Twin turbo ls overheating issue

[johnnunez29]

Some people will bypass the thermostat by leaving it out or plug the heater ports and on an LS they are required to route the coolant flow into the places that need cooling, so if you have a Tstat and the heater ports are looped, that's a good first check.

Do you have hot water going into the rad? If you put a temp probe into the rad through the cap, is it 180F+?

Is the water coming out of the rad hot? Or is it cool?


If the water is going in hot and out hot, it's an airflow issue.
If it's going in cold, it's internal block or flow issue
If the water is going in hot and out cold but it's still overheating, it's probably a volume issue

Stick a temp probe in the rad and touch the return hose on the rad and figure out where the heat is going (or staying)

in/out hot. but these fans move a ton of air. maybe just not enough

 

[johnnunez29]

fans are dual 1500cfm pullers with shroud

 

[64nailhead]

So no driving yet - are you sure it has all of the air out of the system? It can take 6-8 heat cycles on particularly stubborn setups. When it has gotten to 225, is the upper radiator hose both hard and hot (too hot to touch for any amount of time)? And how long does it have to run to get to 225?

You said the fans are moving a ton of air, is the air being pulled from the radiator hot? And is the fan shroud very close or touching the radiator.

 

[johnnunez29]

So no driving yet - are you sure it has all of the air out of the system? It can take 6-8 heat cycles on particularly stubborn setups. When it has gotten to 225, is the upper radiator hose both hard and hot (too hot to touch for any amount of time)? And how long does it have to run to get to 225?

You said the fans are moving a ton of air, is the air being pulled from the radiator hot? And is the fan shroud very close or touching the radiator.

should be out, ran it with funeel on and fluid until it got hot and kept it on til water began to smoke in funnel. approx 215 degrees. unfortunately upper hose is aluminum or steel, unsure, but it was fabricated along with turbo piping. fan shroud is pushed up against the radiator the fans are https://www.summitracing.com/parts/mar-mjs22k i believe there is a small gap up top. but yes fans are pullers on the inside of the radiator.

 

[64nailhead]

should be out, ran it with funeel on and fluid until it got hot and kept it on til water began to smoke in funnel. approx 215 degrees. unfortunately upper hose is aluminum or steel, unsure, but it was fabricated along with turbo piping. fan shroud is pushed up against the radiator the fans are https://www.summitracing.com/parts/mar-mjs22k i believe there is a small gap up top. but yes fans are pullers on the inside of the radiator.

Until I drilled several 1/8” holes in the thermostat, I would have to heat cycle mine 4-5 times before all of the air was out of the system. I put a motor in an SN95 that used the factory heater core (much higher than motor), and that took 8-9 heat cycles.

If it’s still taking coolant after it’s shut off and cooled down, then it still has air in it.

 

[johnnunez29]

Until I drilled several 1/8” holes in the thermostat, I would have to heat cycle mine 4-5 times before all of the air was out of the system. I put a motor in an SN95 that used the factory heater core (much higher than motor), and that took 8-9 heat cycles.

If it’s still taking coolant after it’s shut off and cooled down, then it still has air in it.

I’m bypassing heater core. I’m going to drop fan turn on temp and swap to 160 tstat. Not sure it’ll work though. You think I should tap holes on the tstat

 

[64nailhead]

I’m bypassing heater core. I’m going to drop fan turn on temp and swap to 160 tstat. Not sure it’ll work though. You think I should tap holes on the tstat

You definitively do not need a 160 degree thermostat. A 180-205 degree thermostat will work fine. Dropping your fan temps isn’t needed either. The idea with the fan temps is to have those settings be active only when the thermostat is open.

I’m concerned that you have air in the system. If you do, repeat if you do, then it will overheat until it’s out - and the thermostat and fan settings won’t be able to help an issue that’s created by air in the system.

Drilling holes in the thermostat will definitely help speed up the bleeding process. It doesn’t help cold weather operation, but I’ll guess your Florida address won’t care lol.

 

[Streetbu]

From everything you've told us so far, you don't have a parts issue. It's a software, possibly temp sender, air flow, or coolant flow issue. In other words, I don't think spending money on it will fix your problem. The fix will probably be free, but need to find the true cause.
Do you have an infrared temp gun? Is the air coming off the fans hot? It should be VERY hot if you're overheating. No chance the thermostat is in upside down?

 

[johnnunez29]

Until I drilled several 1/8” holes in the thermostat, I would have to heat cycle mine 4-5 times before all of the air was out of the system. I put a motor in an SN95 that used the factory heater core (much higher than motor), and that took 8-9 heat cycles.

If it’s still taking coolant after it’s shut off and cooled down, then it still has air in it.

its not. when cools off i remove cap and it is full to the top. either way this weekend i will remove water pump to inspect it, swap out tstat to 160 and drill 2x 1/8 holes in the top. anything helps i suppose.

 

[johnnunez29]

From everything you've told us so far, you don't have a parts issue. It's a software, possibly temp sender, air flow, or coolant flow issue. In other words, I don't think spending money on it will fix your problem. The fix will probably be free, but need to find the true cause.

Do you have an infrared temp gun? Is the air coming off the fans hot? It should be VERY hot if

its not. when cools off i remove cap and it is full to the top. either way this weekend i will remove water pump to inspect it, swap out tstat to 160 and drill 2x 1/8 holes in the top. anything helps i suppose.

I do. Air from fans is hot as hell