Broken Timing Chain = Bent Valves? GY6 170 By bblickle (Read 1,616 times)

[bblickle]

I found a reference where someone said pretty unequivocally "Broken Timing Chain means Bent Valves on a GY6 150"

Is this true?

I have the head off and I see no nicks in the faces or edges of the valves or the (61mm) Piston.

The engine has been building up a lot of pressure in the crankcase and blew out the valve cover gasket so there was a massive sudden oil leak. No signs that anything bound, burned, or anything of the like. I've looked closely at all the bearings in the Top End and they look and sound fine. This is a young engine, maybe 25 hours since a complete empty case build-up.

That said, the Timing Chain presumably did break for a reason. Any thoughts?

Bob

[Alleyoop]

No it does not mean bent valves, see if you can turn the crank over by hand. It could be the crank is binding bad bearings etc.. Something may have cause the motor to bind and snapped the chain. Of the chain was old and fatigue and a roller snapped or a tooth broke off the crank sprocket etc..
Alleyoop

[bblickle]

I checked that pretty thououghly. The Crank seems happy and when the chain went the Starter would spin it like mad (no compression). I'll eyeball those teeth again tomorrow in the daylight to be safe.
I just pulled the Tensioner. It's a rickety PoS. It seems to want to bind. It was new with the rest. It was fully extended but that doesn't mean much at this point. It was well-fastened.

Bob

[bblickle]

Everything in this motor is under 25 hours except the Case, the Trans Gears, and a couple bolts.