thermostat for LS Engine

Bobalos

Bobalos

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the Water Pump thread got me to wondering what folks are doing for thermostats in their LS powered cars? 

My car has the freeze plug pressed into the back of the pump with a roughly 3/16" hole drilled in it & no thermostat @ all, and the heater hose nipples have the holes plugged with threaded plugs. 

I have a fairly large radiator up in the air & if it needs any kind of "temperature regulation" the ECM manages it with the fans. my temp gauge sits @ 180 almost all of the time (once its warmed up) & given that there is no thermostat in it, it seems kind of surprising to me how consistent it is.  

 
I have tried everything from the Redline adjustable thermostat blocker to actual thermostats to the Freeze plug , and  in every car I have done the Freeze plug by far the best  - its also easier to get air out of the system  - it burps well. OIn high HP cars with bigger radiators I go to 1/4

" hole - thats my big change in the design...  I am sure if I played with the redline adjustable piece more it would be great - but Freeze plugs don't fail  KISS.

 
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Fullthrottleguy said:
I have tried everything from the Redline adjustable thermostat blocker to actual thermostats to the Freeze plug , and  in every car I have done the Freeze plug by far the best  - its also easier to get air out of the system  - it burps well. OIn high HP cars with bigger radiators I go to 1/3" hole - thats my big change in the design...  I am sure if I played with the redline adjustable piece more it would be great - but Freeze plugs don't fail  KISS.
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i dont think i ever seen a 1/3" drill bit hmmm,

 
I have tried it all,  it all works pretty good, 

I try to stay away from the freeze plug, have had one fall out,  I now weld a aluminum plug to plug the Pressure bypass hole, I am like redline, i do not put any holes in the bypass,  these passages are near the heater outlet not really any part of the pump for cooling, 

I tap the heater hose out lets, with pip plugs, or i will weld them up,

I do not agree with the horse shoe hose on the heater hose going from outlet to inlet,  i want all my water to go through the radiator, 

I now use the Redline plug, it makes life very easy, no welding no machining, 

On my car it has a thermostat, but to make it easier i have drilled 8 each 1/8 holes in the thermostat to help fill the water, 

I never just put a thermostat in without a couple of holes, if you do you will need to fill the water in from the upper hose, holes will help fill the block up with water,   

 
J Alper said:
I have tried it all,  it all works pretty good, 

I try to stay away from the freeze plug, have had one fall out,  I now weld a aluminum plug to plug the Pressure bypass hole, I am like redline, i do not put any holes in the bypass,  these passages are near the heater outlet not really any part of the pump for cooling, 

I tap the heater hose out lets, with pip plugs, or i will weld them up,

I do not agree with the horse shoe hose on the heater hose going from outlet to inlet,  i want all my water to go through the radiator, 

I now use the Redline plug, it makes life very easy, no welding no machining, 

On my car it has a thermostat, but to make it easier i have drilled 8 each 1/8 holes in the thermostat to help fill the water, 

I never just put a thermostat in without a couple of holes, if you do you will need to fill the water in from the upper hose, holes will help fill the block up with water,   
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Jason - Its a good point about drilling holes in the thermostat for people that don't use a Vacuum filler.   I will not ever "static fill" an LS again with a thermostat  - you cannot get them to properly Burp   and will always have some trapped air.  While its not terrible in general  - I cannot always vacuum fill a car that is running a bit warm and lower the temps 5-10 degrees. With a freeze plug You usually can get away static filling  as long as let the engine come to temp before putting on the radiator cap. 

Using a vacuum filler Its also a faster way to remove the coolant and less messy 

I have to say every engine for 50 years had freeze plugs on the side of them  - none ever feel out when properly installed ... well at least on 100 Million cars or more ... so I would use US made Brass or the right size  :biggrin:

 the proper name for Vacuum filler a is "cooling system vacuum purge and refill kit"

I use  very simple and inexpensive one that works better than most for Sand cars with "interesting" radiator placement

https://www.amazon.com/COKCOL-Universal-Radiator-Coolant-Cooling/dp/B099598SFM/ref=sr_1_9?keywords=coolant%2Bvacuum%2Brefill%2Bkit&qid=1647491638&sr=8-9&th=1

 
The freeze plug with drilled hole has worked great for me in several cars and different engines, always with temps around the 180 range sometimes higher after a long dune ride on a warm day but no over heating unless there is another issue. 

 
Redline plug.  Works great.  Easy.  Won't ever get "stuck".

IMG_3680_900x.jpg


 
Can someone post the link for this redline plug. And maybe how it installs?

 
What is the theory behind the freeze plug or the redline plug? Why not just run it wide open?

 
@Jtmoney714, when there is a freeze plug in the water pump & nothing else, it is wide open. 

the normal LS thermostat goes down into the pump & the metal plate @ the end of the thermostat plugs that hole up.  when the thermostat is removed that big hole has to be blocked or all the water will run through that hole & the water will get sucked from the outlet of the motor back into the suction side of the pump back into the motor. 

While I suppose this design might work well for rapid heat cycles & for vehicles that have heater cores, strange radiator positions & other oddities, for a racing/off road application it seems kind of strange.  you have to do more to it to make it simple and robust than you did with the old Gen1 SBC's.

GTO_Thermostat__47278.1549375260.jpg


if you look @ this cooling system diagram, the plug goes into the water pump where I have the arrow.  its between the small hole & big hole that is shown on the side of the pump.  the thermostat actually goes to the right of that where the blue line goes into the water pump suction hose bib (where it says #13, thermostat). 

LS Cooling system, BW, 17Mar22.png

 
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Jtmoney714 said:
What is the theory behind the freeze plug or the redline plug? Why not just run it wide open?
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The hole in the center of the water pump is a Bypass Hole, it has to be plugged, The thermostat is in the water neck portion, 

Bypass hole was designed to bypass pressure so it would not blow the caps off the side of the factory radiators, the factory radiators have plastic pressed on radiator caps, using aluminum radiator you can run no bypass,  

I like using some plug also, the Redline is pretty affordable and easy to install, LIke @Fullthrottleguy said freeze plug works good also, and welding in an aluminum plug is easy for me also due to i have aluminum stock and a lathe,  and my personal car has a MR, gasket thermostat with holes around it, 

A lot of good info here for people getting into the LS Motors for the first time,  

 
This one all STILL hurts my head. There has GOT TO BE a way to make a thermostat work in these LS buggys. Mine is not any super high HP motor but higher compression 480hP stroked LS1. Out running HARD in the dunes she gets warm (210-215+) but if I  stop and let it idle, it comes back to 180 and the fans shut off. (has a plug in the pump with a 3/8" hole.  Other guys I run with (LS1 motors) have the drilled plug and dont get hot.  My radiator is a big-ass RonDavis with dual fans (but is in a STUPID mounted ocation behind the back seat at an angle) But that's all besides the point,, There has GOT TO BE A WAY to use a thermostat and have it maintain temp like it does ina street car.

 
My LS has a regular thermostat and the u shaped hose connecting the heater hose ports. It runs just over 160 all the time but I have a hell of a time filling if I have to drain it. If I plug the small hole in the water pump where the thermostat goes and plug the heater hose ports will it be even harder to refill? I usually try to plan it so I can fill the radiator and just let it sit overnight and that usually works. My radiator is up high in the rear so sitting overnight kind of let's gravity do it's thing. What worries me is if I have a problem while I'm out riding then refilling is going to be a PITA.

 
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So, 1 misconception is 210-215 is "hot".

It isn't.

Look at any "LS" engine in a car and what does it run?  210-230 all day long.

Everyone out there thinks because we run these motors in a sand car or whatever, that they should run as cold as possible.

My car runs 225-230 when it is 80 outside and we are running hard.  I keep on going and have been doing this since 2007.  No issues.

What folks should be worried about is engine oil temps.  But that is for a different thread.  :)

 
MarvD said:
This one all STILL hurts my head. There has GOT TO BE a way to make a thermostat work in these LS buggys. Mine is not any super high HP motor but higher compression 480hP stroked LS1. Out running HARD in the dunes she gets warm (210-215+) but if I  stop and let it idle, it comes back to 180 and the fans shut off. (has a plug in the pump with a 3/8" hole.  Other guys I run with (LS1 motors) have the drilled plug and dont get hot.  My radiator is a big-ass RonDavis with dual fans (but is in a STUPID mounted ocation behind the back seat at an angle) But that's all besides the point,, There has GOT TO BE A WAY to use a thermostat and have it maintain temp like it does ina street car.
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JMHO, but 3/8" is too big a hole in that freeze plug.  that is a LOT of water that is not going through the radiator that is in the dumb azz location.......  I think if were me I would replace the WP, and either use the redline flow restrictor or put a freeze plug in it & drill a small hole in it, AND put a diesel radiator up higher in the airflow & get rid of that nonsense.  you can see how that helped Doug......... 

 
Rorschach said:
My LS has a regular thermostat and the u shaped hose connecting the heater hose ports. It runs just over 160 all the time but I have a hell of a time filling if I have to drain it. If I plug the small hole in the water pump where the thermostat goes and plug the heater hose ports will it be even harder to refill? I usually try to plan it so I can fill the radiator and just let it sit overnight and that usually works. My radiator is up high in the rear so sitting overnight kind of let's gravity do it's thing. What worries me is if I have a problem while I'm out riding then refilling is going to be a PITA.
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Mine was a HUGE PITA to bleed.  it took hours to get it to burp.  I removed the steam hoses from the top of the heads (it only has the one hose on the WP side of the motor & block offs on the clutch end).  the steam holes were completely blocked.  2 hours in some CLR & some time with a small screw driver, and it was good as new.  filled it up & it was bled almost instantly. 

IMO, there is no scenario where the bypass hose belongs on a water pump. 

 
Bobalos said:
Mine was a HUGE PITA to bleed.  it took hours to get it to burp.  I removed the steam hoses from the top of the heads (it only has the one hose on the WP side of the motor & block offs on the clutch end).  the steam holes were completely blocked.  2 hours in some CLR & some time with a small screw driver, and it was good as new.  filled it up & it was bled almost instantly. 

IMO, there is no scenario where the bypass hose belongs on a water pump. 
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Ya I think I'm going to get rid of the bypass. I think my steam holes have a hard line on them. I've thought about pulling it before when I was trying to fill but didn't want to mess with it because it runs under the throttle body but now that you mention it maybe I should check to make sure they're not blocked. Red circle is the steam hole you're talking about, right?

IMG_20220314_205416__01.jpg

 
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