVERS does not mean it flows backwards throught the radiator that term is related to the block and heads and how the coolant travles through the engine. An LT1 water pump has 4 ports that lead to the block. the pump, pumps water into the block via 2 ports on either side of the block and it travels up to the heads first then down to the block and back out via the other 2 port on both sides of the pump. This is reverse cooling. How it travles through a radiator has nothing to do with reverse cooling.
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Old Feb 5, 2010 | 11:37 PM
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Originally Posted by jaycenk
It still does not make sense. There is a bleed screew on all of the water pumps on the neck that holds the thermostat. This shows that cooled water from the radiator flows in through that water neck. You cant bleed an intake water line because it will inject air through siphen. Also why would you need a bleeder there if it flows that direction because the radiator cap is less than 8 inches away, and is a higher point.
Wether it makes sense or not someone somewhere got paid alot of money to design it and it works.

That and the Bleeder Screw is there cause that is the final point that water travels to.
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Old Feb 6, 2010 | 12:15 AM
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Originally Posted by the_merv
Wether it makes sense or not someone somewhere got paid alot of money to design it and it works.

That and the Bleeder Screw is there cause that is the final point that water travels to.
I think you and I are saying the same thing but in different words and not on the same page lol. The Water neck on the water pump is the out flow of hot water from the engine to the radiator. Are you agreeing with that?
The picture up at the top shows cool water flowing from the radiator into to the water neck that holds the thermostat and then into the engine. Thats my point about the bleed screw and what I was asking shbox about in his picture. cold water that flows that way into the pumpshould cause the thermostat to not open. All of the stuff I read in the manuals says that the water neck that holds the thermo is the outlet for hot water from the engine to the radiator.
If I am wrong by all means I am soory for dragging this out.
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Old Feb 6, 2010 | 12:32 AM
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It's all good..me and you are saying the opposite thing..

At first I thought it was the way you are saying..but then I thought about it and it made sense.

That Neck is the point where the Water is let in to the pump..as in it flows out of the Radiator. If you take it apart you will see the actual functioning part of the Thermostat is in the Waterpump, and therefore in the hot water. As it reaches it's temp it opens up and lets cooler water in..then when it evens out it closes, and re-opens when necessary.
It's the same way with the LS1..that is what made it make sense for me when I thought about it.
That Bleeder is there cause that is the final point of the Water travel through the Engine.

Make any sense?
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Old Feb 6, 2010 | 09:00 AM
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Originally Posted by jaycenk
It still does not make sense. There is a bleed screew on all of the water pumps on the neck that holds the thermostat. This shows that cooled water from the radiator flows in through that water neck. You cant bleed an intake water line because it will inject air through siphen. Also why would you need a bleeder there if it flows that direction because the radiator cap is less than 8 inches away, and is a higher point.
I see you now agree with me. Then, below you don't again.

Originally Posted by jaycenk
I think you and I are saying the same thing but in different words and not on the same page lol. The Water neck on the water pump is the out flow of hot water from the engine to the radiator. Are you agreeing with that?
The picture up at the top shows cool water flowing from the radiator into to the water neck that holds the thermostat and then into the engine. Thats my point about the bleed screw and what I was asking shbox about in his picture. cold water that flows that way into the pumpshould cause the thermostat to not open. All of the stuff I read in the manuals says that the water neck that holds the thermo is the outlet for hot water from the engine to the radiator.
If I am wrong by all means I am soory for dragging this out.
Why would the direction of flow keep the thermostat from opening? The thermostat is opened by heat produced by the engine. Water is circulated in the engine by the pump until the thermostat opens, then it can cool the water in the radiator.
You looked at two diagrams that called the the thermo housing the outlet and you got hung up on this. Every other piece of documentation says it is the inlet.
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Old Feb 6, 2010 | 10:24 AM
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ok again asnswer this for me what dose your picture show as far as were the hot water comes out of the engine? I am so lost here I may need a Quack. May be I am just not saying it correctly. does the blue arrow represent the path of the water back into the engine?
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Old Feb 6, 2010 | 10:27 AM
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Yes blue is back to the Engine..that's why it's blue(cooler).
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