Here we go again.

[gil sonsino]

I really don't know what is happening with Picco's engines but in less than a month a second failure....maybe someone has a clue.Motor mounted in a Jae fuel Wildcat 35% nitro 18% oil during break in.

 

[Joe Wiebelhaus]

I would look for a flex shaft problem, roll it on a table, and also check the end shaft to be true. Collet on the engine ?

What type of engine mounts ? Im thinking vibration is the culprit.

 

[Ray Sametz]

Gil, hard to tell from pic but the bottom of the rod seems mushroomed. Maybe rubbing on the drum, how much end play is there in the shaft at flywheel. Should float about .003 tho. If it's too tight it could put stress at that point. OMHO ==={}

 

[Lennard Cuenco]

wow..that reminds me of the time i busted two cranks in a month (did your crankshaft break in both instances?)

turns out the cranks were improperly heat treated at the factory during that production run....replaced the cranks never had an issue with the motors after that

 

[gil sonsino]

Joe the flexshaft is perfect also collet.I use CMDI rubber mount type.There are five boats i.e. all Jae's 45 that i built for customers with same set up ...three CMB's running with no issues and only the Picco's presented these failures.Ray I gues with the rupture of the crankshaft the back of the engine was pressed against the drum ....no end play in the shaft at flywheel......as said motor still working on break in??????? .Well too late to complain and have boats ready for next saturday ..first race of our season so for me Picco is definitely over...curiosly my Black head (2000) is still running good but a CMB 45 VAC is ready on my workbench lol..

Thanks for your input.

Gill

 

[gil sonsino]

Lennard we have failures in almost same instances ..one after 1 gallon and this last one during break in and how to explain to customers that's not my fault is the real problem.

Gill

 

[Rick Sowell]

looks like it picture two that the crank counter weight has a lot of rust on it and in picture one there is rust and corrosion on the top of the crank case, could possibly be the reason.also looks like in picture two that the broken end of the crank looks discolored, kind of brown around the edge, again possible rust.

 

[JeremyEdge]

Heat...

 

[Norm Doerr]

Is the flywheel cone soft brass material or hard steel?

Just guessing.. Good thing about it is that is is just the crank, could have been a LOT worst if it were inside the "busy" area of the crankcase

 

[mtruex]

Gill,

I also broke a picco crank in the same spot after about 5 gallons of fuel, the new one is on about 3 gallons and so far so good.. I dont think you are doing anything wrong, there is not much of a radius where the crank OD steps down to go through the front bearing..

 

[gil sonsino]

Rick the corrosion you see on top of the crankcase is due to the steel screws and on the crank something absolutely normal considering we use methanol fuel so if you take your motor apart affter few runs it will be discoulored but not rusty.

Norm the flywheel cone is stainless steel no brass as this motor came from Mike Hallan,,,considering the whole package I agree that things could be wrost.

I guess Mtruex is right about the radius problem "dejávue" in previuos exr editions so now is wait for the new parts.

Thanks to all.

Gill

 

[Norm Doerr]

Rick the corrosion you see on top of the crankcase is due to the steel screws and on the crank something absolutely normal considering we use methanol fuel so if you take your motor apart affter few runs it will be discoulored but not rusty.

Norm the flywheel cone is stainless steel no brass as this motor came from Mike Hallan,,,considering the whole package I agree that things could be wrost.

I guess Mtruex is right about the radius problem "dejávue" in previuos exr editions so now is wait for the new parts.

Thanks to all.

Gill

You are making too much power..

 

[Tim_Duggan]

Was your flexshaft collet running true?

 

[Mike Larson]

Norm hinted at the deal, and I'm sure they may send it out with a brass cone.... inherently i saw, with the old silverheads also, the brass cone will compress over time, or prematurely if you really crank on it, and the endplay will allow it to hammer against the little front bearing until it spins from an over rev, or pockets in the water.... the cone will grind into the bearing, throwing the brass to the bearing, either allowing the prop to push the tolerance to the drum, or even the flywheel to the case..... whatd the inside of the flywheel look like?... gold?... Used to be a guy around made the steel cones..... i'd went to installing a hardened metric steel washer and kept the shield on the front bearing ..... picco disease.... but i liked 'em... Mike

 

[David Bryant]

there is not much of a radius where the crank OD steps down to go through the front bearing..

yeah, when analyzing that vertical image (of the broken crankshaft) it does look as though there's not enough chamfer at the transition from the main crankshaft section O.D. to the smaller O.D. front (threaded) section.
Was your failed crankshaft on the new version Picco P45R motor (black case/blue head) as well?

 

[Jim Allen]

I wonder if the older materials used for crankshafts (8620, 9310, case hardened steels) have been changed to stronger through hardened steels. Even with a very small radius the crankshaft should not fail at this point. A ground inside radius that does not have a very smooth finish will have many stress points.

Jim Allen

 

[Tom Foley]

Basically a piece of shiz . Don't these guys run the piss out of these things before they start selling them ?? WTF .

 

[mtruex]

there is not much of a radius where the crank OD steps down to go through the front bearing..

yeah, when analyzing that vertical image (of the broken crankshaft) it does look as though there's not enough chamfer at the transition from the main crankshaft section O.D. to the smaller O.D. front (threaded) section.
Was your failed crankshaft on the new version Picco P45R motor (black case/blue head) as well?

mine was the previous version, silver case blue head..

 

[FloridaScaleBoater]

Well Tom,, not sure how YOU really feel,,, But if Picco were to be the only nitro engine on the market,, today.... I would be running gas, exclusively!!

 

[Brian Sorgente]

I really don't know what is happening with Picco's engines but in less than a month a second failure....maybe someone has a clue.Motor mounted in a Jae fuel Wildcat 35% nitro 18% oil during break in.

How much time did you have on the engine? I'd be interested in seeing a shot focused directly on the failure points of both pieces which shows their mating textures.

Brian