1968 55 hp Johnson - metal pieces in exhaust Housing Behind Propeller

[atengnr]

Hello, have a 68 55p and after pulling out of the lake yesterday I noticed that the prop spun fvery roughly. I removed the prop and found pieces of what looks like sheet metal shrapnel that seems to have been pushed out the exhaust. It chewed up the back of the prop a bit. Where did this come from?? Thanks for your help. See pic attached. The metal was pulled out from the hub behind where prop sits.

 

[racerone]

More pictures ?

 

[interalian]

How did the motor run?

 

[atengnr]

Motor ran fine overall, though did run rough at low speed (probably due to been in storage for last year)

 

[atengnr]

No Title

Here are other pictures of the pieces.

 

[interalian]

Hard to guess by the pictures. How big are the pieces? Are they aluminum? Steel?

 

[jimmbo]

Can you post some pics of the gearcase, mainly the exhaust exit area. from the sides, back, and in between.

One more question. How long have you owned this engine?

 

[atengnr]

Will do in the am. I have owned this engine since 1998. In 2009, I had a shop rebuild motor with newer style Pistons/rods for hefty price tag (I'm into having 1968 motor since is same year as boat). Has many many new parts in and on power head. It however had not been used much since the rebuild (25 hrs maybe).

 

[emdsapmgr]

Whenever a powerhead blows up, inevitably pcs wind up down the exhaust tube. Esp those small enough to get past the exhaust ports. Many times they wind up in the exhaust area just in front of the prop. See if any of the pcs look like bits of chewed up piston rings. Or, parts of a disintegrated piston. Probably been there since 1998. Once it blows up, someone needs to look in that area for broken pcs in order to clean them out. Not an uncommon problem-esp if you paid for an overhaul a few years ago.

 

[oldboat1]

chewed up prop parts, by any chance?

 

[atengnr]

Prop is without a ding. This metal has to be new at least to have gotten to its place behind the propeller because I know that I would have noticed the rough feeling when spinning prop by hand.

 

[oldboat1]

well, tangled with a crab trap once and lost. no additional ideas offhand.

 

[atengnr]

These pieces were caught behind propeller jammed in hub of prop at back of propeller. Could this have come from the water and somehow worked its way behind prop??

 

[racerone]

They are much too big to go through the screen of the water intake , yes ??------Likely parts from the exhaust housing.-----Easy to identify if parts / motor was on my workbench.

 

[atengnr]

I had thought this as well. Looked at pics of exhaust housing and seemed that this is cast aluminum??? These pieces are 2 to 3 inch bent up sheet metal. Is there something like this on inside of exhaust housing? If so, should I drop the gearcase to inspect the housing?

 

[jimmbo]

I recently saw a motor that had been damaged by the owner forgetting to put the thrust washer on the prop before installation. To subsequently seal the gap created by the gearcase being machined by the prop, the owner fabricated a sheet metal extension that extended into the prop to prevent the exhaust escaping in front of the prop. Maybe your motor suffered the same thing, which is why had asked for a pic of the lower unit in a previous post.

 

[atengnr]

Oh interesting. I will take pic of motor once I get back to it. The shop that rebuilt motor put the prop on back in 09 so would hope that they removed any home made crap. It has thrust washer in place.

 

[atengnr]

No Title

Here are some pics of exhaust area...

 

[jimmbo]

Your gearcase has not been custom machined by a thrust washerless prop. Is there a chance that somebody just put some garbage into the prop? Is it stored in a place where people can access it?

 

[atengnr]

It is stored in my parents garage, no uncontrolled access.