Oil injector pump failure 787 motor

[oneday0914]

Hello,
I have a 787 motor that seized up. What I found looks to be overheating and the wrist pin clip has also come out. I think it was due to a damaged piston. After further investigation, I found:

• - Magneto cover removed and was full of water.
• - Injector pump shaft coupler to flywheel 420837392 most of the plastic teeth had snapped off (thinking lack of injector oil because of that).

Can anyone tell me why there would be water in the magneto cover and also why the plastic teeth snapped off the coupler? Also do they make a stronger updated coupler than plastic?

 

[mikidymac]

My guess is someone did something wrong since those are oversized pistons.

Water in the magnito is typically from the starter.

That is the new updated oil pump drive.

You should be able to easily turn the oil pump by hand and can test it with a drill. I haven’t heard of one failing ever.

Some people switch to premix but leave the oil pump and if it doesn’t have oil it could seize.

Your pistons look like they were getting absolutely no fuel and or lubrication. I would say you were running extremely lean.

 

[oneday0914]

What do you think is better the older style pump drive or the new one ?

 

[mikidymac]

The new one is.