We've got a problem with our '73 Chevy 3/4 ton 4WD pickup with a 350 and 4 on the floor, which we bought new in '73. Around 1993, the harmonic balancer started hitting the crossmember, and we had to have the engine rebuilt. Since then, we haven't put a whole lot of miles on it but we are continually having to replace the motor mounts because the balancer starts hitting the crossmember again. We have also replaced the tranny and transfer case mounts. We've had it to several mechanics, and they can't figure out why this is happening. All parts we've used are from the dealer. We don't think the crossmember or frame are bent. When we put new motor mounts on, it does solve the problem for a while, but then it starts happening again. Does anyone have any ideas how to solve this problem? Thanks.

 

You could search for some poly urethane motor mounts since they last alot longer than the factory rubber ones.

 

OK. Meanwhile, someone has told us that he had the same problem after someone instaled the wrong balancer on his engine, one that was too large. He said he just cut an area out of the crossmember to make room for the balancer so it wouldn't hit. Sounds to me like that would weaken it, but we are about to give it a try. The last mounts we installed still look very good.

 

The wrong balancer was put on. I dont suggest cutting the crossmember.

 

can you vary balancer diameter on the engine? if it doesn't hit a crossmember that is I'm putting together the 350 engine in my tahoe and is wondering if a smaller diameter balancer from Summit will make the car worse or better.

 

If you dont cut it, which im not against, you might also think of spacers under your motor mounts. just an idear. we had to do this to my best friends 4x4 cause the motor had so much tourque any time it was under load it would hit the crossmember we used 3 3/4" washers it added up to about a 1/4" and has been fine ever since.

 

I don't suggest cutting the crossmember...

Either find a way to raise the motor(spacers or larger mounts) or you could get a smaller diameter balancer.

Also check and make sure you're getting the right mounts to begin with. Whoever is getting your parts for you, make sure they run it with your VIN # and not just the make and model and such.

Also I dunno if you have the original mounts that the truck came with but you could also try matching the newer mounts up with it to make sure you're getting the right ones.