engine revved up

[holden66]

I had a recent occassion where I applied the brakes and the engine revved up and I had difficulty stopping the car.  I took the car to a mechanic who replaced the brakes and put in a new transmission.  He thought the CO mixture on the fuel injectors had something to do with the car revving up when I applied the brakes.  After the brake work was done and the transmission replaced, it happened again as I pulled up to the gas pump at a low speed.  As I applied the brake, the engine revved up on its own, and I had to turn off power to stop.  I have been driving the car daily and it has not happened again. 

Anyone ever experience this?  Any ideas how this could happen.

Holden66
1966 230SL (with 280SL engine)

[redpagoda]

 I cant believe that you put in a new transmission. There is a solenoid that is meant to increase the revs slightly when the brakes are applied to avoid the engine stalling. If you follow the linkage sometimes the solenoid fails to return causing the over reving, alternatively if the knuckle in the linkage is worn this may not be properly aligned also causing the same problem. Hope your mechanic is a Merc specialist

Regards

[Desertpagoda]

This is usually caused by an internal vacuum leak within the vacuum brake booster. Try to narrow things down by disconnecting the single large vacuum supply hose to the booster and plugging it. Do things change....is the rpm rise gone?  If so, replace the booster with new.    Keith

[holden66]

It happened twice this morning.  As I was slowly going into a parking place, the engine revved up......a half later, while backing out of a parking place, it revved up while in reverse. 
holden66