Fan permanently clutched in after steering pump replacement

Bulldogger

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I noticed after a few driving sessions following the installation of a new steering pump on my Humvee last weekend that the fan is always clutched in. This means that the fan changes speed with the motor. It also means the engine takes a long time to get up to operating temperature. It doesn't lend the system to over heating, of course, and yesterday no matter how I tried on the highway I was not able to get the coolant system temperature above 220. I was hoping getting above 220 might help reset the Cadillac valve and fan clutch controls. I did try unplugging the leads to the Cadillac valve cleaning them and plugging them back in. No apparent change. I did bleed the steering system according to the tech manual after the installation last weekend. I tried again yesterday but it made no change in fluid level. The fluid level appears stable at the proper mark. After careful loosening of all hose clamps I verified there is fluid in the supply and return lines at the Cadillac valve.
The fan is definitely clutch in because I can hear and see it change speeds with the motor. I tried to stop it carefully and definitely could not while the motor was running. The steering system is great. The wheels steer easier than ever before. And the steering wheel turns smoothly.

I followed the tech manual closely during the steering pump installation. The only thing we did that wasn't recommended was to remove the alternator so as to get at the steering pump more easily. We didn't touch or make any adjustments to the Cadillac valve or the fan or its clutch assembly.

I can't find anything in the tech manual about a stuck fan. The only conversations about that in the manual suggest bleeding the steering system or doing some kind of electronic checks regarding gauges and instrumentation.

I bled this system last weekend according to the tech manual. I drove the Humvee and then once it got up to temperature on the highway fan kicked in and I thought it also disengaged but by then I had pulled off to the side roads and was headed home. So I'm not certain. The next day it sounded like the fan was moving in time with the motor, which made me start checking on that

I searched but had trouble finding any information here on the site because the word fan is too common.

I wonder if anyone has had this problem and could give me any more ideas to try.

Thanks,
Bulldogger
 

86humv

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Sometimes the clutches get stuck inside the assembly if it was not working for long periods of time.
Remove hose to fan clutch [ with truck off ] and apply and remove about 90 psi to fan and see if it moves.
If it does....then your problem is electrical.
If it don't move....Need to take a mallet and wack the silver fan clutch with pressure applied, but not the cap that the hose hooks to.
Sometimes this will free it up.
 

Bulldogger

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The fan was working fine before I replaced the steering pump and boosted the system pressure. (certainly steers like I have more pressure)

Retiredwarhorses, does this mean the system failed for some reason because I upgraded the pump? I assume I have to obtain a new replacement thermostatic switch then?

I was thinking of replacing the temperature gauge and sensor anyway. Sounds like this is a good time? Or should I wait for some reason, just in case.

As far as a "today" thing to do, I'll pull up the schematic and trace the wiring to make sure it didn't jar loose or get disconnected by mistake.

Bulldogger
 

Action

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why were you trying to get it over 220 degrees?
an easy way to see if the fan is stuck or not is to leave the motor running and unplug the connection by the washer bottle. If you see a change in fan spped or distance from motor, clutch is not stuck.
 

Retiredwarhorses

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Simple test...it's a normally closed switch, thus allowing 24v to flow, once its hot it opens and denies 24v to the TDM.
So take a meter and check continuity, when the engine is cold, it should be closed, if you want to test when hot, unplug and you should get a full open. Your TDM could be bad as well.....plug and play
 

Bulldogger

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Thanks for the extra information. I will run some electrical checks when I get home. Having a swim meet for my 7yo at the moment!
Bulldogger
 

Bulldogger

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Well, here is what I figured out tonight. My fan temperature switch which is on circuit wiring number 458 is located in the coolant system crossover piping, which is normally closed, is closed when cold. So I think my fan temp switch is ok.

I verified that this switch is indeed electrically connected to my time delay module over by the washer pump reservoir. I then confirmed that 24 V is being sent on wire 583 into the clutch fan solenoid. This solenoid is also sometimes called the Cadillac valve depending on where it was made.

Logically then, based on the wiring diagram, what the time delay module does is ground out or open the circuit to the clutch fan solenoid so that this solenoid does or does not send high-pressure fluid to the fan clutch.
I experimented with putting 24 V across the clutch fan solenoid with the engine off and heard a very very faint tick noise but nothing to make me think a lot was going on in there. I then started the motor and again grounded the clutch fan solenoid wire 93 and disconnected that ground several times. This made no difference in whether the fan clutch was engaged or not when I tried to stop the fan.

My air compressor is dead, so I have not been able to test the fan clutch itself yet. However my suspicion is becoming focused on the Cadillac valve. I can say that it used to make that hissing noise some people have reported and I isolated it with a piece of rubber as is recommended in another thread here. I doesn't make a hissing noise anymore.

I will see if I can borrow my neighbors air compressor tomorrow and see if I can get the fan to declutch.

If someone has ever tested a Cadillac valve manually with power across the leads and can tell me it should make more noise than mine does I welcome that information.

Bulldogger
 

Retiredwarhorses

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It's possible you got debris in the lines and the Cadillac valve is clogged...seen that before, blow it out with air. If that don't do it, replace the TDM
 

Bulldogger

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Action: yes, that happened as a matter of course when I was fiddling w the Cadillac valve as part of all that. Didn't appear to make a difference. Sorry to not mention it.

I'll try to blow out the valve. It could have picked up something when the return tubes and primary pressure tube were disconnected.

Bulldogger
 

Katavic918

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Sometimes unrelated things fail for no apparent reason at just the right time. I just replaced my thermostat and now my battery isn't charging. Turned out that my voltage regulator failed on the next start up. It sounds like you are troubleshooting properly but my point is to never assume that anything mechanical is logical.
 

Bulldogger

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Took apart my cadillac valve to try to get my fan working correctly again. Didn't see anything wrong w the valve internals but after bleeding all air from it and driving a few miles my fan is declutched now. Have to drive farther to see that it turns on at high temp.

So so far so good. I'll definitely keep an eye and ear on it now. It is hissing like it used to, a little louder in fact but only a touch. Given that my steering pump is putting out more pressure that is believable.

Bulldogger
 

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Bulldogger

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What type of pump did u install?
Napa 81-1411

I can't remember offhand where I got that part number. Probably from the hummer knowledgebase. My Napa jobber was speechless for a moment after I gave him that part number to look up in his system. He finally spoke and said "I've never seen a part in our database without any kind of vehicle associated with it, but this part number has nothing next to it". I told him put Humvee next to it!

Bulldogger
 

3000gt

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Hope your not using a MILE MARKER winch with that pump. cause it will eat it for breakfast. I went thru 3 before I went with oem.
 
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