Community Forums

RobRV · 09-14-2009, 02:05 PM

At approximately What mileage/Hours would most consider to be the "Break In" point for a Cummins Diesel? It is the C 8.3 Mechanical!

Mileage is 36,000 which is I'm told is low for the age (1998) of the Coach!

It has been well maintained and runs fine!

JackHammr' · 09-14-2009, 02:19 PM

I think 75-100k , is a hard one to answer ..

I drive for a living and my C15 is considered "broke in" at 100k

Gary RVRoamer · 09-15-2009, 12:09 PM

I guess it depends on what you mean by "broken in". At 36k it is in the teenage years of its lifespan (at least 250k miles). But if you mean will the fuel mileage improve more in the future, the answer is probably no.

JackHammr' · 09-15-2009, 12:37 PM

Several of our work trucks have the 8.3 and a couple are approaching 500k ..

Stay on top of stuff , and the 8.3 with not give you much trouble ..

Thats one of the things about a diesel tho' , you have to catch the little things , before they become big things , and with a diesel they become big things pretty quick ..

Ray,IN · 09-15-2009, 05:22 PM

Hopefully no-one minds me chiming in about my 5.9 Cummins. It always used a little oil from day one. We made one trip to SW CA.(nother story) Eastbound from Bakersfield to Las Vegas on the return leg, there is a looong uphill grade. My 5.9 heat gauge ventured into the red zone, and I'd stop long enough for the engine to cool. When I asked my son-in-law(maint mgr for major trucking firm) why my engine stopped using oil on that return leg, he said I finally worked the engine hard enough for it to "break-in". That was at 89K miles. He also said the harder a diesel is worked(within reason) the better it runs.

nplenzick · 09-16-2009, 07:07 AM

Quote:

Originally Posted by Ray,IN

Hopefully no-one minds me chiming in about my 5.9 Cummins. It always used a little oil from day one. We made one trip to SW CA.(nother story) Eastbound from Bakersfield to Las Vegas on the return leg, there is a looong uphill grade. My 5.9 heat gauge ventured into the red zone, and I'd stop long enough for the engine to cool. When I asked my son-in-law(maint mgr for major trucking firm) why my engine stopped using oil on that return leg, he said I finally worked the engine hard enough for it to "break-in". That was at 89K miles. He also said the harder a diesel is worked(within reason) the better it runs.

That's interesting. We even see they same thing on air/oilcooled BMW motorcycles. At least 24K until they break in sometimes more. It also seems the hotter you get them during that time the better the rings seal the less oil they use. My dealer told me a story of one of their customers who started their bike and then got a phone call, he forgot he started it and it ran for 2 1/2 hours. The oil temp was in the red zone when he remembered. He thought he did considerable damage to his new bike. The dealer said it was one of the best running BMW's that they ever had. Used zero oil after that.
My 8.3 is using about 3 quarts of Rotella T in 10K which I would think would be normal. The coach has 53K on it and is worked pretty well as I tow a 6500 pound trailer around the country. I expect this motor to last a very long time. I really don't know if it's broken in or not be it really seems to run better and smoother since I bought it with 19K on it.

J Walker · 10-01-2009, 08:24 AM

My ISB never burned oil so I don't have that break in issue, but I have heard that at some point the MPG increases. I have not experienced that for 60,000 miles but coincidentally at that point I began to use 55 MPH as my max speed and I installed Air Tabs at about the same time (Google Air Tabs for info). My MPG went from 10 to 12. I don't know if any break in was involved but I surely am pleased with the change.

cwg · 10-26-2009, 07:14 PM

At a Spartan Motors tour, the Cummins rep stated that on average their engine is considered "wet" until at least 28,000 miles, meaning that it was capable of using some oil until then. Of course it varies, but he said the majority will get the best fuel economy and not use any oil after that mileage.

He also stated that the relatively small weight we move by a motorhome is akin to a small shell on the back of a turtle. They are capable of so much more work than we make them do, thus the long warranties and mostly maintenance free engines we enjoy.