broken piston ring damage

[crabbydad]

took my boat out for the first time this year Friday and broke a piston ring. I pulled the head today to access the damage. broke off part of the piston end and looks like it broke a small piece off the bottom one of the ports. Also see a small crack. Is this repairable? I couldn't get a clear picture of the exhaust port. can I weld the crack inside the port? the motor is a 140 hp omc seadrive. My thought was to bore the 1 cylinder. the other 3 are at 120psi and you can still see the cross hatch marks in the cylinder. tried to upload pics but couldn't

 

[boobie]

You might be able to resleeve it.

 

[racerone]

Very, very common damage.----------The cast iron sleeve will be difficult to weld.

 

[Faztbullet]

1) you cannot weld a sleeve as it will draw when cooled and 2) if welded the weld would be so hard you could never bore or hone it. That why you resleeve them. Also seeing crosshatch in other cylinders means nothing ..

 

[crabbydad]

I'm gonna run the boat over to a shop close by maybe tomorrow and they said they will take a look and see if its repairable, but I'm pretty sure its not. They sell used blocks for around $200. If I can find one that hasn't been bored, i'll get it bored .020 over and I can use my 3 good .020 over pistons.

 

[gm280]

I'm gonna run the boat over to a shop close by maybe tomorrow and they said they will take a look and see if its repairable, but I'm pretty sure its not. They sell used blocks for around $200. If I can find one that hasn't been bored, i'll get it bored .020 over and I can use my 3 good .020 over pistons.

If you can get a good block for $200 dollars, I wouldn't even try to repair yours. If they have to sleeve your and then have to bore and hone and such, I suspect the total cost will be more then $200 dollars. But that is just my opinion. And as anal as I am, I would absolutely make sure all cylinders were the same size and pistons... I know others talk about okay to miss match, but when every cylinder is pull an equal share, the engine is stronger and smoother running...

 

[Hahn007]

Very, very common damage.----------The cast iron sleeve will be difficult to weld.

What causes this "common" damage?

 

[racerone]

Numerous causes.--One is wear on the top ring and due to the shape the side clearance increases with wear !

 

[crabbydad]

ended up having to have the cylinder sleeved. cost me $200 total to have it sleeved and hone the other 3. should be done the first of the week. the bad cylinder cleaned up at +.064, but I didn't want to have 1 cylinder +.064 and the other 3 +.020. now I have to order everything. it had wisecos in it and the 3 good cylinders had some scuff marks on the pistons. after measuring them , I will call wiseco this week to see if I should replace them. I know the forged pistons are a little smaller to allow for greater expansion when they heat up, but these are-.015 in some spots. If they need replacing, I may go with another brand.

 

[racerone]

New they would have 0.015" in some spots.-Clearance measurement is taken at the bottom of the skirt !---What do you measure there ???

 

[crabbydad]

at the bottom, I'm getting as low as 3.505. I was going to call wiseco tomorrow to see if this is ok. at the top, they measure 3.517. the other 3 cylinders had 120 psi before I tore it apart, so I'm thinking they may be ok, but I want to be sure. I'd like to just replace the rings in the 3 honed bores. I don't want to spend all this time and do a halfa** job for the sake of saving the cost of 3 pistons.

 

[racerone]

Your numbers do not make any sense !---------Is the 3.505 " near the rings or at the bottom of the skirt ?-----------Is the 3.517 near the rings or the bottom of the piston ?

 

[crabbydad]

3.505 is at the bottom of the pistons. 3.517 is at the top of the piston.i called wiseco today. I didn't realize that the pistons are actually not round. from what they said, my pistons are ok. i'll just rering them.

 

[racerone]

Sorry , I was trying to help based on 40 years of experience.----Do my own boring / honing / fitting of O/S pistons and rings.-----I can not see how the top of the piston is bigger than the bottom here !---Any pictures of where you did the measuring ?--------If the skirt measures at 3.505 " your rebuild will not last long !-------Or are you calling the " bottom " the area where the rings are ???

 

[crabbydad]

sorry , 3.493 at top, 3.513 at bottom. ordered 1 replacement piston and 3 sets of rings today, but after checking them over, some of the scuffs may be a little too much. they measure as low as 3.503 at at the scuffs which are just below the rings. I think I may cancel my order tomorrow and order 4 new pistons