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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: uemjg on May 09, 2013, 01:42:01 PM



Title: bus wont start...
Post by: uemjg 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.


Title: Re: bus wont start...
Post by: luvrbus 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 


Title: Re: bus wont start...
Post by: uemjg 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"?


Title: Re: bus wont start...
Post by: luvrbus 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


Title: Re: bus wont start...
Post by: bobofthenorth 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. 


Title: Re: bus wont start...
Post by: Utahclaimjumper 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


Title: Re: bus wont start...
Post by: rusty 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


Title: Re: Re: bus wont start...
Post by: Seangie 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


 www.herdofturtles.org  (http://www.herdofturtles.org)
1984 Eagle Model 10S


Title: Re: bus wont start...
Post by: Mike in GA 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/ (https://www.mohawkmfg.com/)
     Just FWIW
Mike in GA


Title: Re: bus wont start...
Post by: uemjg 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!


Title: Re: bus wont start...
Post by: rv_safetyman 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:

(http://i697.photobucket.com/albums/vv334/beltguy7043/Governor.jpg)

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

Jim


Title: Re: bus wont start...
Post by: wg4t50 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


Title: Re: bus wont start...
Post by: TedCalvert on May 10, 2013, 05:53:18 PM
Schraeder made many valves.


Title: Re: bus wont start...
Post by: luvrbus 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


Title: Re: bus wont start...
Post by: rv_safetyman 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 (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


Title: Re: bus wont start...
Post by: Lin on May 10, 2013, 10:45:07 PM
Sometimes a very popular item's name becomes the same as the name of the company that makes it. Although the Schrader company might have many products, the term Schrader Valve is generally used for the tire type air valve.

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

Interestingly enough, the same is thing happened with Sloan's Royal flushometer that is commonly known as a Sloan valve.


Title: Re: bus wont start...
Post by: Ed Hackenbruch on May 11, 2013, 03:35:00 AM
 Two other examples would be Kleenix and Q-tips. ;D