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Mud flap Mythbuster

Yahoo Message Number: 75916
I took my mud flap off my 2001 Intrigue (40' with 350 Cummins) and ran it for several trips totalling about 800-900 miles with the following results:

MPG improvement: zero

Engine temperature: 190 (no change)

My mud flap is going back on.
Bob
11237

2001 Intrigue

Re: Mud flap Mythbuster

Reply #1 –
Yahoo Message Number: 75917
Good for you Bob. Mine stays off (going into fourth year). 6% improvement in MPG, 10 to 15 degree drop in transmission temp, not engine temp.

Probably why they make vanilla and chocolate ice cream.

George

'04 Inspire 51061

Re: Mud flap Mythbuster

Reply #3 –
Yahoo Message Number: 75920
Walt,

I have no idea. Not being an engineer I won't even try a guess. My problem was with tranny temps and removing the flap helped. I am firmly convinced the only purpose for the flap was PR. It does nothing in the way of protecting the towed, the rear wheel flaps handle that.
George

'04 Inspire 51061

Re: Mud flap Mythbuster

Reply #4 –
Yahoo Message Number: 75922
Where you will see a drop in engine temp is on long grades, pulls longer before getting up there and cools quicker. Thermostat keeps it the same otherwise. I also noticed a drop in transmission temps. Mine stays off as well. The flap acts a an air dam not allowing air to move through, around and out from under the coach.

Leonard

97' Magna 5418

Re: Mud flap Mythbuster

Reply #5 –
Yahoo Message Number: 75923
Bob,

I too removed the mud flap seeking a reduction in both engine and trans temperature. And both did came down. I haven't done any comparisons with fuel efficiency so I can't speak to that. Improved airflow, less the mud flap, is easy to make sense of. The air pressure necessary to raise the mud flap needs to build up behind it which implies an increase in air pressure within the engine compartment. It also implies reduced circulation of fresh incoming air. Any flow restrictions (pressure increases) would impede the cooling fan which draws air into the engine compartment. Removing the flap increases the area by which air can exit from the engine compartment which I think is a good idea. All of it means better air flow. I'm not surprised that different busses show different results with the mud flap gone. In your case you didn't see expected improvements which is good to know for those running the same bus as yours. Most here have focused only on engine and trans temperatures. But what about the average temperature in your engine compartment?? This temperature isn't easy to measure and to the best of my knowledge no OEM sensors exist to measure it. As for electronic components, heat usually shortens their life meaning steps taken to keep them cool would make sense. I can only speak about my bus and as previously mentioned, experiences will vary.
Thanks to this forum, I got the idea to remove the mud flap. I did so as an experiment with encouraging results. So my flap stays off and my engine compartment, engine and trans run cooler as a result. For me, cooler is better, even if only 5 degrees F or so. Every little bit helps. Documenting our findings on a per bus basis is also good information. Keep the data flowing!!

At 05:49 AM 11/30/2011, you wrote:

Re: Mud flap Mythbuster

Reply #6 –
Yahoo Message Number: 75926
I also removed mine and immediately saw improvement on Trans temps. The trans has a much smaller area of cooling than the engine in the radiator set up. It seemed that my mileage improved by watching the Silver Leaf, however I am reserving an final opinion until I have run for more miles. 1800 so far indicated about .4 mpg. Well worth it if it continues.
The comment about pressure in the engine compartment is valid. I had tried running with the engine access door open and it helped cooling and airflow and dust in campgrounds.

Dave aka Billy Byte (trusty hound)
2000 Allure #30443


Re: Mud flap Mythbuster

Reply #7 –
Yahoo Message Number: 75943
My mud flap came off on its own (not going there) and I noticed my engine temp never got above 218F on the steepest climbs this summer. Then I went into a body shop and had them cut a big hole in my engine door and put an aluminum vented grade over it and paint it to match the coach. That is were the temperature really started to fall. Now the C12 engine never gets above 198 which is about where the thermostat opens up and then immediately drops to 192 when I am not climbing. Another change was that my rear bedroom stays cooler after shutting down the engine.
It is pretty clear to me that I am not going to go try to find my flap and put it on (besides I would not know were to look for it). My coach was built just a few serial numbers in front of the coaches that came with the vented engine doors so obviously CC saw the merrit in venting the coach engine area better in late 2003, early 2004 without the risk of diminishing their advertising.

Dallas 2004 intrigue 42' C12 11688
 

Re: Mud flap Mythbuster

Reply #8 –
Yahoo Message Number: 75946
Very wise choice. The mud flaps have stopped some road debris from causing massive damage to towed vehicles. Not sure how anyone ever got better mileage and running cooler without it. 98 Intrigue Hal