Looper eats rod bearings?

[MartinW]

Well, it started out as a good day on the lake. '91 175 Faststrike was tooling along about 5500 rpm, lost power, so I pulled her back and she died. Restarted and it didn't sound good so I shut it down and used the trolling motor to get back(not far fortunately). Pulled the heads back at the house...

#4 piston and head beaten up with what looks rod bearing pieces(arrows show 2 that are imbedded into piston), quiet a bit of aluminum transferred to cyl, but little on piston top.

#6 piston top has aluminum on it and a little transferred to cyl.

Any thoughts on what may have caused this? The other cylinders look good to me. Does this look like a lubrication problem or plain mechanical failure?

What all am I going to need to fix?

Thanks for any input. I'll try to post pics

[MartinW]

Here's #6

[MartinW]

Port Head

[MartinW]

#4 Closeup

[Jay R.]

I recently read an article about Bombadier taking over OMC and shutting down production until they had answers on why OMC's quality took a nose dive before the company went backrupt. one of the things they found was that in an effort to make production more cost effective they changed they way they made parts and what they found was the process was leaving casting marks in the rods that were chewing up rod bearings. i havn't heard of this actually happing till your story. but i would pull the rods out and see if you see anything resembling the situation i just described. might want to get all new rods from Bombadier.

[84exciter]

jay,
havent seen that story,sounds plausable.but martin did post it was a 1991 motor that was a long time b4 bankruptcy.

martin,
how warm was the motor?
i've seen this once b4,bad gas,det 2 pistons.
the motor tried to shove the piston up the small bore(alum. on cyl wall)
put dents in the crank from rod bearings,when it went down the bearings fell out.sucked thru the transfer ports and into the cyl.
it was a x-flow.
i was thinking bad gas or cold seize.check out the rod journal and the crankcase for the rest of the pieces.
may help with what happened
sorry to hear about it.hope your boatin soon

[racer]

To small to be a big end rod bearing, looks more like a ring locating pin.

[84exciter]

bow,bow,
now that he said that and i looked again it does look very small

we are in the presence of greatness

[NEECAPR]

Martin W: Racer hit it on the head! Assumging this is a 60 degree looper with 3.600 bore, the full pattern indents at the top of first picture scale to a pin length of 5/16" with a diameter of about 0.040"- locating pin size. This is about 1/4 the diameter and 1/2 the length of a 60 degree looper or crossflow rod bearing roller. If you need bearing/crankshaft help, let me know! Hope you get back to the water soon! NEECA

[Jay R.]

amazing how easily over looked that was, good call racer.

[MartinW]

Thanks for the diagnosis.

I'm kind of new to breaking these things and I won't be able to tear into it right away. Looking for root cause. Do you think that a locating pin fell out, causing the damage, or did a pin come out as a result of something else? Other than pin impressions, I can't see any scoring/damage on the piston, cylinder, or head, just aluminum transfer. The ports don't even look chewed up like I'd expect if the rings were spit out.

Thanks again. -Martin