Cruise STILL jerky
 

I've got a 1987 300e with a jerky cruise. It feels like someone is tapping on the gas pedal. I've replaced the speed sensor on the back of the speedometer, I've had the amp rebuilt and I've lubricated the speedometer cable and my speedometer is rock solid. It would also seem that my throttle linkages are reasonably tight, but of course I can't really reach the actuator under the intake manifold.

I suspect 2 things:

1) the alternator is an AutoZone rebuild and does not provide real clean DC. Could an unstable voltage be causing the jerking???

2) the cruise actuator

Any help is appreciated, especially the help that doesn't have me buying and replacing the dreaded actuator.

Thanks,

Bob Kopicki

Bob
 

the GDL website has (last time I checked) a troubleshooting section on cruise amps and actuators.

Search the forum for "general development labs"

TRY THIS
http://www.fix.net/~gdl/trouble.html

Thanks for the tip, I've contacted GDL to see what they say. I ran their troubleshooting checks about a year ago with all tests passed. I'm wondering if the actuator is just worn out. GDL says what the failure modes are, but is the actuator "failed" when it "taps" the gas all the way down the road?

Thanks again,

If the throttle linkages are tight/sticky, then that might cause the symptom you are seeing. Just a thought.

Some guys on the diesel forum have cleaned/lubed their actuators to improve the performance, old hard grease perhaps? Could also be the common solder joint problem on the PCB, does it correlate to hitting bumps?

Am I wrong about this, but I've always been told that voltage fluctuations are the first thing to check with a gimpy cruise. And that includes use of light bulbs of non-European amperage anywhere on the circuit.

I've lubed the daylights out of my throttle linkages so sticky wouldn't be a problem. I'm not sure how "loose" the linkages can be before I run into the jerky cruise. I've not removed the actuator and tried to clean and lube it. It looks nearly impossible to reach - I was going to wait till head rebuilding time to pull that one.

Anyone know any shortcuts to getting the actuator out and tips on lubing it up?

Thanks,

Oh, my voltage fluctuations may be due to a bad capacitor on the back of my alternator. Anyone know where I can buy a spare???

Thanks,

The linkage is sloppy the actuator is trying to adjust the speed for slop in the actuator linkage