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Yanmar 3gm 30 engine seized

Jun 12, 2013
202
Hunter 31.5 Cedar Creek
It is the position I had to put the connecting rod in to get the rod slid next to it as I was hammering the piston up the connecting rod got jammed on the lower lip of the liner but I figured I could just bang the piston back down a little bit and then try to guide the connecting rod into the center of the liner
 
Apr 3, 2019
268
Macgregor 26M P Cub Boo Mobile AL
Yikes. You have to be careful not to do any damage to stuff you're going to re-use. Might only be the connecting rods, crank and block, but try to do as little damage as you can.

I know it isn't easy to be careful when you're trying to beat pistons out of an engine from the bottom end. Take it easy and monitor the progress as it goes to make sure nothing is binding. Take a break if you get frustrated. That's usually when I tear something up...

Bump it back down and get it free. It's got to come apart. If you bent or gouged the rod, you will probably be able to source a new one. Watch the bearing surfaces on the crank. You don't want to damage those.
 
Jun 12, 2013
202
Hunter 31.5 Cedar Creek
Pistons, rods and sleeves came out in one piece!! Pistons are welded tight and had to hammer the connecting rods to get the pistons out!! What next?
 
Nov 6, 2006
8,418
Hunter 34 Mandeville Louisiana
Rings are $63 per cylinder and the liners are $155 each.. You can probably save the pistons by carefully, patiently, slowly.. tap them down then up with lube oil in the space between them and the liner.. The ring lands in the pistons may have been damaged by the removal effort, which would make them toast and require new ones. A new piston with rings is $113.. It may be possible to reclaim the liners by honing after the pistons are out, but your description of how bad the rings are stuck probably says that they are toast as well.. These are part prices from Toad Marine Supply and if you can cross-match the 3GM30 to the Yanmar tractor motor, you can probably get these parts at a significant discount. From where you are now, a valve job and new seals and bearings would be in order..
Quite a job.. Good luck
 
Apr 3, 2019
268
Macgregor 26M P Cub Boo Mobile AL
The hard part is done. Decide how much of the rest you want to take on. I agree with @kloudie1 - do the valves, seals, and bearings while you're here - especially if you're keeping the boat. You should be able to get a rebuild kit that has most of the stuff you need. Then, you'll have to add things like pistons, rods, and sleeves that don't typically come in the kit. You'll have to shop around and see what's available.

If you get queasy, check with a few machine shops and see what they want to put it back together for you including the cylinder head work.

I know it's a bit of cash, but I don't think I would mess with the old sleeves and pistons. Also, replace any rods that you damaged.

You're doing great!

I assume that the crank turns now?