what happened to my yamaha crankshaft

[Streamin Along]

I tore my 1988 yamaha 225 down to replace the pistons had lots of hours on them and also a tiny water leak every thing was in spec so reassembled with new pistons, bearing etc. Took boat out on water Monday night ran it for 35 mins at less than 3000 rpm. It started to idle rough and shut of so loaded it back up and tore it back down to find that # 4 rod had dug into the crank and cut a groove in it. What could cause this to happen. it wasnt like this the first time I tore it down and I've never seen this before. The rod wasnt miss aligned or anything like that .The pic is of # 4 journal on the bottom side that is damaged. Thanks, Jason

[Streamin Along]

pic

[Ray Neudecker]

Is the oil injection still hooked up? If so there is a good chance the valve to that cylinder in the oil line is stopped up.

[Streamin Along]

No the oil injection isnt hooked up. I spoke w/ David at Marine crank repair in California this afternoon he said about half the yamaha cranks he gets in for repair are like that. He also said that he delt w/ Hydro tec and Yamaha and they cant come up with a reason for it happening and that there must be some miss alignment in the manufacturing process and that they cant come up with a pattern for it either, sometimes #3 or # 6 or which ever journal decides to do it. Sometimes he gets a crank w/ 3 or 4 journals like that. Said he could fix it for 350.00. Have you seen that before Ray?
Thanks Jason

[Superdave]

Don't wotk on Yammy's much. What about crankshaft end play? Looks like the bearing cage dropped down. Was that it?
Dave

[H2OPERF]

If you didnt bore or over hone the block and its an original rod i would say the piston is bad, the wrist pin bore is probaly not exactly square in the piston.Did you use factory or aftermarket pistons. Just my guess Dave

[Streamin Along]

the pistons were vertex and I have thought about it being the cause.
I'd use oem but one cyl had been bored to .020 before I got it and oem is standard or .050. Superdave the bearing didnt drop down just the rod. Jason

[Ray Neudecker]

If the oil injection is gone. Then I would suspect either that the bore was not true or when assembling the engine the crank did not get properly aligned in the pins in the crankcase. I have used the Vertex pistons in everything from fishing to race motors with excellent results. I would not put it back together with out having a very competent shop checking the line bore. I have had very good results with the remanned cranks in engines that do not turn high (6400 or so) RPM's. They have been a total disaster where the RPM's exceed 7000.

[Ray Neudecker]

Also, the cases where the engine was factory assembled, the problem has always been accompanied by poor oil quality and long periods of non use allowing the valves in the oil injection lines to clog up. May be why the cylinders affected vary so much.

[Wayne Worthy]

The pre-1990 2.6L blocks had line bore problems. When certain "forged cranks" and blocks with questionable line bore, you will see this type of "cheek wear" on the crank and the rods. We made the problem better with a different treatment on the rods. These rods were serial numbered on the rod beam.

[valero1990]

if you need a crank i do have a nice one from a 97 225 and everything else in the short block.

[J Lamb]

The pre-1990 2.6L blocks had line bore problems. When certain "forged cranks" and blocks with questionable line bore, you will see this type of "cheek wear" on the crank and the rods. We made the problem better with a different treatment on the rods. These rods were serial numbered on the rod beam.
Any particular #'s to be aware of??