Piston chip, cylinder question

levsmith

Member
Got the new (used) gas engine in the 3400 today. Since I had to swap the oil pan and the head, I figured I might as well pull the pistons and check it out. The previous owner said it ran when he took it out to replace it with a diesel, but said it used oil. I think I figured out why... As you can see, the top ring on the front piston is broke into multiple pieces. But I also noticed the top edge of that piston has a few chips in it. I checked he cylinder and it has a spot in the top edge in the same spot as the piston chip. Its not deep, but definitely worn in that spot. I planned to hone and re-ring the cylinders and pistons. I can replace the rings, but I'm wondering if that spot in the cylinder will just cause problems with the new rings. Is the piston OK to use? Do I need to replace the sleeve in the cylinder? Thanks

Oh and in case you are wondering, the line you see in the bottom half of the piston is not a crack.
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That piston pretty much looks junk to me, that is a lot of ridge also, clean up the ridge, hone and see what it looks like.

I am really doubting that will clean up.
 
(quoted from post at 16:06:20 03/24/18) Do we know for sure it is sleeved?

Rick, I'm just about positive it is sleeved. This picture is taken from the underside of the block, showing what I believe is the sleeve sticking down from the bore. My old block was not sleeved and this one definitely looks like it has been.
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(quoted from post at 18:48:21 03/24/18) My best guess that engine was ran extremely lean... You need to go completely thru it $$$$...

How can you tell that? I'm new to getting this this deep, so I'm genuinely curious
 

Because its not normal ware... Go to page 16... I was thinking heat are coolant getting into the cylinder its heat related... The reason I went with a lean condition is I don't see skirt damage... OK you are new you pix of the piston is bad "not good" it was headed toward a nuclear meltdown... The guy that sold you the engine at least used lube when he stuck it to'ya... He gave you a fair Waring are i would have said he stuck it to ya with out lube...

http://engineaction.com/FailureManual.pdf
 
What do you plan to do with the tractor If you are going to pull it hard day after day replace the piston and liner. If it is light duty chore tractor ream the ridge hone replace the piston and go that small imperfection in the wall won't cause any problems.
 

Thanks hobo, that's got alot of good info. So far everything else looks fine to my uneducated eyes but I do appreciate the heads up. Unfortunately I don't have time to go through the whole thing right now, my house just sold so I've got to get the tractor put back together so I can get it moved. For now, I'll have to get a new piston and sleeve and work on tuning the carb to try and get rid rid of the lean condition and see what happens. Worst case scenario, I've got the old block still. The reason I bought this engine was because I was missing so many parts on the original engine and it needed bored out and sleeved anyways. Even if this one is toast, I've got less in it than what I would have had in buying all of the parts I was missing.
 

I appreciate your opinion! My plan is to use it to dig a septic system for a new house (it has a backhoe attachment), then once that's done it might get used once or twice a week to feed a bale of hay or do some mowing around the farm. I definitely won't be working it as hard as it was designed for. I thought about doing exactly as you said, but wasn't sure if that imperfection was what caused the top ring to break into so many pieces.
 

Unfortunately you can't simply install a sleeve in that engine, it'll have to be torn down a taken to a machine shop for them to remove the old sleeve and install a new one.

For no more than you plan to use it remove the ridge with a ridge reamer, hone the cylinders and install a new set of pistons and rings. That piston is junk, if the others have a wide top ring land like that one they are also junk.
Pay close attention to the valves in the head to make sure they haven't sunk due to valve seat wear, unleaded gas is hard on these old heads and many need new hardened seats installed.
 
(quoted from post at 09:24:54 03/25/18)
Unfortunately you can't simply install a sleeve in that engine, it'll have to be torn down a taken to a machine shop for them to remove the old sleeve and install a new one.

For no more than you plan to use it remove the ridge with a ridge reamer, hone the cylinders and install a new set of pistons and rings. That piston is junk, if the others have a wide top ring land like that one they are also junk.
Pay close attention to the valves in the head to make sure they haven't sunk due to valve seat wear, unleaded gas is hard on these old heads and many need new hardened seats installed.

Thanks for your expertise yet again Destoked. Thats a bummer to hear, but I appreciate you letting me know. I found a heck of a deal for new tisco pistons on ebay so i went ahead and bought 3 of them. I have a newly rebuilt head that I am planning on using on this block, so the valve seats shouldn't be a problem.

From what I read last night, it sounds like an exhaust valve leak could cause a lean condition, therefore making it run hotter. I'm wondering if that was the problem with this engine. I did a leakdown test on this engine before I even tore into it and no matter what position the piston was in, even TDC on the compression stroke, it was leaking pretty bad out of the exhaust. I wonder if the exhaust valve didn't get closed completely, allowing the piston to contact it and chip the edge. Anyways, hopefully the rebuilt head takes care of this
 

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