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Old 06-20-2016, 05:11 AM   #1
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Post diesel buying/maintenance question

I am about to buy my first MH (after owning a small TT). I will be traveling from September to the end of March thru several states from CA to PA. It's possible that I will live in it for a year (with my wife & 6yo girl). As I read about MHs I learn that Diesels are stronger and last longer. My question is:
What is the most common repair in diesel units, and what is the most difficult and most expensive repair? And if I want to buy a used one, is there anything I should avoid?
I would like to buy a used 41' 2007 All Star Family Edition 350hp Cummins w/Slide - Bunk House (about $87.000 with 52000miles). Should I expect to repair anything in such model before I hit the road?
Thank you so much for your help.

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Old 06-20-2016, 05:23 AM   #2
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Maintenance records will indicated if the previous owner maintained the engine. Get an engine survey/inspection before buying.

I have 2 Cummins series B engines in my boat. They can be very reliable or very expensive depending on their maintenance history.

As a heads up on costs, Oil changes once a year will cost you about $100 if you do it yourself.

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'07 40' American Tradition & '14 Honda CRV
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Old 06-20-2016, 07:15 AM   #3
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Probably the most frequent issue with Diesel Motorhomes is the engine or related parts.. You can frequently read about injection pump problems. There are also some reports of engine failures but considering the number of coaches/people it is a rare occurrence. Maintenance is the key to preventing these types of problems. Changing fuel filters on a regular basis helps along with adding additives like algaecides to prevent algae. Turbo chargers can also fail. which depend on clean air and oil for lubrication, both maintenance related.

Buying a used coach the most important thing is maintenance records, making sure the oil changes have been done at the prescribed intervals.
Jim J
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Old 06-20-2016, 07:27 AM   #4
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As others have stated these Cummins diesel engines are pretty reliable and long lived when properly maintained. Although not a motorhome, my brother recently sold a 1992 Dodge pickup with the series B 5.9 Cummins diesel. The truck had been used in his air conditioner business hauling a/c's, ducting and other stuff. Did not live an easy life. He maintained it well, changing oil, filters, etc. as specified by Dodge. The truck had over 650,000 miles on it!! The beast still ran well and he never did a thing to the engine other than routine maintenance. We won't talk about how the body held up!!
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Old 06-20-2016, 08:12 AM   #5
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I think jacwjames covered most of it... Clean fuel... meaning care for the fuel filters, on a over the road truck that might be 40K miles... on a low mileage RV that might have to be every 15K miles... I personally use a fuel modifier... something that will add some lubricity to the fuel and help prevent algae.. oil change annually... for sure... on my pickup, its every 7K miles... On a Class A its annually even if its 5K miles...

A lot of people will suggest that you start and run the engine and gen set monthly... I don't personally do that... but what I do do is start and run it to allow them to come up to operating temperature for at least 30 min... that's at least 90 most of the time...

I watch the fluids, check for water in the air tanks, and work to change the transmission oil, power steering fluid, coolant.. etc... at 5 year intervals... and I add a modifier to the coolant (CAT) annually... Remember that set of belts might have only 50K miles but might be 10 years old... you know what the heat/sun do to tires at that time frame... so the belts need attention as well....

The key here... is to get on a schedule and stay on it... I personally do an annual inspection when I prep for winter... I'm mechanically inclined so I do this myself... taking care to examine, look and see....

Hope this gives you some thoughts...
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Old 06-20-2016, 08:36 AM   #6
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Originally Posted by Kuba View Post
.... Should I expect to repair anything in such model before I hit the road?
Thank you so much for your help.
Hopefully the previous owner will have detailed maint records for you. The keys to a trouble free diesel are frequent maintenance changing fluids & filters. Most diesel problems are owner caused, bad fuel, clogged filters, mixing coolants, etc. In a diesel, coolant is as important as engine oil, having the right type of coolant and maintaining the right pH in the coolant is critical.

Lacking previous maint records, I would start by changing all the fluids & filters immediately to have a known starting point. Sending an oil & coolant sample off for lab analysis can give early warning to potential problems.
Otherwise its just when the typical chassis items are going to wear out: brake pads, shocks, batteries, air leaks, etc
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Old 06-20-2016, 08:40 AM   #7
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2007?? Tires. Hint: wrong answer is "Oh, they have lots of tread." Six tires times $400-1000=YIKES! Well worth the peace of mind.
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Old 06-20-2016, 09:03 AM   #8
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Maybe someone has compiled figures, I don't know. My observation is that the most common repairs of significance (aside from appliances and etc.) are air system failures and cooling system failures. Most air failures seem to be a governor, lines or fittings, which are relatively inexpensive. For me it was a $20 governor and a $60 air dryer rebuild kit.

Hydraulic cooling failures can be huge. We had a pump fail and the repair was under $2K. It seems that any reconfiguring due to no-longer-available parts will result in a $10K repair.

Engines do fail, but it seems uncommon. We replaced a transmission computer for around $1K.

My best advice - buy something that has a good history, Have access to several thousand in CASH. Learn as much as you can. When our transmission failed, I understood the symptoms from reading forums. I knew the computer was a plug-in and knew where it was, I knew that they could be repaired component-level. This information saved me a 60-mile tow, $175 an hour labor, maybe waiting days for the repair, and a savings of $1200 for a refurbished computer over new. Oh, and a cash discount!

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Old 06-20-2016, 05:46 PM   #9
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I echo what everyone else said. When buying an older coach, make sure you get a complete set of maintenance records and then compare those records with the recommended maintenance for that chassis and engine. You will be able to see any holes that may cause a problem. Besides, the owner that keeps detailed records is one that has probably taken meticulous care of the coach.
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Old 06-20-2016, 09:08 PM   #10
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Don't limit yourself to diesel power. I know a couple who full-timed is a gas power MH(towed-Honda CRV) for 14 years. No telling how many still are.
2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member,FMCA."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert the Constitution. "Abraham Lincoln"
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Old 06-20-2016, 09:12 PM   #11
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Originally Posted by timjet View Post
Maintenance records will indicated if the previous owner maintained the engine. Get an engine survey/inspection before buying.

I have 2 Cummins series B engines in my boat. They can be very reliable or very expensive depending on their maintenance history.

As a heads up on costs, Oil changes once a year will cost you about $100 if you do it yourself.
Even that won't catch a valve about to break, ask me how I know!
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Charter Good Sam Lifetime Member, FMCA, SKP
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Old 06-20-2016, 09:17 PM   #12
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All of the Allstars I have looked at had a Cummins ISL mounted mid coach and a side mounted radiator with a hydraulic fan. Keep the maintenance up and failures will be low. The most common failure on ISC/ISL family engines is the 1. exhaust manifold. If replaced by you 400-500 dollars, manifold can sometimes be resurfaced but you need new bolts, gaskets etc. 2. Turbo/waste gate failures. Turbos are expensive especially VGT turbos but can be rebuilt. Waste gates are rebuild able depending on which shop you go to. So anywhere from $100 in parts if your a diy'er to 3-5k depending on problem. 3. Air compressor, usually inexpensive depending on access to it. Now for example if you do not inspect your intake system and something is loose or you don't change air filters like you should it could lead to a $25,000 engine rebuild at worst not a diy'er project for most people. Gotta pay attention and stay on top of things can't stress that enough. The Allstars I have seen have great access to the engine through the floor in the kitchen. As mentioned earlier anything mechanical can break maintenance or lack of is usually the deciding factor but Murphy is out there. I replaced an exhaust manifold a couple months ago but other than that have not any major issues with my ISL. Had a Cat powered DP before and didn't have any issues with it either but I stay on top of maintenance also. These DP's are complex and require a certain amount of attention but it's not something to lose sleep over there should be manuals that come with the coach that let you know maintenance schedules. I would have it inspected by a good mechanic if you are not real knowledgeable about diesel Motorhomes and not the mechanic at the dealership. It's a lot of money. Also consider a good warranty, could save you a lot of money. Good luck Newmar/Spartan makes a great product.
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Old 06-20-2016, 10:21 PM   #13
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Upon inspection if you notice that the coolant reservoir bottle is empty -- RUN!
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Old 06-22-2016, 04:03 AM   #14
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Originally Posted by Ray,IN View Post
Don't limit yourself to diesel power. I know a couple who full-timed is a gas power MH(towed-Honda CRV) for 14 years. No telling how many still are.
Thank you. I consider a gas one as well. I know they are much cheaper. Maybe I am wrong, but it seems to me that diesels are more reliable than gas ones. It is also very important that they are much quieter (we are entertainers and will use our MH for a concert tour in US. My wife is a singer and she can easily loose her voice during a ride from venue to venue ). It is possible that I am going to upgrade in a year or two.

Thank you all for your replies. Extremely helpful!
I am glad to hear that diesel engine don't have to be super expensive to maintain. I will definitely look for a maintenance record before i buy anything.
All the best! and safe travels!

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