Radiator shutters revisited

[Paladin]

Ok, so I guess my beast had shutters at one time. There are lines terminating at the radiators but nothing else. Until recently I never even knew what these were, had only vaguely heard of them and still admit that I don't really understand them beyond obvious basic theory. I was looking in the archives and it seems that there is a bit of confusion about them all around and I couldn't really find anything solid, maybe I'm just a little slow.

Does anyone who really understands them want to elucidate on their purpose and function?
Bottom line, is it worth it to try to repair the system? Where would parts (shutters) be found and how much would I expect to pay for them?
How well do they work and are they prone to failure? Should I just leave it alone? It seems like they would be most useful in cooler climates?


-Dave

[boogiethecat]

Pretty simple.  A story:

Driving years ago in New Mexico in an old pickup at night, freezing outside, wondering why the truck won't go over 45mph when it had gone faster that day. Lots faster.
Noticing that the engine temp was 120 or so.  Finally noticing a LOT of trucks coming the other way, with everything on their radiator covered but a 1 foot hole.
Aha!!! I whipped out a playboy, ripped it up, duct-taped the two covers and a few pages to the front of my radiator and wheeee, the engine warmed up immediately and the truck went fast again.
All it was, the radiator was doing such a good job even with the thermostat closed that the engine wouldn't heat up in the freezing weather, and the carb wouldn't vaporize gasoline quickly enough to go faster than 45.


On our buses, the shutters do much the same thing... when it's so frikking cold outside that even with the thermostat shut your engine won't get hot enough, the shutters close to restrict air to the radiator and allow the system to get up to operating temperature.
In the case of my Bluebird, the shutters also assist in warming the engine up more quickly- they stay shut until it's at least 160 or so.

Another thought, driving around with the thermostat closed isn't good for your engine because restricting water flow, especially in a diesel, can cause hot spots inside the engine even though the overall coolant temperature is apparently ok.  This could obviously damage your engine.  Case in point, my 5.9 cummins Bluebird came to me with the wrong serpentine belt installed (too long) and the only way that the prior mechanic could get the belt path to work was by unknowingly making the water pump go backwards.  The bus was fine driving school kids around in Utah...until I bought it and took it on the freeway... due to the reduced water flow, even though the temp gauge read "normal", #6 cylinder got so hot that it ate it's piston.  Shutters avoid that problem by allowing the thermostat to fully open, then control the engine temp by modulating the shutter position...

Bottom line, if you drive around in the deserts like me, don't worry about the shutters.  If you're always driving in snow country, maybe give 'em a second thought!!!

[tekebird]

good reply boogie

[Paladin]

Ahhh, so it's just like the old shoving cardboard over the radiator trick!

Since I'm in Utah and don't plan on spending much time in the colder climes I guess I'll leave it alone.

Thanks for the great explanation. So simple even a caveman could understand it! 

Ugg!

[HB of CJ]

Yeah...about the same answer.  Shutters are usually mounted because there can be operating conditions of climate and temperature that require their use.  Sounds pretty basic and it actually is.  A heavy truck may work in 120 degrees (F) in SW summers and six months later work in minus 40 in NE winters.  An extreme example but quite possible.  Ths enginering spills over into the coach market.

Sossss, just imagine your coach being engineered for a variety of climates and the shutters then make sense.  My 1974 Crown Super Coach ex-schoolie has shutters and they are neat in the winter because, like already mentioned, they stay shut until the coolant is around 160 degrees.  This helps the coach warm up; the heaters and defrosters work better and sooner and stuff like that.

During the hot summer, the shutters usually begin being shut, then quickly open up completely as the coolant warms up, then remain open for all the time during road operation.  The thermostats (I think there are two?) carry the summer load just fine.  Perhaps overengineered for a school bus, but that is the way Crown built stuff.  Your coach may be the same. 

[akroyaleagle]

Good answers already.
Like you when I got my Eagle, I spent several hundred dollars to get the shutters working properly. I finally took the shutters off and threw them away. Neither the 8V71N nor later the 8V92TA needed the shutters because I use propane for heat if needed on the road. Both engines quickly heated up to 190 degrees and gave me defrosters and driver heat when needed.
You are probably going to discard the bus heat if it isn't already gone so no need for the shutters.
I've driven mine to 25 degrees below and the engine still maintained 180-190 degrees.
Diesels are most efficient at 195 degrees. You will have no problem keeping the engine that warm.
So between Anchorage, Alaska and Mazatlan, Mexico I haven't used the shutters during many trips in 12 years.
Toss them.

[tekebird]

First he doesn;t need to toss them because he doesn't have them to toss.

Second there are alot of coaches that in cold weather will never get up to op temp or only get up to op temp after being run down the road a ways......with al detroits you do not want to run them cold...just about as bad a lugging them. 

Shutters will exponentailly speed warmup in cold weather.

the didn;t put em on for shits and giggles

[luvrbus]

I could see where shutters would work on a MCI bus with the cooling fan set up they have, but on a Eagle like Joes most have a thermal fan clutch or a Horton air fan clutch you can turn off.I have seen very few Eagles with shutters my Eagle runs at 190 summer and winter and I have been in 10 below weather     have a great day

[tekebird]

truew with a hydraulit fan clutch the need for shutters is reduced

[gus]

Miy shutters didn't work when I first got it and I could never get it to run above 150*. I  discovered that the air valve was turned off because it leaked. Installed a new valve and now it runs 180*-195* no matter what the weather.

I also found that the original bypass thermostat has been bypassed by a hose directly from the thermostat housing to the water pump suction side so the bypass thermostat is  out of the system. It looks as if the housing was changed to allow this hose bypass to be attached in that a boss for the hose fitting was added to the housing.

This was done because bypass thermostats are no longer available.

[Hartley]

Well, I won't get into the shutters nonsense again....

I use mine, had to fix them to get everything to work.

The reason was that the old radiators from NJT were clogged up and started
blowing cores..

I always ran at 195 to 200 before I changed radiators.. After that a 20 mile run
would only get 160 degrees at highway speeds. I installed a temp gauge on the
water pump suction side and found that 110 degree water was coming from the radiators... This in 90 degree weather... At idle it dropped to 120 on the dash and remote gauges...

I fixed the shutters and now I get to operating temps much faster. My drivers defroster and heater now works like it should. I couldn't get enough heat up front to make a difference before that.

Just because you don't go into cold areas is not a good excuse to avoid maing the system work for you. I have had rainy days that although it was 80 degrees, Cold rain on the windshield will fog up inside. Having hot water up there for heater/defroster is very welcome.

A Note: While climbing Signal Mountain at night towing an 8,000 lbs trailer the engine temps stayed at 190, the pump temps were at 158 degrees constant under full throttle.
6V92TA (MUI) 83 MC9 fully loaded and maxxed out... 5 mph uphill....9,000 mph downhill.
Yes you can hear the turbo screaming at full throttle with low road noise....!!!!

Dave.....

[gus]

Dave,

Your experience pretty much was the same as mine. My engine has run consistently at the proper temps no matter what the air temp since I got the shutters back on line.

[JohnEd]

I'm with Dave.  Anything that gets your engine up to 190 faster is a good thing to have operating.  I have seen Prevos with 8V92's that had full shutters over their enormous radiator.  Owner said the engine is up to temp and the heater is working in about a mile or so.  More likely the "or so" is more correct.  The thing that amazed me is the stories that a properly operating shutter will make you engine overheat.  POO POO!

John

[NJT 5573]

Shutters provide two purposes. The first is to maintain proper operating temperature for warmth. They never really cared if it was warm in a truck until they broke alot of crankshafts. Early diesel engines would spend 30 minutes on some mountain grades and would clear the top in a hot condition only to be subjected to alot of cold air coming thru the radiator and no fuel, just brakes for the next 30 minutes.

Turned out the repeated rapid temperature drop of going down the mountain was breaking the cranks, so Mr Cadillac invented a device that would close in front of the radiator, stopping the air flow at a preset temperature, (usually 180) allowing the truck to descend  the mountain and retain steady oil and water temperatures.

Shutters are normally open if you turn the air supply off. So why bother to remove them?

Shutters are aluminum and look nice polished. Technology has made shutters obsolete but they sure sell alot of weather fronts for cold weather trucks. Guess in a way a shutter is just an automatic weather front.

If my rig was designed to run shutters I would have them in good working order as a matter of routine maintence.

[Bob Belter]

Ahoy, Bus Folk,

Everything mentioned about  shutters and engine temperature sure sounds valid and valuable.  One factor not mentiond on the subject of shutters:  Cooling horsepower.  "Choking" or resricting the airflow through a squrrel cage blower reduces the power required.  Easy to see for yourself --  Just close off the inlet or outlet of an ordinary squrrel cage electric heater blower and hear it wind up. 

Putting your cooling shutters into working condition on the MCI's should help reduce the cooling power required.  Look at the size of the belt which runs the cooling blowers.  Those blowers can absorb a LOT of horsepower, and this power does not help to make the wheels go around.  If you MCI  //  DD two stroke  //  Allison 740  guys are perfectly happy with your fuel mileage --  Don't bother.

Some of these buses cruise down the road putting 120 -- 150 hp into the wheels and 40 hp into the cooling fan.

On my -01 Eagle with a Cummins M-11 and 10 speed OD Roadranger, my radiator is about 25% bigger than the original.  My cooling fan is a 12 blade 34" diameter unit which runs at only 0.61 engine speed.  I never heat up, and my cooling power is almost off the bottom of the chart.  So:  If you can install a bigger radiator and slower fan, it helps cooling AND mileage. 

Cold weather driving and engine temp?  I grew up in 'Minnesquito', and early decided that snow was to be endured -- NOT played in.  Hence, cold weather driving is not an issue with me and my Eagle.

Reducing cooling drag  (horsepower) is the most difficult problem in 'go-fast' airplanes.

Enjoy  /s/  Bob