Jake brake 8V71 730 Allison

[cascabel3]

On a recent drive in SoCal I used my jake brake extensively, especially since I just acquired my bus and wanted to try them.  One more time before my destination; I tried again on a shallow grade, ~2-3%.  With foot of the accelerator I hit the switch but nothing happened.  Questions is; is there a need for certain amount of grade hence more back pressure or did my Jake crap out on me? 

[tekebird]

I think ye have a problem.  A jake should come on every time you lift your foot of the throttle pedal if the switch is on.

[Nick Badame Refrig/ACC]

Hi Cascabel3,

Welcome!

Teke is correct, it should come on when you lift off the throttle and stay on to about 20 mph.

Here is a typical wiring diagram.


Good Luck
Nick-

[TomC]

With the naturally low oil pressure that 2 stroke Detroits have, on the first try of the day you should have the engine revved up so the Jakes will have plenty of oil to activate them.  If not, nothing will seem to happen.  Try it again, but shift to second and first bump the high rpm governor, then switch on the Jake.  Good Luck, TomC

[cascabel3]

Thank you all for your replies fellow BusNuts.  I advised Bob my mechanic in El Cajon as he is working on the bus right now.  I really appreciate your help, and I doubt I would have even had the guts to own a rig like this without all of you.

[luvrbus]

Cascabel, wiring is  not always the problem with Jakes do like TomC suggests about keeping the oil pressure up and see if there is any difference.Jakes have a tube with 2 nuts and a rubber seal between the units that comes loose and the rubber seal will blow out causing the Jake not to have any oil and they will not activate      good luck

[DrivingMissLazy]

I found that my Jakes worked considerable better when I first started and got on the road. The oil pressure is generally higher when you first start the engine.

Richard

[cascabel3]

Hm, got the oil pressure part but I was already 150 miles on the road when I tried the Jake again and then suddenly I did not get a response.  She worked quite well in the beginning of the trip.  Thank you All.

[TomC]

Sounds like an electrical problem that needs to be traced.  Good Luck, TomC