Cooling issues

[Chopper Scott]

One of the main issues I want to address this spring is making sure the 8V71 is content and cool! I had some issues with it overheating enough that it would shut itself down automatically. The rear gauges only showed 210 and the front dash gauge was normal. Is 210 the limit on temperature for the 8v71? However seeing the cost of a rebuild I'm heading in the overkill direction. I'll be changing both of the kill sending units, installing a tranny cooler and such . Upon checking the radiators and finding that they had been rebuilt I found absolutely no seals around them. It would be hard to even get much air through the rads as is. Also the door seals are either gone in places or not very good. The cones on the fans are all in good shape however. I found that the Allison needs a high flow tranny cooler and found these.  http://www.transmissioncoolers.us/  Click on the Allison high flow tab. I'll do some measuring but am sure I can make one fit easily.   Also I am thinking of putting 24 volt fans that push air through the radiators controlled by a thermostat as well as the original squirrel cages. Has anyone tried that? I found these and will also do some measuring for fit.  http://www.okoffroad.com/stuff-24-fan.htm   Hope I'm on the right track and thanks to this forum I have someone to show me the way!! Later

[belfert]

RickB just replaced his radiators, seals, and such on an MCI.

The OEM cooling system will work just fine if it is up to par.  Adding electric fans is just a band-aid fix.  As Bus Warrior always likes to say, these buses cooled fine from the factory and it is better to fix the problems than to add a bunch of extra stuff.

[buswarrior]

With a caveat... an MC7 with an auto will have trouble, the rads were sized to take care of the engine only, not the auto tranny.

See? Emerging technology has been tripping up the design folks even in the analog mechanical days!!!

Size the tranny cooler big enough and put thermo controlled fans on it, that all the possible tranny heat can be accounted for, then through an engine rad loop to return to the tranny.

You won't find anyone on here that will support adding electric fans to your engine rads, they won't do anything that the squirrel cages shouldn't be doing already.

And before anything else, get that fan compartment and the rad sides sealed up tight. The smallest gap MASSIVELY steals air flow that needs to go through the rads, not around. I'd bet that's your only problem, other than the capacity for the tranny.

Call me a heretic, but I used spray foam in a can to be sure of it, using the sad collection of decayed originals as a base to spray against. It'll come out fine next time the rads need some service.

Pay close attention to the seals around the fan door, and cut a heavy chuck of rubber to block as much of the blower fan { BELT, I should have written} entrance as you can without rubbing and making a stink.

happy coaching!
buswarrior

[RickB]

Having just went through this here are my recommendations.

Use an IR gun and see if your radiators have any hot spots they can look new and be 60% plugged. If they need replacing call diesel radiator in Chicago and order two of the larger radiators at around a grand each which is considerably less than it will cost you to rebuild/recore the inadequate ones you have. I doubt you would need a tranny cooler with the larger radiators as I am struggling to get my 8v71 up to operating temperature with the new radiaitors, seals and the smaller blower gearbox drive pulley. If you go the new bigger radiator route you will need to go to gumpys website to see how to modify the bulkhead

Without your seals working properly you will have so much air going around your radiators that they won't get the airflow they need to work properly.

The smaller drive pulley is really a must (around $50-75 used)

Are your shutters working correctly, if they are not opening you will need to check and possibly replace your shutterstat.

I found that once I was in there I might as well do this all right because I NEVER want to do it again.

The litmus test is that you should put a piece of paper up to the radiators and it should stay stuck to the radiator. When I finished yesterday I started to put the piece of paper up there and it tore it out of my hands.
Needless to say I am HAPPY.    Life is good when you're bus is running great...

Good luck with whatever option you pick.

Rick

[Chopper Scott]

I have been taking a lot of everyone's advise to heart this winter and filing it away in what is left of my memory bank!!  The previous owner had the rads redone (obvious tell tale clues) and I am assuming he had a cooling issue. Unfortunately he had no idea of needing to seal them off. I had read earlier about the "great stuff" remedy and while not ideal it does work and it's not hard to remove when you need to. Yesterday I fired the bus up and felt the draft through the radiators for a comparison. I had some automotive weatherstripping from some toolboxes I built and it worked perfect for the fan door and I great stuffed the HUGE leaks after readjusting the rads back to even close to the original seals. I could put my hands over the rads from one side to the other. I still need to seal off the fronts and top outside areas of the rads but I couldn't wait to see the difference. WOW. She's sucking some air through the radiators now. I'll be putting those ideas for the fans in front of the radiators as a supplement on hold for now and finish sealing those babies off. I also like the smaller pulley idea. But I am going with the tranny cooler and fan setup for sure. I'll be towing a 16 foot enclosed trailer on occasion. The way I look at it is if I'm going to all the work of installing one why save a few hundred bucks and not go for the biggest btu system I can get recommended for the Allison. Lets see what else is on my list...... 12 volt charging system off the engine, rolling lobe airbags, air throttle, relay system for the trailer turn signals, 24 volt led's for the bus signals, window awnings, new curtains, tint the top half of the windshield, maybe some electric wipers, cruise control, fuel gauge, slide out big screen tv, change the stupid fill on the fuel tank, Jakes, rolling satellite tv................. Anything I forgot?    Thanks for all your advise guys. It looks like I drank the Koolaide and am becoming a busnut!!! Don't tell my wife! Later

[mikelutestanski]

Hello:   I found that with new radiators in the 72 7 I still had some issues on a long pull so I installed an outward flowing fan on the driver side engine door and that made the difference.
    With a 318 engine and a 740 allison and mci 9 fans and blowers but not the smallest pulley THe cooling was adequate for my travels. THe new radiators from chicago radiator were the standard mci 7 height but are 4 inches thick.
    I am sure that the 871 in standard configuration would have been fine but adding the 65 injectors and the 740 load  made the new rads adequate.
   I did clean up the blower box and replaced all seals and sealed the compartment.
  Since the repower to a cummins L10 at 275 hp and an allson b400r I have not had any problems at all.  The new engine being 4 stroke and about 275 hp has plent of margin for cooling. The retarder on the tranny does put heat back into the system but so far I have not seen any significant rise.  The only mountains I have seen are in NC around Bryson city. Alot of up down stuff where the retarder get exercised alot. I have not turned on the engine door fan either.
    Regards and happy bussin   mike

[buswarrior]

RickB, you gotta find some pics to have a look at the rad space for an MC7, versus an MC8 versus an MC9.

Just a view of the outside screens is enough.

The notching job you describe is usually related to stuffing MC9 rads into an MC8.

the MC7 was smaller still, as the original design did not anticipate the arrival of the auto transmission.

MC7 were fine coolers with a manual transmission.

The MC8 was fairly marginal in cooling with an auto, but the MC7 was a disaster with an auto installed.

Those with MC7's have less opening as well as less space to stuff anything bigger into.

The smaller pulley is definitely an advantage for them, and getting the auto tranny's heat out of the engine rad is paramount.

happy coaching!
buswarrior

[RickB]

Bus warrior,

Thanks for the info. I thought they were the same.

Rick