Community Forums

johandp53 · 10-22-2020, 10:06 AM

Hi Guys, My main drive belt broke, but I recovered it, no numbers visible. I called Freightliner and they gave me part# 3288867. When the new belt came, it was about 2" longer than the stretched one that broke, 57" vs 59", but I guess the automatic belt tensioner will take care of that right? BTW, the second smaller belt is DCO 17435. All the best!

Skip426 · 10-22-2020, 02:23 PM

No; the auto tensioner will barely handle a 1/4">1/2" longer and as the tensioner nears the end of it's travel , the actual tension decreases and the belt slips.
If you are sure you have the complete broken belt , an auto parts store can measure it accurately.

Tensioner should be marked with a ; usable belt range ; that on a rear rad coach might not be visible .

Skip426 · 10-22-2020, 02:29 PM

I'll add that a serpentine belt is very strong and they seldom break for no reason , check that all the rotating items the belt runs are turning free and smooth. If worn on one edge , you might need a tensioner too. They sag over time and cause a belt miss-alignment , and that will cause the belt to break.

Photo shows where to look for sag in the tensioner.

Bigd9 · 10-22-2020, 02:41 PM

It very well could be the belt was supplied/installed by Cummins and not Freightliner. Might want to give them a call.

johandp53 · 10-22-2020, 03:01 PM

Hi again, if anyone has any tips in getting that main drive belt back on, I would appreciate hearing from you! Thanks!

Martind4 · 10-22-2020, 05:26 PM

I guess the first tip would be to make sure you know why the original belt broke, in our case it was a seized AC compressor. Make sure everything spins easily or you'll be doing it again soon.

Be sure you have the proper routing diagram for your engine. If you're persistent enough you can put it on wrong and then wonder why it was so difficult. Don't ask me how I know that.

It's easier with 2 people, one from the top and another working from the bottom and both of them young contortionists.

Check the belt position on each grooved pulley to make sure it's centered properly, it won't correct itself once it's started.

Good luck.

Skip426 · 10-22-2020, 05:31 PM

Well you're going to find out why many members ; myself included ; won't own a rear rad coach .
The best hint I've seen posted for the rear rad set up , is to get a long handle 1/2 drive ratchet on the tensioner , pull the ratchet to get the tensioner to it's max deflection , and tie it there , with a heavy duty zip tie , or a motor cycle tie down . With the ratchet holding the tensioner you'll have both hands free to work the belt around . Depending on your set up and how much !@#$#@! the coach and chassis builders put in your way , you may have to go back and forth from up top to under the coach , to work the belt through it's routing .
Do you have the A/C compressor drive belt off ?
Do you have a diagram of the serpentine belt routing ?
Or are you one of the lucky , owners where the A/C compressor is driven by the serpentine belt ?

veraken · 10-23-2020, 05:51 AM

Make sure you have the right belt!! Get your ESN (engine serial number) and go to https://quickserve.cummins.com/info/index.html. Register your vehicle. It's a great source for info on replacement parts. You can also call Cummins Customer Service ( 1-800-343-7357 ) and give them your ESN

This will tell you where your ESN is located: https://www.dieselpartsdirect.com/fi...-serial-number