pnichols
The Other California
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I'm curious ... does the Sprinter have a mode in it's transmission like our E450's Tow/Haul mode?
I push a button on the end of the gearshift to engage Tow/Haul mode. In this mode the transmission automatically downshifts one gear whenever I lightly tap the brake pedal once. This is a real handy and quick way to maintain complete control on downgrades.
2005 E450 Itasca 24V Class C
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DRTDEVL
SPAM Town, USA
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No, there is no tow/haul mode. The transmission is calibrated for hauling at all times, so it is unnecessary. As for engine braking, it is almost non-existent. This has to do with the differences between diesel and gas.
On a gas engine, the intake butterfly closes, creating a high vacuum within the engine. The computer shuts off the fuel supply, and you now have a very large, hard to turn air pump under the hood. This is what holds back your speed.
On a diesel engine, there is no butterfly, nor is there any vacuum. A separate pump is mounted to the engine to make vacuum for those systems. There is a slight braking effect from the engine, but there is no vacuum drawing down your speed. this is why you hear big rigs making a lot of noise on deceleration... the invention of the Jacobs Engine Brake (Jake Brake). It opens the exhaust valves and closes the intake valves differently in order to create vacuum in the engine. The result of this is the loud B-A-A-A-A-A-A-A-A-A-A-A-A-A-A-P when going downhill or slowing down. Yes, some abuse these just to make noise, but its actually an important safety device.
A more recent invention is the exhaust brake. These are more common on large DPs and buses, as they are nearly silent. Only a loud hiss is emitted by the exhaust, and most of that is quieted by the muffler. These do not offer as much braking effect as a Jake Brake, nor are they as long lasting and reliable (actuators get sooted up and stick, etc), which is why they are not commonly found in big rigs.
Resurrecting an inherited 1980 Minnie Winnie 20RG from the dead after sitting since 1998..
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CharlesinGA
South of Atlanta, Georgia
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You do gain a measurable amount of engine braking from a diesel, via the compression in the cylinders. When descending a steep grade I gear it down manually (it has a left-right tap up-down shifter) and will take it down to 1st if necessary, usually before beginning the decent. Short jabs of the brakes and its fine.
Charles
'03 Ram 2500 CTD, 5.9HO six speed, PacBrake Exh Brake, std cab, long bed, Leer top and 2008 Bigfoot 25B21RB.. previously (both gone) 2008 Thor/Dutchman Freedom Spirit 180 & 2007 Winnebago View 23H Motorhome.
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wolfe10
Florida
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DRTDEVL wrote:
the invention of the Jacobs Engine Brake (Jake Brake). It opens the exhaust valves and closes the intake valves differently in order to create vacuum in the engine. The result of this is the loud B-A-A-A-A-A-A-A-A-A-A-A-A-A-A-P when going downhill or slowing down. Yes, some abuse these just to make noise, but its actually an important safety device.
Slight correction. An engine compression brake (aka Jake brake) works by allowing the piston to come up on the compression stroke-- it takes a LOT of energy to compress 18 or more "volumes" to 1. Then the exhaust valve opens, allowing all that compressed air to go out the exhaust. No fueling occurs during its activation.
With the throttle closed, engine compression brake OFF, the same compression occurs, but once the piston passes TDC, most of that energy is used to push the piston back down. So, with the exception of a small amount of friction, not much braking action occurs. No fueling occurs with the throttle closed (same as with engine brake or exhaust brake on).
Now, an EXHAUST BRAKE works basically like a "potato stuffed in the tail pipe". It provides back pressure (the amount speced by the engine manufacturer). The engine (basically a large "compressor" has to work harder/produce braking HP) to work against that back pressure.
* This post was
edited 05/01/18 08:33am by wolfe10 *
Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240
Diesel RV Club:http://www.dieselrvclub.org/
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ronfisherman
SE Michigan
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Many of the pickup trucks like the Duramax use vanes in turbo to work as a Exhaust Brake. Closing the vanes does the same as a closing the baffle in a exhaust pipe type Exhaust Brake.
2004 Gulf Stream Endura 6340 D/A SOLD
2012 Chevy Captiva Toad SOLD
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Oldtymeflyr
Arapahoe Hills, CO
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Downhill braking on a Sprinter is in the transmission.
When you let off of the throttle in 5th (hi gear) there is some but little slowing effect.
Tap the gearshift to the left and each time you will drop a gear. With each lower gear there is more braking effect from the transmission. Tap the gearshift to the right to climb up a gear. The gear you are in will show up on the dash between the tach and speedo.
The shifts are limited by RPM, if you have too many RPM for the gear the transmission will not let you shift into that gear.
Recently we were coming down Raton Pass, in our Sprinter with a toad, settled on 3rd gear for the steepest parts, little foot braking necessary.
Rick
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LunarSea
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ron.dittmer wrote:Thor and Jayco are still lower-end brands based on everything I read on forums. The lower price translates to more issues of which new owners deal with. That old saying applies, you get what you pay for.
The ***Link Removed*** sure looks interesting. Too bad it is so heavy. A full-length slide out with a Murphy bed, or two slide outs, all add significant weight. A typical slide out adds around 600 pounds. I can see how it gets down to 700 pounds for you and whatever you bring on-board. Their website does not break the specs down per model leaving me to wonder if the twin bed model 24TW with one small slide-out could double that ridiculous 700 pound limit.
Are you dead set on the Sprinter chassis? There are many interesting shorter class B+ motor homes built on the Ford E350. You do seem to be diesel-seasoned, maybe staying away from gasoline models. But in-case you are curious, here are some considerations to thing about.
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Advantages Of The Ford E350 with V10 Engine, Over The Sprinter Diesel
- Given identical motor homes both brand and model, the Ford is around $13,000 MSRP cheaper
- The Ford V10 engine has 50% more horse power and torque
- The Ford E350 chassis handles 1430 pounds more weight.
- The E350 is able to tow a heavier load.
- The E350 rear axle is significantly wider which translates to better stability.
- In most places traveled, gasoline costs less than diesel fuel
- The Sprinter diesel has limited mechanical service shops around North America
- The Sprinter diesel is typically outfitted with a propane generator. Propane is a critical fuel for RV operations, and generally needs to be rationed when dry camping.
- This Next Point Is Debatable But Still Worth Noting....The V6 Sprinter diesel engine is not allowed to idle for extended periods. This limitation is detrimental when you need a/c but there are generator restrictions, you are low on propane, or you have a mechanical failure with the generator or roof a/c. The Ford offers a great backup system. The V10 can safely idle for hours on end with 55 gallons of fuel to support it, heating, cooling, and battery charging, all valuable if you have a baby, pets, or health/respiratory issues.
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LunarSea
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The Tiffin Wayfarer on the Sprinter Chassis generator is Diesel.
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CharlesinGA
South of Atlanta, Georgia
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A number of folks have complained about the size of the Sprinter fuel tank. Mine, and for quite a few years after, are 100 Litre/26 gallon. When MB designed the 4 wheel drive system for the sprinter, they had to reduce the size of the fuel tank to about 24 gallons and they made this change universal rather than making two different fuel tanks. In a Sprinter van, its not an issue given the 24 mpg or so that they get, but in the motorhomes, with 16-17 mpg, it becomes an issue, especially out west where the fuel stations can be far apart.
Charles
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