Engine Brake - "Jake Brake"? No response

[mike groves]

All,

On a trip north through the mountains of southern Oregon I pressed the Jake Brake switch as usual on my descent of the first hill.  The transmission downshifted as expected, cruise shut off as expected, but rather than the low hum noise associated with the engine braking and resultant decline in the RPMs no change in the engine rumble at all happened and the RPMs continued to increase. 

Same results with either the low braking or high braking.

I've found by reading online that:

a)  It could be the switch (but can it be given that the transmission downshifted and cruise shut down?)
b)  It could be an electrical issue from the switch to the ECM
c)  It could be an electrical issue from the ECM to the brake solenoids in the engine
d)  It could be a mechanical issue (engine runs great as always)

I did find 2 bosch relays in the electrical cabinet marked  "retarder" and "cruse-retarder" and thought perhaps I'd replace one or both to begin with (before I give up and take it in for service).  These are cheap and easy to replace.

Any experience with this problem?  Any ideas?

Thanks,
Mike

[Dave Atherton]

Mike, problem could be just an adjustment of the engine to compression brake. Not
knowing what kind of engine you have. The adjustment is required after you reset
Injector adjustment and checking valve lash. Could be wire connection to solenoid
actuator. I would check this area first. If you can provide engine S/N number, I can
Technical information on Ask Dave where you can address the problem.
Dave Atherton Retired Cat Mechanic

[mike groves]

Dave,

Here is what you sent to me before -

S/N  9NS11095,  A/R  156-2049 Build: 1998-06-12,  Test Date 1998-06-13,  Shipped Date
1998-06-22  Test Results: Engine 425 HP,  Speed 1796 RPM, Fuel Rate 18.5 GAL/HR,  Adj Boost 22.5 PSI,
Fuel Pressure 94 PSI, High Oil Pressure 48.4 PSI, Engine Load Test, TQ CK Fuel Rate 15.6 GAL/HR,  TQ CK
Adj Boost 19.8 PSI, TQ CK SPeed 1196 RPM,  TQ CK FOR TQ 1550 LB/FT, Low Speed 590 RPM,  Low Oil
pressure 15.1 PSI, High Speed 1813 RPM,  Temp Water Pump Inlet 192 DEG F,  Inlet Manifold Temp 109 F,
Inlet Air Temp 122 DEG F,  Maximum Altitude 10,000 Ft  above you have eengine S/N number and
A/R number, which again when getting parts using the S/N number along with the A/R number will get
your engine build.  Dave Atherton Retired Cat Mechanic

thanks, Mike

[Dave Atherton]

Mike, thanks for info on engine that I sent you before. I do not keep copy of each member
inquiries on technical information ( just ask for engine S/N ). Looks like we are talking about
something your engine is not equipped with and going down different road. Later today will
post what is required for your engine on Ask Dave. Dave Atherton Retired Cat Mechanic

[mike groves]

Dave, what do the numbers for "high speed" and "low speed" represent?

Thanks, Mike

[mike groves]

Now working.  I can suggest that if this happens to another that you find the relays in the electrical bay and tap them.  I unscrewed mine, tapped them (both retarder and retarder-cruise), took off a couple of the leads then reseated them.  Anyway on the trip north to Sequim, WA they worked just fine.  I will therefore buy replacements. 

Mike