Oh dear GT550 Engine not sounding good

[Alan H]

Not much little about you
at first or even second
glance Martin, so it must be summat else eh?

[mizzytheman]

Not much little about you
at first or even second
glance Martin, so it must be summat else eh?

You need a big hammer to knock a big nail in.

[Harrymail]

Something I have noticed is that the little brass tube in the inlet manifold of the LH cylinder, where the scoring is, is much smaller than in the other two cylinders. A bit of brass could have broken off and got into the bore ? Pics below show the brass tubes. The tube in the LH looks much smaller and may have broken off ?

[teazer]

Now that's unusual. I wonder if the damage to that oil feed has restricted oil flow to that side.

The bits of metal you found look like parts of a big end cage and the piston shows signs of overheating and has seized. That big end also looks like it ran hot but not easy to tell if it overheated through lack of oil through the other oil feed or if it was just wear and tear and got hot as it failed. I don't see evidence of the piston hitting the head which can cause rings to stick as the crown gets hammered, so I would think it overheat on the left side and failed. I have a GT750 crank that failed on one side at the bits of metal that came out of that motor were also hard to identify.

Left side on a 550 is notorious for the seal behind the alternator going hard and failing, but that will be replaced as a matter of course.

First guess is that the short oil feed is restricted which lead to overheating and partial seizure and that contributed to the failed big end.

[barney01]

Have you tried some long nose pliers on that short oil feed. It looks to me like it has dropped back inside as apposed to breaking off as the end has shape to it.

[Harrymail]

Have you tried some long nose pliers on that short oil feed. It looks to me like it has dropped back inside as apposed to breaking off as the end has shape to it.

That's a very good suggestion Barney. I agree that the pipe does not look broken off. If it has dropped back maybe the oil flow was restricted. As the motor is with Baz I cannot have a look but will be able to do so in due course. Thanks Barney.

[Alan H]

You need a big hammer to knock a big nail in.

You been on the wacky baccy again bud?

[Harrymail]

Now that's unusual. I wonder if the damage to that oil feed has restricted oil flow to that side.

The bits of metal you found look like parts of a big end cage and the piston shows signs of overheating and has seized. That big end also looks like it ran hot but not easy to tell if it overheated through lack of oil through the other oil feed or if it was just wear and tear and got hot as it failed. I don't see evidence of the piston hitting the head which can cause rings to stick as the crown gets hammered, so I would think it overheat on the left side and failed. I have a GT750 crank that failed on one side at the bits of metal that came out of that motor were also hard to identify.

Left side on a 550 is notorious for the seal behind the alternator going hard and failing, but that will be replaced as a matter of course.

First guess is that the short oil feed is restricted which lead to overheating and partial seizure and that contributed to the failed big end.

Thanks Teazer. You have jogged my memory. Whilst waiting for the van I did notice that the LH crankcase cover was very very hot. In fact when I got home first thing I did was remove the cover to make sure the alternator had not broken up. So yes you are correct the LH side had overheated badly. With everyone's help I am getting a good picture of what has more than likely happened. Great to have everyone's input. Let's hope Baz can fix it !

[BAZ]

Engine ready to build..

[canaletto5]

Looks like it's going to be a stunner