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Old 09-28-2018, 04:44 PM   #21
Mini-Skoolie
 
Join Date: Sep 2018
Location: Tacoma, WA
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Year: 1990
Coachwork: Thomas
Chassis: Transit liner
Engine: 8.3 Cummins
Rated Cap: 33,280
Thanks for the great info. The previous owner had recently replaced the hydraulic pump, and I replaced the filter shortly after purchase. I do need to test my motor speed solenoid. I also need to double check that I have a pressure relief valve, but I don't believe I do. If not, I'll be adding one. Hopefully after all of this, we'll be trouble free for a while.

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Old 10-03-2018, 04:40 PM   #22
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Originally Posted by bigbadblazer View Post
Hey guys, newb here. My wife and I recently purchased an already converted 1990 Thomas transit-liner with 8.3 cummins 6cta and allison mt643. We've taken it on a number of trips already and are completely in love with it. Had a hiccup today though... This morning when I started it (luckily from the engine bay), after running for about 1 minute, I gave it a little throttle and the hydraulic cooling fan completely grenaded. I was able to shut the engine off very quickly so the pump was never starved of oil or anything, etc. After a few hours of making a mess and realizing that I'm not used to working on large diesels, I got the motor out and can't find a part number on it anywhere. So my question for you is where do you look up/buy parts from? Google has not been helpful, at least with the search terms I'm using and I need to get one on order. Thanks in advance!
Schetay NW in Portland is the Thomas distributor/repair/parts etc I believe for Oregon and Washington. 800-255-8341.

They've been extremely helpful for me. I'd recommend that you give them a call.
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Old 10-04-2018, 01:13 PM   #23
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Location: Rapid City, SD
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Year: 2001
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Chassis: CS RE
Engine: ISC 8.3 L 260 hp
Rated Cap: 36
The fan motor runs off of the power steering pump on my bus. It calls for a 15-40 motor oil. I am planning on changing the filter and oil and am thinking that replacing it with a synthetic. Is this a good idea? Has anyone done/looked into doing this?

Thanks

Ted
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Old 10-05-2018, 11:59 PM   #24
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Year: 1990
Coachwork: Crown, integral. (With 2kW of tiltable solar)
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Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
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The fan motor runs off of the power steering pump on my bus. It calls for a 15-40 motor oil. I am planning on changing the filter and oil and am thinking that replacing it with a synthetic. Is this a good idea? Has anyone done/looked into doing this?

Thanks

Ted
The radiator fan motor cares less than the PS box about what oil is used. The steering will determine what oil you choose, and as long as it's OK for the motor and pump you'll be OK. Why do you want to spend a lot for several gallons of synthetic oil, when dino works just fine there? Keeping the PS oil filtered and cool is more important than using synthetic there. Just use what the manufacturers recommend.

I use cheap ($20-ish a gallon) Dexron for the Ross steering and the Webster KB pump and YC motor, and I added a full-flow Baldwin 10-micron filter just before the reservoir. With the original cooler the fluid rarely gets much over 140 degrees hot, nowhere near hot enough to derive any benefit from using synthetic oil; the motor is rated for up to 180 degrees.

John
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Old 10-06-2018, 12:20 AM   #25
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Year: 1990
Coachwork: Crown, integral. (With 2kW of tiltable solar)
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Quote:
Originally Posted by bigbadblazer View Post
Thanks for the great info. The previous owner had recently replaced the hydraulic pump, and I replaced the filter shortly after purchase. I do need to test my motor speed solenoid. I also need to double check that I have a pressure relief valve, but I don't believe I do. If not, I'll be adding one. Hopefully after all of this, we'll be trouble free for a while.
Did you ever find the reason for the motor failing? I'm suspicious that the pump was recently replaced - why? Is the replacement pump exactly the same capacity as the old one? Is the relief valve in the solenoid directional control valve OK or is it jammed solid? You need to determine exactly what happened and why, otherwise the new motor (and they're NOT cheap) will also fail. Just bear in mind that lots of hydraulic shops really don't know that much about bus cooling systems, and they will try to sell what's not always the best for the job. PS boxes, hydraulic/PS pumps, hydraulic fan motors, and everything that works with them, MUST be sized and matched appropriately - changing just one thing to a wrong size or spec can have dire consequences for the entire system.

Just out of curiosity, what make and model are your pump, motor and directional control valve?

John
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Old 10-08-2018, 02:15 AM   #26
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Year: 2001
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Quote:
Originally Posted by Iceni John View Post
The radiator fan motor cares less than the PS box about what oil is used. The steering will determine what oil you choose, and as long as it's OK for the motor and pump you'll be OK. Why do you want to spend a lot for several gallons of synthetic oil, when dino works just fine there? Keeping the PS oil filtered and cool is more important than using synthetic there. Just use what the manufacturers recommend.

I use cheap ($20-ish a gallon) Dexron for the Ross steering and the Webster KB pump and YC motor, and I added a full-flow Baldwin 10-micron filter just before the reservoir. With the original cooler the fluid rarely gets much over 140 degrees hot, nowhere near hot enough to derive any benefit from using synthetic oil; the motor is rated for up to 180 degrees.

John
I am thinking the synthetic would be a good idea as its viscosity would remain more consistant over a larger range of temperatures and the oil would break down more slowly than conventional. Also synthetics typically have better heat dissipation. I plan on using the bus often in the winter for traveling to ski and the 15-40 will be very thick untill the oil warms up if it does warm up much. With the long lines from the engine in the rear to the front axle it may not warm up well. I'm not as concerned about the viscosity with summer driving but synthetics are supposed to conduct heat away better and maintain thier lubricity longer.

I'm not too concerned about the cost as the power steering fluid wont be changed as often as the engine oil. I may also buy the synthetic in 55 gal drum as I may use it in the engine for the same reasons as above. Right now I'm using conventional until my conversion is finished and I really start putting miles on it.

I do like the idea of adding a secondary oil filter provided it dosnt add too much restriction to the system.

Thanks

Ted
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Old 10-08-2018, 07:52 AM   #27
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You both have good points.

You won't find much of a benefit by going with a 15w40 synthetic in the power steering system. Both your synthetic and conventional 15w40's have the same viscosity and thickness. After some use, the synthetic will maintain the correct viscosity better due to the uniform molecular size of the oil, but you won't see the oil breaking down in a similar fashion as you would if it was used in the engine. The heat transfer ability is also a moot point between synthetics and conventionals. The main reason there is less heat with synthetics is because of the lubricity, not the heat transfer.

You will see a difference by going to a 5w40 synthetic over a 15w40 conventional. So if your goal is to buy a barrel of oil, and use the fluid in both systems, buy a 5w40 synthetic because both systems will benefit. And with you using this in hot and cold climates, I highly recommend a good 5w40 synthetic over a 15w40 conventional.

Fluid filters are a good idea, as are coolers. A simple inline cooler with a few fins attached can do wonders.
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Old 10-10-2018, 06:41 PM   #28
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Need some help with fab system

So I have a re bus I ve been fighting. Does anybody know how to check and test the vavle And where is the vavle located I running around 210 plus going down the road. Bad thing is there is not much info on this stuff I have changed the gauge in the dash and power washed the radiator.
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Old 10-11-2018, 10:23 PM   #29
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Year: 1990
Coachwork: Crown, integral. (With 2kW of tiltable solar)
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Quote:
Originally Posted by Darvin View Post
So I have a re bus I ve been fighting. Does anybody know how to check and test the vavle And where is the vavle located I running around 210 plus going down the road. Bad thing is there is not much info on this stuff I have changed the gauge in the dash and power washed the radiator.
You need to help us here. Where are you located, what bus, what engine, what valve where, exactly what's happening?

John
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Old 10-12-2018, 02:20 AM   #30
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Sorry guess that might help lol 2001 bluebird 5.9 Cummins. 51000 miles. I am up in Warsaw Indiana I am assuming I need to check the diverter vavle that regulates the flow of hydro oil. I guessing my fan is not speeding up fast enough going down the road Bus runs fine just seems to run on the hot side going down the road. Gauge reads around 210 to 215
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Old 10-12-2018, 10:51 AM   #31
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Year: 1999
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Engine: 5.9L 24V-L6 Cummins ISB
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Sorry guess that might help lol 2001 bluebird 5.9 Cummins. 51000 miles. I am up in Warsaw Indiana I am assuming I need to check the diverter vavle that regulates the flow of hydro oil. I guessing my fan is not speeding up fast enough going down the road Bus runs fine just seems to run on the hot side going down the road. Gauge reads around 210 to 215
There ain't no hills in Indiana. My fan on my 1999 Cummings 5.9 (really more like 2000 model year) only comes on when.....it it very hot outside (>90°F) and I am in stop and go traffic, accelerating quickly from a stop, only to then sit at the next light 500 feet away: no airflow through the radiator.....or anytime I climb a big long hill.

I would suspect the thermostat in the motor that controls the coolant flow: this is a valve of sorts. At the front-top corner of the motor is the outflow coolant hose. (the one with the big green stripe in my pictures) Just below the hose on the motor is the thermostat housing, held on with 3 small bolts.

Get a new 180°F thermostat (optional OEM lower temp - 190°F is the OEM standard) from NAPA and replace it. The temp ratings I show here are for my 1999 motor (is more like a 2000 Dodge Ram series, so it is more like yours).

The job is easy. Find the drain cock either at the bottom of the radiator, or in the pipe coming out of the radiator bottom. Drain about 3-4 gallons of coolant and stop. You don't want to get bubbles of air in the lower cooling system. Then loosen the bolts for the thermostat housing. A little coolant will dribble, but if a steady stream comes out, re-tighten them a bit first and go back under the bus and drain more coolant out there until it stops dribbling from the thermostat housing. Save the old coolant if it is clear (not cloudy - colored green or orange is OK) (you may also want to test it - ask your auto parts guy for a tester) and reuse it to refill the system. But make sure you filter it through an old t-shirt: you will be amazed at how fast the filter clogs with small particles that you cant see in the fluid! - just keep shifting the t-shirt to new filter spots.

Fully unbolt the thermostat housing (you may or may not want/need to remove the hose first - use a hose removal tool that looks like a giant bent pick), and there is the old thermostat. Replace it; but first if the level of coolant in the motor is not right up to the thermostat, you should add coolant (right into the hole where the thermostat sits) until it is. Clean both surfaces where the housing meets the motor head, put a very thin smear of black RTV silicone (or better yet, aviation gasket sealer - found at NAPA) on the mating surfaces, and bolt it back together. If that hose is old or shows any signs of fatigue, replace it also; it is a weak link in the system, as it carries the hottest coolant to the radiator and takes a lot of stress. If fact, check all your hoses and consider replacing them at this time, but bleeding air from the system is then required, and I'm not getting into explaining that now.

Refill the cooling system with the reclaimed coolant, and top off with new coolant if necessary.

This is not hard, not expensive, quick, and is great preventive maintenance if it is not your problem; but I bet it is.

A final note: online repair manuals for Dodge Rams with Cummings motors show 1998-1999 having a thermostat housing hiding under the alternator bracket in the same corner of the motor, while 2000-2002 motors have it on top, like in my pics. Much easier not to have to remove the alternator first!
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Old 10-12-2018, 10:53 AM   #32
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Year: 1999
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Engine: 5.9L 24V-L6 Cummins ISB
Rated Cap: 26 foot
Quote:
Originally Posted by Darvin View Post
So I have a re bus I ve been fighting. Does anybody know how to check and test the vavle And where is the vavle located I running around 210 plus going down the road. Bad thing is there is not much info on this stuff I have changed the gauge in the dash and power washed the radiator.
Wait...you have a RE (rear engine) bus with a 5.9L Cummings?
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Old 10-12-2018, 11:35 AM   #33
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Gnome

Gnome that was the next thing I was gunna try. Now if the thermo was sticking closed and it was getting hot wouldn’t the fan kick in high to cool it down? I never heard it kick in high
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Old 10-12-2018, 11:40 AM   #34
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Gnome that was the next thing I was gunna try. Now if the thermo was sticking closed and it was getting hot wouldn’t the fan kick in high to cool it down? I never heard it kick in high
Then the fan switch needs replacing, likely. But the it shouldn't need to come on in the first place, under basic driving conditions. Gotta run...more later if you want....
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Old 10-12-2018, 10:06 PM   #35
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Year: 1990
Coachwork: Crown, integral. (With 2kW of tiltable solar)
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Most RE Blue Birds' hydraulic fans are broadly similar to my bus's. Hydraulic fluid from the hydraulic/PS pump is sent to a solenoid-operated directional control valve, then to the fan motor. This valve is actuated by a temperature switch, in my bus 195 degrees: at 195 coolant temperature the switch opens, the solenoid no longer is powered, the poppet valve closes, forcing all the fluid to the motor, making the fan go from half to full speed. It's a fail-safe system - if power is cut the fan should run at full speed, and it runs at half speed only if the switch is at less than 195 and there is power. For half speed the valve opens and allows some of the fluid to return directly to the reservoir. Crown used the same system as Gillig, using a Sauer Danfoss 7WA110-2 solenoid directional control valve in an aluminum cavity housing that has the two high-pressure hoses in and out of it, and the low-pressure hoses also in and out of it with a 1" tee connecting them to the housing.

You need to find the cavity block or housing that has four hydraulic hoses, probably somewhere near the fan motor. The valve will be screwed into it, with one wire going to the temperature switch. It's a fundamentally simple system, even if Blue Bird also tied the CAC or intercooler into it which they did with the 8.3 engines. I don't know what exact valve Blue Bird used, but if it's an Eaton or Parker you can get replacement valves at any good hydraulic shop; if it's the same one as I have, there are just two new ones left in this country! The valve itself also may have an integral pressure relief valve in it - do NOT touch the adjustment for it which is factory preset, or Very Bad Things may happen to the motor.

At full speed the fan should turn at about 1800 RPM if the pump is at 2100 RPM; at half speed it will be barely turning at low idle, at a few hundred RPM at high idle, and maybe 1000 RPM at 2100 pump RPM, ish. If the pump is internally worn, if the solenoid valve's poppets are leaking internally, or if the motor is internally worn, the fan will not run fast enough. Gear pumps and motors can be rebuilt with new gaskets, but it's a PITA to do so with no guarantee they'll be any better afterwards. If the gear tips themselves are slightly worn or if the gear housing is worn or scored, fluid will leak past and result in lower fan speed, and there's nothing to be done except replace it.

Somewhere on the internet there's a copy of Blue Bird's AA RE hydraulic fan info - it's well worth you reading it! Now's the time to really learn about your bus and all its systems.

John
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Old 10-12-2018, 10:15 PM   #36
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Year: 1990
Coachwork: Crown, integral. (With 2kW of tiltable solar)
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
Found it!
https://www.centralstatesbus.com/wp-...s/a3hydfan.pdf
Table 2 has all the good stuff.

Obviously the hydraulic system is just one part of the overall cooling system, and you'll also need to check the radiator, the fan, the fan shroud (you do have one, I hope?), the water pump, the thermostat, the coolant itself (when was it last tested?), the hydraulic fluid filter, in other words everything. Did you test your new gauge in boiling water before you installed it? (Gauges can be surprisingly inaccurate, even straight out the box.)

Good luck!

HTH, John
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Old 10-13-2018, 08:32 AM   #37
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Thanks john a lot of good info. I will read threw that today. The new gauge I got plugged into the factory blue bird bus harness so no way to check it It’s reading same as old one so I suspect it s prob fine Is there any way to jump that temp switch to get he fan to kick into high ? I did notice if I rev the engine the fan does speed up .
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Old 10-13-2018, 04:12 PM   #38
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So today I ran the bus to Menards and got it up to temp where it was saying 210 and I took one of the hand help lazer temp gauge and right at the thermostat I am reading 177 and about 130 coming back into the bottom of the motor. So I would say I have a bad temp sensor
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Old 10-13-2018, 06:28 PM   #39
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Quote:
Originally Posted by Darvin View Post
So today I ran the bus to Menards and got it up to temp where it was saying 210 and I took one of the hand help lazer temp gauge and right at the thermostat I am reading 177 and about 130 coming back into the bottom of the motor. So I would say I have a bad temp sensor

Bad sensor can do that yes. Bad as in corroded is another possibility.


Take ohmeter and check resistance then find out what a new one reads at.
Might be worth taking out and cleaning up the thing and threads where it is mounted. Will give you a cleaner ground and you know it won't be that again for a long time.


Good find with the lazer. 47 degree difference makes one wonder what is going on for sure.



John
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Old 07-19-2020, 03:20 PM   #40
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Location: Southern VT
Posts: 154
Year: 2001
Coachwork: Thomas Bus
Chassis: Allison MD 3060
Engine: Catepillar 3126B 210hp/605 ft lb
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? 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.
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