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Author Topic: Electric Radiator fans for MCI  (Read 6995 times)
Tenor
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« on: March 06, 2008, 06:41:02 PM »

The thread running right now about the MCI 7 Combi with electric radiator fans got me thinking.  Has anyone attempted to use the electric motor from either the condenser bay or the heater system to run the radiator squirrel cages?  There may be some very simple reason not to, such as proper rpm etc.  All the necessary pieces are there in the heating system, relays, wiring etc.  Maybe just run wiring from the alternator direct to the motor, with the relay to turn it on?  I think that's kind of how the heater system works.  Any thoughts? 
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Glenn Williams
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1968 MCI 7 Ser. No. 7476 Unit No. 10056
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4 speed Spicer
Lin
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« Reply #1 on: March 06, 2008, 08:38:21 PM »

There was a big debate a while ago about whether one could cool with only electric fans.  Someone was trying it and, I am told, it did not work out.  However, there is a guy posting on BNO that says that is just what he is doing.  It's not at the beginning but further down.

http://www.busnut.com/bbs/messages/11/20738.html?1204862467
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tekebird
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« Reply #2 on: March 06, 2008, 09:21:33 PM »

Anything can be done...just a matter of how much time and money you want to throw at it.

I think the guy in the post referenced above decision was skewed by the fact he was repowering with a cummins.

probably much easier to engineer his elec setup than try to get pully's and gearboxes figured out
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TomC
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« Reply #3 on: March 06, 2008, 10:37:23 PM »

Simple- you just can't get the air flow with an electric motor compared to direct drive electric.  Now with Hydraulic-that's another story.  You could run it off the power steering pump with a priority valve that gives the power steering first crack at the pressure with the fans being secondary.  Electric was tried on big rig trucks that have great frontal ram action into the radiator, and it just plainly didn't work on those long grades in summer time.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #4 on: March 07, 2008, 05:37:57 AM »

There is lots of engineering data and empirical data on how much horsepower is required to move sufficient air to cool an engine. Detroit two strokes are one of the hardest engines to cool, consequently they need the greatest amount of air flow.

You can increase the surface area of the radiator or you can add more rows of tubes, but in either case you increase the horsepower required to move sufficient air.

Anything is possible even if not practical, and there seems to be little reason to redesign a system just to eliminate a belt.

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BEN MC7
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« Reply #5 on: March 07, 2008, 06:40:51 AM »

It can be done, because I have already done it.  When I bought my bus in 1998, the previous owner had removed the belt drive for the fans and replaced it with a 24v motor (which wasn't working well).  During my investigation, I removed the bad motor and cages and installed 2 pairs of electric fans, 2 push and 2 pull, and connected them to a thermostat.  The fans operate fine, cool the engine well, but here in Florida I needed more water flow and decided to install an aluminum radiator in the condenser bay behind the drivers side front wheel.  This made an even more dramatic impact on the temperature and it also had an electric fan.  I have since decided to get rid of the original 'suitcase' radiators in the back and replace them with similar aluminum radiators because they are much more efficient.

I have found that the problem is not using a particular type of fan (electric, hyd, belt) but the efficiency of the radiators themselves.  The originals in mine are 8 row, staggered, smooth tube, straight fin and I believe 1/4" tubes.  The additional radiator installed is 2 row, 1" tubes and is all aluminum. Part of the problem is trying to get the airflow all the way through the core. By using the push and pull fans, I have kind of gone around the problem of improving the air flow, but these 'antique design' radiators are essentially hot water bottles that have poor air flow.  The design is much older than most of our buses and is inefficient for cooling. When I check the airflow and temperature around the new radiator core, the center is much, much cooler than around the perimeter of the fan.  The older radiators (stock) are hot all over and do not have a cooler area to be found.

When I install the new aluminum radiators, I will be installing shrouds to improve efficiency and they will be a 'pull' type fan only.  By the way, the current setup has been working fine and not a single temperature problem was encountered during my recent 6k mile trip that included going into Mexico.  I hope this helps.
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Stan
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« Reply #6 on: March 07, 2008, 06:54:17 AM »

Ben MC7: As so many people have said, anything is possible if you spend enough time and money on it. I am intrigued by this statement
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The fans operate fine, cool the engine well, but here in Florida I needed more water flow and decided to install an aluminum radiator

Why would you add more coolant and an additional radiator to a system that was working well? If you needed more cooling in Florida, try one of the long grades in the SW mountains on a hot day!
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BEN MC7
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« Reply #7 on: March 07, 2008, 07:15:33 AM »

One small error in my description of the system--

I removed the heater core that is installed in the forward baggage compartment.  With the lack of water flow (and quantity of water) going to the front of the bus, it made the system much smaller.  By installing the additional radiator in front I regained the system capacity that was limited without the heater core that was originally removed. 
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boogiethecat
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« Reply #8 on: March 07, 2008, 07:22:07 AM »

Yup. Stan has the idea.  Any bus can function with electric fans... on the flats going slowly... but get over to this part of the country and try, for example the Baker grade when it's 115 outside, or the grapevine under similar circumstances, or even the final grade going west on I-8 in the middle of summer, and you'll WISH you had belt or hydraulic-driven fans again.
  For example, my Crown runs at 180 day and night at 70mph fully loaded with a 6000 pound trailer, with the fan spinning at 20% of it's normal speed (I have a Horton eddy-current 2 speed clutch on it).  Probably very equivalent to the biggest set of electric fans I could ever muster. But as soon as I hit those grades, the fan goes fully on and I'm also thankful that I added 3 inches of thickness, the new style to boot, of core to my radiator, or I'd never make it.  Even then I'm pushing 205 degrees which is the limit for my old Cummins 220.  It's only those times when electric won't cut it.

This has been thrashed over and over during the years.  Everyone from the 2dogs debacle to Tim S. has said they could, actually done it, or whatever, and thus far no-one has been happy with the results.  And as I recall, Tim even did it "right", with a gigantic high horsepower DC motor and the proper controls, then given it up 'cause it just didn't work.  Bottom line, you just can't easily get that 20-30 HP from electric fans, and that's absolutely needed when the goin' gets tough....

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1962 Crown
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Tenor
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« Reply #9 on: March 07, 2008, 07:36:24 AM »

Wow!  I had no IDEA of how much this has been discussed.  I found the BNO post dealing with Two Dogs.  What a mess.  I think I'll drop the idea and stick with what works.  I know there is merit to going to aluminum radiators when possible/practical.  I did the same on a 63 Ford Galaxie.  Makes a big difference.  I don't know if I'll ever get west, but I don't want to be stuck worrying about not being able to!

A side note,
As I read through the Two Dogs post on BNO,  I was really taken aback by just how unpleasant the postings were.  I am glad that I have never seen such inappropriate behavior here.  I also have to say that things have not been as bad as that since I joined BNO as well.  Different opinions are one thing, but there is no excuse for being hurtful.
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Glenn Williams
Lansing, MI
www.threemenandatenor.com
1968 MCI 7 Ser. No. 7476 Unit No. 10056
8v71
4 speed Spicer
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Tom & Phyllis
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« Reply #10 on: March 07, 2008, 07:45:51 AM »

This is not exactly on the topic of electric fans but it is related to this post.

According to this post & the others I can find, belt driven is the only way to go when it gets hot on long grades. It also appears that the belt driven system takes 25 to 40 HP depending on whose figures you want to rely on.

Assuming the above is so, it would be nice to reclaim that HP, when it is not needed for cooling, to increase fuel mileage.

To that end, is there anyway to easily adapt an air operated fan clutch to shut off the fan and gear box when not needed on an MCI? Has anyone done that?

TOM
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'82 BlueBird WanderLodge PT40 being rebuilt
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« Reply #11 on: March 07, 2008, 08:21:33 AM »

Granted aluminum radiators do work well-Freightliner, Sterling, Western Star have all switched to them as the standard radiator.  But look at Western Star (the heaviest duty truck we make), when the radiator needs to get big (1850 sq in) we switch back to the good old copper/brass design.  Although aluminum has excellent heat exchanging qualities, it also has excellent calcium collecting qualities since it is a more porous metal than copper.  Hence after a few years, the calcium collects and blocks the tubes, and since aluminum is so soft and the tanks are just clamped on plastic tanks, they are typically not repairable-just replace them.  As compared to the copper/brass radiators that have metal bolted end tanks that easily facilitate rodding out the core when needed.  When I had my copper/brass radiator core changed from a 5 row straight fin to a 6 row serpentine fin core, the radiator guys said the original core was clean and still in good shape-and I've owned the bus for 15 years alone!  During that 15 years if you had a aluminum radiator, you'd probably already have replaced the radiator once with getting close to replacing it again.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #12 on: March 07, 2008, 08:21:47 AM »

Ben: The heater core has nothing to do with the fans cooling the engine unless you are running the heater fans to remove heat from the core. Increasing the volume of the system only delays the point where the fans cannot keep up.

Just to add to Boogie's comment about the grade between El Centro and San Diego. I have driven that road with three different cars and not one of them would pull the grade to the top in the highest gear without overheating.

Tom: I think the original MCI design does more or less what you want. With a proper operating shutter and damper system, you unload the squirrel cage fans when cooling is not needed.
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« Reply #13 on: March 07, 2008, 08:41:49 AM »

The MC-5 cooling system is as I've been told, marginal at best. While I have my 8V71 out to replace the clutch I am considering adding a third radiator with electric fan where the AC compressor used to be. Anyone have experience with this approach? It looks like it would be easy to add the third radiator in series with the passenger side radiator.
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Fred Thomson
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« Reply #14 on: March 07, 2008, 09:06:59 AM »


A side note,
As I read through the Two Dogs post on BNO,  I was really taken aback by just how unpleasant the postings were.  I am glad that I have never seen such inappropriate behavior here.  I also have to say that things have not been as bad as that since I joined BNO as well.  Different opinions are one thing, but there is no excuse for being hurtful.
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Tenor, you should have been here before Nick,Phil,Dallas, and Richard  and the new board    I forgot Jack sorry
« Last Edit: March 07, 2008, 09:09:34 AM by luvrbus » Logged
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