M35A3 Cooling fan air supply issue

[Pajaro]

Can someone please tell me how the air driven cooling fan is suppossed to work and how to t-shoot it? I have 95' M35A3 and the fan is driven by the belt, but there is an air line running to the fan hub in the front? The fan never speeds up unless the engine RPM's do. The motor gets up around 240 degrees at times while going slow (no air flow) and it seems the fan clutch should "kick in" and speed up the fan to increase air flow. The tranny cooler needs more airflow as well when pulling, as it overheats the tranny. It seems to me the fan should be kicking in. I traced the airline back to the block where it looks like there is a sensor or a solenoid.. Could I put a manual valve in the line to turn the fan clutch on?? I appreciate any help with this.
There are no other air system issues, just the fan.

Thank you.​

M35A# cooling fan question

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[R Racing]

Sounds Like You Have A Bad shutter stat Most Are Set To Open Up At 190 and provide air to the fan clutch.

 

[Warthog]

The air line only locks the fan in or out. The speed is controlled by the engine speed.

Have you downloaded the free Technical Manuals for your truck? There is a link at the top of the page.

Item #6 in Figure 51 of the TM 9-2320-386-24P parts manual shows the shutter valve. It is temperature controlled and will turn off the air and turn off the air at a given temperature.

 

[Pajaro]

The air line only locks the fan in or out. The speed is controlled by the engine speed.

Have you downloaded the free Technical Manuals for your truck? There is a link at the top of the page.

Item #6 in Figure 51 of the TM 9-2320-386-24P parts manual shows the shutter valve. It is temperature controlled and will turn off the air and turn off the air at a given temperature.

Thanks for the info and the link to the TM!

So the air locks it in or out you say? You mean it makes it direct drive and not free wheeling?? Where does one get a shutter valve? I believe this is a 425 CAT. Probably a CAT dealer item?? I will look at theTM. Thx again for the help!

 

[Pajaro]

Sounds Like You Have A Bad shutter stat Most Are Set To Open Up At 190 and provide air to the fan clutch.

Thanks for the quick reply! Is the shutterstat a hard to find item? Is there a way to t-shoot it or just replace it??

 

[Warthog]

From the parts manual I looked for the picture of the item, found the part number - RCSK15028 and googled it.

Erik's Surplus has them. $120
http://www.eriksmilitarysurplus.com/enfanclairco.html

 

[swbradley1]

Thanks for the info and the link to the TM!

So the air locks it in or out you say? You mean it makes it direct drive and not free wheeling?? Where does one get a shutter valve? I believe this is a 425 CAT. Probably a CAT dealer item?? I will look at theTM. Thx again for the help!

Pretty sure you have a Cat 3116 in it. That is, unless someone did an engine swap.

 

[Pajaro]

Pretty sure you have a Cat 3116 in it. That is, unless someone did an engine swap.

I checked and you are correct.

Great forum! Thank you all for the help!

 

[Pajaro]

From the parts manual I looked for the item, found the part number - RCSK15028 and googled it.

Erik's Surplus has them. $120
http://www.eriksmilitarysurplus.com/enfanclairco.html

Great advice and lots of help. THANK YOU Warthog.

 

[goodguyzy]

Both my trucks kick on at 225. You definitely have an issue.