specific 6-71 hydraulically driven fan hub question.

zubzub · July 18, 2009, 05:21:56 PM

These are some snaps of the fan hub on my '04. When I compare tham to the illustrations in my manual they seem different. My '04 is a very early one PD4104-040 so i got to thinking that maybe this puppy doesn't have the thermo hydro lock thingy arrangement. Any input appreciated, sorry the pics could be better.

gus · July 18, 2009, 09:40:03 PM

Zub,

My s/n 1274 doesn't have a thermo hydro lock thingy arrangement either, I don't even know what that is??

The parts book shows different parts at a s/n which I don't remember now but you can easily look it up. It shows a bunch of different parts including the interior AC/Heat vents.

zubzub · July 19, 2009, 05:05:48 AM

" a thermostatically-controlled hydraulically-driven fan that operates only when the engine cooling is needed is used as standard on trucks and as an optional on coach engines" pg 92 Detroit Diesel In-Line Series 71 maintenance manual. That's what I mean by "hydro lock thingy" also I guess this was really a 6-71 specific question, I'll try to modify the title. The reason I'm asking is a few here have had this hub fall apart, and I thought it would be cool (too cool) if I didn't have one. Also my bus takes forever to warm up which sounds like maybe the fan is always on. Finally, on cars when there is a thermo couple on the fan you can stop the fan from moving on a cold engine, how do you tell with this system?

Dallas · July 19, 2009, 07:02:56 AM

Zub,

You don't have one. It's known more often as a hydraulic fan taurus.

Yours is more like my PD4103 with a direct drive fan and was only helped by the shutters. Personally, I like this method much beter.. fewer things to go wrong in the middle of a sweltering desert or while climbing a steep grade.

zubzub · July 19, 2009, 07:16:43 AM

Excellent, more good news! ...I like keeping things simple and the taurus sure seems to be a disaster when it breaks. My shutters are long gone, but knowing me in the long run I'll mgyver something together if I can't keep the heat up.

gus · July 19, 2009, 06:28:21 PM

Zub,

Sorry to hear your shutters are missing. I finally found out how to make mine work and they really do the job in cool weather.

In hot weather I just turn off the air and they stay open all the time.

zubzub · July 20, 2009, 03:33:07 AM

One of my old volvos has a window blind kind of shutter. It rolled up on a spring in hot weather. I'm thinking I could do something like that and if I was feeling clever I could control it from the cab.

Len Silva · July 20, 2009, 06:08:41 AM

I think you would be far better off finding a shutter assembly form a parted out 4104 than trying to cobble up your own.

gus · July 20, 2009, 08:25:38 PM

Zub,

Some old farm tractors used shutters, JD for one.

RJ · July 20, 2009, 10:46:24 PM

Gus -

Maybe if you could take some pics of your shutter assembly and control mechanism for Zub, he might be able to fabricate something similar.

FWIW & HTH. . .

zubzub · July 21, 2009, 11:18:28 PM

I will look into this at some point. For now I'll move forward on the other bits. Also I have used the usual northern trick of a square of cardboard between the fan and rad.

zubzub · July 22, 2009, 05:47:31 PM

The bus gods are with me. Turns out transits here in the north still use shutters, also some of them have the same size rad, so I will be scrounging through the many transits in the bus yard where I store mine 'til I find the right size, plus no trouble finding all the control bits for it. These buses are on their way to Africa and South America so most won't be using the shutters etc. I'm already pretty close and that was only checking 3. Having an '04 in a yard full of transits turns out to be quite the score. The yard owner is bringing in a '06 sometime soon to keep mine company I guess.

johns4104s · July 23, 2009, 04:17:29 AM

ZubZub,

The main area in the fan/crankshaft are to keep your eye on (i mad a mistake and did not) is the fan hub, this is a two piece metal part vulcanised to gether. This hub minimizes any vibration from the fan reaching the crankshaft.
I did not keep a close eye on this hub, it came apart and allowed the fan to break loose and screw up the radiator.
You can tell when its going bad as it will allow the fan to move when you push the fan in either direction.

John

zubzub · July 23, 2009, 05:26:29 AM

thanks for the tip. I am slowly getting this old beast into trip form.

gus · July 23, 2009, 10:39:23 PM

It would probably be better to hook up a manual shutter system to avoid future problems.

By this I mean eliminate the thermostat and control the air to the shutter cylinder with a manual or electric solenoid operated valve.

I figure I'll have to go to that system one day when the old obsolete parts fail.

specific 6-71 hydraulically driven fan hub question.

Dallas