Borescope reveals tell-tale half moon paterns from exhaust valves... - Page 2 - Dorkiphus.net
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  #11  
Old 09-29-2007, 08:02 PM
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Makes sense. Then there is always the "while I'm in here" stuff I'll probably want to do as well. Now I just have to decide if this is something I want to take on doing myself....
It's an RSA, besides "head work" what's there to do?
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Last edited by Trak Ratt; 09-30-2007 at 10:01 AM.
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  #12  
Old 09-30-2007, 08:07 AM
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I'll give you $6K for the car.
ARF
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  #13  
Old 09-30-2007, 08:25 AM
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I'd recommend doing a full rebuild. Replacing rod bearings is alot cheaper than a crank. Yeah, it's painful to the checkbook, but it also gives you the confidence on the track or when you're pushing the car.

My mechanic has rebuilt a fair share of 3.6 air cooled engines. When we did mine, the p/c were all within spec, as was the crank. We did replaced everything on the top end using the existing heads. The valves for the 3.6 aren't as cheap as the 3.0's. At least we don't have 4 per head Good luck.
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  #14  
Old 09-30-2007, 08:36 AM
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it went to about 8500 RPM. Dang....full rebuild...
I think it is quite possible that you damaged the rod bearings with such a healthy over-rev. You really have no choice but to crack the case.

Sorry, Dave, there is no easy or cheap way out of this. That's why it's called the "money shift".
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  #15  
Old 09-30-2007, 06:58 PM
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Okay, question. When I had my over-rev 5 years ago, Ivan said he did everything but split the case. He also referred to "top 2/3." Can you take off the cylinders and examine the crank from above, below the pistons?
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  #16  
Old 09-30-2007, 06:59 PM
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Hey, Dave. I'll trade you an almost-perfect '86 Targa...
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  #17  
Old 09-30-2007, 07:46 PM
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Ok, so Stephen Dubovsky came over last evening and took a look in the borescope and had a much more positive assessment than my initial impression. He said the half moon shapes didn't look like impact because every one he's looked at have a shiny "C" where the steel valve hits the aluminum piston. He thought that the half moon on mine were either the relief in the piston face itself or shrouding of the carbon from the valve on the piston, or possiby both.

So after much deliberation, I decided to button it up, put some oil in it, and try to fire it up this evening. Guess what.....it runs!....seemingly without back-fire or missed cylinders. It's loud as shit with no exhaust but seems to be running fine. Could I possibly be ok!?!? Could it have just been that one valve with the retaining nut that fell off? I'm too skeptical right now to declare victory and I'd really like to get another person or two to observe/listen to it before I decide what to do next.
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  #18  
Old 09-30-2007, 07:47 PM
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Quote:
Originally Posted by Dr K View Post
Hey, Dave. I'll trade you an almost-perfect '86 Targa...
Ok, come on over and pick up your new ride.....not.
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  #19  
Old 09-30-2007, 08:05 PM
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Quote:
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Ok, so Stephen Dubovsky came over last evening and took a look in the borescope and had a much more positive assessment than my initial impression.
Great news (maybe), Dave! Who is Stephen Dubovsky?
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  #20  
Old 09-30-2007, 08:36 PM
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A very nice dorki who responded to my request in the prior thread to have someone give me a hand. He goes my "smdubovsky" here.
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