Air Brakes / Wet Tank / Radiator Fan Questions

[Alexandninasdad]

Subject Vehicle: 1083A1 . I have been working through the obvious (audible) leaks on my air system. Replaced: Governor, Dryer, Fan Solenoid and one of the Cab support Air Shocks. I cant hear any more hissing air leaks near / around the cab and engine and was expecting the Radiator Fan to Stop rotating ( Completely ). >But it still moves sitting at idle cold< SO :
Q: What are the other "usual suspects" for me to look at or keep an eye on for Air leaks ?
Also I left the Air System Charged. Q: Best practice for 30 day storage is to leave it Charged or leave it drained ?

Thx for your 2 Cents

 

[Ronmar]

Leave it charged, you should purge some from all the tank drains on a regular basis to look for any signs of moisture…

the fan will still turn just due to friction in the clutch/hub bearings. The test for if the fan clutch is disengaging properly is with the truck full of air, turn on the main switch But DO NOT start the engine. This should energize the fan air solenoid under the passenger dash.. If you then go under the front of the cab you can reach the fan from the bottom and you should be able to easily rotate/spin the disengaged fan by hand. Now go turn off the main switch. You should hear the fan air solenoid de-energize and vent the air from the clutch assembly. Go back under the truck and try and rotate the fan. It should be locked in place with it’s clutch engaged.

while the main sw is on, try and wiggle the fan assembly for-aft and side-side and see if there is any appreciable free-play. This would indicate worn bearings.

do the same test with the power off/clutch engaged. Any fan movement could indicate a problem with the hub that holds the fan to the clutch. The old style fan hubs use a rubber insert as a breakaway/vibration damper union. The rubber in these breaks down and has caused fan, hub and sometimes even radiator damage if not caught soon enough.

the fan on my A0 freewheels and still moves quite a bit of air, but you certainly know it when it does engage. I wish it freewheeled better/moved less air. It does have some bearing slop so it will probably freewheel better when I replace the bearings… want to hear what it sounds like when it engages? Remove the passenger kick-panel and unplug the fan air solenoid connector while the engine is running. This will de-energize the solenoid and engage the clutch…

here is a quick vid I did on how the old style fan hub is put tohether with the rubber insert, and how to bypass the rubber and mechanically bolt the fan to the hub. The new style fan hubs don’t use the rubber and are hard bolted…

 

[Mullaney]

Leave it charged, you should purge some from all the tank drains on a regular basis to look for any signs of moisture…

the fan probably will still turn just due to friction in the clutch/hub bearings. The test for if the fan clutch is disengaging properly is with the truck full of air, turn on the main switch But DO NOT start the engine. This should energize the fan air solenoid under the passenger dash.. If you then go under the front of the cab you can reach the fan from the bottom and you should be able to easily rotate/spin the disengaged fan by hand. Now go turn off the main switch. You should hear the fan air solenoid de-energize and vent the air from the clutch assembly. Go back under the truck and try and rotate the fan. It should be locked in place with it’s clutch engaged.

while the main sw is on, try and wiggle the fan assembly for-aft and side-side and see if there is any appreciable free-play. This would indicate worn bearings.

do the same test with the power off/clutch engaged. Any fan movement could indicate a problem with the hub that holds the fan to the clutch. The old style fan hubs use a rubber insert as a breakaway/vibration damper union. The rubber in these breaks down and has caused fan, hub and sometimes even radiator damage if not caught soon enough.

the fan on my A0 freewheels and still moves quite a bit of air, but you certainly know it when it does engage. It does have some bearing slop so it will probably freewheel better when I replace the bearings…

here is a quick vid I did on how the old style fan hub is put tohether with the rubber insert, and how to bypass the rubber and mechanically bolt the fan to the hub. The new style fan hubs don’t use the rubber and are hard bolted…

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Really nice description of things to look at @Ronmar !
Especially the troubleshooting on the fan clutch and how it operates...

 

[Alexandninasdad]

Wow ... Nice to have you hanging around the Motor Pool. Printed your post and added to my TM. THX !!

 

[Mullaney]

Wow ... Nice to have you hanging around the Motor Pool. Printed your post and added to my TM. THX !!

.
@Ronmar will be a good source on air lines and their control boxes in the air system too. Don't hesitate to try it on your own with the TM's, but having a person to bounce off ideas is the best part about this site! The Flow-Charts in the books will teach you a lot if you use them.

 

[coachgeo]

wonder if dripping/spraying some Mothers rubber treatment around top edge where ever fan stopped each time you have the cab tilted would help that rubber last longer?

Mothers Plastic/Rubber/Vinyl Protectant Spray 16 oz - Ace Hardware

Mothers Protectant is a penetrating UV blocker, effective on rubber, vinyl, plastic and fiberglass. Constructed to recondition and maintain the original condition and appearance of dashboards, bumpers, trim, tires and more. Protectant isn't an oily surface-coating film. It's an ozone and smog...

www.acehardware.com

 

[Mullaney]

wonder if dripping/spraying some Mothers rubber treatment around top edge where ever fan stopped each time you have the cab tilted would help that rubber last longer?

Mothers Plastic/Rubber/Vinyl Protectant Spray 16 oz - Ace Hardware

Mothers Protectant is a penetrating UV blocker, effective on rubber, vinyl, plastic and fiberglass. Constructed to recondition and maintain the original condition and appearance of dashboards, bumpers, trim, tires and more. Protectant isn't an oily surface-coating film. It's an ozone and smog...

www.acehardware.com

.
I dunno... Most of the rubber protection "schemes in a bottle" are generally for protection from UV rays. The fan lives more or less in the dark. I think what may be happening to a lot of trucks that we have are 20 years old now - and built to last for 7 - so they need to be replaced?

 

[Ronmar]

Well I am sure some of the degradation is also due to drying out/dry rot. like putting silicone grease on O-rings, an additive might help with this but wether it would interfere with it’s intended purpose by breaking down friction or reducing durometer would be an unknown until it is tried.