What to buy in a used Diesel

I remember stopping by a local bus service shop about 10 years ago. We were looking to find a place to service our coach, and so were interested to see what this shop had to offer.

When I walked in, there were several fellas sitting around, chatting, and when I explained our mission, they explained that the shop serviced buses with Detroit engines. They then asked what kind of engine our coach had: 'Cummins', I replied. "Oh, good engine", they responded ...

I've had several such encounters over the years and have found that owners of Cat, Cummins, or Detroit engines are all happy, regardless of the paricular manufacturer. Why? I think it is because all the engines are very well built, heavy duty pieces of machinery. What matters more is whether the particular engine in a coach meets the needs and expectations of its owner. Some people want to be able to drive over the summit on I-70 going West from Denver at 70 mph; others are happy just to get over the top!

The Cummins 350 in a 2003 model year coach would likely be an ISC series (Electronic engine) and is an extremely reliable series of Cummins engine. When I bought mine, I called Cummins with the engine serial number to check if there had been any known issues or recalls. There had not been. In conversation with them, the person at Cummins said that they generally don't consider that engine fully broken in until around 140K miles.

I can't rightfully comment on the CAT. While I've driven MH's with CAT engine, I've never owned one.

Most importantly, it boils down to how well the motor has been cared for by the the previous owner(s). If properly maintained, I don't think that you could go wrong with either.

The one that has the floorplan and living features that suit your needs. After that, condition of the house.

My experience in 10+ years with a RV club is that more folks end up trading RVS, or giving up RVing, over livability issues than one chassis or one engine being better than another.

Executive wrote:
Cumming is a City in Georgia....:W....Dennis

No kidding? That is not what I was thinking!!! ;)

lfeather wrote:
CATs are good engines, but their facilities do not cator to motorhomes like Cummins' nationwide Coach Care service does. Cummins Coach Care can work on your house stuff as well as the engine. I talked to the Orlando Cummins Coach Care facility and mentioned to them that they sure had a lot of motorhomes in for repair and wastold that motorhomes are 56‰ of their business. Just my 2 cents.

I've heard that most Cummins centers will work on Cats, as well. Either way, not a problem and an engine is an engine, as far as most Cat service centers are concerned and have talked to one already. Then there's the service centers that cater to all, that are without spark plugs.
There's a lot of high end units running around with Detroit power, as well and don't think they're left to fend for themselves, either.
I know what you're saying however and nice to have a campground located within the facility, like a lot of Dealerships are catching on to, by learning from the Lazydays people.

CATs are good engines, but their facilities do not cator to motorhomes like Cummins' nationwide Coach Care service does. Cummins Coach Care can work on your house stuff as well as the engine. I talked to the Orlando Cummins Coach Care facility and mentioned to them that they sure had a lot of motorhomes in for repair and wastold that motorhomes are 56‰ of their business. Just my 2 cents.

jrp wrote:
Just another opinion, but mine is that 132,000 vs 25,000 is meaningless on these heavy duty diesels. Its just getting broken in at 100,000 miles. Again, its more important to know the previous owners habits than the odometer reading or brand name. A bad, reckless driver could do more wear & tear damage in 25,000 miles than a responsible, careful driver would do in 500,000 miles.

I will never understand the mindset, that mileage has no bearing on a DP and like the engine is the only thing in the whole rig that has moving parts. Besides that, with extra miles, usually comes extra living in the house and subjecting the body and chassis to the elements, as well.
Evidently, I'm missing something here, but like most, I think, I usually steer towards the lower mileage vehicles, when making a purchase.

msmith1199 wrote:

jrp wrote:
If its a 2006 Cat its likely a C7 engine, which can be set for 300, 330 or 350 HP, just by changing the ECU options.

Which engine is better is a question with no answer, just personal opinions. What's more important is which previous owner was more faithful in assuring each fluid & filter change was performed as recommended. I would buy whichever one came with the best maintenance records from the previous owner (assuming there were no other deciding factors in the rest of the rig). An owner that keeps detailed records of all maint performed, is usually an owner that makes sure maint is done on schedule.

What does that entail? I have the Cat C7 that is set at 330 hp. If I wanted the 350 HP is that just a software change or does it require hardware too? How much should it cost?

Best advice is to call the Caterpillar RV Hotline with your engine serial number: 877 777-3126.

You could have a C7, or one of the last 3126's. Remember it depends on engine production date, not chassis or coach production date.

And, I would not get too excited about 20 more HP. I believe that torque remains exactly the same. Remember, the time you want more power is on those long climbs-- exactly the time that you are already stressing your cooling system. Adding more heat (which you WILL if you want more power) only adds to the cooling load.

jrp wrote:
If its a 2006 Cat its likely a C7 engine, which can be set for 300, 330 or 350 HP, just by changing the ECU options.

Which engine is better is a question with no answer, just personal opinions. What's more important is which previous owner was more faithful in assuring each fluid & filter change was performed as recommended. I would buy whichever one came with the best maintenance records from the previous owner (assuming there were no other deciding factors in the rest of the rig). An owner that keeps detailed records of all maint performed, is usually an owner that makes sure maint is done on schedule.

What does that entail? I have the Cat C7 that is set at 330 hp. If I wanted the 350 HP is that just a software change or does it require hardware too? How much should it cost?

Pick the one with Aqua Hot and Air leveling.