Author Topic: MC-8 Radiator Fan Assembly  (Read 333 times)

Offline Glennman

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  • 1974 MCI MC-8 8V71 Turbo
MC-8 Radiator Fan Assembly
« on: November 11, 2019, 08:06:01 PM »
My bus has a highly modified electric fan system blowing onto 4 radiators. 2 of them are the 2 vertical ones on the sides with an electric fan on each. Then there are 2 horizontal radiators between the 2 vertical ones laying above the engine compartment with a fan on each of them. Those 2 fans actually suck air from the engine compartment; a questionable arrangement. The 8V71 has a turbo that I believe was added equipment (?).

Luke at US Coach is parting out a couple of 9's that may have an available stock fan assembly that I could install to go back to a stock system.

I don't really know how that stock system works, by way of where the airflow travels. I'm assuming the fans are squirrel cages, but do the fans suck through the side radiators? And if they do, do they blow the hot air down into the engine compartment? Have people had problems with overheating with this system, especially if a turbo was added?

Any info on how these systems work will be helpful.


Offline lostagain

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Re: MC-8 Radiator Fan Assembly
« Reply #1 on: November 12, 2019, 07:12:39 AM »
Yes the fans are squirrel cages. They suck air in through the side radiators, and push it down through the engine compartment and out the bottom. It has worked well for decades, as long as the engine was kept stock with relatively low  horsepower, and a manual transmission. Now with the addition of a turbo, bigger injectors, and an automatic, the stock cooling system become insufficient to shed the additional heat. Some people like your previous owner try to reinvent the system with varying degrees of success. Going back to the stock arrangement is a good idea. You should look for a smaller pulley on the squirrel cages gear that would spin them faster. You could have some radiators made with extra rows and fins to maximize cooling, etc.

Blackie AB
1977 MC5C, 6V92/HT740

Offline buswarrior

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Re: MC-8 Radiator Fan Assembly
« Reply #2 on: November 12, 2019, 07:21:24 AM »
Many MCI cooling system problems are the result of failing to keep the fan compartment "air tight"

Space around the radiators, the seals on the compartment door, rust holes inside the cavity, all conspire to defeat the fan's efforts to pull air through the radiators.

Fred Hobe put a 400 HP military engine in his personal MC8 a quarter century ago, and got it all to work. Google his name, some reference material is still hosted someplace.

Fred converted buses for people, long ago and far away, several pages of tips, many/most of them still just as good today.

Happy coaching!
Frozen North, Greater Toronto Area

Offline Dave5Cs

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Re: MC-8 Radiator Fan Assembly
« Reply #3 on: November 12, 2019, 07:33:00 AM »
"Perfect Frequency"1979 MCI MC5Cs 6V-71,644MT Allison.
 1998 Jeep TJ & 2002 Buick Century, Roseville,CA
Congressmen should wear uniforms, like NASCAR drivers, so we could identify their corporate sponsors