4106 fan clutch drive control

lostagain · February 04, 2021, 08:03:37 AM

I am not a GM bus guy at all, but, in MCIs, in my learned opinion (ha, ha !), the belly pans under the engine were there to keep the gravel and road grime out of the engine bay. They were louvered as well. I think the air out of the radiators flows out the bottom easier without them. I removed mine out of the MC5 and I think it runs cooler without them.

richard5933 · February 04, 2021, 08:22:06 AM

Without the belly pans there is going to be a lot of turbulence in the engine bay. The air coming in through the radiator has to go somewhere, and if there is turbulence in the engine bay the route down and out is not clean.

The louvered belly pans create a negative pressure area as the airflow goes over the outside of the louvers, effectively pulling the air out.

A similar situation which demonstrates this is the vent tube on our waste water tank. It goes down and exits through the floor of the bay. When I first got the bus the bottom of this vent tube was cut straight across, and as we drove down the road air was pushed up through the tube resulting in foul odor inside the bus. I cut the bottom of the tube at an angle, creating a situation similar to what the louvers do on the belly pans, and now as we go down the road there is a negative pressure created pulling the foul odor out instead of forcing it up into the bus.

Friday1 · February 04, 2021, 08:42:29 AM

Quote from: richard5933 on February 04, 2021, 08:22:06 AM
Without the belly pans there is going to be a lot of turbulence in the engine bay. The air coming in through the radiator has to go somewhere, and if there is turbulence in the engine bay the route down and out is not clean.

The louvered belly pans create a negative pressure area as the airflow goes over the outside of the louvers, effectively pulling the air out.

A similar situation which demonstrates this is the vent tube on our waste water tank. It goes down and exits through the floor of the bay. When I first got the bus the bottom of this vent tube was cut straight across, and as we drove down the road air was pushed up through the tube resulting in foul odor inside the bus. I cut the bottom of the tube at an angle, creating a situation similar to what the louvers do on the belly pans, and now as we go down the road there is a negative pressure created pulling the foul odor out instead of forcing it up into the bus.

Richard, I have two 17" SPAL fans mounted in my rear engine door to expel the engine heat so the bedroom is not like an oven after a day of driving. The fans are controlled manually. I have several of the original spring fasteners still below my engine. The PO had a frame welded in the back to tow his toad and I think some of the original springs are gone. Mainly I want to keep my engine clean and sanitary. I also have a design for a "tail" on the edge of the roof to break the vacuum and keep the oil freckles at a minimum. I am talking a tail like on a racecar that is over the drag chute also to break the vacuum. Free horsepower? With the flat rear end of the body there is a lot of turbulence back there.

Friday1 · February 04, 2021, 08:48:30 AM

This was just after installing the fans. I built an awning over them to keep the rain out later.
Richard, I have two 17" SPAL fans mounted in my rear engine door to expel the engine heat so the bedroom is not like an oven after a day of driving. The fans are controlled manually. I have several of the original spring fasteners still below my engine. The PO had a frame welded in the back to tow his toad and I think some of the original springs are gone. Mainly I want to keep my engine clean and sanitary. I also have a design for a "tail" on the edge of the roof to break the vacuum and keep the oil freckles at a minimum. I am talking a tail like on a racecar that is over the drag chute also to break the vacuum. Free horsepower? With the flat rear end of the body there is a lot of turbulence back there.
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richard5933 · February 04, 2021, 09:08:33 AM

If you're looking to keep the engine clean, then that rubber guard just behind the rear axle hanging down from the bulkhead would be important. The belly pans will help, but make sure they are louvered. Those fans will help when you're parked, but they won't be able to keep up with the amount of air coming in through the radiator.

For the deflector to keep the back of the bus clean, check out what they install on school buses. May not be necessary to reinvent the wheel on this one, as there are many options to choose from. If nothing else, you can copy their designs. Most I see have two layers.

https://www.seeiiairfoils.com/uploads/Slide-1.jpg

Friday1 · February 04, 2021, 12:17:56 PM

I have the rubber flap at the bulkhead. I only run the fans after running hard and then in slow traffic or when I am stopped for a while to draw the heat out of the engine compartment. There is a lot of heat that comes out of that rear door with the fans on. I see the rear wing and that might work good. I had something different in mind and will send a pic when I find one.

Friday1 · February 04, 2021, 12:37:17 PM

This is what I have in mind. The wing will bend around the bus roofline at the ends. I'm thinking if I extend it 18" it will work to break the turbulence and make it more stable driving.

richard5933 · February 04, 2021, 12:59:03 PM

I seriously doubt you'll feel a bit of difference in the way the bus handles going down the road. That wing is really huge in relation to the size of the vehicle, but on the bus it would have negligible effect. If I remember correctly, there was a slight amount of that shape to the rear of your bus from the factory - I know there is on my 4108.

To keep the rear of the bus clean you're going to have to create a pretty sharp downward air flow. That's why the school buses use one shaped like I posted earlier. When I was a kid and my dad had a huge station wagon, it had a wing on the rear like the school bus wings. The only purpose was to deflect air down and across the rear window to prevent it from gathering road debris and wheel spray. This was before rear window wipers, and it seems to me that it made a difference from the one we had before without the wing.

Lots of oil and other splatter is going to come up from the exhaust and engine drippings, and having the positive downward airflow might help.

Of course, realize that anything you do to the airflow around/over the bus could have negative consequences in other systems. Would really suck if you obtained a clean bus rear end at the cost of starving the radiator of air flow somehow. Not saying it would do that, but all the air flow around/over a bus is interconnected and what you do in one area does affect others.

RJ · February 07, 2021, 12:03:54 PM

Friday -

Before you start messing with a wing on the rear roof of your '06, perhaps you should take a look at some other ways of reducing the oil splatter first:

1) Fix any oil leaks you've got.

2) Use a "catch can" for the air box drains.

3) Extend the tailpipe slightly beyond the bumper, and include a downward facing tip.

4) If a PO installed one of those "skirts" that hangs off the rear bumper, remove it.

5) Run the rack on the engine to make sure all the injectors are set correctly.

Glad to hear that you've got the full-width "mud flap" at the bulkhead - that alone creates a huge low pressure area under the engine compartment, helping to draw out the hot air. Folks that remove that flap have no clue as to it's purpose.

FWIW & HTH. . .

chessie4905 · February 07, 2021, 12:13:56 PM

clean engine and work on the leaks. using catch can will help a lot if you dont already have one. Rear spoiler has been done and not the cure all expected.

Friday1 · February 07, 2021, 12:48:07 PM

I replaced the fan hub seals and bearing. Removed the shaft that used to drive the AC compressor and made a plug to fit in there where the pinion was and sealed it all up. However the fan seal has started to seep again and it is probably getting strewn around by the fan. I have a catch can. Have not run the rack. I sent a dozen emails to BGM, Scott and never got a reply trying to get on his schedule for that service. I had five surgeries close together and still recovering from that so projects I start have to have a likely chance of completion so someone else won't have to finish something I start. I don't have a skirt at the rear bumper and I do have a downward facing tailpipe extension facing toward the ground. The freckles are not that bad but I know they are there. When I wash the back, I spray a little Simple Green on the rear and they come off easily.

RJ · February 07, 2021, 09:20:03 PM

Quote from: Friday1 on February 07, 2021, 12:48:07 PM
I sent a dozen emails to BGM Scott, and never got a reply trying to get on his schedule for that service.

Friday -

There are other technicians scattered around the country who can run the rack on your Detroit besides Scott.

If you'll take a couple minutes to edit your profile to include your coach's VIN and your home-based city and state (similar to mine at the bottom of this post), then perhaps we can better assist you in providing nearby help.

FWIW & HTH. . .

richard5933 · February 08, 2021, 03:54:34 AM

Are you still in the Toledo area? If so, there appear to be a lot of heavy truck and bus shops in your area. Have you tried any of the local Detroit Diesel shops to see if they have a 2-stroke trained tech on staff?

luvrbus · February 08, 2021, 04:26:42 AM

Quote from: Friday1 on February 07, 2021, 12:48:07 PM
I replaced the fan hub seals and bearing. Removed the shaft that used to drive the AC compressor and made a plug to fit in there where the pinion was and sealed it all up. However the fan seal has started to seep again and it is probably getting strewn around by the fan. I have a catch can. Have not run the rack. I sent a dozen emails to BGM, Scott and never got a reply trying to get on his schedule for that service. I had five surgeries close together and still recovering from that so projects I start have to have a likely chance of completion so someone else won't have to finish something I start. I don't have a skirt at the rear bumper and I do have a downward facing tailpipe extension facing toward the ground. The freckles are not that bad but I know they are there. When I wash the back, I spray a little Simple Green on the rear and they come off easily.

A rack setting has nothing to do with spotting,if the engine starts and runs good leave it alone the old Detroits get into their comfort zone and DD has no schedule for tuneups .Check and see if you have a check on the lower head for the air box drain if so clean it if not install one,Jake brakes will cause one to spot more also, sounds to me like you don't have much of a problem rfepair what leaks you can find Detroit's can be leak free

Friday1 · February 08, 2021, 04:44:35 PM

Quote from: richard5933 on February 08, 2021, 03:54:34 AM
Are you still in the Toledo area? If so, there appear to be a lot of heavy truck and bus shops in your area. Have you tried any of the local Detroit Diesel shops to see if they have a 2-stroke trained tech on staff?

I was a mechanic for the Toledo Fire Division for 30 years. I know some of the techs at Williams but was wanting someone that knew about conversion buses and would give me a break on the labor if I helped. My engine has about 65K on it since it was installed-a crate motor due to the PO not paying attention to the water temp in the mountains. I put an ISSPRO water temp with 270 degree sweep needle and a warning light at 205F. I have a custom dash with ISSPRO instruments and warning lights for low water, low oil, high temp and No charge. When we raced the dragbike it had 13 readouts of computer data to look at after each pass. The passes were high 7 seconds and low 8's so you couldn't depend on the rider's @$# dyno to tell you what just happened. Info, data keep you out of trouble. When I retired the new fire trucks were just getting into "multiplexing" and all the info displayed on the pump panel where the pump operator stood and controlled the pump came down four wires. I didn't have much to do with that. I prefer mechanical instruments but in the case of water temp they don't make any with 40' Burdon tubes. ISSPRO guaranteed me accuracy to less than 2% on my instruments so I guess that is tolerable. Thanks for reminding me to fill out my info. Check out my avatar.