Humvee Radiator Fan Clutch

[captkennyboy]

Hi all, I’m working on my 2004 M1123 with a 6.5 non turbo. The radiator fan clutch stays engaged all the time. I have changed the Fan Clutch solenoid valve, Thermostatic Fan Switch and the Time delay module and still no change! Any help would be greatly appreciated.

Thank you in advance

 

[springer1981]

What are you using to determine that it is engaged all the time? Is it just because it is still spinning? Just an FYI but the fan spins all the time when it is running but when engaged it spins with much greater force. When the engine is running you can disconnect the the time delay and that will engage the fan. The sound of the fan should change. I watch the end of the fan clutch and you can see it move in and out about 1/8" when you plug and unplug the time delay. If it is moving then it is engaging and disengaging. When you unplug it, it should move towards the engine to engage the fan.

Not sure how much experience you have with HMMWV's but I learned this when working on mine.

 

[captkennyboy]

What are you using to determine that it is engaged all the time? Is it just because it is still spinning? Just an FYI but the fan spins all the time when it is running but when engaged it spins with much greater force. When the engine is running you can disconnect the the time delay and that will engage the fan. The sound of the fan should change. I watch the end of the fan clutch and you can see it move in and out about 1/8" when you plug and unplug the time delay. If it is moving then it is engaging and disengaging. When you unplug it, it should move towards the engine to engage the fan.

Not sure how much experience you have with HMMWV's but I learned this when working on mine.

Thanks the fan does not move back and fourth when i disconnect TDM and the sound doesn't change . the fan can not be moved when the truck is not running which i understand is normal.

 

[Mogman]

Well the first thing I would do is apply 50lb or so to the fan clutch line and see if the clutch is stuck, that may be a little low but I am sure someone will chime in here if I am way off base.
Do this of course when the truck is not running and see if you can turn the fan by hand.
But of course you have already checked to see if the Cad. valve is getting 24v yes?

 

[captkennyboy]

Well the first thing I would do is apply 50lb or so to the fan clutch line and see if the clutch is stuck, that may be a little low but I am sure someone will chime in here if I am way off base.
Do this of course when the truck is not running and see if you can turn the fan by hand.
But of course you have already checked to see if the Cad. valve is getting 24v yes?

thanks didn't think to check for the 24 volts. i replaced the engine wiring harness when i first got the truck - i will test it!

 

[Mogman]

thanks didn't think to check for the 24 volts. i replaced the engine wiring harness when i first got the truck - i will test it!

No doubt there is a trouble shooting procedure in the TM you should have made sure there was NO 24V going to the valve before ever changing a single component, now you have added several more items that may or may not have been a problem but now you can have multiple problems, you should always troubleshoot the problem before replacing any parts, parts "swapping" is a very poor way to troubleshoot an issue.
Sorry if this seems harsh but this is something that comes up far too often.

 

[Action]

it took about 90psi of air to check the last one i worked on.

 

[86humv]

Also...If fan has not been operated for long periods ...
The clutch material inside housing will get stuck to side wall do to rust....sometimes it takes a wack with something.
If you do wack it...make sure you DO Not wack the nose cone.
Then pressurize it to 90 psi.

 

[Retiredwarhorses]

90-120psi, tapping on the fan clutch housing to break the clutch plates free…
you can even loosen the 5/16 backing plate screws and do same till it breaks free.
this is common on these auction trucks from sitting.

 

[RJTM998]

Also...If fan has not been operated for long periods ...
The clutch material inside housing will get stuck to side wall do to rust....sometimes it takes a wack with something.
If you do wack it...make sure you DO Not wack the nose cone.
Then pressurize it to 90 psi.

Are you wacking it with the hood off, the radiator stack removed? How do you access it?

 

[osteo16]

You could look at my clutch unsticking procedure here.. But use your best judgement. I probably would have gone with a less aggressive punch when whacking my clutch.. But it freed it up,, https://www.steelsoldiers.com/threa...o-your-hmmwv-today-lately.147917/post-2308819

 

[RJTM998]

You could look at my clutch unsticking procedure here.. But use your best judgement. I probably would have gone with a less aggressive punch when whacking my clutch.. But it freed it up,, https://www.steelsoldiers.com/threa...o-your-hmmwv-today-lately.147917/post-2308819

You could look at my clutch unsticking procedure here.. But use your best judgement. I probably would have gone with a less aggressive punch when whacking my clutch.. But it freed it up,, https://www.steelsoldiers.com/threa...o-your-hmmwv-today-lately.147917/post-2308819

Thanks, did you run an air hose to it during the procedure? Or did you just spray it, let it sit and then hit it with the hammer and punch?

 

[osteo16]

Sprayed front and back of that lip for 2 days maybe.. tapped a bit, resprayed, came back next day.. Repeat.. Maybe 2-3 days total.. Depends how aggressive you feel .. After every couple hits, id run engine and unplug/re-plug in Cadillac to see if it was free yet.. And don't try to spray it while fan is running ..

You could probably run air to it,, I didn't but that might have been lazy on my part.. Didn't really want to blow air into my hydraulic line and have to purge later.. Probably easy enough, but I didn't..

 

[Coug]

the clutch is a dead end system, and the only thing after it is the reservoir so getting a little air into it usually isn't a big deal.
Having air applied will provide some force to help unstick everything as you tap on it, but isn't absolutely necessary.

 

[RJTM998]

Sprayed front and back of that lip for 2 days maybe.. tapped a bit, resprayed, came back next day.. Repeat.. Maybe 2-3 days total.. Depends how aggressive you feel .. After every couple hits, id run engine and unplug/re-plug in Cadillac to see if it was free yet.. And don't try to spray it while fan is running ..

You could probably run air to it,, I didn't but that might have been lazy on my part.. Didn't really want to blow air into my hydraulic line and have to purge later.. Probably easy enough, but I didn't..

Awesome, thanks for the info!!

 

[FMFHMMWV]

the temp sensor has two plugs that connect to the harness. there might be a disconect there. Im talking about the tempsensor on the coolant hard line. its got two wires coming out of it.