Engine temperature

Attachment 15766

If during assembly u stick the 2 magnetic rings togeather these r rare earth magnets they r very strong.

DO NOT ATTEMPT to install the hub like this. EVER. Seporate them.

If u do not it will be assembled without 3, 1/4 in bolts on the inner ring that really ought to be there. Im pointing to the bottom 2 holes in the photo.

Another clue for proper instalation would be u dont have hardware left over when u r done. Sorry couldnt help that one.

Just for the record it never takes someone who knows what they r doing longer than around 3hr or so, even out in the field, to switch a hub out. about 07 they get a bit more challanging they r in deeper. Then they went to a driveshaft now they have electric fans. If u have this done dont get charged too much. On the 02 chassis (i think) there is slight grinding nessessary on the bracket to fit. Check your service bulletins for your vin if u have such a chassis it will have a bulletin on it.

Ive never made this mistake or ever seen it. astonishing the mistake didnt have a different result in a multitude of ways. Thank goodness for that. Aint these buses somthin.

I think Fratto has got to the bottom of this. Happy to help Fratto. Thank God and Country (and Jamie) for POG

And Fratto im not completly convinced nothing else would have also been done wrong. Approach repair accordingly. I wouldnt take it far in this summers heat like that. Get it over to Prevo. Ya know, I was in Boyd 2 weeks ago. How far is DFW from KC? Around 500. Ill be in KC all next week if prevo cant get u in. Just up the road a piece.

Attachment 15767

How many of u married guys get away with decorating like this? Hmmmmmmm??

Im currently incubating ideas for all the push in brass and old norgrens and caliper slide pins im accumulating. Stay tuned!!

Attachment 15768

Both magnetic rings

Attachment 15769

stuck togeather. Do not install like this. install 1 at a time.

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if u do assemble stuck togeathet u can tighten it in place with these outer bolts.

Attachment 15771

Unfortunatly the 3 bolts that hold the first ring in when assembled incorrectly r burried and it is not attatched to the hub. When assembling seperatly and the first ring is fastened there is airspace a very slight gap between the 2 rings. A mistake like this is why its locked up without power it was assembled with both rings stuck to eah other and no way for them to disengauge. Again quite remarkable u can actually go like that if u ask me. For how long, who knows.

Fratto how good r u with tools. I think I can talk u thru it over the phone if yer game. Dont have to take the whole thing out. Unless something else was done wrong. On second thought better not.

Attachment 15772

Nother image showin the backside of the outer ring.

Ok, so your office rocks! THANKS for the pictures and your help, these are great.

I am good with tools and I would love to do this but unfortunately, I don’t have the time right now and dont want to get part way in and find that there is more to it. So for this time, I am going to Prevost. I have an appt with Jason for Wednesday of this week and will let you know what they find.

Thanks again, you guys and this sight are great.

So if we have rare earth magnets and electro magnets? Not sure now I understand how this thing is getting two speeds.

Mark,

The beginning of this video will give you your answer. Eddy current for low speed low speed and spring pressure for high speed.

https://www.youtube.com/watch?v=zlhugkLzjlI

Fratto just like a hound dog after a rabbit u knew something was there and u didn't quit. Well done, u knew something was not right. Let us know if Prevo ever encountered this before I think this was a very unusual instalation mistake.

If nothing else was done wrong that will take about a half hr to get straight. Worst case is there was friction happening where it shouldnt and u need another hub.

Seems to me just like a fan clutch on a car when its not locked in its not static, the hub its free wheeling on still has it turning. I have also viewed the info on eddy currents but Gill is the electrical yoda not me.

Mark i just realized u have your first name in your signature LOL do u have a preferance??

Most people call me Fratto ...

Get to pick the bus up from Prevost later this afternoon. They confirmed that the clutch was locked up. They are supposed to leave the old one in the bus so maybe I can learn something.

They recorded temperatures of 195 to 205 during the test ride with the replacement clutch. As long as they were in there, I also had them go back and replace the tensioning bag for the fan belt since it looked hard to get to from the top.

I will let you know if I find anything with the old one after I get it back.

Buddy that hub was locked because it was installed wrong with 3 bolts missing. I assume it then chewed into something that prevo deemed nessassary enough to pull it. Id prob have done the same thing.

Pull the rings apart on the old one, dont thow away the magnets.

Sorry it took so long for an update. After I had the fan clutch replaced by Prevost, we took a trip to Kerrville and it was still running hot with the dash AC on. After limping into Kerrville, I found that the belt tensioning system was only at 20 psi. I had asked Prevost to double check that but I guess they forgot. I adjusted the regulator up to 50 psi hoping that would solve the problem. I was assuming that with only the fan, 20 psi was adequate but with the added load of the dash AC compressor it was allowing the belts to slip.

Leaving Kerrville, it was running hot even without the AC on. We stopped in Fredericksburg and checked the air pressure ... still 50 psi and noted that the fan was just idling. So locked the fan in place with the new style tabs. With the fan locked in, she never ran over 195 even with the AC on. You could watch the water jacket thermostat work between 180 something and 195.

Back home a little trouble shooting pointed to a failure of the main fan relay #99.

So, now with a new fan clutch, proper air pressure and some new relays, things appear to be running fine. I am in now in the camp of it runs cooler with the dash AC on. With the AC on and the fan in high, the temperature appears to be primarily controlled by the thermostat and never goes over 195. Without the AC, the temperature appears to be primarily controlled by the fan and you can see it go over 195, the high speed fan kick in and then back down to 195 when the fan goes back to low speed.

I will send a second post with pictures of the disassembly of the locked up fan clutch and my thoughts on failure.

Here are pictures of the locked up fan clutch. As you can see it had multiple problems. The bolts securing the heat sink to the flange were driven into the outer rotating assembly locking them together, the locating pins were all sheared off and the bearing for the inner rotating assembly was fried. Definitely glad that I replaced the clutch. I am thinking that it was all caused by the heat sink to flange bolt issue. This put the rotating assemblies in compression and then it was one failure after another.

1) Fan clutch assembly prior to disassembly
2) Fan clutch assembly prior to disassembly
3 and 3A) Heat sink flange which is pinned to the inner silver rotating assembly. Note that all of the pins are broken!
5) Note that the bolts that held the heat sink to the flange were driven into the outer rotating assembly effectively locking these two pieces together!
6) Outer rotating assembly removed exposing the inner rotating assembly. Note the broken pins that should tie this to the heat sink flange.
7) This is the spacer that goes over the shaft but inside of the inner rotating assembly. Note the extreme heat damage on the bottom which was in contact with the failed bearing in the bottom of the inner rotating assembly.
8) Inner rotating assembly removed.
9) Inner rotating assembly with its base removed.
10) View of the failed bearing in the bottom of the inner rotating assembly.
12) Spacer removed. Note the bevel which should face down towards the rotating base.
14) Rotating base removed. This is keyed to the shaft.
15) Note the degradation of the material holding the windings and note the exposed windings.

Thanks for the follow up. Make sure you replace the speed control relays as well as R99.

I turned on the AC to prove that the high speed worked. I did not want to wait around for it to warm up for the low speed so I did replace that relay at the same time just to be safe. I bought extra relays just in case the high speed relay fails. After your note, I may just replace it anyway and keep the one in there as spare.

Thanks for all of the back ground knowledge you guys provided. It sure helped in the trouble shooting process.

Take the good relay you removed and break the tabs off that energize the coil. That relay will engage the clutch to the speed you inserted the relay in, High or Low. This works if R99 and the clutch are good. This relay that can't energize is good for troubleshooting. FWIW, the DDEC energizes the relay to turn off the associated fan speed.

Great idea thanks Gil

Trip before last, the high speed relay failed but it was older so thought nothing of it. This last trip, the low speed relay failed and it was new :-(
Has anyone had multiple relay failures?

Good news is that I am getting Indy 500 fast at locking in the fan ha!