So, this is an old motor that was on the back of my snapper rear riding mower, and the engine was run without much of any oil for a brief period. After I filled it with oil, and it ran fine for the rest of the 2011, still had a good amount of power but was blowing out alot of blue smoke. I tore it down this winter, but haven't gotten to do anything else with it. Now with spring here I need too finish. It's all apart pretty much, and the cylinder wall looks meh. I can catch my fingernail in a few places. Being on a very tight budget, and being a old dirty worn motor (from the 80s), would it be too horrible to just buy a ring and gasket kit and be done with it? Or is it worth it to spend the money to bore it out and get a new piston and connecting rod as well?

quote Originally posted by mattwa: Being on a very tight budget, and being a old dirty worn motor (from the 80s), would it be too horrible to just buy a ring and gasket kit and be done with it?

What's the point? If there are grooves in the cylinder walls, it's going to continue to burn oil like crazy with new rings.

[This message has been edited by Patrick (edited 03-13-2012).]

I have re-ringed small engines without any work on the cylinder walls. Usually the oil control ring gets worn down bad, which is one reason they burn oil. If it isn't scored too bad you might get away with it, but don't be disappointed if it still burns a bit of oil.

Would it be less expensive to get a donor engine from a bone yard and just swap out internals?

Brad

I will try to take a picture when I get home. But most small engines this old that would be donors are in the same or worse condition. Of course I could repower it with a new 14hp motor, however thats $450...

[This message has been edited by mattwa (edited 03-13-2012).]

quote Originally posted by mattwa: ... most small engines this old that would be donors are in the same or worse condition.

Well, perhaps if they had also been run low on oil and had galled the cylinder walls. But yeah, finding an old block in good condition is kind of a crap shoot.

I had a mower here which upon tear-down revealed cylinder walls which had been deeply scored. Off to scrap metal it went...

[This message has been edited by Patrick (edited 03-13-2012).]

Hey, I admit it was a mistake on my part, damn thing doesn't have a dipstick.

If anyone has a good donor let me know. Lol. Or any horizational engine with a 1" x 3 5/32" shaft

[This message has been edited by mattwa (edited 03-13-2012).]

Although it's difficult to tell from the pictures, those grooves in the cylinder walls aren't as bad as I envisioned. Sometimes the alloy cylinder walls get real ugly looking rips in them.

If the grooves aren't too bad/deep, you might get away with roughing up the cylinder walls with emery cloth (by hand in a crosshatch pattern), and installing new rings. What does the piston look like?

Ok, that's what I might just do. I can live some some blue smoke, just not what it was before really. There is one groove that is deep, the rest aren't.

The piston looks fine actually. I can see some vertical "lines" in direct light on the two sides of the skirt, but nothing major, If I recall correctly.

Looks like just getting new gaskets and rings is what I'll do.

[This message has been edited by mattwa (edited 03-13-2012).]

Get a honing stone or some 440 paper and clean the wall up, then replace the oil ring and others if you can afford it then slap her back together and run her till she dies.

Melanie has run our old Murray 16 HP lawn tractor low on oil and I just keep putting more oil in every time she mowed. Smoked like an old V8 with bad rings, one good thing about that, it keeps the bugs away when you are mowing.

Steve

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The piston on the aluminum bore blocks is plated (hard chrome, I think) and if the coating gets scratched, the bare aluminum bore and piston try to stick together, causing worse scratches. Go ahead and get a new piston, connecting rod and set of rings.

By the look of it, I'd do the rings and bearings and have done with it.

Remember, these are low compression engines and low rpm. It may use a bit of oil but there's life still in it.

Arn

If possible, "lap" the exhaust valve and put a new valve spring on it.

I agree with the cylinder hone idea. You can get one very cheap at your local auto parts store and it attaches to a hand drill. As mentioned above, you go up and down while the tool is running to create a cross-hatch pattern:

[This message has been edited by IMSA GT (edited 03-13-2012).]

quote Originally posted by IMSA GT: I agree with the cylinder hone idea...

A cylinder hone is great, but unnecessary in this case, and can actually cause more harm than good when used improperly on an alloy cylinder (which is relatively soft compared to iron). You can easily go off kilter and dig a stone into the alloy cylinder walls.

A hundred years ago, my first job out of high school for a number of years was rebuilding air-cooled engines. When the cylinders weren't being rebored and oversized, we just used emery cloth (I forget what grit) and removed the glaze from the cylinders by hand being careful to produce a cross-hatch pattern. The new rings would seat perfectly. (Make sure to also sand/hone down the ridge at the top of the cylinder a bit.)

quote Originally posted by Patrick: A cylinder hone is great, but unnecessary in this case, and can actually cause more harm than good when used improperly on an alloy cylinder (which is relatively soft compared to iron). You can easily go off kilter and dig a stone into the alloy cylinder walls.

Oh crap, I missed that part. I was just looking at the picture and assumed there was a steel liner for a cylinder. Never mind the hone idea

I bought a new gasket and ring kit tonight for this thing, so I'll have that coming in a few days. I was working on it tonight, cleaning, removing old gasket, sanding and wire brushing removing carbon in the exhaust port, etc. I finally got the intake valve spring and retainer in (thankfully I have a spring compressor for Fiero door hinges and that worked) after some trouble, but how in the hell do you get the exhaust retainer back together?! It seems impossible with having to get those little keepers on some-how, then the retainer itself?! I know how it goes together, it just seems impossible to actually do it in that little space in the engine block...stupid rotater.. Whats the trick to this?

The piston is worn more then I thought, but so is everything else. The area where the crankshaft sits on the removable part of the block is all grooved and marked up, same with the connecting rod end, but to a much less degree. Like I said, my fingernail gets stuck in a groove in the bore, and there is a matching groove in the piston...oh well. I'll run it till it really dies...then it's trash. The rebuild kit was only $30.

quote Originally posted by mattwa: It seems impossible with having to get those little keepers on some-how, then the retainer itself?! I know how it goes together, it just seems impossible to actually do it in that little space in the engine block...stupid rotater.. Whats the trick to this?

If it's the type I think you're describing, the retainer is held up with a spring compressor, and then the two keepers are held in place on the end of the valve stem with a dab of grease while the spring compressor is released.

[This message has been edited by Patrick (edited 03-13-2012).]

quote Originally posted by mattwa: Whats the trick to this?

Turn the engine upside down.

Figures. I don't have that "special tool". But I will try flipping it upside down.