cooling fan question! Need Help!
Thread Starter
Racer
Joined: Jan 2005
Posts: 315
Likes: 0
From: tomahawk wisconsin
cooling fan question! Need Help!
Ok yesterday I carbed my 91 383 and today I went out to tie up all the small stuff and for some reason my cooling fans will not come on. I did use the sensor that was in the front of the stock intake. It is mounted right next to the thermostate housing.
Does anyone have any idea why it wont turn on? I dont even know where to start looking on this one!
Does anyone have any idea why it wont turn on? I dont even know where to start looking on this one!
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
On an 87 the sensor by the dip stick operates the dash temperature gauge and nothing else. The fan is turned on by the ECM from temperature info from the sensor that is located on the front of the block and under the MAF. On an 87 there is a thermostatic switch on the left side of the block between cylinders 1 and 3 that turns on the auxilliary fan. Your fan should come on at 228 F and go off at 210 F. Maybe you didn't let the engine get to that temperature. The fan receives power from a relay and the relay coil is connected to 12v and the coil is grounded by the ECM to turn on the relay. Try grounding the coil wire that goes to the ECM to force the relay on. You may have a defective relay. On the 87, the relay ground wire is green/white. If the fan doesn't come on, unplug the fan motor and jump 12v to the fan motor wires to see if it will run. If it does, then check the ground connection on the wire from the motor plug, it may be corroded and not grounded.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by rick lambert
I really don't know how a 91 compares to an 87, but you should have
a temperature switch on the passenger side cylinder head just behind
the dip stick-sure it's connected?
a temperature switch on the passenger side cylinder head just behind
the dip stick-sure it's connected?
On your '87, the device you describe is the IP water temp gauge sending unit. The auxiliary fan switch is in the corresponding hole in the left head, between the #1 and #3 spark plugs. The ECT sensor that informs the ECM is in the front of the intake manifold, facing forward. The ECM uses that sensor for all it's temp related functions, including switch the main fan on and off. The 1991 is similar, but there is no auxiliary fan switch. The ECM controls both fans.
ar91c4,
That is the correct sensor, but after a conversion such as yours, the location of the problem could be anywhere. Is the ECM still connected to everything left?
RACE ON!!!
of course I am a little lazy this AM-didn't look up the info in my FSMs-just took out the not to trustful Haynes and gave him the info
Thread Starter
Racer
Joined: Jan 2005
Posts: 315
Likes: 0
From: tomahawk wisconsin
Originally Posted by CFI-EFI
Rick,
On your '87, the device you describe is the IP water temp gauge sending unit. The auxiliary fan switch is in the corresponding hole in the left head, between the #1 and #3 spark plugs. The ECT sensor that informs the ECM is in the front of the intake manifold, facing forward. The ECM uses that sensor for all it's temp related functions, including switch the main fan on and off. The 1991 is similar, but there is no auxiliary fan switch. The ECM controls both fans.
ar91c4,
That is the correct sensor, but after a conversion such as yours, the location of the problem could be anywhere. Is the ECM still connected to everything left?
RACE ON!!!
On your '87, the device you describe is the IP water temp gauge sending unit. The auxiliary fan switch is in the corresponding hole in the left head, between the #1 and #3 spark plugs. The ECT sensor that informs the ECM is in the front of the intake manifold, facing forward. The ECM uses that sensor for all it's temp related functions, including switch the main fan on and off. The 1991 is similar, but there is no auxiliary fan switch. The ECM controls both fans.
ar91c4,
That is the correct sensor, but after a conversion such as yours, the location of the problem could be anywhere. Is the ECM still connected to everything left?
RACE ON!!!
But one thing is for sure this thing pulls wicked hard!
