Broken oil pump drive pulley, help

[Nick Squire]

Hey guys,

The end of last year my oil pump drive pulley snapped off, today I finished opening up my 7m to check whats going on, nothing seems seized, I can turn the engine over just fine by hand, I can also turn the oil pump shaft without a problem. If anyone has had a similar problem or knows what happened it would be great to find out, my teacher took a look and isn't sure either. I know that Beech performance has their retention plate that they sell but my plate looks fine and fully intact, so I don't see what went wrong.

This is the pulley hanging where it should be, you can see its broken and quite a bit of metal was sheered away


This is the inner section of the pulley

 

[GC89]

It's discussed a little bit starting here.http://www.supramania.com/forums/showthread.php?183939-Ridiculous-1000HP-7M-Street-MK3-Build/page19

I thought I saw it mentioned somewhere else but cannot find it now. Seems rare but it has happened. Likely caused by a stress mark at some point, I have seen cam gears fail in a similar way a handful of times.

 

[Piratetip]

Take some macro photos of the spokes and center.
Will be pretty easy to determine failure mode.
Likely cyclic stress crack propagation.

 

[3p141592654]

I recall reading somewhere that those pulleys are sintered metal and have heard of a couple of them coming apart.

 

[SeeUSmile]

I recall reading somewhere that those pulleys are sintered metal and have heard of a couple of them coming apart.

It was the crank timing gear, it was about the front part part of the pulley snapping off in that particular thread.

 

[Piratetip]

These oil pump pulleys are also sintered metal.
Link posted by GC89 goes into some of this detail.

Also here:
http://www.supramania.com/forums/sh...ontrol-build&p=1953409&viewfull=1#post1953409

 

[Nick Squire]

Thanks guys! I read almost everything you guys posted and I'm in the midst of checking if a friend of mine can get the older style pulley for me, if not then I'll get the new one and be sure to be extra careful installing it!