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Author Topic: Radiator Fans  (Read 1157 times)
ChrisP
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« on: February 05, 2014, 04:35:48 AM »

Hello,

 I have checked the archives and struck out. My squirel cage fans on my MC8 are worn out, parts are discontinued and the ones you can find are whole lot of money. How many CFMs did they put out? I want to replace them with new electric fans with fabricated shrouds but I cannot find out how much air they need to blow, even the MCI tec line dosen't know. ( Sorry about posting this in the wrong place earlier)
 Thanks Chris
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ChrisP
1981 MCI 9
Nashville, TN
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« Reply #1 on: February 05, 2014, 08:02:35 AM »

There has been a lot of discussion about using electric fans in the past and also some failed experiments.  The general consensus is that it would be very difficult to get enough air, although I have heard it said that someone had succeeded with it.  Do you still have the original 50DN alternator?  You would need a lot of power to run such fans if it could be done.

On the other hand, as mentioned in the other section where you first listed this, try contacting Luke and US Coach in New Jersey (888 262-2434).  Have you already called MCI?  Mohawk Manufacturing (800 323-7652) would be another one to try for new parts.  For used parts, you might try Sam Caylor (785 878-3405).  Fred Hobie, whose number I can't find, was getting rid of a bunch of MCI stuff last year. I don't know if he has anything left though.
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RJ
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« Reply #2 on: February 05, 2014, 08:08:24 AM »

Chris -

My squirrel cage fans on my MC8 are worn out. . .

Please explain in more detail what you mean by "worn out."

. . .parts are discontinued and the ones you can find are whole lot of money.

What parts on a bus are NOT a whole lot of money??   Grin

How many CFMs did they put out?

Time to get out a measuring tape and your calculator:
http://www.cincinnatifan.com/catalogs/EngData-203-internet.pdf

I want to replace them with new electric fans. . .

Do you still have the big electric motor running the condenser fan for the coach's A/C in the compartment behind the LF wheel?  How about the big electric motor running the main cabin HVAC blowers in the heater/evaporator compartment in the center of the coach behind the front axle?  The condenser fan motor, IIRC, has more HP than the main cabin blower, so TWO of those MIGHT provide enough HP to equal what the OEM set-up generates.  See what you come up with after doing the calculations given in the link above.  I think you're going to find that it will be a lot less expensive and much less of a headache if you simply fix what you've got.  Oh, and FYI, MC-9 fans will work, too.

This topic has been beaten to death several times over the years, primarily over on the BNO board.  (www.busnut.com)  You'll find most of the cuss/discussion in the Archives.

I'm fully aware that you'll find electric fans on most of the newer transit buses nowadays.  Here locally, they're running eight fans on the big radiators in an attempt to keep them cool.  But they're also running four-stroke CNG engines and rarely get over 45 mph, so they're running cooler than your engine to begin with, even with our 100o summer days.  These radiators also have a LOT more surface area than both of your MC-8's combined, thus more cooling capacity to begin with.

Clifford will probably chime in here with a comment about another busnut that IS using electric fans for cooling on his coach, but it's also an Eagle, again, another coach with a larger radiator than your MC-8 to begin with.  I'm not sure, but IIRC, it's also got a Series 60, a four-stroke that runs much cooler than your two-stroke.

FWIW & HTH. . .

 Wink
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RJ Long
PD4106-2784 No More
Fresno CA
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« Reply #3 on: February 05, 2014, 08:50:10 AM »

Bite the bullet and replace the assembly it takes hp for CFM I think around 38hp for the MCI  the 1-1/2 hp 40 amp motor from the HVAC system is not going to cut on a MCI for engine cooling  

I read someplace the fans on a MCI are 10,080 cfm running at the 1:1 ratio@ 2000 rpm On our 8 I kept on increasing the blower speed with different pulleys till it threw it's self apart back then you could buy a rebuilt unit from MCI that was a $4000.00 and 3 day lesson for me I went back to the 1:1 ratio MCI were delivered with Undecided Detroit has a publication that will tell you how much heat rejection is needed for your engine and the hp setting if you don't achieve it you will have a hot running engine 

good luck
« Last Edit: February 05, 2014, 09:22:11 AM by luvrbus » Logged

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« Reply #4 on: February 05, 2014, 09:10:26 AM »

Unless your squirrel cage fans themselves are rusted out, broken, bent or otherwise useless, you should simple rebuild the cooling system from the gear box out to the radiators. It is really not a difficult job or very expensive. I would be very reluctant to trade the very simple and effective MCI system for a complicated electrical solution. You can get a good idea of the job at our blog. I just went through it on our MC9 and it was well worth it and not really expensive.

http://mightybus.wordpress.com/2013/09/16/cooling-system-rehab-oh-why-not/
http://mightybus.wordpress.com/2013/11/12/cooling-system-rehab-par-deux/

Jim
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RJ
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« Reply #5 on: February 05, 2014, 10:37:28 AM »

Chris -

As a follow-up to my previous post, ponder this question:

If electric cooling fans would work, don't you think the factory would have installed them as OEM?

FWIW & HTH. . .

 Wink
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RJ Long
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Fresno CA
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« Reply #6 on: February 05, 2014, 10:49:12 AM »

Chris,
Welcome aboard this crazy hobby!

Now have I got a deal for you!

I just happen to be scrapping out an '85 MCI 96A3 right now and we rebuilt (all new bearings, shims and gaskets( the blower gear box shortly before this bus was taken out of service.
At the same time we replace the blowers seals. (the rubber around the housings)

I'd be willing to sell you all this for a reasonable price and the best part is no need for shipping as I'm only about 2 hrs from Nashville! (just 15 mins. N of I-40 @ exit # 108)

You could come pick up the parts or next time I'm coming to Nashville I could bring them and we could meet up.
Grin  BK  Grin        seven 3 one - 9 eight 6 - five 9 nine 9
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robertglines1
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« Reply #7 on: February 05, 2014, 10:55:04 AM »

? to help Chris and for MCI guys.. Is there a chance the hvac fans are the same size?? and would fit his shaft if his miter box is good.  On my MCI 8 I found the biggest help was making sure no air got around the suction side.. but was sucked thru the rad..   Bob   BK got the deal!!!!!   he was typing as I was.
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« Reply #8 on: February 06, 2014, 12:34:33 PM »

There is only one application I know of that uses electric fans-and that's using 9 of them. That's on transit buses. Why-because they haul @$# for less then a minute, then sit idling picking up and dropping off for 2-3 minutes-enough time to cool back down again. As stated, electric takes way to much. You could switch to hydraulic-but then you're re inventing the wheel. Keep with what works. Get rebuilt or new blowers made, and have your radiators cleaned and/or replaced. Good Luck, TomC
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« Reply #9 on: February 08, 2014, 10:30:25 PM »

Well I guess we scared him off!
Grin  BK  Grin
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ChrisP
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« Reply #10 on: February 09, 2014, 03:57:21 PM »

Yep - a little scared.  Worn out means the shafts are grooved, the air tension valve leaks ( I think I found rebuild kits) and they blow oil.  The radiators will need re-cored soon as well.  MCI has most parts but one shaft was 3k minimum order of 3. No all of the big draws (condenser fans, A/C compressor, ect.) for the alternator are gone.

I just gotta think there has has to be a better way in 2014 to cool the engine whether it is large aluminum radiators with 12v high performance fans or an even more exciting possibility might be an inter-cooler.  I have a high performance pull tractor/truck (talk about a crazy hobby!) engineer/excavation tech looking into these ideas. He has made cooling systems for pull tractors with 6+ International Harvester, John Deere, CAT diesels tied together on a single rig - maybe those techs have some ideas. Or maybe I'm just chasing a foul ball but it doesn't hurt to look. Thank you all very much for all of your thought and input.

Chris
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ChrisP
1981 MCI 9
Nashville, TN
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« Reply #11 on: February 09, 2014, 04:05:56 PM »

Chris those pull trucks/tractors only go a short distance before being pulled into the pits and shut down.
Yer looking to keep going down the highway! It's not quite the same. Now I'm not saying that your guy can't come up with something, but chances are it's not going to be as simple or practical as fixing/replacing what you have. Good luck

I have the parts you need if you decide to go that route!
Grin  BK  Grin
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TedCalvert
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« Reply #12 on: February 09, 2014, 05:55:27 PM »

$3k for a shaft sounds like a shafting!  Find a steel supplier and buy cut to length. Valves can be rebuilt or replaced.  I'm not real familiar with MC8, but parts is parts. You don't need to rebuild the baby; all you need is fresh bathwater!

Regards,
Ted
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bevans6
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« Reply #13 on: February 09, 2014, 07:19:32 PM »

The air tension valve can be rebuilt with an off the shelf o-ring, I had one that fit in my box-o-o-rings (a kit I bought years ago with two dozen different sizes of common o-rings).  Same with the air tension cylinder, probably.  Shafts can be welded or chromed back to spec by a grinding shop (I have used a good crankshaft rebuilder before) or if its worn on the seal area look into a speedy-sleeve repair kit.  It's entirely possible to re-engineer the cooling system but the challenge is that the two stroke puts out around twice the heat of a similar power four stroke engine.  I have met people who have a S-50 four stroke who cool it with one of the stock MCI radiators.  People have replaced the belt drive and gearbox with a hydraulic motor to run the squirrel cage fans on a two stroke MCI but you need to run a hydraulic pump - I don't know if the power steering pump can do it.

Brian
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« Reply #14 on: February 09, 2014, 07:24:07 PM »

The shafts I saw used in a MCI blower gearbox looked like there was a bunch of machining & grinding required before the gears, bearings & seals would work. Machining ain't free around here.  Wink

As for redesigning/ improving the system - yes, it is possible, but ain't likely you will find a cheaper method that works as well as a properly maintained factory setup.  Shocked

The smaller the radiator, the more air needed for the same effective cooling. Like Brian said, for the same HP level, 2 strokes need lots more Btu rejection.

Start with DD specifications to know the heat rejection required, then based on the radiators used, you will then be able size replacement fans based on required airflow. Sounds easy, but it usually ain't.  Sad
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