<VV> engine knock

[Dennis Dorogi]

I don't know any thing about the history of the car.  The gentleman that bought it saw the corvairs  at the convention and came across the car in Meadville, Pa.  He attempted to drive it home (about 100 miles)   It was a hot day and he thought it was overheating  because it was running bad so he stopped about half way home and had it trailered the rest of the way. He said the temperature never got over 400 degrees but thought that was too hot.  It evidently was making some noise at the time (but not like now).  He took it to a local mechanic who said it needed rod bearings and he replaced them.  On start up it began to make the heavy knocking sound.  For some reason they also put 50 weight oil in it.  
       I explained to him that 400 degrees is not hot for a corvair.  The engine needs sealing strips, heater hoses etc. a typical engine worked on by someone that doesn't understand corvairs.  I am just trying to help out.  I assumed it was something done by the mechanic, and it could be wrong size bearing inserts, loose cap etc.  or  maybe the rotated rod.  The engine should obviously be gone through and torn down, but that is something a new corvair owner doesn't like to hear.  The knock seems consistant at all speeds and loads and you can really feel it while driving. Doesn't pulling the plug wire on a cylinder change the sound if it is a rod knock?  It doesn't change.  The knock does not go away when the clutch is depressed.
     I am afraid a new corvair owner is going to be very discouraged.    Dennis Dorogi
  ----- Original Message ----- 
  From: BobHelt at aol.com 
  To: dfamily at cecomet.net ; virtualvairs at corvair.org 
  Sent: Thursday, September 07, 2006 12:27 AM
  Subject: Re: <VV> engine knock


  In a message dated 9/6/2006 7:26:19 PM US Mountain Standard Time, dfamily at cecomet.net writes:
    It has an engine knock unlike anything I have ever heard.  It is a very pulsating knock and you can feel it when you touch the engine or while driving it.  Pulled plug wires and there was no difference in the sound.  It recently had the rod bearings replaced and almost sounds like a bent rod.  What would happen if a rod was rotated or the numbers not up as they should be.  Would this result in a knock?  It is the only thing I can think of.  It doesn't sound like a main bearing but I guess it could be.
          The engine seems to run and idle OK but it also has no oil pressure showing on the guage but I think that is a wiring, sender, or guage problem as he drove it over 40 miles to get here and it is still going.  This is not much to go on but I think it has something to do with the rod bearings being worked on.  They were replaced with standard inserts but  the originals didn't look that bad to me.    Any ideas?   Dennis Dorogi

  Hi Dennis,
  Not much to go on. Did the knock just start after the bearings were changed? Any possibility that the wrong size bearings were installed? Does the knock sound at all speeds and loads? 
  I wouldn't worry about a rod being installed upside down. This is not a problem. Yes, the pin offset might cause some noise, but not like you state.
  Can you find out just when the knock started relative to any work done on the car? Why were the bearings changed anyhow? That may tell you something.

  Sorry I can't be of more help, but it's hard to tell what's wrong from here. Regards,
  Bob Helt