Jake Brake Issue

[RJ]

Troops -

I'm having an issue with the Jake Brake on my MCI.  First, the set-up:

MC-5C with a stock 6V71N.

OEM working fast idle.

On/off switch for Jake located on OEM LH switch panel (no floor control.)

The issue:  During normal operation, the Jake comes on immediately when you release the throttle pedal.  However, my Jake will come on, but it may take anywhere from 3-4 seconds or up to almost 15 seconds after releasing the throttle.  When it does kick in, it works normally.  If I touch the throttle a little, then release it, again the Jake doesn't come on for several seconds.

Suggestions as to cause?

Suggestions as to repair?

TIA, Troops!

[luvrbus]

You don't have but 2 solenoids on your engine and they are getting tired and takes awhile for the current to work it is sorta normal after 10 years or so.You can add a 24v capacitor to help but I replace the solenoids.
Or you could have a broken jumper tube or blown o-ring and it takes time for the oil pressure to build up in the drones not a major fix in any case     

[bevans6]

Yep, tired solenoids or oil pressure getting lost due to badly adjusted jumper tubes, or missing/damaged 0-rings.  Or possibly a flaky micro-switch.  I would verify that the switch is operating when the governor gets to no fuel, and that the wiring to the solenoids is good.  You can test that the switch operates when the no-fuel lever on the governor is applied, as if to stop the engine.  I do this with the engine off, and I can barely hear the switch click when I operate the lever to the no-fuel position, if it's quiet about.  You can pop the valve covers off, there will be a master Jake head with electrical wires going to it, and slave heads with a bridge to the master head to transfer the oil, you can back the bridges off and visually inspect the little square edged o-ring, and re-set the clearance when you do them up again.

[Lin]

I have noticed something similar at times and thought it had to do with what gear the transmission was in compared to the engine rpm at the time the Jake was switched on since they would immediately engage if I downshifted before or after throwing the switch.

[lostagain]

RJ, you can get the service manual off the Jacobs site. The whole system is actually quite simple.

JC

[buswarrior]

Are ALL those nasty zerks in the throttle linkage, up into and out of the tunnel, fresh and free?

I like the idea of finding something being lazy in returning to closed throttle.

Pursue all external avenues religiously before cracking into having to adjust all those internals.

Lazy man wins many prizes, those too ambitious to dig in, make their own trouble?

happy coaching!
buswarrior

[luvrbus]

All he needs to do to check the linkage binding is disconnect throttle from the governor top turn the Jake switch on give it fuel and see if engages when it returns to no fuel if he still has the same problem look else where.
If he has the combo control those are bad about the dust cover on the micro switch deteriorating causing problems or the nylon rollers and pins breaking      

[Geoff]

The throttle linkage binding ever so lightly was my first thought.

--Geoff

[Boomer]

Russ if it turns out to be the micro switch, I have one.  Kind of sounds like loose or broken oil tubes, the flimsy lock nuts back off sometimes.

[bevans6]

I thought there was a neutral switch so they wouldn't engage in neutral with auto trans, but the official MCI schematic only shows a clutch switch for standard transmission, no neutral switch.  So I won't suggest  checking that...