Piston Pics, are these worth cleaning up??

[rothfm]

Got my 1984 Johnson 115 pistons out finally. 2 of 4 have a patch of moderate to heavy carbon build up (thus 1 broken ring!). Are these worth cleaning up???..I"ve tried a couple different cleaners, that havent cut the carbon/varnish. Otherwise they seem ok.

Sort of explains this new to me motor having a partial broken outter ring. The rest were bound to break soon also. the PHead is out getting cleaned and measured, I really didnt want to have to replace them if they are salvageable.

 

[1946Zephyr]

Re: Piston Pics, are these worth cleaning up??

Is that a chunk broken out where the wrist pin is? If so, I wouldn't use it. If there's any scoring on it or chunks broke out, then it's junk.

 

[ENSIGN]

Re: Piston Pics, are these worth cleaning up??

You need to clean it up and check the piston to cylinder side wall clearance and check it against the specs.

 

[orbanp]

Re: Piston Pics, are these worth cleaning up??

That piston should clean up. New rings and light honing to break the glaze on the cylinder should work if the cylinder is not scored. The measurement data will also tell if the piston/cylinder is too worn for reuse.
That "missing" piece on the piston is a machined relief for assembling the retaining ring of the piston pin.

Good luck, Peter

 

[phillnjack2]

Re: Piston Pics, are these worth cleaning up??

It dont look to bad to me.
it only needs to be cleaned up.
I would use something like autosol and give it a realy good go.
its not often that the piston is worn, its the rings that wear not the alloy piston.
if scoring has taken place then that is totaly different matter.
On the sides of the piston there is normaly marks from makers that go around the piston, if
these there then just clean it and use it.
The only reason it looks bad is the broken or worn ring let the carbon build up on it.
give it a clean, but dont use wet n dry paper, just use a compound type polish to get it off.

you could always try a drop of nitric acid to help clean it but do make sure to give it a realy good rinse afterwards to
make sure no carbon deposits or cleaner is left on the piston.
you can also try toothpaste on a rag to clean it, youl be suprised how effective that can be on alloy !!!!!

send us a pic when youve got it nice and clean


phill

 

[rothfm]

Re: Piston Pics, are these worth cleaning up??

Thanks all,

Will give it a go and see how they clean up. Yes, the "chunk" is a manufacturing hole to remove the wrist pin retainer.

They seems to be unmarked, as are the Cyl walls (Head is out to be degreased/cleand and measured). the rings were just about all stuck, although it hasent run in quite some time. I'll work on a good cleanup and post some pics after.

Thanks

 

[Faztbullet]

Re: Piston Pics, are these worth cleaning up??

Measure the skirt first to see if in spec's, will save a lot of time cleaning. That piston is going to be out of spec due to carbon buildup causing excess side thrust load on piston. I would not use it in any of my customers rebuilds, heck I throw better looking ones away!!!

 

[rothfm]

Re: Piston Pics, are these worth cleaning up??

Measure the skirt first to see if in spec's, will save a lot of time cleaning. That piston is going to be out of spec due to carbon buildup causing excess side thrust load on piston. I would not use it in any of my customers rebuilds, heck I throw better looking ones away!!!

Faztbullet, Thanks for that input...I'm leaning that way. I'm dropping the Block and other parts to be cleaned and professionally measured as well as 2 broken bolts that aged me by a few years! Going to have the shop look and them and measure them also. If I can find them at a good price, I may replace all 4....I've gone this far, be a shame to chance some thing!

Thanks