I had an overheat issue yesterday when test drive for a fuel problem. The engine shut itself down a couple of times before making it back to shop. (8v71 in MCI5B) Today drained antifreeze,and will change thermostats tomorrow. I also removed shutterstat as it might be this that is sticking. I realize that this thing contols air to the shutters and fan doors by sensing the antifreeze temp. Does the shutterstat make the doors open or close only or is the control proportionate? Is there ever a 1/2 way? Is the following picture of my shutterstat a reliable unit? According to dash guage and the one in engine compartment engine temp was almost 200 when shut down occured. High temp sensor are new. Do I need to consider changing these also? Is there anything else I should check while antifreeze is drained? My engine is at 1650rpm @60mph if dash tach is correct. From all the reading I do this rpm too low for best engine life. If I got up in 18-1900 rpm I would be close to 75mph (guessing) Is this 1650rpm maybe a part cause of heat issue?
Do they close completely at shutdown with no air? can you dissconnect the air cylinder and open them manualy? make sure that mechanically there are free to move as well.
Larry,
The shutters will go to wide open if you disconnect them. I bought a cap a couple years back and just capped off my shutterstats. If I'm driving my bus in the winter I'll use them but they really don't do much of anything in the summer. I wanted the extra time in case I overheated to deal with it before anything major happened. My bus stays around 170-180 during the summer and I'm fine with that. The shutterstats were designed more to get the bus to temp quickly than to actually hold a temp. There's probably folks here that will disagree with me about the need for them but especially if you just want to see if they're working correctly that's a way to start. I also seem to remember a valve somewhere in the engine compartment that shuts off air to them. My valve was leaky which is why I capped the whole system off. A couple things to check. Get an IR thermometer and check for blockages or hot/cold spots in your radiators, at the thermostat housings and the inlet outlet of your water pump. The litmus test for your cooling system externally is the suction from your system at idle should pull a piece of paper out of your hand and hold it to the side of the bus while running. If that's not happening, the seals around you scroll fans, the seals at the top, sides and bottom of your radiators and the seals around the blower box door itself need to be examined. Look at the system design wise as a system that wants to make all or most of the air that your bus is using to cool itself has to go through the radiator to accomplish that. All the seals, especially the door seals, need to be as airtight as possible or it's going to suck air through places other than across the cooling fins of your radiators. Many of us here have had to rebuild our whole blower box assembly from top to bottom'. New bigger 8v92 radiators from Chicago, new seals, rebuilt blower gearbox and the smaller diameter pulley. It is a lot of work (go to guppy's site, he details it completely) but you end up with a motor that has to have something other than weather or a long pull to overheat it. I hope this is helpful for you and keep asking around, there's a lot of knowledge here on the board to take advantage of. Good luck with this and keep us informed
Rick
Sorry go to gumpy's site not guppy's. Oh boy Craig's gonna kick my butt next the I see him for that! It was autocorrect...I was framed I tell ya!
Rick
Rick B, what is Gumpy's site name? Link? Thanks.
Larry B, 1650 rpm is a little slow, but it should not make you overheat unless you are lugging it, such as climbing a slight incline in hot weather, and/or going against a head wind in hot weather, in which case you would down shift to increase rpm. You must have 3.36 diff gears? It is more likely related to what Rick B explains.
JC
Just close the air supply valve to the control unit off, and open the manual exhaust valve on the bottom.
Confirm that the shutters have opened by looking in the screens, and then confirm FOR SURE that the damper doors are freely opening absolutely all the way. If they are sticking so much as an inch into the airflow from against the wall of the fan exhaust, there can be overheat trouble.
You have better things to do with your time right now, leave the shutter system neutered for now and remove at your leisure when you've run out important things to do.
happy coaching!
buswarrior
Thanks for all the good advise. I got the thermostats changed and all the other little pieces back together today. The shutterstat will not be here until tomorrow morning. The rest will not take long to put together, then antifreeze back in. When I get it running again I will do some checking for hot spots with IR heat gun and try the paper check. I will likely try things on automatic control to see if it works correct and doesn't overheat again. Then close the air supply valve to the louvers for the summer months. The reason I asked if the system was proportionate is the one time I was at the engine after an overheat occurrence I noticed exactly what you mention bus warrior, the flaps up inside the fans was about an inch from full open. When i barely touched the arm, the flaps opened the rest of the way. I checked today does not seem to be any tight or sticking spots.I sprayed some wd in the air lines while open ,a little lub on the o rings in the air cylinders will not hurt. If running this with louvers full open and still maintaining 180 deg engine temp. is OK then that is what will happen. I think my air/fan/cooling system is in fairly good shape. I put new rubber boots inside the fans and when I installed the rads after cleaning them I formed pieces of sheet metal in break for around rads to try and force as much air as possible though cooling fins.Again thanks for all help, another test run should be happening tomorrow. Each test run gets me closer to a holiday run.
Thanks Larry B
I spent a bit of money when I first got my bus to make sure the shutters worked.
I couldn't tell they did anything to help except maybe try to hold the temp up for passenger heat when it was a seated bus and was idling.
We heat with propane.
I removed the shutters and threw them away about 15 years ago. We have travelled down to -45 with no problems. The water temps stay normal while driving. I can see where it might be a little problem with the defroster, but it has never happened to us.
My recommendation is to get rid of them and have one less nuisance to maintain!
I do have a low mileage shutterstat somewhere around here that would go cheap. I think I remember it was about $100 when I bought it.