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Help needed Jacobs Extarder

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dpickard:
We have the Jacobs Extarder on our coach and can never seem to know if its working or not.
What gear do these things usually kick in at?
Our coach is a 1993 Pace Arrow Vision Turbo Diesel with the C8.3 engine.
Dont tell me to read the manual. It says less than nothing.
I flip the switch on and never feel anything different. The regular brakes have been checked and they are supposedly in fine condition.
At least thats what Freightliner said. I dont feel confident with them and would like to know about using the Jake.
Can someone shed some light?

Ned:
With an electronic engine the Extarder will activate when the ECM senses zero fuel flow.  The ECM will also preselect a low gear on the transmission (usually 2nd but some have reprogrammed to 4th).  It will also disengage the cruise control.  As long as there is positive fuel flow, the Extarder won't engage.  With it on, when going down hill and your foot off the accelerator, it should engage and you should feel the effect.

I'm not sure just how it works with a non-electronic engine, but I would expect similar behaviour.  It is possible that the valve mechanism has corroded and isn't activating.  I would take it to a Freightliner Oasis service center if you think it may not be working correctly.

Ron:
I hate to be the bearer of possible bad news but it could very well be that your Jacobs Extarder exhaust brake is not working if it was not maintained properly over the years.  Exhaust brakes require lubrication with a high temperature synthetic lubricant such as Super Lube. in Failure to lubricate properly results in the shaft becoming frozen and/the actuator becoming frozen into usually the open position.  Infrequent use can also have a negative effect on exhaust brakes.  

Operation or non-operation of the exhaust brake can be confirmed by having somebody drive the coach and engage the exhaust brake while observing the exhaust brake.  The exhaust brake is located in the exhaust stream just prior to the turbo.  
I would recommend taking the coach to a cummins shop for check and repair/replacement.

dpickard:
Ron, I found this hard to believe at the tme, but I had previously taken the coach to Cummins Atlantic in Greensboro, NC. The highly touted "Coach Care Specialists" people said they had never heard of an extarder brake. I reminded them of the fact that they were a Cummins DEALER and they said an "extarder isnt a Cummins unit." At that point in time, I gave up. I will call the Freightliner people like Ned suggested and see if they can help.
Thanks to both of you.

Jim Dick:
Hi Dianne,

Just found this after responding to another message from you.

The Jake Extarder is an exhaust brake. Exhaust brakes work better with the smaller engines. I have one on my ISC and it does not do much in retarding unless the rpms are high. I complained about it to a Spartan rep. He said nobody will admit it but Cummins apparently had problems with burnt valves and made Pacbrake put holes in the butterfly to reduce the back pressure. I would assume they might have done the same with Jake Extarders. I have not removed mine to see if that is true. I have driven Bounders with the smaller engines and the brake works much better than mine.

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