help! bus overheating; i think it's the radiator fan not turning on...thoughts?

[DROdio]

so, i'm embarking on a 2500 mile trip and 350 (uneventful) miles into it, the bus shuts off while going down I-81.

The bus has shut off on me before in exactly the same way because a coolant hose had sprung a leak and it overheated.  i know the problem is NOT the following:

- not low on fuel - just filled up 200 miles ago
- not a fuel filter issue - just changed that about 500 miles ago

so i poked around in the engine and then i realized the radiator fan wasn't running.  Which was strange because the coolant level was all the way up in the indicator, and some coolant was even seeping out, which told me the engine was very hot (note: i don't have any temp guages installed yet).  The radiator fan turns on & off with regularity, and it was strange that it wouldn't be on, especially since right before this happened, I'd been sitting at a rest stop for about 20 minutes w/ the engine running. 

So at any rate, i'm fairly certain that the problem is that the thermostat sender that tells the fan to turn on isn't working.  So my proposed solution would be to hard-wire the fan to always be on when the master power is on.  But i'm not sure how to do this, and i'm hoping some kind soul can guide me.

Here is a link to some pictures of the 3 wires that run from the fan to the thermostat.  i'm thinking that if i simply connect the 1st wire from the left with the 2nd wire from the left, it should turn the fan on.  the 3rd wire (farthest to the right) looks like a ground wire to me: http://www.kodakgallery.com/I.jsp?c=1ykjv3f.46gwpqzj&x=0&y=-4u6cn3

BTW i checked the fuses and didn't see any burnt fuses.  I also took out my voltmeter and, with the master power on (but the engine off), i tested the voltage between the 1st (positive, i assume) and 3rd (ground)  and also between the 2nd (positive i assume) and the 3rd (ground i assume).  i only got .04 volts on the 1st wire and .06 volts on the 2nd wire, which doesn't really seem to be any significant voltage.  but maybe there's not a complete circuit, and hence no voltage should be showing???  Not sure if the results i got are indicative of anything.

thanks again for your feedback - going to sleep now but i'll be checking this 1st thing in the morning!!!

[akbusguy2000]

Two things come to mind:  The terminals at the thermostats appear corroded.  You might remove them and clean them up.  Also, the power to the fan motor is most likely supplied by a continuous duty relay.  Find the bigger wires coming out of the fan motor.  One will  be to ground, the other to the relay.  The relay could be bad.  When you short the thermostat wires to ground you should be able to hear the relay close, if its in the vicinity.



tg

[Nick Badame Refrig/ACC]

Daniel,

The readings you posted seem to be just a feed back from ground.

Sounds like your not getting the 24v through the relay. Can you jump it out?

The pics you posted looks like a low water cut out at the top of the radiator and not a thormostat.

Let us know..
Nick-

[ChuckMC8]

Daniel, Make the water temp gauge work........

[Sammy]

You need to get your temp guage working, even if you only mount a mechanical one in the engine compt for now.
I never wrenched on Van Hools, but it appears that you have a large electric fan motor to cool the radiator.
As a few folks have already mentioned, look for a large barrel style relay that could possibly control the fan motor.The motor might pull 40 amps or more when running, therefore the large relay to handle the current draw.
The 3 small wires probably control this relay, again this has already been mentioned.
Hey BK, do you have any of these in your fleet???
Best of luck with your repair. 

[TomC]

Usually with a temp sending unit, all you have to do is to ground it out to make it work.  Try grounding the sending units one at a time to see if you can get the fan working.  It could also need cleaning.  Good Luck, TomC

[Nick Badame Refrig/ACC]

Just recieved a text msg. from Daniel,

He is back on the road to Vegas, Turns out he wasn't overheating..??.

Replaced the fuel filter and he was back on the road..Hummmm?

I'll post if he contacts me more.

Nick-