Pin on Piston

[bumblebeetn]

Took head off 90 hp 1989 motor after it blew. The pin holding the #3 piston looks like it came loose from the rod. Motor had about 40 hrs on it since rebuild. You think it was a bad rebuid or something else? Im getting another powerhead to put on it. Any suggestions would be appreciated. Thanks

 

[rodbolt]

Re: Pin on Piston

did the circlip fall out or did a bearing fail? some "rebuilds" are not much more than a set of rings, a bogus hone job, and a new can of paint. how much was actually "rebuilt" last time?

 

[bumblebeetn]

Re: Pin on Piston

Hi Rodbolt,i didnt have it rebuilt but and i bought out of state recently rebuilt.Looks to me,i just took back cylinder plate off ,that the bearing failed,its gone. Ill take some pics of it and show ya when i get time. It was supposed to have all new pistons rings bearings,rebored ,the works. Im gonna get a powerhead off this site and ill know for sure im getting a good powerhead. But it was running great before this happened using right amout of oil right rpm speed. The cylinder walls look good but it does have a hole in side of block where the pin hit against it.

 

[rodbolt]

Re: Pin on Piston

if its not totaled look into haveing it sleeved.<br /> may be a bit cheaper than a total power head. that is assuming all the other pistons and bearings were new at the rebuild. if the pistons are not marked with an oversize number such as .25 or .5 most likly it got a set of rings and a can of paint.

 

[bumblebeetn]

Re: Pin on Piston

Hi Rodbolt,its got pistons that say .050 on them. Im not sure if you can sleeve this or not. Its got a hole bout the size of a quarter behind #3 cylinder right in front of reed valves

 

[rodbolt]

Re: Pin on Piston

is it in the sleeve or the block or the crankcase cover?<br /> when they sleeve it all the original cyl is bored out of the aluminium liner and a new sleeve pressed in.so it depends on where it broke and did it break up the outer liner.

 

[bumblebeetn]

Re: Pin on Piston

its in the block right where the carb assembly bolts to the block

 

[rodbolt]

Re: Pin on Piston

ok we got a terminology issue running.<br /> one of us has no clue as to the technical terms being used .<br /> sounds like a rod bearing or bolt failed. at first you said Pin and the only Pin it has is the wrist pin at the piston end. the block is two parts. the block which contains the cylinders, and the crankcase cover which is the front half of the block assy. the intake manifold holds the reeds and bolts to the crankcase cover. the carbs bolt to the intake. most likly your crank is damaged. if its not the rod is most likly damaged. the hole may be weldable if it did not break into any sealing surfaces. weld them all the time but it would be the welders call. its possible someone reused the rod bolts or failed to torque them or the motor had water in it and the bearings rusted.

 

[bumblebeetn]

Re: Pin on Piston

Sorry for the confusion rodbolt. The crankcase cover is fine. When the wristpin came loose from the piston it knocked a hole right where you bolt the crankcase cover to the block. If youre looking at the engine on the boat from starboard side its about an inch from where crankcase cover bolts up. You can pull the #3 piston out of the cylinder by hand . Its all beat up from where the wristpin came loose. The rod is still connected to the crank but all ive pulled off so far is the cylinder head looking at the top of the pistons. I can see where the metal did knock some dents in the crank also. Maybe it is weldable but from what these marine dealers in this area charge for that i can get another powerhead off here.

 

[rodbolt]

Re: Pin on Piston

most likly<br /> if its that damaged. general rule is if the crank is bad its done. you do need to determine the cause of the failure. if you dont the next may fail as well.

 

[bumblebeetn]

Re: Pin on Piston

Any suggestions on why it failed? This was the best running engine ive ever owned. And then boom it blows. Compression was excellent oil flow excellent gas fresh plugs all same color(coffe color) rpms around 5500 . It has the precsion blend which seems to be working fine. Is there a simple test to determine that oil is getting to all 3 cylinders? From the piston it seems oil was getting to that cylinder.

 

[Ray Neudecker]

Re: Pin on Piston

The rod coming out of the piston is normally the result of a hard siezure. Basically, if the rod bearing on the crank is bad, you suspect an oiling problem, if not a fuel restriction problem.<br /> Sometimes things get a little more iffy where a rebuild has occured, but a botched job there will usually show up in less than 40 hours.<br /> If Wiesco instead of cast pistons were used. then you have another can of worms since pins either holding the rings or the piston pin clip failures are not uncommon with them. I have actually seen the piston pins come by the clip in some cases of Wiesco failures.<br /> In any case if the cause of the failure is not identified and corrected, it will happen again.

 

[bumblebeetn]

Re: Pin on Piston

Motor had around 37 hrs on it.. I havent took the crankcase cover off yet to check bearing there.Im gonna try to get it tore the rest of the way down this weekend and ill let you all know what i find. <br />Thanks everybody for all the suggestions.

 

[bumblebeetn]

Re: Pin on Piston

I just ordered a powerhead to replace the blown 1 i have here off iboats. Any suggestions of what i should check before starting this powerhead up would be apprciated.