| Author | Message | ||
| Robert H. (Ultimarv)
Registered Member Username: Ultimarv Post Number: 10 Registered: 2-2007 Posted From: 83.208.52.10 Rating: N/A |
We have a Detroit Series 60 engine in a factory built Vogue motorhome and I am wondering about the high-idle. We run a couple hours down the road at about 65 and when we pull into a truck stop we usually high idle for about 5 minutes at 1000 rpm before shutting it down. Is this right? There is no high-idle switch, so we need to set the cruise control while in neutral. I understand that we need to high-idle if we are parked with the engine running somewhere, but am not sure of the rpm. Also, do you high-idle while refueling? Thanks, Robert | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 321 Registered: 7-2006 Posted From: 66.217.106.160 Rating: N/A |
With a load of passengers, and the bus air conditioner (or heaters) going full tilt, along with all the lights, etc.... if it wasn't in fast idle and we sat longer than 1/2 hour , the batteries would become depleted. What other reason for "fast idling"? Unless the engine's under load, all it's going to do, is burn more fuel... (Let the battle begin) | ||
| JC Alacoque (Jc_alacoque)
Registered Member Username: Jc_alacoque Post Number: 30 Registered: 7-2006 Posted From: 154.11.109.30 Rating: N/A |
Turn it off! Iddling just wastes fuel and pollutes the air. It is also not good for your engine or your cooling system. Greyhound did a study on iddling about 5 years ago or so and found just that. They sent all drivers and agencies/depots a memo asking that busses be shut down when parked. The figure for wasted fuel was in the millions of dollars. | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 168 Registered: 10-2004 Posted From: 72.80.31.118 Rating: N/A |
hi idle was used for a cool down of hot motors, usually with turbo's, just before shut down.It is not a long period . Soon vehicles will be shuting down at stop lites. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 571 Registered: 12-2000 Posted From: 76.1.180.218 Rating: N/A |
On the 2 cycle detroits, fast idle keeps the oil pressure a little higher and I have been told it helps prevent excess fuel from washing down the cylinder walls. I agree a better solution is to shut it off. Only time we idle is long enough to build air, and we frequently build air before starting by using our aux. 120 volt air compressor. If we idle the bus to build air we do it on fast idle. Jack | ||
| Robert H. (Ultimarv)
Registered Member Username: Ultimarv Post Number: 11 Registered: 2-2007 Posted From: 83.208.52.10 Rating: N/A |
Interestingly, when we were on our trip last week I parked next to a Greyhound bus that was on high idle at a truck stop. He was letting off and taking on passengers. I asked him about high idle rpm's and he said he had a high idle switch, but thought it to be around 1000 rpm's. He also had a Series 60 engine onboard and mentioned that the high idle ensures oil to the engine parts on prolonged stops. Makes sense since my DDEC tells me if I have excessive (normal) idle and tracks the stats. Nothing was mentioned about high idle after a hard haul. On my sport cars (apples to oranges here) the turbos can sieze if not cooled down after a hard run, but Featherlite said it was not a problem to shut it down. Guess I will continue as is, but not worry if it is shut down. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 141 Registered: 8-2006 Posted From: 207.231.81.59 Rating: N/A |
High idle was/is installed on passenger buses to provide heat/air while stopped to load/unload. On MCIs, at least, it is interlocked thru the parking brake valve, and will only operate if the parking brake is applied. Prolonged idling at any speed, (500-1000) RPM, or operating at very low load, is not good for any diesel engine, as it doesn't get warm enough to burn off all the fuel, causing fuel to wash oil off the cylinder walls and dilute the lube oil. This 'no long idle advice' is also published in the diesel pickup owners manuals. HOWEVER, there are also specific instructions about cooling down turbos after being run under load. Turbos are cooled by lube oil, and when shut down hot, the heat turns the oil left in the turbo into coke, which plugs the oil passages, and that's the end of the turbo. EMD locomotives (just a BIG Detriot) have an electric lube oil pump and a 20 minute timer to provide cooling oil to the turbo, which operates anytime the engine is shut down. There are also devices sold which will keep the engine idling with the key removed until the turbo is cool enough. This lets the driver shut off and lock up without waiting for the turbo to cool. Everything else is shut off, and the truck can't be driven during the cool-down period. Bottom line? Idle for 5 minutes before shutting down after operating under load, especially on hot days, turbo or not, your exhaust manifold(s) will thank you also. High idle on buses so equipped will give better a/c, but on our mechanical injected buses, it won't work until about 80-90psi, as it is air operated, so it won't help build air quickly in the morning. (If the engine needed high idle oil pressure to survive, it wouldn't be built with normal idle, and high idle tied into the parking brakes!) As John said, the battle will continue. George | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1229 Registered: 12-2000 Posted From: 67.181.161.137 Rating: N/A |
Robert - As John mentioned above, the ONLY reason for using fast idle on a revenue-service coach is to keep the massive HVAC system operating properly. A three bucks a gallon for diesel, you're throwing money away by using a fast idle setting. In just the time it takes you to pull off the freeway, then mosey around town to pull into line at the truck stop, your turbo has spun down sufficiently that shutting it off will not harm anything. Look at the size of the oil line feeding the turbo on your S-60 vs the one on your car. Huge difference when you compare an industrial application to a consumer product. Also, the S-60 has higher oil pressure at idle than the two-strokes, so that argument for fast idle is non-applicable. Finally, due to the nature of diesel fuel systems, keeping the engine running while you fuel the coach may, in fact, give you a "false full", due to foaming. It's also illegal in some states. Bottom line = shut it off. FWIW & HTH. . .  | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 142 Registered: 8-2006 Posted From: 207.231.81.59 Rating: N/A |
A question: If a running diesel engine foamed its fuel tank, (and I assume expands the volume?) what would happen if the fuel tank were filled with the engine shut off, then the vehicle is started and driven? "False full" foaming would then push fuel out of the tank overflow, etc.??? A comment: Look not only at the size of the oil line to the turbo, but at the size of the turbo itself. (A whole lot of thermal mass to cool off!) George | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 552 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
I have to shut my engine off when I fuel it, because it burns it faster than I can put it in! BTW, another tip...to save some fuel- plug the coach in a couple of hours before you plan to start it, also pre air the system with your home air compressor, and you won't have to run it so long before you start out. Also, less smoke and unburned fuel and oil in two strokes. | ||
| Robert H. (Ultimarv)
Registered Member Username: Ultimarv Post Number: 12 Registered: 2-2007 Posted From: 83.208.52.10 Rating: N/A |
I have to hand it to this community: a lot of good facts and no nonsense! Thanks guys (generically speaking gals :-) | ||
| Jim Rink (Fakeguy)
Registered Member Username: Fakeguy Post Number: 32 Registered: 1-2005 Posted From: 24.33.85.105 Rating: N/A |
AIR UP WITH A HOME COMPRESSOR??? I have the compressor but not sure how to air up my 1962 PD4106?? how do I tap into the air system to do it...would appreciate input | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1230 Registered: 12-2000 Posted From: 67.181.161.137 Rating: N/A |
Jim - In the engine compartment, near the "ping" tank, you should find a valve similar to that on a tire that you can tap into. The "ping" tank is at the top of the engine compartment immediately above the transmission access door. Has a drain valve on the bottom. Make sure your air compressor has a moisture trap on it to reduce the risk of putting water into the coach's air system. FWIW & HTH. . . | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 115 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
I replaced the drain on the air comperssor dischage muffler with a valve that allowed me to install an air coupling on it. I then just plug on my air hose to air up the bus. This makes it easier to work under the bus also. | ||
| Jim Rink (Fakeguy)
Registered Member Username: Fakeguy Post Number: 33 Registered: 1-2005 Posted From: 24.33.85.105 Rating: N/A |
RJ AND Zimtok...thanks for the come back...I know which ping tank you are talking about...drain it regularly but never thought of tapping into...will rig up...I keep my 4106 at a campground when not on the road and air leaks off during the week...this is the answer to airing up without starting and idling just to fill the bags | ||
| Jim Stewart (H3jim)
Registered Member Username: H3jim Post Number: 291 Registered: 10-2004 Posted From: 68.6.175.166 Rating: N/A |
My series 60 has a factory high idle. I undertand it was for use when running the big HVAC while parked. High idle only comes on when the parking brake is engaged and its in neutral. My high idle is set about 1100 rpm. I don't generally use it ecept when running my over the road air when parked, other than that, I shut it off. Although I have to confess, I usually leave it running when refueling. Generally, the weather is hot and I'm running the air, so I just leave the bus run. | ||
| Brian Elfert (Belfert)
Registered Member Username: Belfert Post Number: 34 Registered: 7-2006 Posted From: 132.148.80.215 Rating: N/A |
My Dina with Series 60 will shutdown after 5 minutes of normal idling. Normal idle is around 700 RPM. There is a fast idle switch that increases idle to 750 RPM. The engine will not shutdown if the fast idle switch is turned on. My cruise control can also be used to increase the idle RPM. If I do want to idle the engine for some reason, I usually use the cruise to up the RPM. 750 RPM is most likely not enough to stop engine damage. Brian Elfert |