351mach11647545510 Posted January 23, 2007 Report Share Posted January 23, 2007 My mom has an 88 Astro that started shaking real bad. It shakes whether it is sitting and idling or going down the road and increases with the engine rpm. I thought for sure it was one of the motor mounts because of the way it feels but when i checked, the motor and transmission mounts appear fine. Any one have any idea as to what I might check for next? It feels like it's not balanced right. Do harmonic balancers go bad? That is the only other thing besides the flywheel that would make any sense. Any insight would be greatly appreciated Quote Link to comment Share on other sites More sharing options...
AJ Posted January 23, 2007 Report Share Posted January 23, 2007 replace the distributer cap and wires. Quote Link to comment Share on other sites More sharing options...
351mach11647545510 Posted January 24, 2007 Author Report Share Posted January 24, 2007 ? the motor is running fine? it's not the motor running rough that is making it shake. it's a really rough shake like when a motor mount breaks or something isnt balanced right. Quote Link to comment Share on other sites More sharing options...
AJ Posted January 24, 2007 Report Share Posted January 24, 2007 maybe the balance shaft broke, i don't remember what years they had them but some of the 4.3ls had a balance shaft and they had some problems with them. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted January 24, 2007 Report Share Posted January 24, 2007 if its a 88, it dont have a balance shaft. aaron you know what im going to say. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted January 24, 2007 Report Share Posted January 24, 2007 check the harmonic balancer and see if the outer ring slipped its not common but it happens other than that I'd have to look at it Quote Link to comment Share on other sites More sharing options...
Buckeye1647545503 Posted January 24, 2007 Report Share Posted January 24, 2007 So you think it is running fine but alot of engine vibs are transfering to the cabon or is the motor running with more vibration? Quote Link to comment Share on other sites More sharing options...
351mach11647545510 Posted January 24, 2007 Author Report Share Posted January 24, 2007 the motor still runs fine it's just transferring it's movement everywhere else. I'll check the harmonic balancer. thanks rob, but I do my own stuff unless it's a tranny issue. Quote Link to comment Share on other sites More sharing options...
351mach11647545510 Posted January 24, 2007 Author Report Share Posted January 24, 2007 Edited for my ignorance: if the "outer ring" slipped how would i tell if there are no reference marks? Is this one of those things where if you cant find anything else wrong, just replace it and hope thats it? Quote Link to comment Share on other sites More sharing options...
AJ Posted January 24, 2007 Report Share Posted January 24, 2007 you can check it with a timing light Quote Link to comment Share on other sites More sharing options...
351mach11647545510 Posted January 24, 2007 Author Report Share Posted January 24, 2007 hows that? I dont know where the timing was set to begin with. My uncle was the last one to adjust the timing but he's an hour away and deaf. Quote Link to comment Share on other sites More sharing options...
AJ Posted January 25, 2007 Report Share Posted January 25, 2007 there is a notch on the balancer and a tab on the timing cover...where? i don't know its either off to the driver side or right dead center straight up. it could either look like a timing tab or like a tube your suposed to look through. if the balancer sliped the timing will be way the fuck off according to the balancer. i've seen it look like 180 off. since the truck runs you know the timing is ok. Quote Link to comment Share on other sites More sharing options...
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