Those who follow my blog for the RV repair advice can find my newest repair at this link: https://chaos.goblinbox.com/rv-repair-section-2/rv-repair-section-2004-winnebago-journey-dl/c-engine-2/broken-serpentine-belt/
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Read your post on AC compressor explosion. Mine was the alternator froze, either one will eat a belt right now. The constant wonder for me: These Cats were commercial engines, designed to run three days past forever. Do the RV manufacturers just spec lessor quality accessories? I can’t see big trucking companies tolerating such a mess at such low mileage! Ohhhhh, got to use my exclamation point! And again!
Congrats on getting to use “!”…three times!
In this situation, my compressor wasn’t a low quality part as far as I can ascertain. Plus I hadn’t used the A/C since the previous May because it had a freon leak – which might suggest the compressor was on it’s last legs had a bad bearing and that caused the leak and the subsequent freeze of the idler pulley. It might have been caused by the tensioner…a Cat part and typically they are well made. OR…it could have been the bad compressor bearing that caused the tensioner to go bad.
My reading suggests that the tensioner on these particular Cat engines give out between 70-90K miles for whatever reason. Might be the design itself, or simply because of the hard work it does every mile. I’ve not read about repeating failures of the tensioner like if it goes bad, it’s replaced, than fails again shortly after, at differing low mileages like you’d expect if it were all that poorly designed, but that could suggest that Cat realized they had a component that failed too early and redesigned it years ago. Can’t know for sure of course but I’m hopeful that the replacement part will last for as long as I own the RV…probably another 8 years.
But one mechanism of the failure type is shown in this video: Tensioner Behavior Video – Bad vs Good
When it’s jerking around like that, it’s jerking the other components along the belt too. Because the flywheel is so big and strong, it doesn’t usually bother that but the fan hub, if not properly lubed periodically, can and does go bad, the alternator bearings can go bad as you discovered, and as in my case, the compressor bearings went bad.
The RV manufacturer, the chassis manufacturer and the engine manufacturer can’t really be directly blamed I don’t think. Just one of those things.
If you didn’t replace your tensioner back when your alternator went bad, I’d suggest you do it now.
Here’s a link to the engine page of my blog…there’s a nice picture of the front of the engine without the Radiator in the way: Engine Section
I did replace the tensioner – not really rough, but not really happy, either. When in doubt, change it out.
Mine did have a slight ‘tick’ as I spun it around. So it was bad. But I would have changed it out anyway even if it hadn’t had the tick. The spring goes bad on these things too and I couldn’t really tell that just holding it. You are right though, when in doubt, change it out for sure.
When you can, check out our Beaver Ambassador Club Forum for threads where Dave Atherton contributed posts.
Unfortunately not all of Dave’s vast CAT help there is available if you aren’t a member of the club, but much of it is. His posting skills are not exactly expert and often difficult to interpret, but who cares; he is likely the primo CAT technician in the Americas. He has saved many members thousands in repair costs by correctly reinterpreting less-capable technicians’ analysis, and by providing spot-on preventive advice in his blog and Forum posts.
He knows just about every aspect of every CAT engine, has access to CAT documentation, and zeroes in on individual coach issues by ascertaining owners’ engine serial numbers. Most help he provides is via the Forum, but many fortunate members have him check out or repair their rigs in person at his business site (near Quartzite I think) or at one of our rallies. He’s all about determine what’s really wrong or prevention at minimal or no cost but with the right parts, not aftermarket. He’s not at all about profit.
http://beaveramb.org/forum/index.php?action=dlattach;topic=7495.0;attach=7577
You should be able to view our Ask Dave section off the main Club website here:
https://beaveramb.org/ask-dave/
I’ll check out this Dave guy, can never have enough advice when you have an engine problem. We have a Cat expert on RV dot net too. Wolf10.
If that’s Bret Wolfe, yes he was active in the old CAT Club before it converted to the Diesel Club when Caterpillar bailed on supplying motorhome on-highway engines. Bret is a respected advisor and answered a question or two of mine when I first got the diesel coach 13 years ago. But when they voted sans Caterpillar sponsorship to dilute themselves with all the other engines I had little interest in about 10 years back, I left the club. I presume Bret is still active there as well as other RV venues.
Dave Atherton knows other engine brands also, but is a CAT specialist bar none. I doubt there is any issue however complex that he can’t diagnose, and he thankfully does not do it by trial and error throwing of parts at people’s investments, a technique he often rails against when a BAC member has been subjected to the practice by lesser techs.
Bummer. The BAC just went private on our Ask Dave column. Apparently it was so good that readers, non-member or otherwise that should know better, were copying his posts and putting them on other websites.
I can see the value in his knowledge, and wouldn’t be adverse to anyone having access to it. But there has to be some value also in the exclusivity of the BAC or there wouldn’t be much point in its existence. And as a valued Beaver owner and member, I reckon Dave deserves protecting. That doesn’t take his business access away from anyone that could benefit from one of the best available.
I hear ya. I wonder how many of my articles have been poached? I’d be kinda sad if none of them had…
Sadly I shared the same experience with a frozen A/C pump pulley on our last trip out. Our coach (2003 DSDP with 3126) has a side radiator so no fan drive pulley in the mix but otherwise the same hassle to get to the pump for replacement. As we were 2000 miles from home and I didn’t have the tools to deal with a replacement on the road I pulled the belt and used the coach generator to keep the batteries up for the trip home. After paying a Freightliner shop the customary one hour rate to get an estimate for the repair (their diagnosis; the A/C pump needed to be replaced, no kidding!) the total estimate came to $2450 for parts and labor. (Nine hours according to the book) And at that price they wouldn’t guarantee that they could replace the pump without breaking the refrigerant hose nipples off which would mean pulling and replacing the hoses. (19 hours labor plus the costs to fabricate new hoses.
I had the same type of experience with a FL’er shop several years ago. They quoted $2300 for a simple master cylinder change. They insisted they also had to replace the brake assist pump at the same time. I laughed at them as I walked out and soon found that all that chassis stuff was Bendix parts. Bought a new MC online for $450 or so. Had a friend help and had it done in just a couple hours. Pumped out some bad looking fluid that had been boiled a year before. Drove it with the new MC for another 6 years w/o problems. I gave FL other chances but they ALWAYS came up with outrageous quotes so I’ve never used them. And never will. To me they’re nothing short of thieves.
I ordered the pump from Freightliner and picked it up before heading home where I replaced the pump (4.5 hours) and found my pump had the removable manifold just like yours did (and most Sanden pumps I’ve ever worked on did) so there was no threat of breaking the threaded hose connections off the pump body. (You would think that in an hours time the Freightliner tech could have at least determined the type of hose connection at the back of the pump).
You and I would think so, but they’re not in the business of helping RV’ers in any way.
I did not replace the belt idler as it was not noisy or rough but after reading about your experience I think I will pick one up and replace it before my hand if forced.
Great idea. They have a limited life because they work so hard.
Not sure what the deal is with these Sanden pump pulleys seizing up but it seems to be a thing. I have several vehicles with GM A6 compressors that are over fifty years old and have never seen a seized pulley. (Locked up compressor, sure, but almost always due to running with low or no refrigerant which means pump died early death due to lack of lubrication).
Don’t think any new compressor built these days will get you 50 years except by accident.
Thanks for your input!