REFLECTOR: Engine troubles

[Mark Magee]

Hi Geoff,
From your data, and presuming a solid bottom end (no obvious crank slop/oil pressure nominal/engine log shows good time to TBO) I would only be considering a top-overhaul. This you can definitely do yourself if you choose. When the jugs are off, you can have an A&P inspect the bottom end; worse case scenario he finds issues and your looking at a Major.
I didn't see Lyc or Cont, but the Lycomings use nitriding for metal hardening in cylinders and elsewhere in the top end. Nitriding is famously subject to corrosion. If a Lycoming sits for years without being properly pickled, the barrels and possibly valve seats will become pitted from rust. Bottom end not affected. I'd move toward a top overhaul.

Mark B. Magee
Sent from IPhone 4

On Mar 7, 2012, at 7:32 PM, Geoff Gerhardt <geoff at thegerhardts.com> wrote:

> Some of you might remember a few weeks ago, after taking my first taxi I did a full run up and found my static was low.  After doing some troubleshooting, I found a couple issues - an intake leak and a faulty electronic ignition box.  My Light Speed ignition box is off to Klaus at Light Speed Engineering to be fixed.
> 
> During the process of checking the timing/ignition, I noticed that when I was trying to find #1 TDC by putting my thumb over the spark plug hole to check when it was on a compression stroke, I was not feeling much pressure.  So, I recently did a compression check.  The numbers were dismal. All were low: #1 - 10/80, #2 - 20/80, #3 - 24/80, #4 - 10/80.  All were leaking copiously past the intake valve.  Exhaust valves sounded tight, some leakage could be heard past the rings.  I took the intake pipe off #1 and put my fingers behind the valve and could feel the air rushing past.  Not sure why its so bad.  Looks like the guy who sold it to me (an A&P and Velocity owner) is either a terrible A&P or dishonest.
> 
> Can someone tell me my options?  My preference would be to rebuild it myself (I've rebuilt many engines, most recently a Porsche 911 - pretty similar!), so I'd look forward to it.  The drawback of that is time.  I could probably tear it down in day, but I suspect sending stuff out for inspection and acquiring all the necessary parts might take awhile.  What are my options for the cylinders?  Send the out for rebuild?  New?  How much $ are we talking?
> 
> The other option would be to send it to a rebuilder - definitely be more expensive, but do they have relatively quick turn around times?
> 
> Geoff
> 
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