Hydraulic cooling fan motor

[Off-season sports]

Hello I'm new my name is Randall. Have a 2004 thomas transit bus mercedes 996 engine rear motor. The hydraulic cooling fan motor went out, and I can't find one. Please help.

 

[Off-season sports]

Hello I'm new my name is Randall. Have a 2004 thomas transit bus mercedes 996 engine rear motor. The hydraulic cooling fan motor went out, and I can't find one. Please help.

I'm sorry my motor is a mercedes 906.

 

[Jolly Roger bus 223]

you might be able to find a universal motor.
if you cant find one with the fan blade and have to use your existing fan blade make sure to try to match the motor RPM anything more and you might blow your blade apart.
been there done that and it took out the radiator and intercooler on a supercharged car.

 

[Iceni John]

I'm sorry my motor is a mercedes 906.

Do you mean the radiator fan's hydraulic motor, or the diesel engine itself (that really doesn't matter in this context)? It causes less confusion if you refer to an internal-combustion engine as an 'engine' and the electric motors and hydraulic motors as 'motors'; these two terms are not freely interchangeable.

If the fan isn't turning, you need to check:
A) The PS/hydraulic pump that powers the fan motor, and its priority control valve for the PS;
The speed control valve assembly that changes the fan's speed depending on engine temperature, including any temperature sensors and fuses/CBs;
C) Does the bus's A/C affect the fan speed? (It does on some RE Blue Birds.)

Hydraulic motors for automotive radiator fans usually have tapered output shafts with keyways and a large nut to secure the fan hub; this is different from most industrial hydraulic motors that typically use straight shafts. Finding motors generally isn't hard: finding one for your application may not be easy.

John

 

[Off-season sports]

Fan hydraulic motor. The pump is fine because it runs the power steering. I need a motor

 

[Off-season sports]

Thomas bus gave me a reference number daf551101293190 the tag on motor cant be read. Anyone can find me a motor please let me know

 

[PorchDog]

Here is one:

https://firsttruckparts.com/product...dynamatic-limited-uk®-hydraulic-fan-motor-asm

And a used one in the US---

https://www.nwrvsupply.com/product/used-sauer-danfoss-hydraulic-fan-motor-551101302190/

And a new one on eBay-- (Free Shipping!) (Sure looks used....)

https://www.ebay.com/itm/374589487790

Some Paccar and MB stuff is European based-- apparently this is a DAF motor.

 

[PorchDog]

Now I see where these only matched the last three numbers-- sorry for that. But they are hydraulic motors.

 

[Off-season sports]

Thanks for trying. It is important to us. We are a 501c3 nonprofit www.offseasonyouthsports.org

 

[Polarweasel]

This it?

Searching (DuckDuckGo in my case) the tag number pulled up this one in Houston. There looked to be other legit options too, at a glance…

https://www.tzsupplies.com/dynamatic-drive-motor-551101293190-i2331947/

 

[wbuttrill]

similar bus - same issue

I have a 2006 Thomas HDX w the MBE906250 which also comes w a hydraulic motor for the radiator cooling fan. I've replaced the motor, but the problem seems to be the control valve not putting the fan in high mode. I can't find a replacement control valve. Does anyone know if its possible to bypass and have it operate at high speed 100% of the time?

 

[ewo1]

I have a 2006 Thomas HDX w the MBE906250 which also comes w a hydraulic motor for the radiator cooling fan. I've replaced the motor, but the problem seems to be the control valve not putting the fan in high mode. I can't find a replacement control valve. Does anyone know if its possible to bypass and have it operate at high speed 100% of the time?

I am not 100% sure but i do remember reading somewhere that it might be a ground signal that sets the control valve/fan in high mode.
A 12v signal turns it off.

If anyone can confirm this, would be helpful….

 

[wbuttrill]

Also, if anyone has a schematic, that would be really cool. Thanks!

 

[Iceni John]

I have a 2006 Thomas HDX w the MBE906250 which also comes w a hydraulic motor for the radiator cooling fan. I've replaced the motor, but the problem seems to be the control valve not putting the fan in high mode. I can't find a replacement control valve. Does anyone know if its possible to bypass and have it operate at high speed 100% of the time?

What make/model of solenoid directional control hydraulic valve do you have? My bus's Danfoss 7WA110-2 valve partially restricts the flow of hydraulic fluid to the fan motor at less than 195F, then allows full flow above that temperature. The valve's default mode is fully-open; for it to restrict flow requires its ground wire to be grounded through the temperature switch that opens above 195F. The valve is always connected to 12VDC positive; only the switched ground actuates the valve. My bus has a self-resetting CB that supplies power to the valve: has the CB (or fuse) in your bus that powers the valve tripped or blown?

Yes, you can set the fan to run at full speed all the time, but it will consume more power from the engine, make more noise, and heat the hydraulic/PS fluid more. In the winter I run my fan through the temperature switch, but in hot SoCal summers I leave the fan on full speed to keep the engine cooler (OK, less hot...): I've added a switch that cuts the ground regardless of temperature.

Your fan's control valve should default to full-flow, not v.v.! Your bus's electrical and hydraulic schematics should explain what does what and how.

John

 

[wbuttrill]

My CV is a Danfoss 1090757 which I've found is no longer manufactured. This is very helpful. I hadn't considered a fuse. Thanks for the info!

 

[Iceni John]

My CV is a Danfoss 1090757 which I've found is no longer manufactured. This is very helpful. I hadn't considered a fuse. Thanks for the info!

I suggest you start looking for more of those valves now while you have time, because if (when?) your valve goes tits-up, if you don't have a spare you'll need to change the entire block assembly that the valve and solenoid are part of, and that will be a royal PIA. Amazingly I found on eBay some years ago, more through luck and chance than anything, what may have been the last three valves like mine in the USA, so I bought them all! I changed out the original one as a preventive measure, so now I have two spares "just in case". I have a tendency to do this with other things as well, accumulating a small treasure-chest of spares for my bus made by a company that went out of business more than thirty years ago.

As the scouts say, Be Prepared!

John

 

[wbuttrill]

I've been searching and haven't found one yet. I was a Scout, so I definitely like that motto! Thanks,
Bill