LS1 BU

iTrader: (13)

My setup is a LS1 in 80 Bu. Radiator and fan setup out of 02 camaro Z28. Stock overflow bottle from 80 BU. I also have a 160 thermostat and fans are set to come on at 189 degress.

Here's my problem. When I driving the temps are fine. I drivin in 95 degreee heat and the car will run in the 180-190 degree area. The fans will stay off while driving. When the car is idleing the temps will keep going up. The fans come on and don't shut off. I had the vechile running the other day with the radiator cap off to check for air. When the temp went up over 200 degress I raised the rpm to about 1700-2000 rpm. The engine cooled down and fans went off. I'm thinking the thermostat is bad or I need a overflow bottle from a F body. What do you guys think.

John B

iTrader: (10)

What temp are the fans set to come on at?

LS1 BU

iTrader: (13)

Fans come on at 189 degress. What type of overflow bottle do you run John??

LS1 BU

iTrader: (13)

Update. I took off the thermostat and check it. I put it in some water and raised the temp on my stove. It opens and closes fine. I reinstalled the thermostat. I ran the car tonight to bleed the cooling system. With the radiatort cap off the cooling system worked fine for about 25 minutes. All the air came out and the thermostat would open at 160 degress. The fans would come on a 189 and cycle and shut off. I did this probably about 10 times in a row. Then I put the cap on and it continued to cycle about 5 times. Then the temps started to go up. The fans came on and wouldn't shut off. The temps were over 210 degress. The coolant flow stoped. The lower radatior hose and the coolant hose that runs from under the intake were cold. I put my hand behind the radiator fans near the engine. Cold air was comming through the fans. I then raised the rpms to 1700-2000. The temps came down,the lower radiator hose was hot. The hose that run from under the intake was hot. I put my hand behind the fans and there was hot air. The coolant stops flowing for some reason. PLEASE HELP

Project GatTagO

iTrader: (7)

Its almost like your water pump is not pumping water at low RPM. I am assuming the belt is tight. Maybe something is wrong internaly with the water pump?
I am just making some guesses here.

Andrew

John B

iTrader: (10)

My fan comes on at 195° for the low speed fan and 215° for the high speed. I just use a standard overflow bottle. Do you have the steam vent tube connected to the radiator?

LS1 BU

iTrader: (13)

The tube that runs to the lines under the intake is hooked up. Water pump is brand new. The coolant would flow for 20 minutes or so then it would stop. I'm gonna try a new thermstat first.

LS1swap

It does sound like you don't get enough flow at low RPM's. I know these are going to sound like easy questions but sometime it is the obvious that is over looked. Are any of your hoses kinked. Do you have the hose that connects to the thermostat hooked to the lower port on the radiator. Are you heater hoses hooked up ( you need this to keep water flowing over the thermostat). Are you using an under drive pulley? Is your overflow tank mounted higher than the water pump?

LS1 BU

iTrader: (13)

You make some good points. I'm using a ASP underdrive crank pulley. The hose to the thermostat is hooked up to the lower part of the radiator. The heater hoses are hooked together. But the hose is kinked.(I'm having a problem finding the right U shaped hose. The coolant jug is mounted above the water pump. It is a vented coolant jug.
I installed a new theromstat today. When I was bleeding the air out of the system. I had the radiator cap off for 30 minutes. The thermostat would open at 160 degress. Then the fans would come on a 189. They would run for a while then shut off. It cycled about 20 times. Then I topped off the coolant and put the cap on. The temps would stay in the 185-200 range and the fans would run all the time. I then turned off the motor and let sit for 5 minutes. I started the car with the raditor cap off. The coolant seemed to stop flowing at time or flow a little bit. The fans wouldn't shut off temps were in the 185-200 range. If I raised the idle to 2,000 rpm the coolant would flow as normal and fans would shut off. I took the car for a 10 minute drive. It would run about 180-195 while dirving. Then I let the car idle in gear for 5 minutes. It would run anywhere from 185 to 200 degress.

Roadster18l

Just a thought try removing the underdrive pully and reinstall the factory one.

LS1 BU

iTrader: (13)

I looped the heater hose. It doesn't overheat when idleing now. I'm thinking of buying an electric water pump over winter.