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Serpintine Belt Tensioner


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Same year coach, same engine, different coach (Dip). Here’s the one I used:

Dayco 89481 Belt Tensioner https://www.amazon.com/dp/B00H491LMG/ref=cm_sw_r_cp_api_fab_6kZGFb7MDYMBR

PS - If you want to double check that part number, go to https://quickserve.cummins.com/info/index.html  and enter your serial number.  That can get you the exact Cummins part number for your engine. 

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Get your ESN (engine serial number) and go to https://quickserve.cummins.com/. 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: https://www.dieselpartsdirect.com/finding-your-cummins-engine-serial-number

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On 10/11/2020 at 11:45 AM, allphase8 said:

I want to replace the serpintine belt tensioner on our coach.

2006 Monaco Camelot ISL400.  S/N 46456908

Having trouble determining the correct part number.

Any help appreciated.

Ron F

2006 Monaco Camelot

How did you determine your belt tensioner was bad? Is there a set number of miles put on an engine that requires it to be replaced?

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Just felt it was time. We have 136000 miles on the coach and the tensioner has never been replaced. 
 

Lots of advice out there from changing every time you change belt to how to check to see if working properly. 
 

When it comes to maintenance I tend to try to take action before there is a problem. 
 

Not always successful but I try. 
 

Ron F

2006 Camelot

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18 minutes ago, Admirial RVr said:

I have a 2006 Diplomat and am looking at changing my belt and tensioner. I am guessing , because of RR This change can only be done from under the coach or do I need someone above and underneath ? Or is it a one person job? Looks like a real pain.

Don T.

I didn't do it myself. Maybe @Bob Nodine could weigh in?  He's done lots of major maintenance projects on his 2006 Dip -- I bet he's done this 😉

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20 hours ago, Scotty Hutto said:

I didn't do it myself. Maybe @Bob Nodine could weigh in?  He's done lots of major maintenance projects on his 2006 Dip -- I bet he's done this 😉

I have not changed the belt tensioner but have replaced the belt and I did that all from underneath without accessing anything from the bedroom. I doubt you could even touch the belt tensioner from the bedroom, let alone change it. I think it is doable from below. I would suggest making wood blocks from 8 x 8 timbers or four 4 x 4's grouped together that are just long enough to fit under the retracted jacks. On my coach they are 10 inches in height at the rear and a single 12 inch one for the front. Their height will depend on where your ride height is set. The objective is for safety while you are under the coach in the event that a major air leak happens while you are under there. With the blocks under the jacks the coach will not drop below ride height. I am not a large person and can get under the coach and work with it at ride height. If you need more room to work you can put the PowerGear in manual and raise the rear using the jacks to give yourself a little more room. Make sure to chock the wheels. If the jacks fail while you are under the coach it will drop back to ride height on the blocks. Just make sure you are not is a position while you are under the coach that could pin you with the coach at ride height.

Edited by Bob Nodine
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When I worked in mining for +30 years I managed individual mines and was responsible for equipment maintenance.   At two points in time under different companies I was operations manager also responsible for all maintenance.

These were underground mines with harsh mining conditions.  Loaders were run 24/7/365 and would build ~18 hours a day, we would change oil 150-200 hours meaning about every 8 to11 days.  We did have an engine rebuild program and would do oil analysis etc to determine when it was time to rebuild.  I would track cost per hour and try and determine the sweet spot as to when to pull engines.   Rebuild engines never got the same $/hour results.  In some cases, if we did not have any major issues with and engine we would actually let it run till destruction sometimes achieving 14,000 hours (equivalent to probably +700,000 miles).   It was more economic then rebuilding.

All the above is background with this simple statement.  We had very few instances that a belt tensioner failed (in fact I don't remember a specific instance my memory is not as good as it use to be).  We never stocked them but if a mechanic found one suspect during a service we would order and replace. 

I checked the maintenance manuals I downloaded for my ISC 8.3L 350HP and could not find a recommended interval change.  I did find a procedure for checking, which basically recommend checking for spring tension and/or bearing play that would allow for misalignment of the pulley.  I saved this to PDF and attached. 

When I change my belt I will check the tensioner for any play.  While the engine is running I'll observe to make sure the belt is running smoothly, not bouncing etc.

Cummins Service_Repair Belt Tensioner.pdf

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I have just completed the visual inspection of the Tensioner . Thanks for the info Jim. Looks good ,belt is centered and clearences look ok. Thanks for all the info. Actually the belt does not look bad no cracks stringer on sides  but it is original and 47,000 miles. 

Don T.

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d/or bearing play that would allow for misalignment of the pulley.  I saved this to PDF and attached. 

When I change my belt I will check the tensioner for any play.  While the engine is running I'll observe to make sure the belt is running smoothly, not bouncing etc.

 

Im with james although he did not say this, i think the In our RV maintance That we tend to over do it and spend cash that that’s is unnecessary.

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I tend to agree.  I try to keep things simple, it if ain't broke don't fix it type philosophy.   I have done some upgrades on my coach but nothing elaborate.  

If I do upgrade there has to be a good reason.  Changed Fluorescent lights to LED, justified in lower power consumption and better lighting, cost was $75.  I did finally add a surge guard but this was after I had a lightening strike that hit the house while the RV was plugged in and it took out my EMS board.  I also added an automatic generator start that senses house temperature, this was to protect the dogs if the AC power went out while we were gone.  The upgrades were justified on a cost benefit analysis (at least in my mind).

My approach to vehicle maintenance is about the same.  I went an extended period of time on oil change since we didn't use the coach while building the house but I did to an oil analysis to confirm no major problems.  I just did a chassis inspection and greasing, crawling under the coach and checking all the key welds and attachments, I do it myself to make sure it gets done.  A messy job but worth the effort. 

The last time I had my rig in the shop is when road debris took out my radiator.  At the time I did not have a place at home to do a repair so it went to a Cummins shop.  This was a benefit as I determined that the radiator was damaged by road debris and reported to my insurance.  The shop worked with the insurance adjuster to come up with an estimate.  I knew the shop manager and he agreed to let me source a new radiator, which saved me a ~50% markup for that part.  They also let me take my CAC for inspection and repair, they normally don't do this.  It still cost me ~$7K but all but $1K covered by insurance.  BUT after I got the rig back I had to rephase the driveshaft because it wasn't installed correctly, check all the metal around the radiator because of missing screws and sloppy work, and replace the thermovalve because of contamination into the valve.  Not a happy camper and Cummins knew about it.    In the end taking it to the Cummins shop was the right decision along with double checking their work. 

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Sorry about switching the subject but seems this discussion is about done and I would like to learn more about the above mentioned automatic gen start based on temperature. Is it something that would work regardless of having a Trace RC7GS already in place or is it Magnum specific? Thanks.

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 Onan made a system that plugs into the generator using a "Y" wiring harness and has wireless remote.  It was the EC30W, but it is now obsolete.  Not sure if they have made a similar new version capable to Temperature sense?  I bought mine ~10 years ago ~$600. Here is a link that explains it in detail   https://www.generatorjoe.net/html%2Fonan%2FEnergyCom30W.html

I mounted the base control to the firewall above the generator and mounted the remote unit on the wall behind the passenger seat, I treid mounting it further back next to the fridge but lost reception quite a bit.  You plug the power supply into a non-inverter plug and if you loose power it senses this and when you set the temperature to a lower F level the generator will automatically start.  You have to leave the AC on for this to take over.  I usually test the system every trip by simply throwing the 50 amp breaker to cut power to the coach and after ~2 minutes the generator will start.  Note that they system will not come one once the coach has been moved so you have to reset it when you set back up. 

 

1 Onan Auto Start High Temp.pdf

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