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Discussion Starter #1
Does anyone have an idea of what is causing an engine knocking sound at highway speeds when maintaining vehicle speed? pressing on the gas or backing off make it stop, but return to a constant speed and it comes back again. Connecting rod bearing? Is it worth replacing or does entire bottom end need to be rebuilt? Maybe something else? Any ideas?
Thanks,
Rich
 

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RT,
I wish you were down here in the southern part of the state, I would take a listen and try to help out. Unfortunately, trying to diagnose noises "long distance" is darn near impossible. If you have never heard the noise before, it is hard to decide what it might be. It could even be a driveline noise, rather than motor. There are a couple of good machine shops out your area, I will try to get a phone number to you on Monday, maybe one of them will take a ride with you and try to advise you what it it is. E-mail me Monday morning and jog my memory as it has been sooooo busy I will probably walk in the shop, all the usual madness will begin, and I will forget !

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100
 

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RT, I lived in Fred. for twenty years before moving south. Try County Engine, near the Harley D store off 355 5915D Urbana Pike
Phone 662-9175. Oops- 301-662-9175. Carroll and his dad are great people.

Rick
67ss bb
TC #326
But all it needs is a harmonic balancer......
 

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This maybe out there, but have you had any tranny work recently? If so, take a look at the bell housing bolts, they maybe loose causing the tranny to bounce back and forth on the block...just a thought, Rob
 

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With more detail and description, we can at least guess. Does it occur only in gear? or also with the car coasting at speed in neutral? High pitched, low pitched.
How about at idle ? Can you hear it with the hood open and engine running when parked ?If so, can you pinpoint it ??Etc, etc, we can give it a try - still just guesses

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Gotta have a Chevy !In Durham N.C.
Make it look the way you like it, forget what the other guys say!
 

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If it is an engine knocking sound and not transmission related it could be either a rod-bearing or a cracked-piston skirt. The latter being an issue usually seen in older piston manufacturing dates. This was a more common occurance in the old long stroke sixes, but could be the culprit in your case.
 

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Discussion Starter #9
Thanks all, These are all food for thought.
I'll be trying a local shop that Bill K got a refferal on. I purchased this car about a year ago in a condition where it was not driveable (broken control arm mount) so was able to get it at a price low enough to allow for things like this. A year later, I still consider it a bargain! I think at some point soon, I'll be prepared to totally rebuild the engine, then pull it and drop the pan and see what's up. I may be pleasantly surprised to find it was rebuilt already and needs minor work on something that was done wrong, or I'll continue with the rebuild.
Thanks again for the input,
Rich
 
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