Author Topic: MCI 102C stock webasto info  (Read 2775 times)

Offline buswarrior

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MCI 102C stock webasto info
« on: December 09, 2019, 07:51:56 PM »
A friend has a 4 stroke C3 with the fans across the back. The D3 and DL3 is likely the same...

Does anyone have a plumbing schematic?
Where do the Webasto lines run, and is there any flow control?

The Webasto in my friend's unit needs to be bypassed due to leaking bits, the coach has to go home for parts and repair.

The commonly available 96/102ABC manual doesn't appear to cover any of the Webasto stuff.

Difficult to coach over the phone without knowing the plumbing and control logic...

Who has a better manual?

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #1 on: December 10, 2019, 06:50:09 AM »
Her is some pictures of whats in a 1996 D3  (burner removed)
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #2 on: December 10, 2019, 08:40:13 AM »
My concern is advising a bypass strategy or plug it strategy, without knowing the patterns of flow.

Overheating the engine is a potential, if an uninformed choice is made.

What is the flow, from where to where, and is there any valve/control involved?

What would the result be to just put the pipes together, or plug them both?

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Jim Blackwood

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Re: MCI 102C stock webasto info
« Reply #3 on: December 10, 2019, 08:57:08 AM »
On my DL3 there is a valve on each leg of the run to the heater cores. So on the curb side you can close off the manual valve. On the driver's side close to the webasto is a solenoid type control valve but it only isolates the lines and cores. So plugging the line from the engine to the circulation pump would be the way to go I think.

Jim
I saw it on the Internet. It MUST be true...

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #4 on: December 10, 2019, 10:27:44 AM »
Jim, is the Webasto plumbed in line to the coach HVAC system?

Or, if there's a control valve, does it go from the hot side, back to the cold side/return to the engine directly?

I am doing this all on the phone with someone who doesn't know...

Happy coaching!
Buswarrior

Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Jim Blackwood

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Re: MCI 102C stock webasto info
« Reply #5 on: December 10, 2019, 11:23:56 AM »
I'll go in a few minutes and look.

Jim
I saw it on the Internet. It MUST be true...

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #6 on: December 10, 2019, 12:02:11 PM »
It appears to me that the engine produces the heat or the Webasto produces the heat, the water is in constant circulation ( on this C10 Cat engine ) as both shut off valves are "after" the heat producers.
Here is more clearer pictures of the Y's .
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Jim Blackwood

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Re: MCI 102C stock webasto info
« Reply #7 on: December 10, 2019, 01:44:53 PM »
OK I made a drawing but it probably wouldn't photograph well so I'll try to explain it.

First. the heater loop has a manual valve on each leg so it can be shut off entirely.
Then the big solenoid valve short circuits the lines leading to the heater loop.
The engine and webasto are in series, so with the webasto fired up and the solenoid valve open the path of least resistance is through the engine. Assuming the manual valves are also open.
If the solenoid valve is closed. the engine, the webasto, and the heater loop are all in series.

Now I have to make assumptions about flow direction. If the webasto circulation pump is on the cold side for better pump life then flow is through the engine block, out a big casting on the side, through the webasto, through the heater loop (or through the solenoid valve) and back to the water pump housing.

To completely eliminate this system due to leaks both lines to the engine should be detached and plugged. Do not tie them together as this would short circuit the radiator. The two manual valves could be closed to avoid draining the heater loop. The solenoid valve should have little or no effect.

To use the webasto for coach heat only, the simplest solution would be to put a 4 way valve in the lines to the engine to the effect that the engine is removed from the circuit and those two ports blocked with the other two ports connected, but it might not be very easy to find that specific configuration, especially in a solenoid valve and even more in a surplus item.

Jim
I saw it on the Internet. It MUST be true...

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #8 on: December 10, 2019, 03:08:41 PM »
The parts manual shows 4 different illustrations covering the 4 engine options. My pictures are for Cat engine
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #9 on: December 10, 2019, 04:08:49 PM »
So, in paso's figure, there's a lot of "supply" lines... where is the flow to and from?

Which component, if it fails, would make a feedback loop and overheat the engine?

If that "bypass" valve stays open, where does the flow go?

The coach in question has a cummins.

Thanks, we're getting there...

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #10 on: December 10, 2019, 05:12:54 PM »
Sorry there is only 3 options Cat, Cummins, Detroit.
On this Cat engine I would say there is no way to stop constant flow when engine is running.  Following  the normal assumption that the suction side of the water pump is pulling the flow. Even if one valve was closed it would just go thru the
 " y" and continue to flow thru engine and radiators.  I think MCI would not allow an idiot to close a valve and  reduce flow to engine. Also unless  someone added extra valves it's not possible unless thermo was stuck closed. The webasto pump free flows according to service manual
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #11 on: December 10, 2019, 06:10:40 PM »
Where does the hot output from the webasto go? Labelled as "heater supply" on the figure?

The two "supply" and "return" towards the right side, beyond the two isolation valves are to the coach HVAC?

The webasto gets it's input of coolant from the hot side of the engine, or from the cold side of the HVAC return, via that bypass valve?

Besides the current issues, we all need to know how it works, if we are going to be modifying...

Happy coaching!
Buswarrrior


Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #12 on: December 10, 2019, 06:40:52 PM »
Actually the way I see this set up the water is coming from the water supply line on the most left hand side of above picture. It then goes thru the webasto  circulation pump on left side hand side of picture illustrated as a square( cold side ). Then water gets heated and leaves the right hand side of picture.( auxiliary heater) It then goes to the top isolation valve if valve is closed it goes thru the bypass valve and into the  y  just past the lower isolation valve marked on right as return line. The only confusing  part of the diagram is the  word and arrow pointing to the location of the supply its not the actual direction of flow. ( if top isolation valve is open it sends it to front heater)  as you stated, then the return water flow becomes really clear. If the webasto is the only thing working it would get cold water from engine  ( left side  ) and send hot thru the bypass  Y to heat engine.
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Jim Blackwood

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Re: MCI 102C stock webasto info
« Reply #13 on: December 10, 2019, 10:56:21 PM »
The diagram is accurate for the series 60. the "heater supply" comes from a large casting on the side of the block which also feeds the transmission oil cooler. (This would be the highest pressure in the system, directly connected to the engine pump outlet)

The "return" goes to the water pump housing on the engine. (The line that looks like there's a cap on the end of it. There isn't) The solenoid valve bypasses the heater loop.

The heater loop would be the two lines going forward.

Disregarding the two manual shutoff valves, there are three possible conditions and two possible states, meaning six operational possibilities:
1) Engine on, Webasto on solenoid valve open
2) E O, W O, SX (off)
3) EO, WX, SO
4) EO, WX, SX
5) EX, WO, SO
6) EX, WO, SX
And of course everything off.

To properly do the job all possibilities must be considered and coolant flow analyzed.

It does appear to me that a certain quantity of engine coolant will bypass the radiator in condition 3. Perhaps the lines are sized to take that into account.

Jim
I saw it on the Internet. It MUST be true...

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #14 on: December 11, 2019, 05:34:02 AM »
Not shown, is the heat control valve for the HVAC, this regularly interupts the water flow through the heater core.

This "bypass valve" that allows coolant to shortcut back to the cold side causes me concern. How does it work, and what is its failure mode? That's an overheated engine looking for a place to happen?

So, if we just plug the ends of the webasto pipes, there's no feed to the HVAC?

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #15 on: December 11, 2019, 05:46:02 AM »
I think we are stumbling onto a problem for those busnuts who start abandoning parts of the coach HVAC.

Running with the HVAC shut off, where's the coolant going?

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #16 on: December 11, 2019, 06:44:11 AM »
ON THIS UNIT. When both valves are closed the water circulates thru motor then webasto and the two "y's"  back to the motor.  I just looked again and water has to circulate thru the Auxiliary heater ( webasto ) the only shut off in this stock system are the two that sends the water to the HVAC .

Certain combinations ie: webasto solenoid open But highly improbable valve to front Closed the water would still go thru Y back to motor.
Looking at this Cat set up it's " idiot proof "  :D
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #17 on: December 11, 2019, 07:02:03 AM »


This "bypass valve" that allows coolant to shortcut back to the cold side causes me concern. How does it work, and what is its failure mode? That's an overheated engine looking for a place to happen?


Happy coaching!
Buswarrior

Sorry Ewen forgot to GMHO on this bypass valve. If stuck open water free flowing if stuck closed it would back up the water and force it thru the Y back to the return side,

Jim your 1 to 6 list looks like the words to "old Macdonald had a farm "  :)
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Jim Blackwood

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Re: MCI 102C stock webasto info
« Reply #18 on: December 11, 2019, 10:23:41 AM »
OK, as I see it, If you close either of the two valves to the heater loop all you have left is the flow through the webasto, to the solenoid valve, and then to the return. If the solenoid valve is closed, how is there going to be any coolant flow? I don't think there can be. Double check the drawing. So, at that point coolant flow is through the engine, the radiator and the transmission heat exchanger only. I THINK it has to be from the engine and heat exchanger then to the radiator but I'll have to look again. The return from the heat exchanger may go back to the water pump.

Anyway, the solenoid is the only HVAC flow control that I have been able to find, and I think it is the only one in the schematics as well. So the only possible way that it could work for that function is to short circuit the flow through the heater loop, thereby reducing  but not entirely shutting off heat to the HVAC. What this means is that when heat is not required (think summer in Nevada for instance) the flow through that 1" line is directly bypassing the radiator. This strikes me as a singularly inefficient way to do things. But that doesn't make it incorrect.

Unless of course the manual valves are closed and the solenoid valve is closed. In that case, no bypass and no flow in the heater loop. Opening the solenoid would then reduce the heat sent to the radiator, keeping more in the engine and transmission.

The system seems designed not so much to get rid of heat as to provide multiple way to retain it. Do 4 stroke diesels really run that cool?

Jim
I saw it on the Internet. It MUST be true...

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #19 on: December 11, 2019, 11:01:23 AM »
The earlier buses, the coolant only flows to the hvac heat exchanger as the control valve allowed, so there were periods of time that the flow through the hvac lines was stopped.

The temp control valve will be in close proximity to the hvac equipment, not in the engine room.

What powers this bypass solenoid valve?

I drove DL's back then, and they were quite capable of overheating, also capable of cooking automatic transmissions...

Everything is a contradiction, retaining or making heat is desirable sometimes, the very same stuff leads to overheating in other conditions...

This bypass valve is becoming suspect #1 for trouble later on...

My friend has the webasto lines tied together for the moment, due to leaking bits on the webasto. Spare parts are months and couple thousand miles away, he isn't going home til spring.

But the coach is overheating...

Never a dull moment for a busnut?

What powers that bypass solenoid? If a wire has been left off/broken...? Any reports of these failing open?

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #20 on: December 11, 2019, 12:47:02 PM »
Dam i hate when you lose everything in a post if you over load it ( assumption. ) pictures and text gone,  so much for long posts.

Anyway the bypass valve according to the manual is a Normally open valve.
Attached again are the pictures before and after the valvw.

The valve has both electrical and air connections, There is an identical valve in the HVAC compartment.
I'll add a second post for fear of losing it again. :)
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #21 on: December 11, 2019, 12:51:42 PM »
This is the other side of valve upper picture is the other side.
I wonder where the bus nut bypassed the webasto??
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #22 on: December 11, 2019, 01:03:26 PM »
Missed the other side of the valve picture.
If it is overheating since the bypass where did he bypass it has got to be the # 1 question.

I hope I am helping here.  as i really can't see it since both valves can routinely be closed. ( gate valves)

68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Paso One

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Re: MCI 102C stock webasto info
« Reply #23 on: December 11, 2019, 01:17:49 PM »
Okay not willing to let it go I went back to the engine and looked for the " Lazy Mans " way of bypassing the Webasto. ( no offense intended as i am guilty of the lazy mans way lots )  Low and behold if he took the inlet and outlet hoses off the water pump ( they are not close but real handy )  He could indeed reduce engine cooling as the water is going in and out of the pump not pulling  coolant from the engine.
Hope that makes sense...… remember i'm on a Cat engine. water pump is back left of engine.
68 5303 Fishbowl 40'x102" 6V92 V730 PS, Air shift  4:10 rear axle. ( all added )
1973 MC-5B 8V71 4 speed manual
1970 MC-5A  8V71 4 speed manual
1988 MCI 102 A3 8V92T  4 speed manual (mechanical)
1996 MCI 102 D3 C10  Cat engine 7 speed manual  (destined to be a tiny home )

Offline Jim Blackwood

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Re: MCI 102C stock webasto info
« Reply #24 on: December 11, 2019, 02:18:25 PM »
So far all posts except that last one are consistent with what I'm seeing here and I'm just not sure what the last post means, it may be as well. Now that you mention it I remember the solenoid valve up by the main heater core. Both it and the bypass valve are described as being the same part but inverted in the controls. Therefore when the heater valve opens the bypass valve closes. That is consistent with good operation for heat, but seems it would reduce engine cooling in hot weather. Under those conditions it would seem to make sense to close the bypass valve as well.

I had disregarded the heater control valve because it does nothing to further my goal of isolating the engine from the webasto/HVAC loop.

re: the immediate issue, bypassing the webasto due to leaks should work, if the rest of the system is functioning properly. If it is overheating it would seem prudent to close that bypass valve by whatever means available. As it is described as normally open (I believe) it would be necessary to make sure it closes. So, verify air and signal and confirm operation.

Jim
I saw it on the Internet. It MUST be true...

Offline buswarrior

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Re: MCI 102C stock webasto info
« Reply #25 on: December 11, 2019, 02:33:18 PM »
Thank you gents.

The control logic for this bypass valve sounds good, under conditons of cold engine/cold coach.

It makes no sence to feed hot coolant back into the water pump intake under warm conditions...

There must be a temperature component to the control of this bypass valve, or tied into the Webasto firing circuit, to keep it closed when the engine temp is satisfied?

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

Offline luvrbus

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Re: MCI 102C stock webasto info
« Reply #26 on: December 11, 2019, 02:50:20 PM »
Webasto and Pro Heat both are plumbed the same,the bus probably has a L10 or M11 here some photos for the Cummins,there are isolator valves (3) not showed but it will give you the idea on how they plumbed  on the engine if that helps
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