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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: Got Smoke? on July 17, 2011, 07:32:05 pm

Title: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Got Smoke? on July 17, 2011, 07:32:05 pm
Ok went out to start my K20 today and check the fluids and what not because I made a deal to sell my 99 Cummins next weekend and want my back up truck up and going "Just in case".

The harmonic balancer is now rubbing the crossmember below and cutting material off the back of it an 1/8-to-1/4 of an inch toward the front of the truck.

2 weeks ago I went out and started the truck and let it idle to operating temp and shut it off the everything was fine...the truck has not moved since? ??? >:( I checked all the balancer bolts and they aren't loose? No clue what could possibly have shifted while sitting in my driveway?:huh: Anybody ever have an experience like this?

Only think I can think of is possibly pick the engine up with a cherry picker enough to pull the motor mounts out and replace the bushings?
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: chevymanrob on July 17, 2011, 08:02:47 pm
can you see separation between the inner and outer sections? maybe you can see it from under the truck. thats about the only thing i can think of...outer ring separating from the inner and "walking" causing the interference.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Got Smoke? on July 17, 2011, 08:11:28 pm
Quote from: chevymanrob on July 17, 2011, 08:02:47 pm
can you see separation between the inner and outer sections? maybe you can see it from under the truck. thats about the only thing i can think of...outer ring separating from the inner and "walking" causing the interference.

Didn't look at it from underneath...my cousin was helping me look at it and he crawled underneath and I didn't bother too.  I will check that out tomorrow (truck isn't at my house). Thanks for the suggestion.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: 1979C20 on July 17, 2011, 08:24:59 pm
It might possibly be engine mounts? Maybe the engine is sagging enough for it to rub.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Got Smoke? on July 17, 2011, 09:06:44 pm
Quote from: 1979C20 on July 17, 2011, 08:24:59 pm
It might possibly be engine mounts? Maybe the engine is sagging enough for it to rub.

Are the oem mounts riveted or bolted to the frame? I don't remember and as I said the truck isn't here at my house.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: VileZambonie on July 17, 2011, 09:34:53 pm
You need to check the motor mounts
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: 1979C20 on July 17, 2011, 10:46:15 pm
The engine mount brackets are bolted to the frame and to the engine crossmember and the engine moints are bolted to that. The engine bolts to the mounts with a bolt through clamshells.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: bake74 on July 18, 2011, 08:47:30 am
     As everyone else said, I would check motor mounts first.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: chevymanrob on July 21, 2011, 07:15:53 pm
well did you find it?
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Got Smoke? on July 21, 2011, 07:22:12 pm
Quote from: chevymanrob on July 21, 2011, 07:15:53 pm
well did you find it?

I have purchased new motor mounts I hope to swap out this weekend if I can find the time. ::)

I will report back if it fixes it or not.

Thanks guys
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: 1979C20 on July 21, 2011, 08:01:44 pm
Me and my brother will be replacong his motor mounts soon too. If you want we can take pics of how we do it.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Got Smoke? on July 21, 2011, 08:13:03 pm
Quote from: 1979C20 on July 21, 2011, 08:01:44 pm
Me and my brother will be replacong his motor mounts soon too. If you want we can take pics of how we do it.

Oh I have a pretty good idea on how we're gonna do it, just need time to do it. Going to put a chain across from one cyl head to another and pick up on it with our cherry picker. Loosen the motor mount bolts and do them one side at a time.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Blazin on July 21, 2011, 10:02:35 pm
Been there, done this. It was motor mounts.
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: Got Smoke? on July 27, 2011, 08:44:09 pm
Oh yeah it was motor mounts

(http://a3.sphotos.ak.fbcdn.net/hphotos-ak-ash4/248569_234444593254309_100000663093294_780691_4859631_n.jpg)

Now to address a few more issues.. :D
Title: Re: 79 K20 harmonic balancer suddenly rubbing xmember?
Post by: big bear on July 27, 2011, 09:32:53 pm
least that prob was solved