Sandy and I are still learning how to properly use our Foretravel and from time to time we wonder what practice is best as related to these ares. Opinions and suggestions will be appreciated.:
Starting the engine:
When we turn on the ignition key we wait until all clicking starts and we engage the boost switch before starting.
Warm up period
Pretty much a judgment call here. If we are parked close to a road that demands 50 mph or more when we leave the campground, then I wait until the engine temperature is about 150 degrees. On the other hand, if we have a few miles to drive before we will be able to exceed 20 MPH, then we get underway as soon as we know we are safe to move.
Stopping for lunch or fuel after reaching full operating temperatures and we've been traveling for one to three hours
We let the engine run at least five minutes before shutting it off.
Reaching our destination at end of driving day.
Usually let engine idle for about 7 to 10 minutes
Finally, there have been a few occasions when I have had to re-start the engine a second time after a brief cool down period. I try to avoid this. What do you do?
Unless it is very very cold out, I start up and air up and then pull out slowly. You will warm up much faster under a slight load. As to cool down, that is always interesting. I will idle while registering for the site and unhook at the same time. I will then drive to the site and either pull in or back in, if I am staying longer than a day. If I am only overnighting I will not unhook but I will idle the few mins it takes to register and then drive over to my site. It could be a about 10 mins total but that would be on the long end for length of time idling. I have spent much more time idling in traffic at accidents or construction moving 100 feet every 20 mins....
Idle / Warm-up / Cool down
Fast IdleISM engines may automatically increase engine speed under cold ambient conditions to decrease time for engine warm-up.
Engine Warm-upIdling the engine for warm-up is not necessary. When oil pressure is indicated, put motorhome in motion.
Operate with a light throttle and limited RPM until coolant temperature reaches approximately 150 ºF.
Engine Cool downUnder normal driving conditions, such as exiting the highway or parking, cool down is not required.
If operating under extended high power (full throttle/high boost) conditions immediately prior to shutdown, the engine should be idled for 3-5 minutes.
I agree with the startup - after the coach is aired up, you are good to go. Light load as practical until you are at 150F or so. With shutdown, the critical component in a turbocharged engine is heat soak and coking of the oil in the turbo oiling passages. If you had been pushing the engine hard immediately prior, I would recommend a 2-3 minute cooldown idle.
Reality - for a big turbodiesel that would mean pulling into a rest area at the crest of a mountain. The rest of the time you really almost never tax the engine.
Banks recommended waiting until the exhaust temperature dropped to 300 degrees on my Dodge Turbo Diesel truck. I've discovered that most of the time it is not an issue although in high humidity I some times need a couple of minutes. I should look into installing one on the Cat just to see if I need to idle before shutdown.
I have a habit with diesel engines that I was taught 40 years ago to warm up engine before putting to work and cooling turbo down before shutting down.40 years of habit to hard to break.
Excellent post on engine starting, idling our engines.
With our U300, we start it, make sure we have air and get underway from a lunch, fuel or dinner stop. In the morning I usually start it while the heaters are bringing the interior up to temp and perhaps do a quick walk around to make sure I have not forgotten an awning, antenna or tree branch that might be in the way. I don't usually torture it for the first couple of miles but once the temps start to come up, I don't worry much. In a crowded campground, we start up and get moving immediately so as not to disturb the other campers, some of whom may be in tents. On the road, I shut the engine down as soon as we stop, even during a extended wait for a construction flagman. The big exception here is after climbing a long grade, especially in hot weather with the engine temp above the thermostat. In this circumstance I will keep it at a fast idle until the temps normalize, normally 2 or 3 minutes. The reason is heat soak in the turbo. Unless your are running synthetic oil, the petroleum based engine oil will try and refine itself further and make a product called "coke". Coke build up can shorten the life of the turbo. Another good reason for not idling the engine for extended periods is oil pressure. Low rpm means low oil pressure and with an already warm engine, the oil stream that normally is directed to the inside/underside of the piston crown may be weak and not do it's intended job of providing cooling. This will allow the top of the piston to expand in diameter compared to the rest of the piston. Tejas Coach explains it better than I can and has an excellent web site with tips from millions of miles of diesel coach operation. Please read at: http://www.tejascoach.com/tejasoil.html#Drive (http://www.tejascoach.com/tejasoil.html#Drive)
Aside from my Foretravel experience, I drove and was an instructor for diesel fire apparatus for many years. We were all Detroit Diesel with the County FD all Caterpillar. Normal emergency response called for a "pedal to the metal" response up to the 2400 rpm redline (250 rpm more than we use in our coaches) in each gear from a cold start without any kind of engine pre-heater. If not pumping at a fire, we would use a "fast idle" switch (1000 rpm) to keep the batteries charged and maintain proper engine temps/pressures. Many fire apparatus accumulated over 200,000 (and still going) miles of this kind of driving without any problems. This procedure was defined in seminars by Detroit/CAT and Rajay/Rotomaster turbos.
Hope this is not overkill!
Best to all for those late summer trips!
Pierce & Gaylie Stewart
93' U300/36