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> Both cooling fans inop
cambird
post Apr 5 2015, 07:31 PM
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Thanks in advance for anyone's help. I have a 1987 IROC, 5.0 TPI with dual fans that are totally inop. I've checked all the obvious, and even
replaced the cooling fan relays(s)? Checked the grounds, fuses and even put a scanner on the car to see if the ECM was commanding the fans to
come on. I have power at both relays and and the green wire from the ECM is powered when the key is on and a/c switch is activated. I find it very
hard to believe that both cooling fan motors would be bad at the same time, but that's all I'm left with. Anybody else have any ideas? Thanks.
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BigBadLou
post Apr 5 2015, 07:36 PM
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Dang, you could have started a new thread instead of reviving one from 2008.
So I split off your post into a separate thread. You are welcome, sir.

If you can bring her by sometime this week after work, I can take a look. I am north. PM me for info.
Did this start happening all of a sudden or did you already maybe buy her that way?


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cambird
post Apr 5 2015, 08:26 PM
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QUOTE(BigBadLou @ Apr 5 2015, 08:36 PM) *
Dang, you could have started a new thread instead of reviving one from 2008.
So I split off your post into a separate thread. You are welcome, sir.

If you can bring her by sometime this week after work, I can take a look. I am north. PM me for info.
Did this start happening all of a sudden or did you already maybe buy her that way?


No, I bought it that way, also I noticed that the upper radiator hose is not getting hot where the passenger side radiator tank is hot and the l/side isn't. does the
coolant flow up through the radiator and then down to the engine through the upper hose? And, even if the thermostat was stuck , the fans should still come on!
I took a test light and ran power from the battery straight to the motors, and neither one turned on, but will the test light allow enough voltage and amperage through
it to run the motors? I'm not a tech, but I've been working on old muscle cars for over forty years. the newer computer controlled cars keep me guessing, but I'm a
preety good diagnostician. where are you located? I'm in naples, fl. thanks, lou!
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BigBadLou
post Apr 5 2015, 08:52 PM
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QUOTE(cambird @ Apr 5 2015, 08:26 PM) *
No, I bought it that way

Didn't we all? smile.gif Mine came with a lot of "bugs" too. Actually cooling problems as well. I think all of our cars have cooling problems at least once in their lifetime.

QUOTE(cambird @ Apr 5 2015, 08:26 PM) *
also I noticed that the upper radiator hose is not getting hot where the passenger side radiator tank is hot and the l/side isn't. does the
coolant flow up through the radiator and then down to the engine through the upper hose?

The cooled liquid is pulled from the bottom of the radiator (where there always is enough coolant, unlike the top of the radiator) and forced into the block, upward through the cooling passages and heads, into the intake and then fwd through the thermostat to the radiator. As most engines out there, it is a good and efficient flow design.
If you have more than one cooling problem (blocked radiator, inop fans, collapsed hose etc), it will make it that much harder to troubleshoot.

QUOTE(cambird @ Apr 5 2015, 08:26 PM) *
And, even if the thermostat was stuck , the fans should still come on!

Yes, if the engine heats up, the fans should come on.
FWIW, the On temperature for the stock setting is pretty dang high, somewhere around 238*F.
So it REALLY has to get hot before the fan kicks in.

QUOTE(cambird @ Apr 5 2015, 08:26 PM) *
I took a test light and ran power from the battery straight to the motors, and neither one turned on, but will the test light allow enough voltage and amperage through
it to run the motors?

Nope. The test light merely shows voltage but the current through it is very limited and won't allow the fans to run.
If you put straight battery voltage on the fans and they don't run, the motors are likely dead. You can replace the motors, btw, without having to replace the whole fan.

QUOTE(cambird @ Apr 5 2015, 08:26 PM) *
I'm not a tech, but I've been working on old muscle cars for over forty years. the newer computer controlled cars keep me guessing, but I'm a
preety good diagnostician. where are you located? I'm in naples, fl. thanks, lou!

Been working on cars for years as well (though I can't claim 40 years) and the computer controlled cars aren't much more complicated than the screwdriver&ziptie old Chevies. It's just the "mystery" of the "black box" that the computer poses.
Normally, the computer turns on the cooling fan when the engine temperature reaches preset temperature. Or when the A/C is turned on. That's it.
You have already done your homework with the electrical troubleshooting of the relays.
I'd test the fan motors themselves and if they don't even turn, they are the problem then. If they do run, the problem is upstream.

Let us know what you find.
Lou

BTW, we are in Austin, TX. Hence the "Austin ThirdGen" webpage name. smile.gif


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jliroc
post Apr 6 2015, 05:14 PM
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Lou,

I need to swing by your place and say what's up! Interesting thread, because I was actually just re-wiring my fans on Saturday... You were correct, the stock primary fan kicks on at 230 degrees, secondary at 238 degrees. The a/c should kick on the primary fan when engaged. You gunna be around tomorrow night after 5? I drive by your place every day. Would love to hang out and catch up.

Dan


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BigBadLou
post Apr 6 2015, 05:19 PM
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Absolutely, man! I'll be home.
You can help me pull the rear axle and swap the fuel pump ... lol.gif
j/k


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jliroc
post Apr 6 2015, 07:24 PM
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Sweet, camaro or f350?

Whoops, I remember you telling me about that. Let me know if you need any tools to help out, I'll bring em!


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1990 IROC-Z Convertible
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"if at first you don't succeed you're doing it wrong."
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BigBadLou
post Apr 6 2015, 07:47 PM
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No no no, I was kidding, man.
On the F350, there is no in-tank fuel pump. It sits on the frame rail so it can be replaced on the side of the road (unlike the Crapmaro). smile.gif


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