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Old 10-04-2019, 06:42 PM   #1
Mini-Skoolie
 
Join Date: May 2018
Location: Tennessee
Posts: 24
Year: 2004
Coachwork: Thomas
Chassis: Thomas
Engine: Cat 3126
Rated Cap: 84 passenger
No Heat

No heat in my bus, not house heat, bus heat from the engine. The two valves that are on the side of the engine are OPEN, the slide thing on the dash is moved over to the hot side and the aux. pump is turned on. I've been running the engine at high idle and the gauge is showing 200-205 degrees. I think that's normal for a 3126 CAT. The radiator is hot to the touch as is the heater hoses right next to the engine, as I get a foot away from the engine they start to cool off. The heater control valve at the right side of the engine that the slide on the dash controls as far as I can tell is open and is slightly warm. AND NO HEAT IN THE BUS. I left the two big heaters that go under seat in the back, just shortened up the hoses and brought them forward hoping we would have more warmth up front where we will be riding. Anyone with first hand experience that can help a frustrated old guy out? Thanks
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Old 10-04-2019, 06:56 PM   #2
Bus Crazy
 
Join Date: Jun 2013
Location: Picton,Ont, Can.
Posts: 1,837
Year: 1997
Coachwork: Bluebird
Chassis: GMC
Engine: Cat 3116
Rated Cap: 72
Let the bus cool down then open the rad filler cap and then and start the bus. Watch for bubbles of air appearing or not. Might be an airlock in the system from the work you did. If low on coolant top it up as needed.
Thermostat sounds as if it is working if rad is getting hot so could be a rad blockage as well but hard to say until you heck for air in the cooling system.
You might need a good flush of the rad.

Check linkage on those slider controls you mentioned but they only add air to lower cabin heat I think.


John
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Old 10-04-2019, 07:27 PM   #3
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Location: Andrews,Indiana
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Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Just the two of us.
There could also be a air bleed on the top of the main heater/defroster radiator.
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Old 10-04-2019, 09:09 PM   #4
Mini-Skoolie
 
Join Date: May 2018
Location: Tennessee
Posts: 24
Year: 2004
Coachwork: Thomas
Chassis: Thomas
Engine: Cat 3126
Rated Cap: 84 passenger
Quote:
Originally Posted by somewhereinusa View Post
There could also be a air bleed on the top of the main heater/defroster radiator.
I'll look for that. I do have a fitting under the floor about the drivers seat area where several of the heater hoses come together and the aux. pump is there also, this fitting has a schrader valve in it. Never seen thins in a heater hose, A/C maybe, but not heater. Could that be for dumping air?
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Old 10-04-2019, 09:22 PM   #5
Mini-Skoolie
 
Join Date: May 2018
Location: Tennessee
Posts: 24
Year: 2004
Coachwork: Thomas
Chassis: Thomas
Engine: Cat 3126
Rated Cap: 84 passenger
Quote:
Originally Posted by BlackJohn View Post
Let the bus cool down then open the rad filler cap and then and start the bus. Watch for bubbles of air appearing or not. Might be an airlock in the system from the work you did. If low on coolant top it up as needed.
Thermostat sounds as if it is working if rad is getting hot so could be a rad blockage as well but hard to say until you heck for air in the cooling system.
You might need a good flush of the rad.

Check linkage on those slider controls you mentioned but they only add air to lower cabin heat I think.


John
I drained the coolant and put a couple bottles of the prestone radiator flush and then started working on the no heat thing. First thought it might be the valves on the side of the engine but they were both open. Then went to the slide control on the dash and followed it to the control valve in the right corner of the bus. From looking at it on the outside it APPEARS to be working. So I started taking hose connections loose and using compressed air to blow the water through them to see if they were blocked. Everything appears to be clear. You and "SomewhereintheUSA" both mentioned airlock, is that a common problem? Never experienced that on any other vehicles I've worked on but I've never worked with a hundred feet of heater either. Thanks.
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Old 10-04-2019, 10:15 PM   #6
Bus Crazy
 
Join Date: Jun 2013
Location: Picton,Ont, Can.
Posts: 1,837
Year: 1997
Coachwork: Bluebird
Chassis: GMC
Engine: Cat 3116
Rated Cap: 72
"You and "SomewhereintheUSA" both mentioned airlock, is that a common problem?"


In my mind it is a fairly common occurence in that it takes a fair amount of time to get it right, even if one is seasoned in this work. Takes patience more than anything to do properly.
Not sure about that valve you mentioned but it might bleed air, give it a try.


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Old 10-04-2019, 11:14 PM   #7
Bus Nut
 
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Chassis: old f500- new 2005 f-450
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air ..

I would put that schrader valve at the highest part of the internal heater system......... but anyways,,, that booster pump should help also... can you afford to crack a hose loose at one of the higher connections inside the bus?

reaching for unusual solutions for unusual problem.

william
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Old 10-05-2019, 01:57 AM   #8
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Location: south east BC, close to the Canadian/US border
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Chassis: 8 window
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Quote:
Originally Posted by 1dmpo View Post
No heat in my bus, not house heat, bus heat from the engine. The two valves that are on the side of the engine are OPEN, the slide thing on the dash is moved over to the hot side and the aux. pump is turned on. I've been running the engine at high idle and the gauge is showing 200-205 degrees. I think that's normal for a 3126 CAT. The radiator is hot to the touch as is the heater hoses right next to the engine, as I get a foot away from the engine they start to cool off. The heater control valve at the right side of the engine that the slide on the dash controls as far as I can tell is open and is slightly warm. AND NO HEAT IN THE BUS. I left the two big heaters that go under seat in the back, just shortened up the hoses and brought them forward hoping we would have more warmth up front where we will be riding. Anyone with first hand experience that can help a frustrated old guy out? Thanks
I made a 600+ mile trip in the bus I just bought - the valves to shut off heat to the cabin of the bus had been closed for 6 years - it took over 400 miles of driving before the air bubbles were chased from the system and I started to get some heat - now there is lots of heat
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Old 10-05-2019, 02:43 AM   #9
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Join Date: Sep 2015
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Year: 2002
Coachwork: Thomas Built Bus
Chassis: Freightliner FS65
Engine: Caterpillar 3126E Diesel
Rated Cap: 71 Passenger- 30,000 lbs.
I do not know your particular model, but our FS-65 has a Cat 3126. Your CAT has thermostats with bleed holes that allow air to pass through them when filling. The air vents out through the reservoir tank. So, you may care to pay special attention to the level in the reservoir. The heater lines come out of the engine block at the rear of the engine and lead through the heaters and back into the "y" connection at the bottom of the reservoir. The circulation pump moves the coolant through the heaters. So, if you are sure you have the proper level on the reservoir and that the circulation pump is moving the coolant, any air in the lines will eventually move out of the heaters and out the reservoir ... unless you have a blocked heater hose. Again, keep a close eye on the coolant level in the reservoir.
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Old 10-05-2019, 08:26 AM   #10
Mini-Skoolie
 
Join Date: May 2018
Location: Tennessee
Posts: 24
Year: 2004
Coachwork: Thomas
Chassis: Thomas
Engine: Cat 3126
Rated Cap: 84 passenger
Quote:
Originally Posted by Native View Post
I do not know your particular model, but our FS-65 has a Cat 3126. Your CAT has thermostats with bleed holes that allow air to pass through them when filling. The air vents out through the reservoir tank. So, you may care to pay special attention to the level in the reservoir. The heater lines come out of the engine block at the rear of the engine and lead through the heaters and back into the "y" connection at the bottom of the reservoir. The circulation pump moves the coolant through the heaters. So, if you are sure you have the proper level on the reservoir and that the circulation pump is moving the coolant, any air in the lines will eventually move out of the heaters and out the reservoir ... unless you have a blocked heater hose. Again, keep a close eye on the coolant level in the reservoir.
I'm in a flat nose built in '03 with 3126e. There is not a reservoir tank, it has a overflow tube that simply runs down the side of the radiator and dumps under the bus. With switch on and engine not running I can hear the aux pump running but I don't know for sure if or how much coolant it might be moving. I'll try to barely loosen a hose next to it and see if it's moving much coolant. One of my first thoughts was a blocked hose, that was the reason for blowing compressed air through everything. I'll follow up and go through that process again. Thanks.
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Old 10-06-2019, 12:56 AM   #11
Bus Crazy
 
Join Date: Sep 2015
Posts: 1,878
Year: 2002
Coachwork: Thomas Built Bus
Chassis: Freightliner FS65
Engine: Caterpillar 3126E Diesel
Rated Cap: 71 Passenger- 30,000 lbs.
I suppose you'll have to keep your eye on the radiator level then. The statement about the thermostats still holds though (they will work the air out).


Yes, loosening one of the hoses would tell you you have flow. You can start at the one that goes out of the coolant pump which would tell you you have coolant TO the heaters. Then work down the line to the first junction (perhaps the heater core) and see if you have coolant there. Keep following the path until you see no coolant.
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