Honda Mower Seized Piston

[StarTech]

If you want to, try and clean up the crank journal with muriatic acid. But it must be used with extreme caution, and preferably, outdoors.

Definitely an outdoor job with a good moving air away from yourself. Also note Muriactic Acid will produce some pretty nasty fumes in the present of moisture. Plus once the item is cleaned, the acid must be neutralize using water and the item must be immediately coated in oil to prevent flash rusting.

Fumes are heavy so they will linger if not blown away.

 

[bertsmobile1]

Definitely an outdoor job with a good moving air away from yourself. Also note Muriactic Acid will produce some pretty nasty fumes in the present of moisture. Plus once the item is cleaned, the acid must be neutralize using water and the item must be immediately coated in oil to prevent flash rusting.

Fumes are heavy so they will linger if not blown away.

Also very corrosive so if you do it under an awning, expect the awning to rapidly corrode
Ditto for metal cloths lines
The prime gas that comes off is AlCl which is an acid flux
There will also be some hydrogen which likes to find some oxygen & go bang
Usually I would use water to wash then dish washing solution ( alkaline ) the very hot water so when it comes out it will dry very quickly
Spray WD 40 ( or similar ) through the oil holes then the oil , grease ( petrolium jelly works well ) of your choice as per Stars instructions above.

For those who do it regularly , this is all second nature & we forget to give detailed instructions to those who do not
Rust is the oil holes is a big problem
Not sure if your crank has oil holes or is just splash but better safe than sorry.

And we really need to see the bore
If it is trashed then cleaning the crank will only get you $ 5 more as a used crank on craigs list .

 

[NJDan]

Yes, not much use in cleaning the crank if the cylinder is not good. I removed the crank to get a better look and the piston is near the top of it's compression, exposing much of the cylinder walls. It actually looks very good. I have not removed the valves yet. What is the best way to free up the stuck piston so we can see the condition of the cylinder?

 

[Scrubcadet10]

Yes, not much use in cleaning the crank if the cylinder is not good. I removed the crank to get a better look and the piston is near the top of it's compression, exposing much of the cylinder walls. It actually looks very good. I have not removed the valves yet. What is the best way to free up the stuck piston so we can see the condition of the cylinder?

So far PB Blaster/ Liquid wrench or Marvel Mystery Oil has been my go to for unsticking pistons.
but seeing that the bore in the GCV's are aluminum, i have a feeling the piston may be hiding some bad news behind the skirts.

 

[NJDan]

So far PB Blaster/ Liquid wrench or Marvel Mystery Oil has been my go to for unsticking pistons.
but seeing that the bore in the GCV's are aluminum, i have a feeling the piston may be hiding some bad news behind the skirts.

Could I stick a screwdriver down the spark plug hole and try to hammer it loose?

 

[Scrubcadet10]

I wouldnt use any thing metal, for risk or putting a hole in the piston, of course its not very likely the piston is salvageable, but it may be. i use a wooden dowel and lightly tap it. Preferably as large as possible to spread out the impact over a broader area.

 

[mmoffitt]

I have a customer that I think finally learned to check the engine oil level anytime he fills up the tank on his mowers but it took loosing five $1000 + engines to do it. Heck on one it was obivious that was a major oil leak as the whole rear of the ZTR was covered in dirty oil.

Even keeping the oil check it is important to notice if the oil level is changing a lot between checks and to find out why.

Roger That! Check that oil often! a lot cheaper to top up than replace equipment...and yy is the oil level low or High for that matter..Root Cause or it will happen again! Be well Sir Happy New Year

 

[NJDan]

Well the wooden dowel worked surprisingly well!! The piston came right out and there was more oil in there than I would have thought. A quick feel of the cylinder and it seemed fine. Piston is clearly toast.

Edit: It occurs to me the piston did not seize up. Based on how easy the piston came out and the lack of any real damage to the cylinder, I'd guess the journal seized first. Is that something that happens?

So if I can get the crankshaft back into shape with acid or lye then all I need is a new piston and connecting rod correct? ( Not including all of the ancillary gaskets et cetera).

 

[NJDan]

I actually have the muriatic acid and I've been cleaning the journal which looks like it will be a good shape. However I'm still not sure if this crankshaft is going to be usable. For instance I scored the top of it with a pipe wrench while trying to get a nut off the bottom of the mower. Since this is where the flywheel sits with a keyway it is not rubbing against anything so I'm assuming it will be OK.

I also have a crushed thread which should be no big deal. It's the pipe wrench damage going to be a problem?

 

[Scrubcadet10]

I would take a flat file and smooth out any raised area's on that taper for the flywheel... as well as clean up the edges of the key slot, don't go crazy, doesn't appear to be any damage to the keyway so it should be okay as long as you get the nut tight enough going back on.
If i remember right the actual torque spec for the flywheel nut is 38 ft lbs.