Jump to content

R model engine brake

Recommended Posts

I have a 84 R model. It has the Mack dynatard engine brake. It used to work fine but hasn’t for about a year. I want to replace the wiring because it has become chaffed and broken in places. This is where I need some help. The wire come out of the firewall then hooks to each valve cover but after that I don’t know where it goes as it’s missing. Any help would be appreciated. EM6-237 engine 

Edited by JMack302
Link to comment
Share on other sites

opposite end of new wire ,is that going to ground? usually there is only one wire to pump which grounds it self.  now a days they may be using the pump switch as an on/off  to complete the circuit with two wires  the pump switches were a royal pain in a -- -. brass tab inside  always failed. if its staying on with red wire to ground, i'd say try adjusting screw on pump slightly. doubt wire colors can be seen that weathered. based on picture,14  R/G (red/ green ) should be from circuit breaker; 14 BR (brown) goes to pump switch to complete ground side ;14 B (black). to cyl heads. definitely don't want to open top cover with all that dirt  around it.  firewall connection  pictures aren't the worse  ever,  not that there isn't chafing wires  or connections  wrong. brake works when grounded . unravel the tape see what it looks like.  maybe not bad ,tapes only holding plugs together (ya right !!)  wiring is always fun when someone else has been there before... 

Link to comment
Share on other sites


Forgotten which way the brass threaded stud goes in or out to adjust wen Eb comes on/off

remove wires

loosen off top nut

loosen off lower nut

take note of where the slot in the brass stud is pointing

screw out the brass stud as there is a screw driver slot on end of thread

try one turn n C if th@ is better or 2  or 3 

tignten nuts n fit wires wen 100% satisfied

try not to use EB unless Donk iz @ operating temp


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...