Car runs when auto shifter is in neutral

[eauctioneer]

The other day while driving my 67 230 with an auto trans I heard a rattling sound. When I put it in neutral it continued to travel forward when I hit the gas pedal. Any ideas as to why?

[114015]

Shouldn't

When the car still rolls (crawls) while the shifter is in "0" (neutral) at idle most likely the trans is not really in neutral.

Sounds like worn shift bushings to me.

http://www.sl113.org/wiki/TransmissionClutch/Shifter


Achim

[ja17]

I agree with Achim, most likely a shift bushing has failed and the linkage rod going to the transmission is loose and rattling around.

[1405Stby]

I can confirm that this is probably a shifter bushing issue.  The old bushings will disentigrate over time and completely fall off the linkage.  My 69 280 did the same thing, luckily it happened in my garage and did not cause a traffic problem.  The bushings are easy to replace and cost less than $15.00.  You will need to jack the car up and place on stands.  place a jack under the transmission to support it while you remove the metal plate that supports the rear of the transmission.  Once the plate is removed you can access the linkage.  Remove the linkage (it should already be disconnected from either the transmission rod or the shifter rod) remembering the direction the linkage is supposed to be connected.  Remove the remnants of the old bushings and replace with the new.  The new bushings will have a lip on one side.  Be sure to install the bushings with the lip toward the transmission rod and the shifter rod as there is a grove for the lip to fit into.  You will find that a small amount of lub is necessary for easy installation of bushing into linkage rod and also onto the transmission rod and shifter rod.  I completed the job in about an hour.  It would also be a good idea to check the transmission support mount at this time as you have completed most of the work to get to it anyway.  Replacing the mount is very simple and would take maybe another 15 minutes at most.

I hope this has helped.

[ctaylor738]

If you have worn motor mounts, replacing just the trans mount may make cause the hood to hit the rear of the valve cover.  A true story from my 230 - ended up replacing the motor mounts and all was well.

[Benz Dr.]

If you have worn motor mounts, replacing just the trans mount may make cause the hood to hit the rear of the valve cover.  A true story from my 230 - ended up replacing the motor mounts and all was well.

Really? That's a new one. However, I run into '' new ones '' often enough that nothing is really very new.

[merrill]

Here is how I change the shifter bushings on my 66 230 auto

1. with e brake on, put shifter in P.  this puts the forward linkage all the way forward
2. lay on back under drivers side, reach in and pop forward linkage off transmission
3. go in car, lift up carpeting around shifter unbolt 4 bolts holding shifter assy and lift the whole thing out
4. go to workbench and replace bushings.   make sure to put the ridge side of the bushing on the correct orientation.
5 re install shifter assy with out bolting , put in park,  attach front linkage to transmission
6 go back inside car and instal the 4 bolts and align the shifter assy.

this can be done in about 30 minutes. 

[eauctioneer]

Thank you all for your coaching and guidance regarding post. Your diagnoses and repair instructions were very helpful. I made the repairs myself today and all is fine.

Brian
aka eauctioneer