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Old 07-04-2010, 03:36 PM
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engine overheating, fans not coming on

hi guys,

so i finally got my exhaust system on my car (1984 jag xj6 w/ 96 impala lt1), so i've been able to drive it around a bit more extensively. I noticed the heat guage climbing, eventually settling midway between max and the midway point (3/4 of max).

I checked to see if the dual fans were coming on, and they weren't. i checked the coolant level, and it looked ok -- however, i am not sure if it is completely filled on account that the coolant reservoir reached its maximum level after only 2 gallons of coolant.

when i patched into my diagnostic software, i noticed the heat going up steadily while idling, and the fans weren't going on still.

how can i force my fans to be on at all times? i'd like to test them to see if that cools the system. otherwise, maybe there is just a pocket of steam?

any help would be appreciated...

tyler

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Old 07-04-2010, 04:19 PM
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Somewhere in your wiring circuit there should be a temp operated switch to turn these fans on and off....it is likely defective.

To test the fans you could hook a direct wire from the battery to the positive wire of the fans....you could even put a toggle switch in there......I would not leave it that way however as those fans draw a lot of amps......would burn up a switch pretty quick.......these circuits usually use a relay to run them.
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Old 07-04-2010, 09:05 PM
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What computer are you using to run the LT1? The stock B-body computers are set to turn the fans on at a temp that looks scary high on the guage.

I had 2 95 Roadmasters with the LT1. I wish I had them back but I digress. I bet the Jag is a riot with that drivetrain!

Can can get a mail order tune from PCM for Less and they'll set it up where you like. Or, you could get the software and cable to changes the settings yourself.

This is probably the issue. However, I recall both mine were hard to get all the air out of the cooling system. As I recall, the easiest way was to put a tube on the bleeder and feed the output back into the expansion tank.

If you can't get enogh info here, check out the Impala SS forum:
http://www.impalassforum.com/vBulletin/

Good Luck!
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Old 07-05-2010, 08:03 AM
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You can jump them fairly easily if you yank out the relay and jumper it there. You can also test there to see if you are getting the signal to turn the fans on or not. Make sure the jumper you use is at least #12 as the fans draw a lot of current.
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Old 07-05-2010, 12:40 PM
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jumper

thanks guys! i'll check it out... i have a cable and some diagnostic software for the car, but i wasn't aware there was any tuning software that i could use that would go through the port in the car... what is a good one to use?

i'll have a look at the wiring diagram and see where the switch could be... and i'll check about the bleeding, i opened the valve and let some air out, but then fluid began to dribble so i assumed all the air was all drained out...
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Old 07-06-2010, 11:00 AM
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how to test if signal is telling fans to turn on

hey chet,

whats the procedure on testing the signal?
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Old 07-06-2010, 01:41 PM
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On most cars the control side of the relay has 1 pin that is hot all the time and they pull the other pin to ground to close the contacts on the relay. On a standard rely these would be pins 85 and 86. This signal would come from the ECM. The ECM reads the Temp sensor and decides when to turn the fan on. Most air conditioned cars will also run the fan anything the AC is on.
When the relay pulls up it connects pin 30 on the relay to pin 87 on the relay to turn the device on. If you pull the relay and jumper pins 30 and 87 in the relay connector the fans should run. This will prove out the relay to fan wiring.
If the fans run it is a control issue. If not there is something wrong from the relay block to the fans.
Here is link that shows the relay pins and what they do

Relay operation
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