Got the Olds out and in "running" condition, however it appears now that I may have some motor mounts going bad. The vehicle is a 70 Olds Cutlass S with a 4 barrel 350 and an Auto Trans. When I put the car in reverse, there is quite a big "jump" or rock that takes place that moves the car. I verified by having someone else put it in reverse and I watched the engine with the hood opened, and sure enough it rocks pretty good when placing it in reverse. Based on the research I have done, this sounds like bad motor mounts. Does that sound correct? (I have not gotten a chance to investigate the mounts yet.)

As a novice to the car repairing world, is it possible to replace the mounts without pulling the engine? I've seen videos of several people saying to jack the car up (just snug) under the oil pan to take the tension off of the mounts. It doesn't appear that this way will work on this vehicle due to the location of the engine mounts, but thought I would double check. Don't want to do anything stupid that would cause additional damage. If you can place a jack under the oil pan, how does it not cause any damage to the trans or secondary engine mount as all the wieght of the car would be essentially hanging on that mount/transmission?

Also, does anyone have the torque specs for the motor mounts as well?

Thanks for everyone's help!

 

The issue you are having may be caused by your idle rpm being too high. Usually it's the drivers side mount that goes bad. Lifting the car a little by the oil pan with a flat piece of plywood between the jack and pan would prevent the pan from being damaged. You're not putting all the weight of the car on the pan, you're only lifting a little to see if the rubber will separate. Torque the bolts to 25-30#'s.

 

Someone I was talking to mentioned that it could be too high of an idle speed, just seems odd that it only just started doing it though, and then sometimes (more rare) it doesn't. I'll have to give that a shot with the plywood and just double check the mounts.

Thanks for your input!

 

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Do you have a tach ? Do you know you are idling at the same RPM's when it "doesn't" rock ?