If the Serpentine Belt Breaks, What Exactly Happens?

[TechWriter]

Took my DP in for its annual service visit and had to have my Cummins serpentine belt replaced because it was cracked.

Which got me to wondering . . . what exactly would happen if the belt broke while on the road?

[Kayteg1]

I use other factors to determinate preventive maintenance or just carry part.
I DIY everything so labor is not an issue, but living in CA and frequent Las Vegas very often I am 150 miles from closest good shop on 120F desert.
So question would be if I would be able to work around hot engine in 120F direct sun.
Belt is easy in this, but lot of CPS require sliding your arm on the side of engine and those have nasty habit of going without warning.

[wolfe10]

Part of the "use old belt for spare" vs "buy a new one and let it age out" depends on how difficult it is to install the belt.

On our side radiator coach, belt replacement takes 3-4 minutes. But, on some rear radiator coaches, it takes two people and considerably longer.

This SHOULD factor into the equation. If labor (yours or pay someone else) is easy, stick with the used one. If labor is very time consuming/expensive, carry a new one.

I have no problem with either answer.

[Tom_Barb]

hacker7 wrote:
THROW THE OLD BELT AWAY. IF YOU ARE GOING TO CARRY A SPARE BUY A NEW ONE. MANY ARE NOT EASY TO DO. WHY DO OR PAY TO HAVE IT DONE TWICE.:@

It's better to have an old belt than nothing. I must order them, as will any one broke down in remote areas.

buy a new belt now, and wait 5-7 years to use it?? Does that make sense?

[DSDP_Don]

When both my coaches were new, I didn't carry a belt. As soon as I got near the five year mark, I bought a new belt to keep as a spare. They're inexpensive if you buy a Napa replacement. Typically around the 6-7 year mark the belt was replaced.

[hacker7]

THROW THE OLD BELT AWAY. IF YOU ARE GOING TO CARRY A SPARE BUY A NEW ONE. MANY ARE NOT EASY TO DO. WHY DO OR PAY TO HAVE IT DONE TWICE.:@

[nemo45]

wolfe10 wrote:
The answer is totally depends on the engine and what the chassis maker drives off the serpentine belt.

Our first two DP's had a separate belt driving only the water pump. Serpentine belt ran the alternator and A/C compressor.

Our current coach's serpentine belt drives water pump and alternator, with a separate belt for A/C compressor.

Please check YOUR owners manual for the information on YOUR coach.

Wolfe10 is absolutely right. It depends on your engine. I just had the serpentine go on my Cummins ISL 400 last week. The water pump quit and the engine overheated almost immediately. The A/C still worked and I'm not sure about the alternator because I shut it down right away. I called Freightliner and they couldn't give me the part number of the belt as the serpentine belt is on the engine delivered. Luckily the mechanic found a piece of the belt with the number on it. I don't see much sense in replacing you belt before it goes. Except for the two hours we spent waiting for the tow, we didn't save anything as we have Good Sam Roadside Asst. I sure as hell couldn't have replaced it myself. However, it is a good idea to keep a spare belt and probably an idler pulley too.

[Tom_Barb]

Having a spare, this is good, knowing how to replace the belt is golden.

[bluwtr49]

Since the serpentine belt on my C-12 only turns the alternator and AC compressor I'm not overly concerned as I can do quite nicely without them by running the gen set as necessary.

That said, I will replace the belt every 3-4 years as a PM item.

[Canadian_Rainbi]

Tom/Barb wrote:
That depends upon what is being driven by the belt, usually the dash air quits, the engine water pump quits and the engine over heats.

OBTW, the belt may be cracked, but in no danger of breaking. most belts have a backing that is the belts strength, the rubber grooved portion it for traction over the pulleys.

Agree. Good plan on your part to change it. And keep the old one (or buy a new one) for a spare. HERE is what happened when ours broke in southern Mexico some years ago.

[rockhillmanor]

Took almost a week to get it from Cummins NW.

Bought a new MH and at same time bought a 'new' belt to keep on board. Everyone of my vehicles has a spare new belt on board. Toad too.

A little bit of insurance which prevents a lot of headaches breaking down without a replacement.

[valhalla360]

Kayteg1 wrote:

I never bought the story about keeping old belt.
How long you think used, 10 or older belt will last when you reuse it?
I always carry new belt and tools to replace it.
New era belts can last 200,000 miles on cars. Don't know about RVs but once you see the cracks on ribs, you better have new belt handy.

How long do you think that "new" 5yr old belt will last?

It's similar to tires, the rubber gets old even if it's not being used. I wouldn't trust a belt that has been sitting for years.

Keeping the old one will likely give you just as much likelihood of making it into the next town where you can find an actual NEW belt.

[Tom_Barb]

My 8.3 ISC is a lot different than the 5.9 truck.
I changed the belts on the Newmar shortly after we to the coach, because of their age, but kept the old one in my emergency pac.

On US 2 in the rest area west of Spokane we pulled in for rest and saw a coach setting with the rear engine compartment open. Being a mechanic with a tool box aboard, I asked if I could help. he showed me his broken belt. we compared it to my spare and it was a fit. Changed it out for him. and told him to pay it forward.

On the ISC in my coach, there isn't much that a belt can hit.
Yes my A/C has its own belt, but runs off a serpentine belt driven pulley.

[Peralko]

Brett Wolfe had the right answer like usual; You need to find out what is driven by the serpentine on your coach. If you don't know, ask the mechanic. Our power steering and hydraulic fans are powered by an engine-mounted pump, so loss of the serpentine does not affect the power steering. We have lost the AC compressor belt. We considered a coach with a C-12 engine, and I noticed the serpentine belt powered the AC compressor as well as the alternator. If I had bought the coach, I would have gotten a belt to bypass the AC compressor. In either case, keep spare belt for your coach. If the belts coming off are real bad, I would replace the belts after a year or so to have better spares.

[45Ricochet]

path1 wrote:
I'm venturing into Class A dept and out of Tow vehicles...But maybe might help someone. Not sure if Cummins has same set up if in MH or in pick up?

My Cummins 5.9 in my tow vehicle(2001 Dodge)the a/c compressor froze up and melted my serpentine belt. Wife noticed little poofs of smoke were coming out from hood. Belt was gummy and very warm. Just a matter of time before it broke. When looking for new belt at part store, I had option of "with or without A/C".

LOL Now ask for the 5.9 belt with A/C and a exhaust brake for a 2006.
Took almost a week to get it from Cummins NW. I was in no hurry though, just regular PM stuff for me. Replace before DOTSOR. MH picture is a bit different but just follow the dots. These should last 100k miles easily.