My project is to replace the rings in the old 8237 lawnboy. The problem I am having is pulling that piston out of the cylinder. It pumps through the cycle without friction, but when trying to pull the piston out of the cylinder it gets hung up..
How can it be pulled out? What technique do I use? Is a special too required?
THanks, Fish.
Hi, My understanding is piston is connected to something called crankshaft. Tony
It wore the head larger than the lower end of the cilinder. Even if you get it out the steel rings probably have less wear than the aluminum head, and stock will be undersized. I guess use force, hone out ridge and measure for correct ring size, or throw it in the trash and buy new, have fun.
You may have a ridge on the cylinder wall up near the top caused by the bore wearing in the region the piston ring(s) sweep through. That's enough to stop a piston ring moving up and out.
Push the piston down all the way and see if you can reach in and feel a ridge with your fingernail.
If you find a ridge, Google for "cylinder ridge remover", a tool like the one pictured on this page:
Jeff
i just pull it out, you think theres a ring ridge or something on the lower cyl the rings are catching on? maybe a brass rod thru the plug hole would tap it out. lucas
It should just pull out! I wonder too if there is a ton of wear in the cylinder and the rings are catching on a step in the cylinder. Greg
Very Interesting. Do you think I can force it out without resorting to the ridge remover? Just curious. Are you an engine rebuilder? You sound very familiar with this type of project.
Fish
Thats it, i didnt think of the rod through the plug idea. I got a wood rod that should do the trick.
Thanks, Fish
Last I read about this, in 1970, the rings wear away some of the cylinder, but the rings never get to the top, so that part is original size.
There's a tool to grind it away, but it might have been a power tool attachment. I';msure there's one for lawn mowers too.
You'll probably have to get oversize rings, iiuc. I suppopse they make those for lawn mowers, but I'd loook into it before going much further.
Or maybe I mean, for cars, I think they redrill the cylinders, and maybe put a sleeve in to get it back to the original size.
But like I say, I haven't read about this since 1970 (wrt cars) and I've never done it.
8-(Remove NOPSAM to email me. Please let me know if you have posted also.
It's called a cylinder hone. It's used to smooth the surface of the cylinder.
If the mower is so far gone that oversize rings are needed, it's time for a new mower.
To get the piston out, use a wood dowl on the top of the piston, placed directly in the center, and strike it with a hammer.
I think it is called a ridge reamer, a hand tool not a hone, a hone is power driven spring loaded to put pressure on the cilinder, it wont work it will probably mess up the cilinder.
TO all who have already replied;
I got one more question on this topic. If the engine seems to be giving good compression and works seemingly fine, who can tell me what danger there is in leaving the current rings in there and just running this engine till it quits?
Would there be *any* benefit of installing new OEM rings at this point--without reaming?
The reason that I ask is that the reamer costs $50.00 and this is raising the cost of repair, I dont think I will ever use that reamer again in my life.
Thanks again guys, Fish
There is a minimum compression needed for that motor to make power and work, contact lawn boy or a repair shop to find out what it is, its maybe 80-90lb, leave it till its gone then rebuild it.
I read you loud and clear. Seems like the right thing to do.
Fish
you cant use a ridge reamer on a lawnboy 2 cycle engine, the "head" is made on the cylinder ,so you cant get to the ridge to ream it. ive seen many a good engine ruined by a novice with a ridge reamer. good compression on a lawnboy is 135-150. there are oversize pistons if you want to have the cylinder bored. if you got it apart, go ahead and put new rings in ....lucas
Lucas,
so you think the new rings will help a little? what will i gain? just curious.
Private Malone, nice song...
Fish
If the head and cilinder are one piece then he will never get the piston out, the rings will be worn in a grove, so basicly you throw it all away when compression is shot, but at replacement parts cost retail and bearings etc etc, ring compressor and other tools needed he is probably at the cost or above of a factory new engine, so run it till its toast. For l;ongest life use a synthetic at 32-1 and keep the air filter clean, and rpm down.
Lucas is blowing smoke! No OS rings or pistons for your Lawn Boy. Also the compression for your engine should be about 80 PSI. I have rebuilt a ton of them. I owned a repair shop for 5 years. New rings are a good idea beings you have it apart, BUT if the cylinder is worn, it is shot! New rings in a badly worn cylinder is better than old rings, but it is a waste of time to repair it if it is worn out! Do it correctly or you will be wasting you time and money. New parts for Lawn Boys are relatively cheap.
Their are enough used Lawn Boys out there so used parts are plenty. In fact I have never bought a new mower in the 15 years I have owned my home. I like Lawn Boys so if I see one in the trash I check it out and maybe drag it home. I gave my first Lawn Boy to my neighbor, a '74 model, he still uses it. I have replaced it with a mid 80's model I picked up out of the trash, brought home and tuned up. Many people are of the throw it away mentality so I find them with little wrong with them. I have three Lawn boys in the garage right now, although they all run I only use the newest one.
Did you get the piston out? What was the hang up? Greg
top post for ease of reading...
Greg,
I am re-thinking taking the piston out, because it seems like a lot of work, for little gain. From what I understand the cylinder is just about worn out, so my perceived effort of replacing the rings doesnt outweigh the expected lifetime of the cylinder.
I havent gotten the piston out yet, I will be heading to Home Depot later today for the dowel if I decide, with your help, if taking it out is a good idea in my case.
Thanks, Fish
Ransley,
Where can I get synthetic oil? Whats the name of it?
Fish
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