Does this piston need to be replaces

[hannez82]

Hi,

I'm putting my mercruiser 350 fron -96 together. Does this piston need to be replaces, it's a 423NP piston.

 

[Bondo]

Re: Does this piston need to be replaces

Ayuh,... Welcome Aboard,.... That's been Detonated, Badly,...

I wouldn't reuse it...

Why is the motor torn down in the 1st place,..??

 

[hannez82]

Re: Does this piston need to be replaces

Thank you

Are you sure? I was told is was corrision due to water in cylinder.

Because it had water in one cylinder.

 

[StevNimrod]

Re: Does this piston need to be replaces

Welcome aboard. I'm with Bond-o on this one. Water will cause a lean condition, leading to the detonation you see. A set of 8 of those pistons is about $90 (I'm not sure what your prices are going to be over there). Somewhat false economy to reuse questionable pistons while you're that deep in it and replacements are relatively cheap. If you have a problem down the line, you don't want to have passed on the $90 insurance policy.

 

[Bondo]

Re: Does this piston need to be replaces

Thank you

Are you sure? I was told is was corrision due to water in cylinder.

Because it had water in one cylinder.

Ayuh,.... 'n yer not borin' it out,..??

 

[sutor623]

Re: Does this piston need to be replaces

Be a shame to put her back together and have issues.

 

[hannez82]

Re: Does this piston need to be replaces

Ok

I have "bored" the cylinder to the same size. I dont know the word for it in english. The piston is more expensive here but i will buy a new one. Thank youfor your input.

 

[sutor623]

Re: Does this piston need to be replaces

Honed?

 

[hannez82]

Re: Does this piston need to be replaces

No. All the other cylinder are honed though.

You put a new "cylinder wall" in and then you bore in that one to the same size as before. Crystal clear?

 

[04fxdwgi]

Re: Does this piston need to be replaces

No. All the other cylinder are honed though.

You put a new "cylinder wall" in and then you bore in that one to the same size as before. Crystal clear?

Think you mean "sleeved"

Never seen anyone sleeve a 350 before. In the states, folks just get another block, but we are spoiled by having millions of them here. I'm sure overseas is a whole nother story for Chevy blocks...

 

[Bondo]

Re: Does this piston need to be replaces

No. All the other cylinder are honed though.

You put a new "cylinder wall" in and then you bore in that one to the same size as before. Crystal clear?

Ayuh,.... That's called Sleeved 'round here as 04fxdwgi says,...

Make sure ya find the reason it was Detonatin', before ya ruin another motor though,...

Lean fuel, 'n poor ignition, or too big a prop at the main causes...

 

[hannez82]

Re: Does this piston need to be replaces

Yeah it's another story over here. Not that easy to find a good block.

I don't know why it has detonated. How can a ignition be poor? Is the coil bad perhaps?

 

[achris]

Re: Does this piston need to be replaces

Sorry guys, but I've seen plenty of detonated pistons, and that certainly does not look detonated. A detonated piston doesn't even look like a piston anymore. That piston has very discernible valve recesses and the ring lands look in perfect condition. As the OP suggested, I think it's just a little water damage. But, I would like to see the rest of the piston crown before jumping to an solid conclusions. And sleeving is what we'd do here too...

Chris....

 

[hannez82]

Re: Does this piston need to be replaces

Sorry guys, but I've seen plenty of detonated pistons, and that certainly does not look detonated. A detonated piston doesn't even look like a piston anymore. That piston has very discernible valve recesses and the ring lands look in perfect condition. As the OP suggested, I think it's just a little water damage. But, I would like to see the rest of the piston crown before jumping to an solid conclusions. And sleeving is what we'd do here too...

Chris....

Hi,

Here is a picture where you can see most of the piston crown.

Br, Hannes

 

[Silvertip]

Re: Does this piston need to be replaces

The pitting (corrosion if that is what you wish to call it) is very close to the top ring land and therefore may prevent proper sealing or premature failure of that ring. Regardless of the cost, I would not put that piston in a rebuilt engine.

 

[MWG2600]

Re: Does this piston need to be replaces

I would run it, the ring lands look fine. If the skirt is not out of spec. I know boats are not cars, but thats a usable piston

 

[achris]

Re: Does this piston need to be replaces

I would run it, the ring lands look fine. If the skirt is not out of spec. I know boats are not cars, but thats a usable piston

Agreed...