MC5a Cooling Enhancement--Some People Have No Shame!

[Lin]

When climbing one of the grades on our way home from a trip recently, the engine water temp reached 210.  It was very hot out, and we were pulling the Jeep (around 3000#).  I have a full width mud flap I am going to install behind the rear wheels, but have to get to it.  In the meantime, I was thinking about the airflow restrictions around the engine that might be inhibiting the blower.  Since I have decks on both sides between the engine and side access doors, I thought that we may need some additional relief.  So we tried this little device.  I just took the bus down and up the same grade, and the needle just went a drop north of 190.  The ambiant temperature is about the same out, but I was not pulling the Jeep though.  Could this have actually helped?

[Brian Diehl]

Lin,
Back when I had my 6v92 I had temperature problems pulling the long grade out of the North Platte river basin up into Denver on a 105 degree day.  I did a very similar thing to you.  I used bungee cords and held both engine doors open using the bungee and the tow bar connection points on my jeep.  This netted a 5 degree drop in indicated water temperature.  So, yes, your trick certainly helps!  There are members I've seen who have used a corrugated rear door to accomplish the same thing while actually being able to keep the doors closed.  I like your "C-Clamp" idea much better then my bungee cord approach.  Nice idea.

[cody]

I think it's a great idea and it shows the creativity in the bus community, remember that 'invention is a necessary mother' lol, I'm sure the subject of interfering with the natural flow of the engineering geeks that designed the air flow around the engine will come up, I'm almost certain of it but in my opinion, it shows great creativity, and it worked.

[gumpy]

Well that a cute little device!!

I like it.

[Lin]

Brian- The difference between a bungee cord and a c-clamp is a temporary versus a permanent solution.

Cody- Thanks for the nice comment.  Your check is in the mail.

Gumpy-  I hope you noticed that a painted it blue to make it look extra classy.

Marathon and Liberty- eat your heart out.

[happycamperbrat]

I had a really HOT day last summer and was doing a grade and ended up pulling over and lifting my back end up in the air (the RTS engine compartment opens UP not sideways like yours). Ive wondered about building a small duct to run from the nose of the bus underneath all the way down the middle of the bus to the engine compartment and then having a vent in the rear to let out extra air...... has anyone done this?

edit: Ive wondered about ducting the air conditioner to the engine compartment too..........

[cody]

check? *perk* now I'm all goosebumpy

[Jeremy]

You can buy 'stand off' brackets for Beetles that move the engine lid hinges outboard for cooling purposes. Whether there is enough air flowing down the back of a bus to make the same idea work I couldn't say



Jeremy

[Lin]

HCB,

The issue is not necessarily keeping the engine compartment cooler.  With the MCI, air is sucked through the radiators above the engine compartment, then blown downwards past the engine and exhausted out the bottom.  I do not know for sure how these buses left the factory, but my guess would be that all the space between the engine and the side of the bus was open to allow lots of air to move.  Some, like myself, have covered those spaces to make it usable for storage and inadvertently reduced cooling.  That may be okay until you start climbing on those 100+ days.  People do different things to make it easier for all that air to exit and thereby reduce the back pressure on the fans allowing more air to flow through the radiators.  More permanent and cosmetic adaptions include installing grills in the side and rear doors.  

Bringing air from the front of the bus is not necessary.  Increased venting for the radiator air to exhaust is the goal, as you did when you opened your rear door.  Also, if you need extra cooling, a mister would be more effective than bringing AC air back to the engine.

[edvanland]

I have a MCI 7 with 8v92 auto.  I put in another radiator I had built on the right rear side in line with the upper right hand radiator, that helped, then like you I had the bright idea to just open the doors, what a difference.  I live in Cornville, AZ and to get out of this valley I have a long hill to climb.  I also found some really neat slotted alumunum and cut a hole in each door for the air to escape when it is not so hot, that helped when I don't have the doors open.  I am trying to figure out where to mount another radiator on the left side in searies.
ED

[Ncbob]

Lin, understanding an MC5 cooling system is not rocket science. It is totally different from Eagle and GMC cooling so please don't depend on the other good guys on the Board who don't own premium MCI's.

You need to know that your shutterstats are working properly or remove them and sell them. the rear mud flap is important because it directs the airflow where it's designed to go, over the engine and out the bottom. You blower shutters also have to be working properly if they're even partially closed when you load the engine with a climb you'll build temperature.

Check these items out before you go into engine thermostats and the like. I run in plenty of hot weather and in the mountains and without shutterstats I haven't seen a 5 Degree difference in temperature.

Best of luck with your search for the culprit I know it can be worrysome. By the way, you didn't tell us if you had a '71' or a '92' in your ride. a '92 will run much hotter than I care to see.

regards,

NCbob

[Lin]

Bob,

Thanks for the info.  The shutters are removed, but we did mount a transmission cooler on each side where they used to be.  I know this adds to the heat load but felt it would be tolerable with proper airflow after knowing of others that had done the same thing.  I will look at the blower shutters.  They should be open since there is nothing automatic left on the system, but certainly should be confirmed.  The thermostats are new.  As mentioned, I believe that by putting shelves on the spaces between the engine and the side access doors I have created some extra back pressure.  Opening the rear doors a bit in extreme conditions seemed like a way to gain some airflow back.  There is a massive wind coming out of the bottom of the doors now at 2000 rpm.  Not much comes straight out the back or out the top.  The PO had a mud flap at the rear bumper, but we have removed that, and it will be remounted behind the rear wheels.  Anyway, although I did not like the temp going up to 210, the 190+ it showed on yesterday's test seems acceptable for a grade that is probably about 8% on a 100+ degree day.  I do register a much high temp differential than you though since it was running at 170 on the desert flats.

By the way, sorry I did not mention it is an 8v71.  Any more suggestions are appreciated.

[DMoedave]

i forgot what i was gonna say!  ( first post since the new rules, lol) Oh yeah. Lin sounds like you are on the right track but that extra load towing will be the real test. We pulled some hills couple of weeks ago that we had to slow down on last August while towing. With out the jeep behind, dident hardly creep higher on the guage. Hook er up and let us know.  I do know that the GM's did have the flap after the rear wheels and we are going to replicate that also, but maybe NCbob and others might have a point with the different cooling of a MCI. Interested to see the results as we have a GMCI!

[bottomacher]

My experiments with square bodied vehicles (mostly step vans) has been that opening anything in the rear draws outside air INTO the vehicle, not out. There is a great vacuum back there, which is why the rear of a bus or tractor trailer or station wagon gets dirty first. I don't understand how opening the engine door will help air flow through the engine compartment, and I believe that the engineers at MCI and elsewhere would have included louvers in the engine door if it would help.