03-01-2004, 06:11 PM
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Certified diesel nut
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Join Date: Mar 2002
Location: Pacifica (SF Bay Area), CA
Posts: 2,946
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Cummins posted this on their website on a FAQ page for Dodge owners who were new to the 6BT a while back, regarding their recommended break-in procedures.
Quote:
The engine in the new vehicle is very new and the piston rings have not had a chance to 'seat' yet and some cylinder pressure is getting by the rings into the crankcase, which is what we call 'blowby'. After you get 1000 or so miles on it, the engine needs to be 'worked' to create some cylinder temperature. If the engine is operated with only light loading, it can take up to 30,000 miles to seat the piston rings.
Here is what we have shared with ours about break-in time: Normal highway driving, without a heavy load, is usually a good way to start, at least for the first couple hundred miles or so, then the engine should be put to work.
If your engine is an on-highway, automotive application, operate the engine at 1500 to 1800 rpm in high gear for the first 80 to 160 kilometers (50 to 100 miles). But do NOT idle the engine for more than 5 minutes at any one time during the first 160 kilometers (100 miles) of operation.
If it is an off-highway, non-automotive application, operate the engine as follows during the first 3 hours. Operate the engine at 75% throttle while loaded. Again, do NOT idle the engine for more than 5 minutes at any one time. Also, do NOT operate the engine at rated speed (rpm) and full load for more than 5 minutes at any one time.
If you 'baby' the engine initially and never put any load on it to increase cylinder temperatures, then it will take longer for the rings to seat. We are not suggesting that the engine be abused in the beginning, but make it do some work and the piston rings will 'seat' faster and will also help avoid any carbon build up or fuel 'slobber' because of light load operation.
We would suggest driving in hilly or mountain areas, if possible or
loading the truck with 700 or 800 lbs. or pulling a trailer (tandem car hauler type). The trailer would not have to be loaded, however, if you use a small single axle trailer then some load on the trailer would be recommended. The idea is to make the engine 'work' and build some cylinder temperature and normal driving with no load on the truck is not 'work' for a heavy duty diesel engine.
Also, it is always a good idea to vary the engine speed in the beginning, so the whole vehicle, as well as the engine, gets accustomed to varying speeds, loads, rpm, etc. We have no specific time or mileage published when an engine is considered to be broken in. Actually, we would consider 1000 miles as the initial break-in period and lets say 'matured' by 6000 miles.
Really, this has not been much of an issue for us. The engines usually run about the same after 5000 miles as they do in the beginning. Of course they tend to loosen up a bit and might improve on oil consumption slightly, when the piston rings fully get 'worn in or seated'.
For more detailed information on break-in, refer to General Engine Test Procedures (Chassis Dynamometer) (14-05) in Cummins Shop Manual B Series Engines before operating the engine to avoid internal component damage. (Refer to Cummins Troubleshooting & Repair Manual for B Series Engines,
Bulletin 3666087, Section 8.)
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