Do I need to buy new pistons?

[MercMark]

What should the top of a used but still servicable piston look like.<br /><br />Mine have this lava rock look to them. I'm not sure if they're worn or if it's just carbon buildup that's uneven.<br /><br />If you click on the thumbnails, the images are quite large. Dial up users beware.<br /> http://www.geocities.com/mercfix

 

[Kenny Bush]

Re: Do I need to buy new pistons?

Man a couple of those look like they need to be replaced. That number 3 looks like something got into the cylinder, and the piston beat the hell out of it. Even the edge of the ring is eat away. How does your head and cylinder walls look?

 

[MercMark]

Re: Do I need to buy new pistons?

It's number two.<br /><br />the ring broke up. the piston is mashed. The cylinder walls look good. A honing should fix the one small groove. I was simply amazed. the piston is shot and I have some work to do on the head inside the cylinder.<br /><br />I was wondering about the other pistons. Is that black/brown lava rock look normal?

 

[alcan]

Re: Do I need to buy new pistons?

I don't know Mark. You will have to measure the pistons and bores. If they are still in spec maybe just replace the one and go with it. The whole show dosen't really look too good. If this were mine I might concider scraping this motor.

 

[suzuki40]

Re: Do I need to buy new pistons?

Im with alcan on this one, what the heck happend?<br /><br />Suzuki40

 

[NathanY]

Re: Do I need to buy new pistons?

Well, for what it is gonna cost you just for the piston and rings, you could buy another motor just like that in running condition. Problem is, not many people know how to run these old Merc, and you might have this problem again. So the question is, do you want to spend the money on this motor and know what it has, or do you want to buy someone elses problem? Just do what you can afford, but if you do decide to rebuild this motor, dont try to be cheap.

 

[MercMark]

Re: Do I need to buy new pistons?

I don't fully know what happened, which is part of the problem. I store my boat out of town and my parents were using it at the time.<br /><br />I may also have bought someone else's problems. As for knowing how to run old mercs, that's not a problem. My dad owned an old 50, 60's vintage since he was 17. Ran perfectly always, even after being overturned once. Skied behind it all the time as a teenager.<br /><br />When I bought this one it had perfectly even compression in all four. 150.<br /><br />I may cheap on it since I'm not exactly sure what caused the problem. I don't want to spend $900 dollars on a new set of pistons and run them in an imperfect block, AND not fully know what caused the problem. I may buy a new #2. Tidy everything up and shove it all back together.... do the water pump and cross my fingers.<br /><br />That is unless of course I can get parts much more cheaply that from the local merc dealers.

 

[greasemonkeyozi]

Re: Do I need to buy new pistons?

If you do decide to replace any pistons, I know where you can buy good used ones for the best prices around. Trust me, I've been in your same boat. Just Email me and I'll get this guy's phone number.

 

[Grant Manning]

Re: Do I need to buy new pistons?

mercury.grease.rag. Scanning pages for piston info. I've stripped my 50hp thunderbolt as the reed valve block blew up and scored one bore with the bits. Suprisingly little damage. But....need an oversize piston and rings. Are these available 'non-genuine'? as new they are horribly expensive. I'm in Australia!<br /><br />Regards<br /><br />Grant Manning