Primary cooling fan starts up when engine starts
08-06-2017, 10:02 AM
#1
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Thread Starter
Join Date: Aug 2017
Posts: 2
Primary cooling fan starts up when engine starts
Hello Everyone,
Ever since I replaced my exhaust manifolds with headers my primary coolant fan starts up when my engine starts. The fan normally turns on at 220 degrees. I know when i replaced my headers, I broke off the coolant fan switch and connector on the pass side of the head because it was old and brittle.
I replaced the coolant fan switch and connector on the pass side of the head with a new one from Napa. I also replace the coolant temp sensor which is located in front of the intake manifold. I also checked the fan relays next to the batteries and it all works well.
So i did that and I replaced one of the fan relay connectors as well.
So I still can't resolve my issue. My fan still starts up as soon as start my motor.
What else do I have to check? thanks!
87 Iroc Z 350 L98 TPI
Ever since I replaced my exhaust manifolds with headers my primary coolant fan starts up when my engine starts. The fan normally turns on at 220 degrees. I know when i replaced my headers, I broke off the coolant fan switch and connector on the pass side of the head because it was old and brittle.
I replaced the coolant fan switch and connector on the pass side of the head with a new one from Napa. I also replace the coolant temp sensor which is located in front of the intake manifold. I also checked the fan relays next to the batteries and it all works well.
So i did that and I replaced one of the fan relay connectors as well.
So I still can't resolve my issue. My fan still starts up as soon as start my motor.
What else do I have to check? thanks!
87 Iroc Z 350 L98 TPI
08-06-2017, 05:51 PM
#4
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,648
Re: Primary cooling fan starts up when engine starts
Did you check the resistance of the new coolant temp sensor? Could be defective.
Only reference I have is a tattered Chilton's. I don't see a fan temperature switch on the engine controls diagram for the 1987 5.7L TPI. It shows a fan switch activated by A/C pressure. In any case, a short in the fan switch wiring could be providing a false ground.
Only reference I have is a tattered Chilton's. I don't see a fan temperature switch on the engine controls diagram for the 1987 5.7L TPI. It shows a fan switch activated by A/C pressure. In any case, a short in the fan switch wiring could be providing a false ground.