How on earth did this happen?

[crazykartman]

Ran into an interesting one. Briggs Twin Intek 23HP broke something while mowing. Tore it apart and found the camshaft broken into pieces and an exhaust pushrod mangled up inside.
I can’t for the life of me figure out how that pushrod got into the crankcase? All 4 tappets were I place. I can’t for the life of me figure out how that pushrod got into the crankcase.
The other thing is the opposite exhaust pushrod was bent but still in the oil galley.
Has anyone ever seen this before?

 

[ILENGINE]

On the Intek V-twins the push rod will fit through the oil drain back hole from the push rod cavity. Could be the push rod got jammed in the camshaft which broke the gear. And most people don't notice the engine running on one cylinder so it give it time for the push rod to work down into the block.

I have seen the push rod chewed up into pieces. I have found the push rod just laying in the bottom of the sump and also have found one wrapped around the camshaft.

 

[Auto Doc's]

Hello C.,

The mangled pushrod found down inside likely popped loose because the valve lash became too wide, or a valve got stuck in the guide when hot.

When that happens the push rod can drop down into the crankcase and possibly get bent terribly by the rotating crankshaft and camshaft. When this happens, some engines are more susceptible to severe damage than others.

The 4 tappets cannot come out of the block until the camshaft is fully removed

 

[hlw49]

Engine over heated valve guides came loose causing valves not to fully open and bending push rods. In that case will need to replace heads and a cam shaft. Had one the push rod got into the crankcase and bent it looking like a paper clip laying on top of the cam gear and did not hurt anything else. New head push rod back in service. I wonder if the head can be fixed like Taryl says to fix it.

 

[Auto Doc's]

What does the rest of the engine inside look like?

Is this a customer's or you own machine?

 

[crazykartman]

What does the rest of the engine inside look like?

Is this a customer's or you own machine?

The rest d the engine looks fine (other than dirty exterior).
It was a customers mower and I had just changed the oil so clear oil. No buildup in the sump.
The valve guide were all fine and the fins were clear for the most part so I doubt overheating was an issue.
I can see how the pushrods could go through the oil galley passage,
I agree with ILEngine, these big engines can be hard to tell if they’re only running on 1 cylinder when the mower is engaged.

 

[Auto Doc's]

Hello C,.

Just for good measure, pull the oil pump gears out of the bottom side of the sump and make sure no damage or metal particles got in there. Cast parts often leave tiny metal particles when they fracture like this and that will cause future damage.

I highly recommend you spray and flush out the insides with brake cleaner to remove any possible metal residue.

Sounds like this engine may only need a new camshaft and pushrods along with new gaskets. I suggest head gaskets as well if you have not already removed the heads.

V-twins do not rock around or vibrate; they just reduce power.