bottom-end G260PUM cleaning

[Mark Prins]

A new G260PUM (my first) with piston turned down ended up with a scuffed piston and cylinder last fall as I was tuning. I found metal flakes or bits inside and before I replace the top end I wanted to ensure the metal was all out of the bottom properly. It has sat around all winter waiting for me to find a way to do it. I don't have alot lying around, aaaannnnnd Im in Canada so perhaps some brands are different, but this can't be rocket science. Just need a little how to.

Thanks!

Mark

 

[troytron1]

I would replace the bearings. They are only $7.00 each.

 

[68Bud]

Sorry to say, but if the engine was eating itself up for any length of time, a complete tear down and bearing replacement is needed. You could do a "flush" with mineral spirits or kerosene, but it won't repair the bearing surfaces that were damaged by the metal fragments as your engine gave up.

 

[Tom Foley]

New bearings , new seals , new crank . flush with a few cans of brake clean , reassemble . It sucks but that's what you need to do .

 

[Mark Prins]

Exellent advice. Clean it out, replace bearings and other parts, reassemble and re-lube like in the after-run thread? I ordered a new G260PUM from Gizmos with piston turned down to buy some time I guess.Really appreciate your comments guys!

The engine could still run only I suspected something wasn't right as starting became way too difficult for a new motor... come to think, my water pump's pulse line is longer than 5 inches and the exaust cooling water does exit the hull with less authority than the engine cooling exits with. Its my second exaust port overheat or scuffing.

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Or do you think I have to open the top and clean the inside before starting the new one? I dont know what is done when the piston is turned down but I fear some material was inside on the busted motor because though I was informed by the seller I was allowing something to get sucked in the venturi, I have a closed canopy and vaccumed the inide of the boat prior to running and watched out for the possibility. I think theres a chance my exaust is not cooling right or both that and there was material in the motor.

 

[Thomas Hulbert]

Take pics and send them to the seller and show what happened could be something broke off after he did the turndown piston for you.

Waterpumps can cause a heating issue if not set up correctly any pinhole in the tubing can cause a real issue.

 

[Mark Prins]

Good call, I did send pics because I didn't know what happened... but the seller was quick to suggest the venturi theory and he wouldn't explore anything else. A busy guy, good guy though, we all know him. I'm not upset because I read a bit afterward, you should open and clean/check all engines in general before running. Seems everyone has to learn it one way or another. About the pump i did replace old waterlines with fresh ones beforehand, I replaced the water pickups too incase clogged a little somewhere. the pulse line was 7 inches long and silicone and just read that's bad. Can see the boat in my album.

 

[Mark Prins]

one's the new one in question, other's 3yrs old been open and uncleaned since September.

there's one of those bits of metal right there in the new one

where'd these come from , the piston?

if its form the poston then what caused it to the piston? hahah its a goose chase

the newer one, looks clean and undamaged, I should throw some mineral spirits in and out a few times if that's correct and change a short list of parts.

 

[Mike Whitney]

The pic with the piston tells the story...when you relieve the piston around the top that much, it causes it to do just that, filings you have are from the piston scuffing/catching on the cylinder. I would try finding another piston from someone else with less material removed. JMHO

 

[Mark Prins]

not from something getting sucked in then, cool thanks Mike!

 

[lohring]

The pic with the piston tells the story...when you relieve the piston around the top that much, it causes it to do just that, filings you have are from the piston scuffing/catching on the cylinder. I would try finding another piston from someone else with less material removed. JMHO

I've over relieved a lot of pistons without that kind of scoring. These days I only take off .001 to .002 inch, but I've run pistons with .006 relief. The wear pattern I see on the exhaust (thrust) side usually comes from the transfer edges and is toward the sides of the piston, not in the center of the exhaust. Is there a bur on the port? What does the cylinder look like in that area?

Lohring Miller

 

[Mark Prins]

The cylinder is smoothe inside, hardly any scuff marks. (will post pic)

So I sent this email right after the incident:

Hi,

I had only gotten the G260 installed and the engine to start recently. I got it in some water and got it to start, it iddle for a few minutes, I pushed it out and did 30 seconds of low speed crusing. The high-speed attempt cut the engine out, so I recovered the boat. When I pulled the starter to tune it, the starter cord wouldn't budge. I forced it to pull but the sound was not pleasant. The needles on the WT 644 were at the stock setting, so I openned the cylinder and it looks to me like both the piston and cylinder are scuffed on the exaust side. I included pictures. What do you suggest? I hoped that the turned down piston would be a buffer incase of high temperatures, and the weather here is cool, so I don't understand what happened.

Thanks,

Mark

This was the seller's reply:

"Sorry but what it looks to me that yuou have picked up somting out of the boat and the engine has sucked it in to the engine. i have seem this very many time. you have to make sure is nothing is laying in the boat. sorry."

 

[Mark Prins]

There's the cylinder...thanks for your interest!