How to tell if Jacobs is installed?

[Mex-Busnut]

Dear All-knowing Bus-ologists,

How can I tell if a 6V92T has or does not have a Jake brake installed? Do I need to dissasemble  the valve covers or something?

A picture would sure be nice!

Thanks in advance!

[white-eagle]

i'm not the premier expert, but i'd look for the buffer switch near the accelerator rod and shut down.  mine is about 4" long with a couple wires sticking out of it.  and some wires going into the valve covers.  if you start the engine, push the accelerator rod in to speed up a little, then mess with screwing the buffer switch in and out alittle, you should be able to make the engine sputter a little.

jacobs has pictures on their web site showing a lot of the install, also.  i've attached a parts pdf.  oops, no i didn't.  too large. but i found an install, parts, troubleshooting pdfs on their site.

[thomasinnv]

If you have the Jacobs brake you will either have the extra tall valve covers, or the valve cover spacers.

[kyle4501]

If you have the Jacobs brake you will either have the extra tall valve covers, or the valve cover spacers.

Tall valve covers do not guarantee jakes - but short valve covers do ensure you don't have them.
There should be a wire going to the jake solenoid under the valve cover . . . .

[white-eagle]

kyles correct.  i had tall valve covers, but no jakes.

[kyle4501]

kyles correct. 

Now I have it in writing to show my wife!