fj40 carb cooling fan...do you run yours? (1 Viewer)

[78GroundUp]

Thanks for the input 456.

It will be coming back apart today for a better look. I saw the same "puking" except that it defies gravity?? The puke heads due west, so I considered that possibly a glue/adhesive. Do you know what that "thing" does??

Will look closely at the solder you mentioned.

Is it ok to gently clean with simple green and a gentle toothbrush?? Or even a solvent like rubbing alcohol?? What would you suggest?

Thanks for the help.

 

[Fast Eddy]

Which wire (if known) tells the motor to "NOT" turn on. I just realized there has to be something that tells it not to? I understand the circuit completes itself when the key is off..... But there has to be a wire involved in that switching process....??

It's a fairly complicated circuit. Don't try to simplify it in your head. One of the pins at the connector will be +12v when the ignition is on and one is +12v all the time through the fuse in the fuse holder. The other two connections are the sensor input and the +12v fan output.

I remember seeing a post where the resistance cold is close to 25-30 Ohms but when heated the resistance drops to almost zero.

25k-35k ohms when cold is what I read. It's a thermistor if you want to google it.

in pict 3 it looks like your electroltic cap has puked itself. If it has it will be at best weak if not open and will need replaced.Lastly in pict 4 - top right solder joint like it might a ring indicating a crack.

Good eye.

I saw the same "puking" except that it defies gravity?? The puke heads due west, so I considered that possibly a glue/adhesive. Do you know what that "thing" does??

If you know an electronics shop they could remove the cap and test it. If it 'popped', it could easily defy gravity, and they are known to pop. It's a $0.05 part if it's bad and it would be labeled with it's capacitance value. A cap can be thought of as a little rechargeable battery.

Is it ok to gently clean with simple green and a gentle toothbrush?? Or even a solvent like rubbing alcohol?? What would you suggest?

Rubbing alcohol and a toothbrush would be safe. A wire brush could damage traces if you weren't very careful.

 

[456z]

Thanks for the input 456.

It will be coming back apart today for a better look. I saw the same "puking" except that it defies gravity?? The puke heads due west, so I considered that possibly a glue/adhesive. Do you know what that "thing" does??

Will look closely at the solder you mentioned.

Is it ok to gently clean with simple green and a gentle toothbrush?? Or even a solvent like rubbing alcohol?? What would you suggest?

Thanks for the help.

That thing is an electroltic capacitor. All capacitors are like batteries, store and give up electricity. I know from doing my 79's, the circuit will work if the capacitor is weak but would guess it won't if it is open. It looks like from your picture it has puked and is common as they have a limited number of cycles (charge/discharge).
I'm not familiar with "simply green" and would want something more aggressive than a toothbrush. I like to use a fine brass brush to loosen the corrosion,then blow off with compressed air.
Capacitors are cheap and easy to replace and I can give more detail if needed.

 

[77mustard40]

Broke out the wiring diagram this afternoon



Wire colors match the book to what I think is my sensor




Tried to get a resistance reading at the terminal connector for the wiring harness, infinite, this isnt good. Pulled the old casing off the wires and snipped off some old connectors to get to bare wire.



Same issue on the bare wire, no ohm reading at all so something must be open in the circuit that i cant see, so I know it's not an old wiring connection. Popping her in the oven on 200 F to see if I can get a reading hot. May be heading to radio shack or the used parts bins if this doesn't work.

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[77mustard40]

Ok 10 minutes in the iron skillet and viola, got an initial reading of 6.4 and watched it drop to 5.9 over a minute so I'm going to clean the connections and try again to get a reading at the connection to the wiring harness.

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[78GroundUp]

77mustard...... Man all that looks so familiar.

Spent another couple hours today on it. It has to be (for me) either a bad sensor. Started the truck did a temp reading all around the Sensor at +200 or more. So I did the heat test. Still no luck . For me, it has to be in the circuit board.

I was told that if that round 16V black thing had puked it would have spilled oil and have a busted seal around it. Is it either of the two square "coiled" boxes that open/close control the kick on/off.

Obviously there is the 12V constant (as discussed) as well another 12V that comes on with key. Should there be a third? That sends 12V when key is off?

Theoretically should have (2) 12V with key off. (1) constant and one that is on with circuit used for fan thermistor??

And yes.... Will be seeking professional help tomorrow if I can find it or "Come Monday" ..... Reminds me, time for a cold beer!!

Cheers

 

[77mustard40]

Yep I'm deep into the "cold beer" phase of the diagnosis. If she doesn't run after temp tomorrow I'm into the relay with you. Best wishes with the suds.

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[BTUMAN]

In each instance I am seeing here I suspect the bad cooling fan relay. Just try and find a working one somewhere and swap it out. A fellow mudder was parting out and I think I got it for $15 bucks. Mine had just a bit of corrosion and was the culprit. Good luck guys and keep us posted.

 

[climber8483]

So what is the point of the cooling fan? My cruiser has never had one for the 5 years I've owned it and it seems to run just fine, even in our 100+ degree summer days. Do I need to try and find one? I'm running a Weber right now, but am thinking of going back to a Aisin.

 

[77mustard40]

So what is the point of the cooling fan? My cruiser has never had one for the 5 years I've owned it and it seems to run just fine, even in our 100+ degree summer days. Do I need to try and find one? I'm running a Weber right now, but am thinking of going back to a Aisin.

Climber I did not have issues with my webber but have switched to stock including the fuel return line. The fan is supposed to reduce the carb area temp after shutdown to prevent or reduce fuel boil in the hard lines and carb bowl which can lead to vapor lock. It is supposed to help hot starting conditions between stops.

 

[Pighead]

Do I need to try and find one? I'm running a Weber right now, but am thinking of going back to a Aisin.

I'm thinking that it depends more on what exhaust manifold you run...those cooling fans came out at about the same time as the thermo-nucular exhaust manifolds. Earlier manifolds & headers don't seem to have any problem.

 

[78GroundUp]

DO not I repeat do not clean the circuit board with anything but "MAYBE" water.

It is my guess that there is a clear coat already on there..... it has mad mine look like it is very dirty. No longer visible to the naked eye are clear clean lines. It was mentioned that the corrosion look around the edges is the clear coat from the factory getting old. Mine is now hardly visible... will edit with pic if you want to see the outcome.... (

I don't think it is damaged, but it is not easily visible anymore.... I used rubbing alcohol (as recommended) and a sponge bob tooth brush... NOT happy with the outcome....

Question: In post #134 pic 2 or 3 Can anyone positively identify which of those is the cooling fan relay?? I am heading out to get it checked and would like to be able to help him if I may?? I assume it has to be either the one inside the plastic box or the thing just next to it.

Thanks for the help.... Just to clarify..... not upset about the cleaning recommendations. It is what it is. I would not recommend doing it. "live learn/ Move on"....

I will win this battle... even if I have to buy one from $pecter... LOL thanks again everyone.

 

[77mustard40]

GroundUp I hope it's just an appearance problem but good to know since I will probably be going into mine soon.

 

[78GroundUp]

Question: In post #134 pic 2 or 3 Can anyone positively identify which of those is the cooling fan relay?? I am heading out to get it checked and would like to be able to help him if I may?? I assume it has to be either the one inside the plastic box or the thing just next to it.

 

[78GroundUp]

Spent the day checking resistors and continuity on the board itself..... All seems good. Then I realized… the wiring schematic in Haynes and on here has 5 legs. My board has 7?

Is this board in combination with something else??

Happy Easter!

 

[77mustard40]

Here is a pic of my diagram from a 77 FSM but the top of the page says 79. Go figure. I never got to mine this weekend.

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[78GroundUp]

Yes same diagram I have.... But if you look back at my board (post 134) it should have 7 legs?? Shouldn't it??

And I am looking at 78 (Canada and USA) did not look at 79, maybe I should?

Edit: when I look at the 79 it has an "M3" relay. The 80 has a "cooling fan" relay.… makes me wonder if the 5/78 doesn't have them integrated on one circuit board?

All assumption on my part....???

 

[78GroundUp]

Here is a pic of my diagram from a 77 FSM but the top of the page says 79. Go figure. I never got to mine this weekend.

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That is the same one I have for a 79. My 78 shows no M3 relay.

 

[77mustard40]

I will try to get my board yanked out of my 8/77 this evening and we'll see what we have. I have no idea how these thing evolved over the years.

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[78GroundUp]

Narrowed it down to the switch relay or the timer....

Not sure where to go from here..... 77mustard, I hope you have an easier time than I am having. White flag in hand, I have a couple other options before I start waving it. Not looking good