Congrats to your success. You know Sept 18 is just around the corner. MVN
is gonna be fun.
On Nov 26, 2017 6:53 PM, "n357cj via KRnet" <email@example.com> wrote:
> Hey Guys,
> Back near the end of May I decided to pull the engine for an overhaul
> for a couple reasons. For more years than I can remember I have had a oil
> leak which I knew was from a crack in the block. While this may sound very
> on safe it never became a structural issue but only caused me a large
> amount of cleaning and adding a quart every10 to 12 hours of operation.
> This past winter it became apparent that the leaking was increasing to the
> point that it became a real irritant. The thing that made the deciding
> factor was during a afternoon flight I noticed a drop in oil pressure while
> nearly a hour from home. I never lost pressure but the lowered pressure was
> a another cause for concern. I always felt that an accident is a build up
> of 3 mistakes and I had 2 already.
> I had a block preped by Roy a few years ago and I had a store pile of
> parts so I figured a several week turn around and be right back at it.
> Well, that didn't work out so well. Through a number of comedy of errors
> (not really funny) and 4 separate tear downs and test runs and even a
> couple test flights, I finally have everything running great again. The
> first big deal was I knocked the block off the work bench when it was
> short block assembled. From there i convinced myself that it had distorted
> the block and it was trashed. MArk Lankford came to the rescue by sending
> me his 3100cc block. I built that all the way up and mounted it to the
> plane. I knew that it was very tight build. It proved to be to tight with
> high oil temps and scorching a bearing that was tight. So back off the
> plane and tear down again. I tore the high volume oil pump apart again and
> looked the gears over again. There was no sign of wear at all but using a
> magnifying glass I noticed that there were some circular scores just above
> the drive gear. The drive gear is a pressure fit to the shaft. It appears
> that the gear when up to temps became loose on the shaft and would slip
> some. I replaced the drive gear and hoped I had this resolved.
> Over this period of time I re-evaluated the case that I had dropped
> from the work bench. Other than a dent in one corner of the casting I could
> not find any misalignment or damage at all. I re-installed 2 different
> cranks and cams to torque and found that the cranks run perfectly true and
> free. So I took everything back off Mark's case and started to rebuild mine
> again. At least Mark's is all cleaned, painted and ready for him to start
> his rebuild.
> I built this one up again and mounted it to the plane again. This time
> it seemed to go together OK. A couple more weeks altogether and mounted it
> back up to the plane again. It started up OK and timing was checked.
> Something bothering me...It didn't sound quit the same. I did a test flight
> of about 20 minutes around the pattern and it still bothered me. I had one
> head temp that was a bit high. But worse yet I had oil all over things
> again... That just isn't going to due again. I cleaned the engine all up
> again and put the dye in the oil that ultraviolet light shows. I ran the
> engine on the ground up to temps for about 15 or 20 minutes.
> My son and I pulled the engine again, took it home back on the bench
> and search out the oil leaks with a black light in the dark. To my surprise
> none of the leaking was coming from where I thought it was. I only had one
> O ring on one push rod tube that was leaking a bit. All the rest was coming
> from the edges of the top cover. Well at least it was an easy fix for that
> part. The noise that was troubling me was the next thing. I just had an
> uneasy feeling about the valve adjustments. When I pulled the cover on the
> right side I found the middle rockers loose on the push rods. I had miss
> adjusted a least one set somehow (inept or incompetent come to mind) I did
> not even bother checking any others. I pulled both heads off, push rod
> tubes pulled out the lifters. I took each lifter apart in order and drained
> them and replaced them in order. Reassembled the right and then the left
> sides with all new O rings again. I carefully adjusted the lifters in order
> and repeated to verify.
> The oil with the dye was left in the oil pan just in case I discovered
> leaking again when it was back on the plane. The engine went back on again
> yesterday. Everything went well which made the process feel better. Nothing
> seemed to be nagging me this time. I finaled everything out this morning
> and with my son at the throttle we checked the timing again. The engine
> fired right up with just a couple cranks and ran very smooth. Nothing
> bothering me this time... sounds great and seemed like it had great power.
> After a few minutes of running and warmed up there was no obvious oil leaks
> I got everything all cleaned and back under cowl. Started her up again
> and did a bit of taxi. Really acting great now and very good power. I
> decided that the only way to really find out was to fly. The take off was
> good with all temps being very normal as compared to the past 12 years. I
> flew for an hour with one full throttle run at 3000 feet just to see what
> happens. Like I said the power seems really good. At 3250 rpm she was
> bouncing the true airspeed at 183 to 184 mph a solid 3 to 4 better than i
> have been able to achieve before.
> I didn't mention the details of what was actually done in the rebuilds.
> The main bearings and rod bearings were replaced. The exhaust valves
> replaced. All valves were lapped. pistons removed and inspected, rings
> inspected cleaned and re-installed. New fifth bearing shell installed. New
> plugs. New oil pump gears. New silicon exhaust gaskets. New cylinder head
> and base gaskets. Mostly all new instrument sensors. all new gaskets. New
> bypass spring and piston. Replaced spark-plug wires. Lots of cleaning and
> rechecking every part for condition. All in all if it wasn't for the oil
> leak that has plagued me I would not have been afraid to have run this
> engine to 1500 hours or beyond.
> There was a period of times during the past 6 months that i was ready
> to call it quits, This rebuild was about the most frustrating thing that I
> have ever done. I fully admit that several of the things that went wrong
> were fully and completely of my own making. But I flew my plane today and
> man oh man does it make it all worth while.
> Keep building guys,
> The sky is waiting,
> Joe Horton,
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