Radiator and Air Cooler Fan Clutches

[Glennman]

I took the bus out for a spin last weekend. After returning, I decided to look into the fan clutch system, as I always check to see if any of the bearings on the tensioners have any hot spots. The clutches do not appear to function properly, as they are continuously engaged, and they have been since purchasing the bus (2002 MCI D4500, Series 60). Each clutch has a 1/4" air line attached to it, and that comes from a 24V switched mechanism that apparently is supposed to turn on and off according to engine temperature (?)

I disconnected the air lines to the fan clutches to see if there was any air in them. No air. I disconnected the air line before it connects to the switched unit, there is air at that point. As a means of testing, I bypassed the switch mechanism and attached the live air directly to the clutches. No change (they still run constantly).

So, it appears that I have a bad switching mechanism, and (2) bad fan clutches, since they are continuously engaged. With the system running constantly, I am probably losing fuel mileage and power.

Would you guys just leave it alone and let everything run constantly, or is this something you would be concerned about? I thought of switching to electric fans, but I don't know if there would be any benefit 

[luvrbus]

You loose fuel milage  and HP,better,new they are around 3k each rebuilt around $1500.00 ea ,there is a bolt on the clutches to lock those in high

[plyonsMC9]

Glennman, did you make any decisions on this?
On our DL3, we had a shutterstat go bad, but only found that after replacing just about everything on the cooling system.  On the DL3 it was almost impossible to get to the bolt to lock the clutches on high. 

Had a second issue affecting the cooling, now the bus is at J&R being looked at.  I'll try to post back here when I get more updates.

Hope this helps, Phil 

[Glennman]

Glennman, did you make any decisions on this?
On our DL3, we had a shutterstat go bad, but only found that after replacing just about everything on the cooling system.  On the DL3 it was almost impossible to get to the bolt to lock the clutches on high. 

Had a second issue affecting the cooling, now the bus is at J&R being looked at.  I'll try to post back here when I get more updates.

Hope this helps, Phil

Not yet. It looks like it will cost quite a bit to do a complete repair, so for now it will just have to run full bore. I haven't been able to figure out how it's been looked permanently with a bolt. I suppose I would have to take it all apart to find the bolt, but I have too many trips planned for this year, so that may have to wait until next winter.

[lhwood]

It would appear that your clutches are stuck either with the "bolt" or from corrosion (my vote is corrosion as I'm not sure if you can actually bolt these without removing the clutch or the fan). 

My son has a 1999 dl3 that had a similar issue.  Turned out the clutches were seized up from corrosion.   I worked on both of them and was able to free one up and it functions fine.   The other leaked air too badly so he purchased a used one. 

His were Horton 99a9555 clutches.  If you get yours off, you can match it up by Horton or MCI part# and then begin the search for parts or a replacement.  If you know the specs you may be able to find one at a major discount on E-bay or FB.

I did find that there are a couple of different clutches with the same dimensions but the logic to engage them was opposite.  One type requires air to engage, the other to disengage.  Either can work but would require you to rewire the valve or possibly re plumb the air lines.

Here's Horton's website if you find they are Horton clutches: https://catalog.hortonww.com/  Punch in the part number and they will have numbers for repair kits, cross-reference numbers, replacements, etc.

I have no idea about electric fans, but I have heard that on a semi, the cooling fan can use 30hp.  I expect that it would take a lot of electric to cool one of these rear radiator buses.

[Glennman]

Thank you. I'll be looking into that more.

[robertglines1]

I tried electric--rate them C-      went back to horton  not a hard task to rebuild. mine were set to come in about 200 and release 180.  60 series 2000yr ..  cost less than 100$ for new clutch disc. I went with less aggressive  fan that is adjustable blades to find sweet spot.  doesn't have a harsh hit when it kicks in. Yours prob already like that.  Keep as stock as possible..

[luvrbus]

Some DL3 have the Lining 2 or 3 speed fan clutches the Horton air control fan clutch  is off or on ,the 3 speed Linning goes to hi speed with the series 60 @ 210 degrees, good clutches but very costly to rebuild or replace