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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: chuckdrum on March 27, 2016, 02:45:41 PM

Title: Buffer switch on 79 MCI5C, 6V92?
Post by: chuckdrum on March 27, 2016, 02:45:41 PM
Guess it's time for my occasional "dumb question from an ignorant bus owner".  I believe the attached photo is a jake brake buffer switch, but I seem to be getting conflicting info as I wander the internet.  All I know at this point is that I'm losing air through this switch.  I'm guessing it needs to be replaced.  So, what is it, and where can I find one?

This is actually a follow-up to an earlier post about said switch, though I never knew the exact name or how it works.  The access is good and it *looks* like it would be a fairly straight forward replacement, but suggestions are welcome.

Thanks!!
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: chessie4905 on March 27, 2016, 02:51:33 PM
You should be able to disassemble it and replace e seals or o-rings. Either Luke or Mohawk bus parts should have seal kits if it doesn't use basic o-rings available at any auto parts stores.
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: luvrbus on March 27, 2016, 03:02:33 PM
That is not a buffer switch it's your shut off air cylinder you don't even have a buffer switch on that engine
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: chuckdrum on March 27, 2016, 03:06:33 PM
luvrbus-

What does it do?  How does it work? 
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: luvrbus on March 27, 2016, 03:29:59 PM
There is a air valve on the firewall that is normally closed with power when you turn the switch off it opens and lets the air pressure ejects the rod outwards on the cylinder you are looking at stopping the engine by pushing on the lever in the photo cutting off the fuel by the way of the rack to the injectors. it's pretty basic you can push on the lever with a stick and stop your engine .
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: eagle19952 on March 27, 2016, 05:49:29 PM
here is what it is....

http://www.ebay.com/itm/Lot-of-2-Schrader-Bellows-Parker-Clamping-Cylinder-150-PSI-033510199-/281974002718?hash=item41a6f5d41e:g:ow0AAOSw9mFWGWtk (http://www.ebay.com/itm/Lot-of-2-Schrader-Bellows-Parker-Clamping-Cylinder-150-PSI-033510199-/281974002718?hash=item41a6f5d41e:g:ow0AAOSw9mFWGWtk)
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: DoubleEagle on March 27, 2016, 08:07:31 PM
There are two of those air cylinders on top, one for fuel shut-off, and one for fast idle. Fix or replace both if they look to be the same age.
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: chuckdrum on March 29, 2016, 09:45:12 AM
Thanks for the assistance, all.  Eagle19952- that eBay item is close to what I have... hopefully won't require too much rework on mounting it.  Can't seem to find the exact replacement.

DoubleEagle- I only see one of those cylinders on mine.  Your 871 must be set up differently.
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: luvrbus on March 29, 2016, 09:48:16 AM
Those cylinders (2) are only there if you have the factory fast idle,you may have a buffer switch since there is no fast idle I just don't see it to the left in your photo 
Title: Re: Buffer switch on 79 MCI5C, 6V92?
Post by: DoubleEagle on March 29, 2016, 08:02:03 PM
I have two air cylinders on both my 8V71 & 6V92.
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