Topic: Cummins Engines (Updated 01/2002)
Presenter: Tim Kelly
Cummins Engine Serial Numbers with potential problems: Build date (last) 4/21/98) SN 45686566. Anything later has the new hardware. These should by now all be corrected. If uneasy, have a Cummins person look at it.
Cummins view on synthetic oil: Can be helpful in very cold lubricity conditions -- 10-20 degrees. Can extend drain intervals. ISB, ISC engines haven't yet been tested, so there is no change in either miles or time (one year) service interval. Additive package depletes after 12 months. Fuel additive for stored coach? :Yes. Fill tank completely when you're stored for a month or more; if six months or longer, use fuel additive. Controls moisture and fungus.
For normal driving, you should not need a fuel additive, and Cummins does not recommend them. Best to fuel at a truck stop where there is a high volume of diesel fuel usages.
Mileage interval for oil change on ISC is 15,000.
Oil blowby or carryover. Oil over the back of the coach and tow car. A lot of the issues in the last 18 months have been with 330 and 350 (less so 370). These engines increase oil flow and air flow significantly. Breather tube can fill up and blow oil out. It's recognized as a problem, and there have been updates to breather assemblies. The hardware is now there to take care of this issue. It's covered by warranty. Even if Pac Brake issue is involved, Cummins will honor it under its warranty, and work it out w/Pac Brake.
Engine coolant temperature should be 190 degrees. It bumps over 200 or to 210 under stress. But should not normally be over about 190 at the coolant level. Overheat is typically a radiator or fan speed issue. As engines age, they tend to run hotter because the cooling system becomes less efficient.
Difference between ISC & ISL. First is 8.3 liter; ISL is 8.9 liter. Cylinder head accommodates engine brake electronically. Piston is now two piece piston, and top of piston is now steel.
Don't idle the engine over 10 minutes. When you idle you don't burn fuel efficiently, and are building soot. He recommends letting the heat build for about 3-4 minutes after starting; but don't go past half throttle until the engine reaches 180 degrees. Okay to use quarter to half throttle prior to that time.
Engine shut down procedure is important. If you're on a flat interstate at 65 mph, when you come into a rest stop you've only been running about 185 HP. By the time you're in, seat belt off, etc, you can turn it off. If you're going up hill 15 miles and pull into a rest stop, you'll need to keep the engine on for 3-5 minutes. If you shut it off, oil in turbocharger will boil and cause problems. 5 minutes is maximum you'd ever need. Manifold temperature should never exceed 1100 degrees at manifold, or 1400 degrees at cylinder head.
Use of exhaust brake. When it's on, transmission will downshift to keep engine speed as high as possible to keep braking at maximum. If you're above 5-6% downhill, and coach continues to build speed despite exhaust brake, at 2800 rpm the transmission will automatically upshift, dropping rpm, and the exhaust brake will be far less helpful. Transmission was protecting the engine -- but now you're having to rely on your service brakes. Therefore at 2600 rpm you'll need to start using service brakes to keep engine speed at 2200-2400 rpm.
Sweet spot for ISC engine will be between 1600-1800 rpm, which should yield about 60-62 mph.
Synthetic oils are excellent, but they are very expensive. On North Slope they recommend it for starting capabilities in extreme cold weather. Not considered suitable for most RV applications. [Ed Note: We've had varying opinions on this...]
Best to use plug-in whenever possible in cold weather. Below 40 degrees it's important. It will considerably ease starting, reducing warm up time and getting you out of the park sooner. It typically warms the engine oil to around 80 degrees, ensuring a quick start, and minimizing cranking. The device is just a rod which uses about 100 watts -- not much more than a unit used to heat an individual cup of coffee.
Palm pilot will read everything from your engine. Will tell total gallons burned, etc. It's a $250 software/hardware. "Road Relay" is dash mounted, engine specific unit available with LED readout and sells for about $1000. Similar to Silverleaf, but less expensive. Both Silverleaf and Road Relay read the engine's computer and provides the data to the cockpit.
Redline at 2500 rpm? That mark is essentially related to acceleration. When braking, the engine will allow for 300 rpm higher than the governed top rpm.
If you're parked for a month or more, always top off your fuel tank and use a fuel treatment that will inhibit algae growth. All truck stops have fuel treatment. These are "biocide" or fungicide specifically for diesel fuel.
Cummins makes an extended life antifreeze that will last to five years. Regular antifreeze has a two year life, and then needs replacement. "SCA" is supplemental cooling addtives. The antifreeze should be tested at each service, and a notation made of the results. Test strip will tell you accurately what the status of the antifreeze is, and SCA level.