Small Engines (Lawn Mowers, etc.): Connecting Rod binding on Crank Shaft, crank shaft, emery cloth

Question
Hi Fred.  This is my first time asking you a question.

I have a Troy built chipper/vac with a Tecumseh engine.   serial number: H50 65582V (B) 3263D

Last fall it stopped running and slowly wound down to a stop (no compression).  I tore the engine down and the connecting rod is in 6 pieces.  There is not other damage i can see with a visual inspection.

I purchased a replacement connecting rod and gaskets online from pat's small engine plus.

once i tighten the connecting rod bolts more then finger tight, the rod starts to bind on the crank shaft. just the slightest bit of tension on the bolts totally prevent the shaft from rotating at all.   loosen the bolts and it turns with the piston with no resistance.

I have rotated the connecting rod 180 degrees and have the same result.

The area of the shaft where the connecting rod joins appears smooth and undamaged.

Im wondering if it could be a bad connecting rod.  it was an after market part.  Any thoughts?

Thanks
Rick.


Answer
Bad rod maybe.  Wrong part maybe.  Double check the part numbers.  Are there any cross references.  Go to tecunseh's web site and search the numbers on the engine shroud.

More than likely there is residual material on the crankshaft journal.  The rod should be very loose once the bolts are torqued.  Try to clean it up with emery cloth.  If the connecting rod broke there is always some transfer because it seized to the shaft to break.  Be sure to check the main bearings for scoring. If there is metal transfer to the crankshaft you may have to replace it along with the main bearings.  It would be cheaper to purchase a short block for the engine.  Hope this helps.