Author Topic: bus wont start...  (Read 6822 times)

Offline uemjg

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bus wont start...
« on: May 09, 2013, 01:42:01 PM »
I have a 1977 MCI 8 bus with a 8v71 engine and all of a sudden wont start.  My first guess was the shrader valve is stuck...see pic.

Offline luvrbus

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Re: bus wont start...
« Reply #1 on: May 09, 2013, 01:46:29 PM »
Your 1st guess is right on it now find out why most of the time it is electrical check the rear start switches for the right position and go from there to the skinner for a hot and ground sounds simple huh 

good luck 
« Last Edit: May 09, 2013, 01:53:55 PM by luvrbus »
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Offline uemjg

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Re: bus wont start...
« Reply #2 on: May 09, 2013, 01:56:25 PM »
Well it had to be the valve because I've never had an issue starting and the valve didn't "look" correct.  So what caused or causes the schrader valve to be stuck?  In the picture is it "open" or "closed"?

Offline luvrbus

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Re: bus wont start...
« Reply #3 on: May 09, 2013, 02:13:44 PM »
looks like in the shut down position to me with plunger out that far just undo the air line supply to the valve and see if it comes back to the fuel position and starts
Life is short drink the good wine first

Offline bobofthenorth

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Re: bus wont start...
« Reply #4 on: May 09, 2013, 02:16:47 PM »
Whenever mine gets sticky I just wash it down with my favorite brand of weasel piss.  Silicon, PB, whatever your pleasure it will likely loosen up. 
R.J.(Bob) Evans
Used to be 1981 Prevost 8-92, 10 spd
Currently busless (and not looking)
My website

Contrary to popular belief, wise men do not learn from their own mistakes
They learn from the mistakes of others.

Offline Utahclaimjumper

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Re: bus wont start...
« Reply #5 on: May 09, 2013, 02:26:09 PM »
 All air has moisture in it,, after setting for some time the piston can corrode and "stick" a shot of lube and some movement will get you going till the "next" time.>>>Dan
Utclmjmpr 
 EX 4106 (presently SOB)
Cedar City, Ut.
 72 VW Baja towed

Offline rusty

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Re: bus wont start...
« Reply #6 on: May 09, 2013, 02:46:02 PM »
Bob is that anything like Panther Piss. Thank You for making my day by remembering  Dad. On the farm that was the product he ask for when a bolt was stuck. I think of Dad most days and I am sure I have not lately and that was a reminder.

Thank You Wayne

Offline Seangie

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Re: Re: bus wont start...
« Reply #7 on: May 09, 2013, 06:30:44 PM »
Uemjg,

I had a similar problem recently.  Do like Cliff says.  Even one better, just take the whole valve off as you'll need to clean it anyways.  Once it's off try starting it up. If it starts right up you'll know that's the problem.  Just make sure you have a way to hit that kill switch with the valve off or a way to cut off the air to the engine or else you'll have to wait until she runs outta fuel ;)

-Sean


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we live in a van (Eagle 10 Suburban)
Driving through the night
To that old promised land'

Offline Mike in GA

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Re: bus wont start...
« Reply #8 on: May 10, 2013, 08:24:38 AM »
I keep a 14-inch stick handy to reach between the miter box belt to close the shut-down valve. I keep it on the interior ledge of one side of the back doors. Sometimes you just have to kill the engine before sufficient air has built to actuate the shut down piston. Incidentally, there are several reasons not to reach in there with your finger.
     If you'd like to replace the electric-over-air piston, I got one a few years back from Mohawk in Illinois - not too terribly expensive.
     https://www.mohawkmfg.com/
     Just FWIW
Mike in GA
Past President, Southeast Bus Nuts. Busin' for more than 15 years in a 1985 MC 96a3 with DD 8v92 and a 5 speed Allison c/r.

Offline uemjg

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Re: bus wont start...
« Reply #9 on: May 10, 2013, 09:43:20 AM »
Well it was the schrader valve...lubed it and moved it bacl/forth manually and bus started up.  THANKS to all for the replies!

Offline rv_safetyman

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Re: bus wont start...
« Reply #10 on: May 10, 2013, 04:54:40 PM »
Just to make sure that the search engine can find this thread:

A Schrader valve is a tire stem valve.

I think the part you are talking about is the cylinder that activates the fuel shut off shown here:



Those cylinders (fast idle and fuel shut off) are activated by skinner valves.

Jim
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Evergreen, CO
’85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
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Offline wg4t50

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Re: bus wont start...
« Reply #11 on: May 10, 2013, 05:08:23 PM »
Sounds like a possibility the dog bone is striped, check to see if the blower / fuel pump is turning.
Dave M
MCI7 20+ Yrs
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WG4T CW for ever.
Central Virginia

Offline TedCalvert

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Re: bus wont start...
« Reply #12 on: May 10, 2013, 05:53:18 PM »
Schraeder made many valves.

Offline luvrbus

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Re: bus wont start...
« Reply #13 on: May 10, 2013, 06:10:32 PM »
Those are made by Schraeder but I call those cylinders doesn't make much difference what they are called to me.

It's been awhile since Jim worked on a engine without a Pro/Link the other cylinder is a holding cylinder not the fast idle Jim
Life is short drink the good wine first

Offline rv_safetyman

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Re: bus wont start...
« Reply #14 on: May 10, 2013, 08:17:08 PM »
Ted, you could easily be correct, but it appears that their primary product is tire valves:

http://en.wikipedia.org/wiki/Schrader_valve

Clifford, you are correct, my main experience is DDEC.

It sounds like schrader makes the cylinder.  If that is the case, my comments really confuse the issue.  Sorry

Jim
Jim Shepherd
Evergreen, CO
’85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/