Thomas Bus Cat motor HYDRAULIC FAN gone??

matthews2001 · 07-19-2020, 11:09 PM

Boy oh boy, regretting this hydraulic fan!!

2001 RE Thomas. After winter storage in Anchorage drove it about 10 miles and the power steering/fan/ oil spewed out , noticied when a car beeped along side just as power steering got hard.

Limped into Trailer Craft (big rig/thomas bus dealer in Anchorage) and spent several days of fear mongering with them (No parts, hoses gone blah blah) then finally a broken bolt on the "distribution" hose manifold and an O ring and $700 made us happy.

200 miles later in Homer I noticied a drip of oil while parked and no increase in flow when engine turned on. Same location. Many phone calls and Buddy's garage in Soldotna 70 miles away towed us to his place (Big wrecker, kids sat in his bunk, nice guy). (thanks good sam!)

So he replaced o ring, got 12 miles away and engine overheats: fan not turning power steering fine. He tows us back and tears hydaulic fan distribution and control (both aluminum boxes, fist sized) apart. Verified power to spool valve in there, but NO SPOOL VALVE in there he says! He spends a day, can't find part so puts it back together with fan on at all times ( I have never noticied whether fan ran all the time or not before).

We get 15 miles and overheat and power steering gone. He drives up with parts and discovers same O ring gone, and replaces it with one same diameter but a thinner ring to fit better. Now at a campground for some down time on our trip only 10 miles from THAT repair.

MY WORRY now is those last 10 miles of driving, flat road going 40-50 my temp gauge is 195 with fan on all times but unknown speed. Spool valve not there ever? or since 2 weeks ago in Anchorage (did that mechanic pull it?) . We drove it up here (Vt to AK)problem free last summer, no overheat problem or leakage.

How will unit operate up hills? Should I find the spool valve and install? Feeling pretty stupid now that I bought a bus. Cripes, Trailercraft in Anchorage ( A thomas dealer/repairer) implied bus might not be going anywahere anymore cause no parts available!

PS very slow internet cant upload photos

Any comments appreciated!! Plan to driveaway in a few days, back through anchorage in a week or two.

banman · 07-19-2020, 11:18 PM

I'm only familiar with your setup from reading an engine manual -- while we have different buses, we have the same basic engine although my fan is mechanical.

I'd say for engine items like this look for a CAT repair place -- this engine was used in a lot of machinery and there's a lot of CAT equipment in AK. You might get better service there.

cadillackid · 07-20-2020, 07:40 AM

running the fan on high all the time wont hurt it, however it will run on high ALL the time even when its winter time..

there's various versions of those hydraulic controllers.. they are "supposed" to fail to high fan speed.. meaning if the valve sticks it runs in high.. meaning if the valve is installed but the computer circuit is open it will fail to high speed..

that said, I helped work on one recently where a short to ground caused the fan to always run in low speed.. unplugging the connector from the solenoid sent the fan into outer-space speed.. (with engine on high idle the fan definitely was ripping)..

the ground short ended up being an easy fix on that one as when an A/C compressor was replaced, a wire got pinched..

hard to believe the spool valve is gone altogether unless the situation was that the fan was on high speed all the time and someone modified the manifold to run on low all the time in winter?

that bus is a thomas, its freightliner based, i would talk to a freightliner shop about it, and also perhaps a thomas dealer.. the fan control isnt terrible to install yourself.. of course if someonereally removed the valve, it couldve been because something else was wrong ie electrically..

Booyah45828 · 07-20-2020, 08:14 AM

Where is "home" base for you?

It's no fun being broke down on the road away from home. And if that valve is truly a rare item, it might be a week or two before you're back on the road, which could mean expensive hotel stays.

So, if home is close, I'd head there.

How you have it now, the fan will run high speed all the time. It causes more wear on the fan and hydraulic components in the long run, but your engine shouldn't overheat now driving around, so I wouldn't worry about hills or anything of that nature.

Or have the nice guy at Bubba's fix it. I'm sure he would, he'll just have to do more computer/phone work to get the right parts.

Your bus being a thomas, the fan, controller and hydraulic setup will all be their proprietary stuff, CAT likely won't have anything for you.

cadillackid · 07-20-2020, 08:17 AM

Quote:

Originally Posted by Booyah45828

Where is "home" base for you?

It's no fun being broke down on the road away from home. And if that valve is truly a rare item, it might be a week or two before you're back on the road, which could mean expensive hotel stays.

So, if home is close, I'd head there.

How you have it now, the fan will run high speed all the time. It causes more wear on the fan and hydraulic components in the long run, but your engine shouldn't overheat now driving around, so I wouldn't worry about hills or anything of that nature.

Or have the nice guy at Bubba's fix it. I'm sure he would, he'll just have to do more computer/phone work to get the right parts.

Your bus being a thomas, the fan, controller and hydraulic setup will all be their proprietary stuff, CAT likely won't have anything for you.

from what ive seen, thomas used a lot of freightliner parts on those, at least the thinbgs ive worked on on the HDX and MVP RE crossed over to friehgtliner on much of the engine compoartment and chassis related parts..

Booyah45828 · 07-20-2020, 01:21 PM

Quote:

Originally Posted by cadillackid

from what ive seen, thomas used a lot of freightliner parts on those, at least the thinbgs ive worked on on the HDX and MVP RE crossed over to friehgtliner on much of the engine compoartment and chassis related parts..

That's because Thomas was bought by freightliner back in '98.

It's all Daimler Trucks North America now.

Freightliner dealers typically have access to thomas part catalogs, but if they're not familiar with thomas buses or their parts, they might shy away from doing it.

Your RE fan motors will made by a manufacturer such as danfoss,webster or haldex, but it will likely need to be sourced through thomas. A thomas dealer will have the best shot at getting you what you need. I don't know of any freightliner trucks that would have a hydraulic cooling fan circuit. Maybe on a rear engine coach?

mmoore6856 · 07-20-2020, 05:21 PM

if you have air onboard convert to a bendix air fan. you could also install a flex fan however good luck as cat dosnt make fans or fan systems. they will tell you to go to the chassis manufacturer for parts. been down that road with a 3126 in a ford. ford dropped the ball on that one. sent me to cat and they laughed at how stupid ford parts was as the broken fan had a ford part number stamped ion it i even pointed it out but they still said it wasnt their fan. we ended calling the people that made flex fans for hot rods and they had a direct replacement so you can skip all those hydraulics that run the fan

cadillackid · 07-20-2020, 06:55 PM

Quote:

Originally Posted by mmoore6856

if you have air onboard convert to a bendix air fan. you could also install a flex fan however good luck as cat dosnt make fans or fan systems. they will tell you to go to the chassis manufacturer for parts. been down that road with a 3126 in a ford. ford dropped the ball on that one. sent me to cat and they laughed at how stupid ford parts was as the broken fan had a ford part number stamped ion it i even pointed it out but they still said it wasnt their fan. we ended calling the people that made flex fans for hot rods and they had a direct replacement so you can skip all those hydraulics that run the fan

the reason for a hydraulic fan is the fact the radiator is on the side and the engine is longitude mounted so you dont have the ability to drive a fan with a belt.. the hydraulics actually are the fan motor as well as the clutch.. ive seen bendix air Clutches but never a fully air-driven fan.. im thinking the compressor and tanks would need upgraded to support that.
-Christopher

matthews2001 · 06-09-2021, 06:18 PM

So rest of summer into early October 2020 was great, no power steering/hydraulic fan leaks, empty Alaska with COVID. Kids school started a month late (In VT) so we stayed and enjoyed!!! Left bus at a storage lot in anchorage again and flew home to vt via Boston ($144 tickets cheaper then driving!!)

So storage lot tells me there is a leak a couple weeks ago. So I have same repair shop go over and its the same control unit (Danfoss) leaking. They want big bucks to fix it. I am into that fan control now for 2gs, 2 different repair facilities. The one in Anchorage IS a Thomas Dealer. Seems they want to order a new danfoss control unit.

Any ideas? Am not on site to repair. If it was home I might try. The 2 repair shops (some 100,s miles apart) know each other and will communicate together. Hoping for the best.

joeblack5 · 06-09-2021, 06:58 PM

I have a thomas bus with hydraulic fan. The danfoss valve / flow controller failed.. that is the computer part of the flow controller failed. As a result the fan was one all the time. It was controlled thru the canbus. A new part was $1500.. I was lucky and found one one fleabag for $150.
We were " resting" for a couple of days in the desert around organ pipe NM.

Not sure if I understand why the O-rings continue to keep failing . Maybe the diverter stays closed and when the fan is of then the pressure builds to high?
I hope you took a lot of pictures and have partnumbers.
Better try to get the hydraulic diagram so that you understand how it works..
It looks like the people you had work on it did not understand what was going on. With the valve at 1500 and a fan motor at 1500 you can rack up a lot of money and not get anywhere if the shop has no real experience with this stuff.
Maybe a schoolbus mechanic / district if they have your style bus?

If you want detailed help then you need to give a lot more details.

Good luck,

Johan

Iceni John · 06-09-2021, 10:15 PM

I assume that Freightliner/Thomas did not make your hydraulic fan drive: they probably bought it from a hydraulics manufacturer such as Eaton. The first thing to do is to find out exactly what make and model of hydraulic/PS pump, fan motor and motor speed control valve you have. Only then will you know what to do. Evidently the places where you've taken your bus have no clue; most truck repair shops don't know about hydraulic fan drives because trucks don't use them. Diesel pusher RVs also use them, but most RV places are equally ignorant of them. $1500 for a fan motor and $1500 for a control valve is crazy talk! I had QCC custom-make for me a reverse-direction Webster YC motor, and it was only $800-ish dollars (a stock YC would have been half that price), I bought a brand-new Webster KB pump for less than $150 off eBay, and I found the last place in the country that had my Danfoss 7WA110 solenoid directional-control valves for only $35 each! Heck, a new Detroit drive gear for the pump cost almost as much as the pump itself. Curiously, my bus uses a Gillig Phantom valve block (complete with Gillig part number), even though Gillig was Crown's main competitor! If the correct valve is correctly assembled in the cavity block it should never destroy O-rings, and if the pump's flow rate matches the motor's flow rate then the fan should run at about crankshaft speed at full flow and about 50 to 60% of that speed at half flow - a simple Harbor Fright hand-held optical tachometer will tell you exactly what the fan motor is doing.

Hydraulic fan drives are usually completely reliable and effective. They're standard these days in most rear-engine buses around the world, and for good reason. Stay away from truck repair shops, learn what you have, then it's not difficult to work on them. Maybe it's worth you shmoozing with a good hydraulic hose shop? Also, adding a simple pressure-relief valve such as a 1500PSI Prince RD1850H can save you a lot of grief if a pressure spike should get past the directional-control valve's own internal pressure-relief poppet: it's not a pretty sight when a hydraulic motor splits apart due to over-pressure!

John

matthews2001 · 06-15-2021, 06:31 PM

First thanks to all for your comments! Really appreciate your input.

So the bus is in storage near a Thomas dealer in Anchorage. Thomas has a 111 day wait for the valve control part that is leaking. 4-5 hoses go to this unit, 2 to power steering, 2 to the fan, 2 to the pump (I assume).

Last summer this place and another place both changed failed O rings but over the winter it leaked a gallon and is leaking now (The Thomas dealer went over to storage facility and put in a gallon and started up the bus).

There is no rebuild kit available.

If part is not available I hope to convince them to bypass control and just run power steering and fan uncontrolled, I never idle the bus nor plan on much winter use. My family heads up next friday to a leaking bus. Any ideas? Any Junkyard mail order places with thomas parts?

Looking like a 3k job if part available which it looks like it is not.

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