Piston Slap

Roblynn · #1 09-14-2009, 08:41 PM

Hi Guys,

I have a question for the motor rebuilders here on the site.

I am talking to a guy that has a 169 for sale with a 149 as a parts tractor. During his ownership the 14 HP motor has been rebuilt and put in the 169 and is running just fine. Then he either rebuilt or had the 16 HP motor rebuilt. He then put it on the 149 since the 14 HP was already on the 169. He said that the motor runs OK but has some "piston slap" at full throttle so he just left it on the 149 and is calling that a "parts" tractor.

Does anyone know what he may be refering to when he says "piston slap"?

Thanks in advance,

Rob

RPalmer · #2 09-14-2009, 09:11 PM

Roblynn,
Piston slap is generally used to describe piston slop or play/looseness inside the cylinder. Piston slap means it's time for the engine to see the machinist.

Roblynn · #3 09-14-2009, 10:19 PM

Thank you Mr. RPalmer.

I will keep this in mind when I go to look at them.

Merk · #4 09-14-2009, 10:58 PM

Sad to say some call a rebuild by honing the cylinder wall and replacing the rings.

That is not a rebuild in my book.

Sections 10 thru 12 in a Kohler Service Manual has the needed infomation to rebuild a motor the right way. I would ask some questions on how the motor was rebuilt.

RPalmer · #5 09-15-2009, 08:55 AM

Quote:

Originally Posted by Merk

Sad to say some call a rebuild by honing the cylinder wall and replacing the rings.

That is not a rebuild in my book.

Sections 10 thru 12 in a Kohler Service Manual has the needed infomation to rebuild a motor the right way. I would ask some questions on how the motor was rebuilt.

Nor anyone else Merk. That doesn't even qualify as an overhaul. The biggest shame is talking to or selling something to a person that would call that a rebuild and you actually do rebuilds and overhauls. They don't even know what you are talking about and can't appreciate what is involved.

Roblynn · #6 09-15-2009, 11:15 AM

Quote:

Originally Posted by Merk
Sad to say some call a rebuild by honing the cylinder wall and replacing the rings.

That is not a rebuild in my book.

Sections 10 thru 12 in a Kohler Service Manual has the needed infomation to rebuild a motor the right way. I would ask some questions on how the motor was rebuilt.

Merk...I just spent some time reading the suggested sections in the Kohler Service Manual. I would tend to bet that there are a lot of engines claiming to be "rebuilt" that have just been disassembled, broken parts replaced and put back together.

I may be an "old fart" but am pretty new to small engine repair. This site ALWAYS is a valuable learning tool for me.

Quote:

Originally Posted by RPalmer
The biggest shame is talking to or selling something to a person that would call that a rebuild and you actually do rebuilds and overhauls.

RPalmer...Excuse my ignorance but what would be the difference between a "rebuild" and an "overhaul"? As mentioned earler, I am just trying to learn!

Sometimes I may need a little

OR

but always end up

AND a little smarter!

Rob

RPalmer · #7 09-15-2009, 03:18 PM

Roblynn,
When you rebuild an engine you go through it and make all clearances like new. Then you replace any and all worn parts with new. That's a rebuild.

An over haul is when you go through an engine and make sure all clearances are within specs and use acceptable used parts in the place of worn ones.

papaglide · #8 09-15-2009, 06:37 PM

Quote:

Originally Posted by Roblynn

.............

RPalmer...Excuse my ignorance but what would be the difference between a "rebuild" and an "overhaul"? As mentioned earler, I am just trying to learn! Sometimes I may need a little OR but always end up AND a little smarter!

Rob

I love that quote Rob, fits me to a T.

Matt G. · #9 09-15-2009, 08:30 PM

Quote:

Originally Posted by RPalmer

Roblynn,
When you rebuild an engine you go through it and make all clearances like new. Then you replace any and all worn parts with new. That's a rebuild.

An over haul is when you go through an engine and make sure all clearances are within specs and use acceptable used parts in the place of worn ones.

I think rebuild and overhaul are the same term. In the aviation engine world, 'overhaul' usually entails new pistons, cylinders, machining, etc. at least to some extent. Sometimes just the top end is done (I think this is referred to as a "top overhaul" ... any A&P in the audience please correct me) and a more major overhaul will bring the engine back like-new condition.

Where I'm from, 'rebuild' and 'overhaul' mean basically the same thing....in my mind, re-ringing an engine and doing not much else would be considered 'freshening up' in my mind.

RPalmer · #10 09-15-2009, 08:56 PM

Quote:

Originally Posted by Matt G.

I think rebuild and overhaul are the same term. In the aviation engine world, 'overhaul' usually entails new pistons, cylinders, machining, etc. at least to some extent. Sometimes just the top end is done (I think this is referred to as a "top overhaul" ... any A&P in the audience please correct me) and a more major overhaul will bring the engine back like-new condition.

Where I'm from, 'rebuild' and 'overhaul' mean basically the same thing....in my mind, re-ringing an engine and doing not much else would be considered 'freshening up' in my mind.

I'm not disagreeing with you, .. but in aviation very few if any used parts are ever used. And you know better than I as to why. So in the av world I believe the terms would be interchangeable.
Hows school?