Engine coolant radiator fans

Tiny
CHICHA
  • MEMBER
  • 2003 CHEVROLET MALIBU
Six cylinder front wheel drive automatic 130,000 miles.

I am the owner of this vehicle and I am relaying the problem as my mechanic has described it to me:

The hi-speed radiator fan is not coming on when the temperature goes over 96 degrees centigrade. (The low-speed fan is operating normally.)

The engine coolant overflows as a result.

We have installed a new engine temperature sensor, a new thermostat and even reprogrammed the engine control module.

What we do not understand is that when we unthread the engine temperature sensor from the housing, leaving the electric connector hooked into it and with the ignition key on, when we place the sensor in a bowl with water and heat it to 96 degrees centigrade the system responds and the fans come on like they should when the sensor is threaded into the thermostat housing.

1) Engine overheats.
2) Coolant overflows.
3) The high-speed fan has been determined to not activate.
4) When high-speed fan is manually activated, engine does not overheat and coolant does not overflow.
5) a) The ECM (Electronic Control Module) controls fan activation, is this not correct?
B) ECM has been re-programmed.
6) New thermostat has been installed.
7) New engine temperature sensor has been installed.
8) Intake manifold is functioning normally.
9) This we feel is the main issue. It seems to be clearly the main issue. Please advise if we are misguided on this:
"The engine temperature sensor screws into the housing. On the other end of the sensor are two wires that connect to the ECM. When sensor is screwed into housing and its wires are connected to ECM, high speed fan does not come on and coolant overflows. When sensor is unscrewed from housing and heated to 96 degrees centigrade in a pail of water, high speed fan comes on and coolant doesn't overflow! The two wires that connect the sensor to the ECM have been checked and are transmitting proper voltage."

A thermo switch has been installed temporarily so that the vehicle can be driven.
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Wednesday, December 2nd, 2009 AT 2:15 PM

4 Replies

Tiny
BMRFIXIT
  • EXPERT
The engine must not be getting how enough and its a blown head gasket that is forcing the coolant out.

Here are two guides to help us.

https://www.2carpros.com/articles/head-gasket-blown-test

and

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Please run down these guides and report back.
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Wednesday, December 2nd, 2009 AT 6:27 PM
Tiny
CHICHA
  • MEMBER
We have analyzed one other thing and do not feel it is related to the current problem.

In the past year, the camshaft and valve lifters were replaced. To get at the camshaft, the engine had to be removed from the vehicle. The coolant problem first occurred after this repair. But, the coolant overflow problem was resolved quickly. It was not until a few months later that the problem recurred which is the point we are now at.

We are getting coolant circulation behind the engine temperature sensor. If the gaskets were not properly placed during the camshaft replacement, the coolant circulation would be impaired, correct? [See all earlier comments.] Thanks.
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Thursday, December 10th, 2009 AT 10:04 PM
Tiny
CHICHA
  • MEMBER
The vehicle is being run without the catalytic converter. I do notice when the vehicle is being run and after the engine is shut off that there are clicking noises. It is as if the coolant was not cooling the metal! But I was told the noise is associated with gases expanding/contracting due to the lack of an installed catalytic converter.

I took it to a Chevrolet dealership to resolve the problem they said it was a head gasket as well. Good job guys, I got the problem fixed. I love this site.
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Saturday, December 19th, 2009 AT 12:20 AM
Tiny
BMRFIXIT
  • EXPERT
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help.
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Saturday, December 19th, 2009 AT 5:02 AM

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