| Author | Message | ||
| Arthur J Griffith (Arthurseagle)
Registered Member Username: Arthurseagle Post Number: 67 Registered: 8-2006 Posted From: 72.236.102.131 Rating: N/A |
I had a Stick & Staples MH in the past. I installed a Grass Skirt under the back bumper.It did a fantastic job in keeping the back of the MH and the tow car clean. The difference was quite remarkable. I am ready to put my Eagle conversion on the road and was thinking about installing a rubber flap across and under the back bumper. But I am concerned about air flow from under the rear engine location. Should I be concerned? Will it create a venting problem? What would be the effect if it was installed just behind the drive wheels? Or should I install another grass skirt under the bumper? Any thoughts or knowledge on the subject would be greatly appreciated. THANKS - ARTHUR | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 785 Registered: 8-2006 Posted From: 74.33.54.207 Rating: N/A |
Arthur,Eagles do not like anything at the rear wheels or bumper I tried that on my Eagle and the temp went up 10 degrees removed it and back to normal | ||
| Roger Baughman (Roger)
Registered Member Username: Roger Post Number: 141 Registered: 11-2006 Posted From: 71.159.230.31  Rating: N/A |
I have a rubber flap hanging from my MCI 1984 8-71. Does anybody know if that could be an issue with my cooling? | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1675 Registered: 10-2003 Posted From: 71.58.71.157  Rating: N/A |
they look nice and keep dirt and grease off the toad, however, at least on GM coaches, they put a full width flap behind rear axle, directly below the engine firewall. Thinking about it, it probably does make one run hotter. I'd imagine that a grass skirt wouldn't be as bad. Think about where that heat has to go after leaving radiator fan. | ||
| Larry & Lynne Dixon (Larry_d)
Registered Member Username: Larry_d Post Number: 229 Registered: 7-2005 Posted From: 71.111.185.149  Rating: N/A |
I have a flap back under the bumper you are saying that will cause heat. My engine does pretty well first two hrs and then heats quite quickly on hills after the two hrs. It is a 4905 with 8/71. Please comment this may be a problem solved after four years. I need all the help I can get. Thanks Larry | ||
| Brandon Merritt (Brando4905)
Registered Member Username: Brando4905 Post Number: 20 Registered: 3-2009 Posted From: 173.69.73.236  Rating: N/A |
Larry, I have very similar heating issues with my 4905. Are you towing anything? Until about 2 months ago I had a flapped bumper, removed it at a truck stop in Arizona. It was about 2 in the afternoon,100 degrees,and I was starring at the temp gauge. Helped some. Now back of bus and trailer get filthy! Brandon | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1678 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
you are going to have to try it with and without on same day over same grade to be sure.Speculation is one thing. Fact is what is needed. | ||
| Larry D Baker (Lbaker4106)
Registered Member Username: Lbaker4106 Post Number: 90 Registered: 5-2005 Posted From: 174.42.212.1 Rating: N/A |
I have a grass skirt on the bumper of my 4106 and it does not seem to bother it. I have heard that a solid flap will cause the temp. to rise. | ||
| Larry & Lynne Dixon (Larry_d)
Registered Member Username: Larry_d Post Number: 230 Registered: 7-2005 Posted From: 71.111.185.149 Rating: N/A |
I do tow off and on the tow vehile gets real oily, also the back of the coach gets dirty. My flap is rite draggiing the ground. I do believe I will try withoout the flap as it is some worn oout. May even try a hula skirt next summer. On real hot days I have to drive in second gear on level ground. Larry | ||
| Josh McElhiney (Zcommanager)
Registered Member Username: Zcommanager Post Number: 42 Registered: 1-2009 Posted From: 75.187.41.177 Rating: N/A |
Larry, how well does the grass skirt work at keeping the back of the coach clean? I drive mine to the end of the block and back, and the tail end is filthy!! And the Mrs. doesn't like it!! So I guess you know who is out there with a mop and bucket washing the ass-end of the bus all the time! LOL On a serious note though, has anyone noticed a significant difference in operating temperature with a grass skirt vs. no skirt?? I wouldn't mind skirting the old girl to help keep her rump clean, but not at the risk of the engine overheating. Josh | ||
| Josh McElhiney (Zcommanager)
Registered Member Username: Zcommanager Post Number: 43 Registered: 1-2009 Posted From: 75.187.41.177 Rating: N/A |
Larry Dixon, why do you have to hold her in second gear on hot days? Sorry for the naivitee, but I'm still towards the tail end of the learning curve, as I have only had my coach for a little over a year, and unfortunately didn't get to play much this past spring and summer. Josh | ||
| Jim Wallin (Powderseeker01)
Registered Member Username: Powderseeker01 Post Number: 39 Registered: 10-2008 Posted From: 173.14.23.49  Rating: N/A |
Another solution used on school busses here in Colorado is an airfoil on the rear roof of the bus that looks like a spoiler. In principle it directs airflow into the vacuum created as the bus moves along the road. By replacing the air in the space vacated by the bus, the oily residue is prevented from reaching the back of the bus. It of course won't stop rocks and other debris from attacking your toad, but no more scrubbing. | ||
| Josh McElhiney (Zcommanager)
Registered Member Username: Zcommanager Post Number: 46 Registered: 1-2009 Posted From: 75.187.41.177 Rating: N/A |
Thx for the "spoiler" suggestion Jim! Honestly, I never gave that a thought. No more scrubbing, and no more wifey nagging about it!! Haha A good set of mud flaps at each wheel will do away with rocks flipping up at the toad and others. Josh | ||
| Larry & Lynne Dixon (Larry_d)
Registered Member Username: Larry_d Post Number: 231 Registered: 7-2005 Posted From: 71.111.185.149 Rating: N/A |
Josh I have a three speed auto,and it will heat uup I guess because the RPM's are not high enough for the fan to cool, In second have slowed down but RPM's have raised to about two K's and will run at cooler temp, Don't kknow if what I should do but it does cool off. If on hill and real slow I will pull over and run at two K's or so. Don't know if rite but seems to work. Larry Jim Thanks for that thot. Larry | ||
| Josh McElhiney (Zcommanager)
Registered Member Username: Zcommanager Post Number: 48 Registered: 1-2009 Posted From: 75.187.41.177 Rating: N/A |
Thx Larry That makes sense to me. So from that, I guess I can infur that the cooling fans are not running all the time - only at higher RPMs? Sorry, I'm not trying to be stupid, but as I mentioned in another thread, I'm still fairly new to the Coaching World, and am trying to learn as much as possible. Earlier this summer, we had our coach out and about, and I noticed a similar situation with ours...at idle, it seemed to be running hotter than when moving along at higher RPMs. Josh | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1679 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
Larry, does that engine have a fixed fan or does it have the hydraulic torus version that can be turned easily when engine is off? | ||
| Larry & Lynne Dixon (Larry_d)
Registered Member Username: Larry_d Post Number: 232 Registered: 7-2005 Posted From: 71.111.185.149 Rating: N/A |
John I always assumed it was fixed did not know there was anything else. Am not familular with a hydraulic one. Spelling is not my best thing, I do know I have to watch girly girl like a hawk or she is over heating. Radiator was gone thru by PO, with recipts. Larry As always I need a lot of help to keep going.thanks | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 610 Registered: 3-2007 Posted From: 71.53.155.14  Rating: N/A |
Larry on my 4905 the fan is hydralic and has a t-stat where the oil line connects on the back side of the engine. If the t-stat is weak or going bad, it will not let the fan run at full speed. You can by-pass it by using a pop rivet in the oil line. check the book for the info you need. Gomer | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1615 Registered: 12-2000 Posted From: 67.182.53.218  Rating: |
Larry, Josh, Brandon & the other GMC owners - The factory put a full-width mud flap all the way across the rear of the coach behind the back axle, starting with the 4104 highway models. This flap creates a low pressure area underneath the coach, directly under the powertrain. Since the engine cooling fan, in essence, pressurizes the engine compartment, the low pressure created by the full-width flap helps to pull the hot air out of the compartment. Hanging a rubber flap off the back bumper potentially contributes to excessive engine temps because it does not allow the hot air to escape - especially when pulling grades. Crown also used a full width mudflap on their mid-engined coaches for exactly the same reason, but they hung it directly behind the front axle. MCI, Prevost & Eagle owners might try hanging a full-width flap across the coach behind the tag axle (or, for MC-5 owners, behind the rear axle) to see if it creates any improvement. As for the oily mess on the back, fix the oil leaks, build a catch tank for the slobber tubes, and avoid black smoke when pulling a grade. Other overheating issues should be researched more thoroughly - especially those units equipped with automatic transmissions. Supplemental cooling may be required for hot weather operation. GMCs came with basically two different types of radiator fan drives - direct and hydraulic. Easiest way to tell which one you have is to try and turn the fan by hand with the engine off. If you cannot move it, it's a direct drive. If you can spin it with some resistance, it's hydraulic. The hydraulic units are called torus drive, and they work conceptually like a lock-up torque converter - as the engine temperature rises, more oil is forced into the torus until it locks up and turns at engine rpm. As the engine temp comes down, oil is released from the torus and the fan begins to freewheel. There is a procedure in the shop manual for testing the torus drive's operation, perhaps it's time to open DA BOOK? In a recent issue of FMCA's magazine, a stick & staple owner had good results with this trucking industry goodie in terms of assisting with airflow around the rear of his rig: http://www.airtab.com/en/35 FWIW & HTH. . .  | ||
| Bob Baldwin (Bob4106)
Registered Member Username: Bob4106 Post Number: 181 Registered: 10-2004 Posted From: 24.74.180.20  Rating: N/A |
I was told that the torus drive when lock-up doesn't run 1 to 1 with the motor, more like .9 I add this to the slobber tube and clean up the back of the bus by 90% http://www.walkerairsep.com/product_detail.asp?id=565 | ||
| L James Jones Jr (Jamo)
Registered Member Username: Jamo Post Number: 95 Registered: 11-2007 Posted From: 74.79.238.160  Rating: N/A |
If I put a wing on the rear of my '04, I'll have to rename it "Flash Gordon"... | ||
| Larry & Lynne Dixon (Larry_d)
Registered Member Username: Larry_d Post Number: 233 Registered: 7-2005 Posted From: 71.111.185.149 Rating: N/A |
To all I didn't mean to try to dominate the post but thot my inserts and questions mite help me and others with same problem, all sugestions are great and informative. I will take the mud flap off the rear and may replace with hula skirt. Had one on S and S worked good, the tabs on top look good also. Am of old school as grew up in log trucking family, Father taught if you fix a sobbering Jimmy it will slobber again in a few K miles. There a a lot of great posts here. 4905Larry | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 342 Registered: 11-2008 Posted From: 75.178.92.43  Rating: N/A |
Gee... I have to say that, in my Frenchie brain, I first thought that this post was about women's skirts made out of weed... Well, still a lot to learn! Nellie | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 405 Registered: 2-2001 Posted From: 69.77.144.102 Rating: N/A |
Well, you're right to a large degree. Most of us call our buses "she". There's a lot of similarity (NOT SIZE!). Very attractive, can be lots of fun or a major PAIN depending on reasons we don't clearly understand. Huge maintenance costs. Easy to get hooked up with but difficult to get separated from. Now Willie's bus would have a skirt, curtains & carpet made of weed. Now, do you refer to yours as "he"? | ||
| Josh McElhiney (Zcommanager)
Registered Member Username: Zcommanager Post Number: 53 Registered: 1-2009 Posted From: 75.187.41.177 Rating: N/A |
Oh My Jim Bob!!!! I done think you mighta opened up a can a worms!!! LOL | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 371 Registered: 10-2004 Posted From: 96.232.132.245  Rating: N/A |
Are there hydraullic fans that are also belt driven? Thats how i thought you could tell the difference but i just now got a hydraulic fan. And of course i have an oil leak on the seal, probably from sitting so long. What color is the smoke coming from Willie's bus? and why is it coming from the windows? | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 343 Registered: 11-2008 Posted From: 75.178.92.43 Rating: N/A |
Jim - Yup. For reasons I mention in my blog, she's a 'he'... nothing to do with cross-dressing or such. He's pretty secure in his sexuality. Nellie | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1685 Registered: 10-2003 Posted From: 71.58.71.157 Rating: |
The torus drive setup is somewhat like a torque converter in an automatic transmission. It is fed oil through internal oil passages in the mounting casting from the engine. The oil is returned to the crankcase through an external oil line. This return oil goes through and is controlled by a thermostatic valve that is installed in the radiator pipe. The colder the coolant, the more the oil flows back to the pan, and the less the fan turns or next to nothing. The hotter the coolant, the less oil is sent back to the pan, and torus is almost to clear full. The torus has bowl shaped halves inside it. One bowl is connected to fan end. The other bowl is connected to crankshaft. These bowls have cupped shaped fins in them. These fins on the crank bowl direct and throw the oil at the fan bowl, causing it to turn; more oil more fan rotational speed. Pretty trouble free as long as bearings are set up with proper preload and good oil seals. This temperature control valve is called a Vernatherm and made by Kysor. It is made of brass, about 7 inches long with two threaded nipples to connect the oil lines to. The bottom is threaded with a sensor that threads into radiator pipe. Anyway, the reason I explain this, is that I saw that they make a valve like this that has a threaded hole in the top of the valve where the dimple is on our coaches. This hole is there to add a controlled air supply when needed to cause the fan to run locked up at full speed.( shuts off the oil from going back to pan regardless of engine temp. This would be useful on our coaches that have the torus setup to engage the fan when needed to override the normal operation. Good for getting full fan control at beginning of long grades before engine starts getting too hot. I think one could carefully drill out the dimple in one of ours to add this feature, or, of course get the other type. I believe they were used in certain city bus applications. You would need an electric air solenoid, like the ones already on the bulkhead for other uses. wire it to a switch in driver's compartment, and you're set. Btw, the 4905 uses a different fan blade with this setup with more blades on it and different size mounting hole. | ||
| Jerry Coombs (Jerry_c)
Registered Member Username: Jerry_c Post Number: 14 Registered: 11-2005 Posted From: 205.188.116.203  Rating: N/A |
Happen to be working on my 4106 cooling system now as the engine has been running hot...lately. UNFORTUNATELY the 4106 manual I have has NO information about this torus / oil filled thing that couples the engine to the fan. I did find that the temperature sensor in the radiator coolant bottom return line IS somewhat adjustable depending on how much housing is screwed on seems to affect what temperature the fan will fully engage when the wax motor moves to seal off the oil flow going to the engine oil pan. Going to dissamble this torus unit and replace all oil seals and gaskets (its leaking) -- and ANY information from DA BOOK would be appreciated. I also put a manual ball valve in the oil line from the torus unit to the engine oil pan for those times I might want it to run continuously - -of course I have to get under the bus (preferably when its stopped) to turn this valve. ps this valve also proved to me why my crankcase oil level varies SO much -- at times depending on whether the torus housing is filled or not -- as much as a half to a gallon differance. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1717 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
make sure that those internal bearings have the proper preload; if they are a little bit loose, could cause the seal to leak. Also check for a wear grove from old seal. |
