We had beautiful weather yesterday. The sky was clear with a gentle breeze and the temperature reached 75 degrees. I went out for a walk, then got to work on the belt replacement project.

When I inspected our coach, I noticed some small cracks in the serpentine belt on the engine. I knew I would have to replace the belt sooner or later. The serpentine belt is flat, a little over an inch wide and has eight ribs. It’s driven by the crankshaft pulley, which has grooves to match the ribs. The belt drives the coolant pump, the alternator and an accessory drive on the engine (I’m not 100% sure, but I think that drive runs the compressor for the air suspension). A spring-loaded tensioner maintains the proper belt tension. If this belt breaks, you must stop immediately or the engine will quickly overheat and destroy itself.

The other day, I was looking things over in the engine compartment. I saw a crack in the serpentine belt that was alarming. When I last shut down the engine, the belt stopped in a position that revealed this crack where the belt wraps around the coolant pump pulley. I had to replace the belt sooner, rather than later.

Crack in belt

I spent a lot of time on the Internet trying to find the correct replacement part number. There was conflicting information. I found a part number for a Dayco belt in the Alpine Coach Owner’s Manual. Cross-referencing this part number, I found it was interchangeable with two other part numbers I found posted on the Alpine Coach forum. This is what was confusing me, but then it started to make sense.

I removed the belt. To get the serpentine belt off, I needed to remove the A/C compressor V-belt first. This entailed loosening the compressor bracket to create slack in the belt to remove it. This was easier said than done. Getting to the bolts on the bracket wasn’t easy.

A/C compressor

Once I had the A/C belt off, removing the serpentine belt was easy. The tensioner mount has a 1/2″ square hole in it. I used a 1/2″ drive ratchet with a short extension inserted into the hole to twist against the spring and release the belt tension. Once I did that, I popped the belt off the alternator pulley.

Serpentine belt tensioner

With the old belt in hand, I found the Cummins part number on the belt. This number was different from the part number in the owner’s manual and the online search. I went online and pulled up replacement cross-reference numbers again. The Cummins part number corresponded with the same replacement part number I had before.

I took the old belts with me and rode the scooter a few miles to NAPA Auto Parts. My online search showed the NAPA on Main Street had both belts in stock. The NAPA-branded belts are made by Gates, right here in the USA. I bought both belts and returned to install them.

The new serpentine belt was rather stiff. I threaded it through the pulleys, starting at the crankshaft. I placed the belt against the alternator pulley. Now, all I had to do was twist against the spring on the tensioner and place the belt over the alternator pulley. Easy, right?

With no belt, the tensioner was resting against the stop. I had to work against the spring and move the tensioner through its full travel to get enough slack to place the belt over the pulley. I reached down into the engine compartment and pulled on the ratchet. This was like doing an extended arm bicep curl. As I placed the belt over the alternator pulley, it came off of the coolant pump pulley. The belt wasn’t cooperating due to being new and stiff. I repeated the process over and over with the same result. My right bicep was getting sore. Finally, on about the tenth try, it went into place. In hindsight, I should have replaced the short ratchet with the long 1/2″ torque wrench in my tool box for added leverage. If I had my old tool box that was stolen by those Dirty, Rotten Thieves, I would have used a long breaker bar.

I took a short breather before installing the V-belt on the A/C drive. The belt I bought for the A/C compressor is a heavy-duty NAPA Fleetrunner Green Line model. This is top of the line, designed to withstand hot environments. These belts are used in commercial applications. I felt that spending a few extra bucks for a heavy-duty belt was worth it. I didn’t want to have to do this job again any time soon.

A/C compressor belt

Getting the A/C belt over the pulleys turned out to be a tough assignment. The old belt had enough wear to have the compressor mounted halfway up the adjuster travel. Belts can stretch a little, but what really causes the need for belt adjustment is wear along the sides of the belt. The pulley groove is a V profile. The side of the belt tapers from the outside to the inner circumference at a 38 degree angle. As the sides wear, the belt rides deeper in the pulley. To get the new belt on, I had to move the compressor all the way to end of its adjustment.

I had to loosen the bolts further. The compressor was stuck against the mount. I couldn’t see the bolts on the back side of the mount – it was all tactile work. I had to reach up and work with my arms outstretched. I’m glad I don’t do this sort of thing for a living. The A/C belt took me longer to install and adjust than the serpentine belt. I’m guessing I’ll need to re-adjust it after a short time as it seats in. The serpentine belt is self-adjusting.

Later, after I cleaned up, Donna and I rode over to the Red, White and Brew. We were meeting Mike Hall and his wife, Jodie at 4pm. We sat at the bar with them and talked. John Huff was there also. Donna ordered mussels vin blanc – it was her favorite dish when we used to come here. I had a chicken quesadilla with chipotle mayo dipping sauce. I washed it down with a Mirror Pond Pale Ale from Oregon.

Last night, we watched two more episodes of Breaking Bad. I don’t see this ending well for Walter, but I don’t want it to end at all.