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Old 10-03-2017, 08:50 AM   #1
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Rebuilt Engines - How Reliable ??

We need our (pre EGR) Cummins ISM 500 repaired and all the "experts" (three independent inspections and opinions/recommendations, each one from professionals specializing in such work/evaluations) say it needs a complete rebuild. The decision is to have the existing engine rebuilt rather than ordering a rebuilt engine from Cummins and doing a swap out. Apparently, it is much less expensive and the work can be completed sooner by overhauling the existing engine. We are to receive a one (1) year warranty on parts and labor once the work is completed. Should we be concerned about reliability of the coach once we get it back? We would sincerely appreciate hearing the experiences/advice of others on this forum regarding the “post rebuild” reliability of a complete overall of a Cummins. Also, what should we be aware of, and what (additional, related) work should be included, during the rebuild. Thanks !!

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Old 10-03-2017, 09:07 AM   #2
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i would rather depend on an engine put together by the manufacturer on their assembly line. I would also rather buy a used unit with a new replacement than a rebuild.

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Old 10-03-2017, 09:27 AM   #3
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It depends on the type of failure, miles on original engine, and if you plan on keeping the coach. What year are we talking about. what failed? IMO a factory rebuilt would be preferable over a field rebuild. I'm assuming the factory has the necessary equipment to clean and inspect the block, head and internal components for cracks and damage as well as installing all new or refurbished components based upon a standardized bill of materials. Whereas, a field rebuild will probably be done in chassis, and even if they remove the engine they may only replace the failed components and not do much additional inspection and cleaning. Regardless, if you plan on selling the coach then you may want to consider the cheapest route.
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Old 10-03-2017, 11:47 AM   #4
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I've rebuilt over twenty gas powered motors. It depends on the rebuilder. The quality of parts being used. Are they replacing the pistons and liners? Are they grinding the crankshaft to specifications? Are they replacing rod bolts with new? Are they resizing the rods? New oil pump? New camshaft and lifters? New timing gears and chain? Complete valve job with new valves if needed? New water pump? These are off the top of my head.

I've seen a lot of factory motors on the maximum of factory tolerances. When I had the machine work done, all parts were matched with the proper tolerances and balanced. The motor I rebuilt in 1971 in my 1969 Z/28 is still running strong.

If rebuilt properly, I would take a rebuilt over a new factory motor any day.

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Old 10-03-2017, 01:02 PM   #5
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Interesting question. Can you get a factory rebuilt ISM 500 without EGR direct from Cummins? How would it be different from a rebuild in an authorized Cummins repair facility?

Medium duty diesel engines are rebuilt in OTR tractors all the time, and they travel another million miles. I would be comfortable having my pre EPA 400 ISL rebuilt by a reputable diesel repair shop.

More of a concern for me would be getting it done in a shop that has experience with engine rebuilds in a motorhome. Cummins has a Coach Care program and specific shops for motorhome power plants. I'd look for one of these shops.

My thoughts,
Towr: 2007 Country Coach Allure 470 - 37 Sunset Bay Cummins 400 ISL
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Old 10-03-2017, 02:16 PM   #6
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I had my ISX rebuilt last spring at Cummins in Coburg, Oregon. They appear to have done a terrific job. I have put 7000 miles on it since the rebuild and no signs of any trouble. However, I ask some of the same questions as the others, what failed, who’s going to rebuild it and who makes the parts?

Best of luck going forward.

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Old 10-03-2017, 07:23 PM   #7
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Will try to keep this short. Last fall before leaving Alaska I checked the oil level on our 1998 M11, it was two gallons low, on an engine that never did use oil. It then used two gallons a day on the trip back to Texas.

I talked to Cummins in Coburg and they said it sounded like a dusted engine, also getting more and more white smoke out of the exhaust and major blow by out of the oil pan. Made an appointment in the spring for engine work. At this time we expected a lower end rebuild, 10 days, in frame, $12,000.

Got it to Coburg in April on our way back to Alaska. They found the dusting problem, a big break in the inlet air pipe going across the back of the engine, and then tore down the engine for the next ten days, then they decided they would not rebuild it and i needed a Cummins Recon engine. After I ok'd the Recon and gave them a bunch of money the engine was ordered and installed in about three weeks.

Then at the time of my test drive I found out it was rebuilt in Mexico. They had already test drove the motor home and said it was ready to go. I did my test drive and found the trans temp not working, no cruse control and a warning light with very low oil pressure. Oil pressure was down to 12 psi at the end of a 100 mile drive. I run a Scanguage and monitor Cummins data.

I fixed the trans temp, broken wire to the sender, the tech fixed the cruse and said the motor was good with oil pressure down to 6 psi. Paid them $34,600

So off we went to Alaska , we almost made it to Salem, 50 miles, warning light and then a stop light, oil psi down to 8 psi. I got into a rest area and the tech came to check it. When the engine cooled off the oil psi would come back up to about 30 so we nursed it back to Coburg.

The next morning they removed the oil filter and took it apart, found bearing material and quite a bit of other metal. Drained the oil and found loads of silicon gasket material. Now we all find out Cummins does not use gasket materal any more, they run silicon beads for a gasket, my guy figured if a little is good, a lot is better, and all the extra fell off into the oil pan and plugged off everything.

They then pulled the pan and found all bearings spun and destroyed. But then we had to follow Cummins procedures and it took another week to order a second Recon motor, then week to install. They test ran the second motor for an hour and then changed the oil and filter four times before the got silicon free oil. Then a test drive and another oil change.

I finally got the coach back in June and we made it to Alaska with no problems. I'm not happy with the oil pressure, runs at 30 psi and down to 12 at idle. I just got the oil changed with 7500 miles and an oil test showed 52 ppm copper. Cummins says that's just break in on the bearings. I will do another test before my one year warranty runs out.

Through this whole boondoggle Cumming acted like this was the first time they have ever had a problem. Why was I the first guy to get a silicon bead motor?

As it turns out, with a little internet research Mercedes Benz also tried not using gaskets and going with silicon beads but went back to paying for gaskets in a big hurry after a few failures.

Sorry about the length of my report, I don't ever want another Cummins Recon and am really turned off at Cummins in general.

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Old 10-03-2017, 07:53 PM   #8
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I worked in the mining industry of ~30 years. In my career I was responsible for maintenance at the mines I managed. Also Technical Services Manager responsible for Maintenance, Deputy General Manager, Director of Mining, VP, and COO of International Mining Company. Enough about my credentials.

We tracked engine performance down to the hour. Ideally we would expect +10,000 hours from an engine before rebuild, sometimes we'd get 14,000 hours (this translates to +500k mile). We would do oil sampling and analysis at every oil change (almost weekly) and monitor for any signs of problems dirt, metal, silica (dusting).

When it came time to rebuild an engine we would send it in, get an estimate, and if the $$$ were reasonable would authorize the rebuild. As a Mine Manager I would take the time to go watch the engine on the dyno, which provides info on HP, Engine Temp, Exhaust Temp, Oil Pressure etc. Well worth the time and trouble, kept everyone honest.

In your case, if Cummins feels they can rebuild the engine and will stand behind it I would lean that way. BUT, I would not do an in chassis rebuild. I would demand out of chassis rebuild and that they run the engine on a dyno and provide the print out as to it's performance. The dyno run takes several hours as they ramp up the load, engine temps, etc. If at the end of the test the oil pressure is good, engine and exhaust temp is acceptable I would not be afraid of the engine.

If they won't agree to an out of chassis rebuild then next best option it to buy a rebuild but after install I'd run the hell of out if to make sure it was OK. Any signs of problems I'd report/document to Cummins to make sure you CYA.
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Old 10-03-2017, 08:00 PM   #9
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I strongly recommend when you get the engine overhauled or install a recon engine that the radiator it pulled, cleaned and flow tested. Make sure it's in good condition for the new engine.
Also a new water pump won't hurt!
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Old 10-04-2017, 07:12 AM   #10
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Jeeez I have to say. I love this forum and all the great info it provides. This is my daily rv outlet as we aren't camping a ton this time of year. Anyway, it is so hard to read some of these stories... We all take such good care of our rigs, service, filters over and over. Then a stupid thing like a broken air pipe letting dust in ruins a motor like that. A broken inlet pipe is something you may not easily notice upon a visual inspection during service either. What is the answer? Yearly oil sampling? Even that wouldn't help if you had a broken inlet pipe and went down a dusty road, blamo. I am going to make sure at every event I do a visual of my air intake system and check the sca in my coolant (I do every service). Hope you make out ok with this.
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Old 10-04-2017, 09:46 AM   #11
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Not to side-track this thread too much - but wondering - how do the engines come out of these older Coaches (the Country Coach, American Coach, Monacos, etc.) with the side radiators. The rear opening isn't big enough from what I've seen. Does the entire end cap need to come off?
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Old 10-04-2017, 10:44 AM   #12
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Originally Posted by CountryB View Post
Not to side-track this thread too much - but wondering - how do the engines come out of these older Coaches (the Country Coach, American Coach, Monacos, etc.) with the side radiators. The rear opening isn't big enough from what I've seen. Does the entire end cap need to come off?
Entire coach is put on a lift and the motor comes out the bottom
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Old 10-05-2017, 09:28 AM   #13
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As the OP, I want to thank everyone for commenting on this thread. Your ideas, opinions, and experiences are appreciated. Again, the decision has been made to go with a complete overhaul of the existing engine rather than a swap out. And yes, they have removed the engine from the coach out the bottom. The work is being done by an independent truck center that is an authorized Cummins service center. The center doing the work is a very large, regional modern facility that has invested in “state of the art” equipment and training. It all sounds and looks professional, and we hope they know what they are doing; wish us luck.
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Old 10-05-2017, 12:07 PM   #14
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I do wish you luck!!!

And suspect you've thought of a 'Go fund me page!'...

Keep this thread going as the process completes, and you get out and about on the road for a few thousand miles!


Roo II is our 04 Country Coach Allure 40'
OnDRoad for The JRNY! Enjoy life...
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