Komatsu PC160 Serpentine Belt Broke

[josephny]

The serpentine belt on my PC160LC7-EO broke.

I ordered a new, original Cummins same part number belt and have spent the past several hours trying to get it on.

I've rotated the idler as far as I can but cannot get the belt over the crankshaft, alternator, water pump (smooth side) and idler -- it's like the belt is several inches too short.

I physically compared the length of the original belt (worked for years) to the new belt and they are almost identical in length.

Am I missing something? Is there a trick? Does something need to be loosened to get the belt on?

10 minute job has turned into multiple days -- very frustrating.

Thank you!

 

[GLyford]

Is there a belt routing diagram? If not, then see if you can find a picture of an installed belt online somewhere.

Any time I have trouble putting the belt on my truck I usually end up finding out I need to go around the pulleys in a different order and suddenly everything works.

 

[radios1]

the alternator should have a tension adjustment, loosen the alternator, get the belt on, then retighten the alternator while holding it in tension with a bar..

 

[josephny]

the alternator should have a tension adjustment, loosen the alternator, get the belt on, then retighten the alternator while holding it in tension with a bar..

It looks like the alternator is fixed mounted, unless I'm missing it.

Is it hidden in some way?

Thanks!

 

[GLyford]

On most serpentine, the alternator does not move, it relies on the idler to tension instead.

 

[josephny]

On most serpentine, the alternator does not move, it relies on the idler to tension instead.

Makes sense.

So any suggestions as to why, when I take a 1/2" breaker bar to the idler and open it all the way, does the belt not fit around all the wheels? Exact same Cummins part # belt that was on it before.

 

[GLyford]

I've had that happen and it ended up I was on the wrong side of at least one pulley. Did you happen to take any "before" pics? I haven't found any manuals online yet...

 

[josephny]

I've had that happen and it ended up I was on the wrong side of at least one pulley. Did you happen to take any "before" pics? I haven't found any manuals online yet...

The belt broke so it wasn't in place when I came up on it.

When you say "wrong side" of a pulley do you mean grooved vs. flat or fan side vs. engine side?

All the pulleys are grooved except the water pump, so I assume the grooved side of the belt goes against the grooved pulleys.

Thanks!

 

[radios1]

Makes sense.

So any suggestions as to why, when I take a 1/2" breaker bar to the idler and open it all the way, does the belt not fit around all the wheels? Exact same Cummins part # belt that was on it before.

you might have to put the belt on the easiest pulley last. maybe the tensioner?. get the belt on everything else first..

 

[GLyford]

Sometimes which pulley the belt goes to next is not obvious. There can be more than one way to hit all the pulleys with the "correct" side of the belt but the total length of each possible way is different. You need to try other pulley orders, when you get it right the belt will go on.

Post a picture of what you have and show which way the tensioner pulls and we'll see if we can think of other ways it might go on...?

Another possibility if you are only a little bit short is you still haven't got the tensioner pulled slack all the way...sometimes they get rusty spots or the springs stick and it feels like you are hitting a stop but it is "supposed" to go a little further (replacing the tensioner may be necessary). But I'd try other ways around the pulleys first.

In general, manufacturers like to have more "wrap" around pulleys that are driving (crank) or driven (fan, alt, water pump) and need less wrap on idler and tensioner pulleys since they are only needed to change direction, not transmit power.

Here's another idea: do you have the Cummins numbers? If you can't find the diagram from Komatsu then maybe Cummins will have something.