Cruise control

The cruise control on my E320 does not work. It did intermittently for a while then it quit altogether. It has not worked for the past several weeks. What is the most likely thing wrong?

Eddie, do a search and I believe you will find plenty of suggestions on possible fixes for your problem. Johnny

[ymsin]

I had a similar problem on the 300SE sometime about 2 years ago. The problem was solved when I insisted they check the fuse in the box. Since an average fuse cost about US$0.05 each, I had them change ALL the fuses, and voilaaah ... the c.c. worked again.

However, this morning as I was cruising on control and going down a hill gradient, I noticed some minor jerks. Perhaps its the system trying to maintain the pre-set speed while going down the slope?

I certainly hope it is.

And I certainly hope its your fuse too ..

[Gilly]

Ymsin: Jerking can be caused by the linkage needing lubed, or else I would suspect the actuator going bad.....Gilly

[ymsin]

Will pay some attention to the lubing this weekend.

Have a safe weekend.

[ymsin]

Gilly - did the lubing today. We found out that the "bushing" needs to be replaced. An order has been placed from Germany as no local stocks were kept. My particular model is a direct import from UK, and thus many locally assembled 300SE may not carry this feature.

Will post update when part arrives ... one months' time.

Is the bushing the same as the actuator?

[Gilly]

No, the bushing they are referring to usually means one of the plastic pieces on the linkage. BIG price difference, too. On the 300SE your are referring to, this is a 126 chassis? The 126 has had occasional problems with the bushings on the longitudinal rod that attaches at the firewall and engine. If this is the problem, it would be wise to replace the bushings on both ends of it, not just one side. The labor would be the same, it all has to come apart to do just one. Not too unusual that it needs to be ordered out, I doubt if our dealership stocks it, but we are a small dealership.......Gilly

[ymsin]

Its the 126 chasis. What do you mean by bushings at both ends of the cruise control unit? I thought its only at one end, that is by the right hand side, if you're looking from the front.

What does the bushing do?

FYI - the part costs approx US$30.

[el Miguel]

I'll bet that it is the amplifier. My 380SE has the same symptoms. It will work fine for a while and then start to speed up. It doesn't stop until I panick and flip it off. Sometimes it will lurch and other times it works fine for the duration of the trip. Check out these guys for testing and questions...http://www.gdl-online.com/testproc.html

[Gilly]

Ah heck, I was thinking of a V8, not the 103 engine. What I meant was on the V8, there is the longitudinal rod, it "twists" instead of going back and forth when the pedal is depressed, and there are plastic bushings on each end that keep this rod tight. They wear out and cause all sorts of throttle problems. I think a 103 engine in a 126 has a throttle cable from the accelerator pedal. There are a few bushings where bellcranks pivot. Usually htese just need to be disassembled to make them work properly. i guess the question goes back to you as far as what was ordered. If you are ordering a bushing, is it actally the cruise control linkage? I didn't think they sold the linkage ends seperately......Gilly

[ymsin]

Its more like the bushing for the cruise control linkage.

What does it really do?

[Gilly]

YM: A "bushing" doesn't make sense to me. There is the actuator arm on the actuator, on the arm is a "ball". The linkage snaps over the ball, the other end of the linkage has a similar snap on it, it attaches to the throttle linkage. I believe the linkage is only available as an assembly, I don't think the ends of the linkage are available seperately. I wouldn't refer to any of these parts as a "bushing", so i am still unsure what this "bushing" is that was ordered. I am also confused about what the relation of the actuator is to the jerking, in that why it would need to be replaced to fix this particular complaint. If the linkage is binding, it could cause this complaint, but all they would need to do at the most is remove the piece of linkage and put a small squirt of high-temp bearing grease to lube it up. If they were really lazy they could spray some penetrant on the linkage ends. It is more common for a bellcrank to be stiff and causing the cruise to jerk. In extreme cases I have seen worn bushings on the bellcrank that needed to be replaced, but usually the bellcrank can be disassembled, the pivot pins cleaned up and lubed and put back together and be good as new. again, there are bushings on the bellcranks, not on the linkage or actuator......Gilly