Overheating problems - trying to make my way up I-80 towards Reno

[daveola]

My 1986 MCI 102A3 bus has been acting weird in the overheating department.  First questions:

1) I can't tell for sure if it's a gauge issue or an actual overheating problem.  The gauge is getting a little bouncy, so I'm not sure I can trust it.  If I use an infrared temp gauge pointed at the engine, what kind of temps can I expect to see for a normal running engine?

2) What causes the engine cutoff?  Is it using the same sensor as the gauge?  (i.e., if my sensor is bad, could that make my gauge be off as well as cause shutoff?)

Failing that, I'm not sure what to do about the overheating.  Almost two years back my radiator fan gearbox went out, and I ordered another one from Luke at US Coach.  The one that arrived was smaller, but the mechanic put it in without checking with me, and it seemed to get us home (though we drove at night).  The bus sat, thanks to covid, in storage.  When I took it out, it immediately started to overheat and I had to stop driving.  It took forever to get it back to storage.

I took it to Prevost Maintenance (there are almost no mechanics around the Bay Area who will look at an old bus).  They kept trying things and claiming the overheating was fixed (flushed the cooland, blew out the radiators, but really not much of anything), but here I am, stuck on I-80.  I am generally able to drive at night and keep it around 190, according to the gauge, but if I climb too much hill then it starts to overheat and I have to keep pulling over to cool off the engine.

So here I am, moving at a snails pace towards Reno.  Any suggestions on what to tackle next?

Is it possible the different size gearbox is at a drastically different gearing and isn't spinning the fans fast enough?  Any thoughts on how to check what my gearing is or is supposed to be?

Any thoughts on who in Reno can help solve this?

[daveola]

There is some sort of sensor that is possibly involved.  I noticed that a wire had come off of it.  I tried reconnecting it and then my bus would immediately shut off when it got air pressure even when it was completely cooled.

Photo attached, or here:

http://tmp.davepics.com/Bus/Cooling-Sensor.jpg

Does anyone know what this sensor is?  It's right next to what the maintenance manual claims should be my temperature gauge - or perhaps this is the temp gauge?

[daveola]

 Here's the page from the maintenance manual:

http://tmp.davepics.com/Bus/Cooling-Maintenance-Manual.png

[buswarrior]

Before anything, because it could be NOTHING wrong...

Confirm that the info you are getting is true.

Open the floor down the back, above the transmission. Identify the coach heater pipes, passing nearby, heading towards the tunnel. Have an assistant get comfortable with shooting that pipe with an infrared gun.

The gate valves in the engine room have to be open, and some coolant has to flow, some heat out of the defroster will be sufficient to get the heat into the pipes for accurate readings.

Go for a drive, and holler back and forth what temps each of you are getting.

The assistant will need eye protection, might get some hurricane blown sand, depending on your road conditions.

Confirm, or deny, that the dash gauge has caused a whole lot of trouble for nothing, or has saved your engine.

The gauge, like a clock, might be accurate twice a day... my MC8 was correct at 180, and then the dash climbed much faster than the "real" temp shot down the back. Take note what each indication on the dash gauge means for now, compared to the IR gun down the back.

None of this works, if you don't get some flow thru those pipes...

Report back.

Happy coaching!
Buswarrior

[daveola]

Thanks Buswarrior, it may turn out that it doesn't matter, because I just talked to Don's Bus Repair in Sacramento (which I unwittingly drove past last night) and he believes that the squirrel fans were put in backwards (left to right and vice versa) so the fan blades are facing the wrong way.

Can anyone confirm that these vanes are facing the incorrect direction from their bus?

I'm driving back down to Sacramento and he's doing me a huge favor to work on it tomorrow, if this solves my heating problem, Don's my new hero!

[RJ]

Can anyone confirm that these vanes are facing the incorrect direction from their bus?

Dave -

Those squirrel fans look correct to me. 

Does the engine compartment temperature gauge match the dash gauge?

Are you sure you're getting sufficient tension on the fan belt?

Are the radiator compartments sealed properly, so that all the air coming in goes thru the rads and not around them?

Is the blower compartment sealed properly, so that the blowers aren't sucking air around the door seals?

Do you have a "mudflap" hanging off the back bumper? If so, get rid of it because it traps the hot air trying to escape the engine compartment.

Are the water valves controlling the flow to the OTR heater and defroster open, and thus getting heat out of both of those?

Just some thoughts off the top of my head. Hope Bob can help!

FWIW & HTH. . .

[luvrbus]

The speed of the blower will effect the cooling ,plus there are 2 different diameter sizes of blowere be sure the doors are open on the blower too

[daveola]

Those squirrel fans look correct to me. 

That would be a huge bummer - are the vanes going in the right direction?  Can you take a photo of yours?  I sent that to Bob and he said it was definitely wrong.

Does the engine compartment temperature gauge match the dash gauge?

I don't seem to have a temp gauge in the engine compartment - see the first photo in the original post.

I believe the radiator compartment is sealed.  I don't have a mudflap anywhere.

The OTR heater works, so the valve is open.

[daveola]

The speed of the blower will effect the cooling ,plus there are 2 different diameter sizes of blowere be sure the doors are open on the blower too

What do you mean by different diameter sizes - are you talking about the pulley connected to the gearbox?

And if by 'doors' you mean the radiator vanes, they are fully open.

[daveola]

Those squirrel fans look correct to me. 

Actually - I'm pretty darn sure that they are not correct.  The scoops are supposed to be going forwards to throw air, but when I start up the engine I can see that the fan is rotating to that the curve of each blade is what is hitting air.  I think this is the problem, and I think Don is right!

[RJ]

Actually - I'm pretty darn sure that they are not correct. 

Dave -

Looking again at the photo of the blower above, I have a question:

When the engine is running, are those vanes traveling "UP" towards the top of the photo, or are they traveling "DOWN" towards the bottom of the pic?

I don't have an MCI anymore, so I can't go out an look at mine, sorry.

RJ

[Jim Blackwood]

Dave -

Looking again at the photo of the blower above, I have a question:

When the engine is running, are those vanes traveling "UP" towards the top of the photo, or are they traveling "DOWN" towards the bottom of the pic?

I don't have an MCI anymore, so I can't go out an look at mine, sorry.

RJ

Be careful about this. Squirrel cage fans are a bit odd and will work both ways, and they are used both ways. I think maybe it has something to do with noise suppression. So be sure you have the right answer before you go changing it.

Jim

[buswarrior]

Yup, backwards, you can't see into the fan blades usually, which is why so many people have fans full of dirt.

You can see into each blade.

Got a winner here!

Someone regarded installing the fans on the shafts as a mundane routine job... when it is a mission critical moment... and mixed 'em up side for side...

Tricky spatial sence thing when the fan assembly is out lying on a bench or the ground.

Happy coaching!
Buswarrior

[lostagain]

Looks backwards to me too.

[Ed Hackenbruch]

If they are backwards they would push air out thru the radiators instead of sucking it in, right? Easy test for that, fire it up and put a piece of paper on the outside of the radiator and see if it sticks to the grill or blows away from it.