Tip: Engine overhaul

[R.P.Ping]

For those of you planning on overhauling your engine or have found a fresh overhauled engine to buy, like myself, do yourself a favor, especially if a reconditioned crank shaft is being or was installed. Make sure to check the clearance between the crank shaft oil slinger and the aft side of the crank shaft oil seal retainer for .002 to .008 clearance. If this clearance is not maintained the slinger will throw oil into the seal and the only way to stop the crank seal from leaking is to split the case and grind the slinger or grind the case to achieve the proper clearance. Ask me how I know..... When a crank shaft is reworked the thrust surface can be ground .003. When this is done the slinger to case clearance is lost.
I will fly 3 more hours to get my 25 test period completed and the engine will be coming apart.
Here is a link to the lycoming site with information about the seal leak.
http://www.lycoming.textron.com/main...eSealLeak.html

[praterdj]

Thansk for the heads up. I might consider a rebuilt engine. I guess that is one of the risks of buying used. Considering the price of the new engines I'll probably take the risk myself.

Sorry to hear about your engine.

[tacchi88]

If you go up to any Lycoming engine, and pull on the prop back and forth you will experience end play. Lycoming is being too critical on this point. There is no oil pressure against the seal whatsoever. If the seal leaks (and this is true with Continentals as well), it is doing so because of improper installation, or excessive crankcase presure. Excess pressure can be either the breather tube is restricted or there is indeed excessive pressure in the crankcase.
On Lycomings with rear mounted prop governors, the oil feed tube may leak. From it's appearance it looks like the work of a leaking crank seal, when in fact it may be the line. In some cases, the oil line fitting may have been overtightened and actually can crack the case. Worst case scenario, to be sure, but it happens.
Check for excessive crankcase presure. If the crank is refaced in the slinger area, it will only increase the gap. The end play area of the Lycoming crankshaft is perhaps it's best feature, and rarely ever fail, in fact the bearing surface is the crankcase itself.

[sslayden]

Just another pilot with a 30 yr. old Arrow that got the RV bug

Okay, it'll be hard to sell mine, too

[tacchi88]

Steve,
It was hard selling mine, but I know where it is, and who flies it. It's like getting rid of a good.................
TT