Broken Pushrod "Read"

[doitmyself]

Posted here for more views. This is a broken pushrod on an overhead valve Kawasaki FE350D-BS25 single cylinder 12hp John Deere Gator engine. I'm guessing that the hydraulic lifter collapsed and resulted in this pushrod breakage.

Can any metallurgists here "read" this break and maybe tell me if this was defective metal or offer any other clues? Thank you. The engine started "clicking" a few days before this breakage. I checked the valve clearance and it was fine. This engine seems to have hydraulic lifters AND a valve lash adjustment set screw (new to me).

 

[Boomer]

Not a metallurgist but to me , it looks like there is a corroded/oxidized area in the middle telling me that maybe the push rod was never sound. It looks like it had a thin void that allowed foreign material in.

 

[Trav]

The rod itself is not broken, the ball end friction weld failed which is a known failure area with welded ball ends vs formed or pressed in ball ends. Manufacturing defect.

 

[ZX11Rebel]

There are NO hydraulic lifters on that engine. At least according to this diagram.

 

[doitmyself]

The rod itself is not broken, the ball end friction weld failed which is a known failure area with welded ball ends vs formed or pressed in ball ends. Manufacturing defect.

Hmmmmmm. I think I can see a bit of the other end of the rod (with ball end) down in the engine. BUT, I will have to do a closer inspection now that you bring that up. Maybe I am seeing the tappet down there (engine not torn apart yet.)

@ZX11Rebel, you are correct. Some of these FE350's do have hydraulic lifters and I initially looked at a different version (dozens).

Since it has solid tappets and the valve clearance was o.k. when I measured it, my mechanic friend suggested that the cam might be worn, causing extra clearance and the "tapping" sound.

Trying to figure out if it's worth me fixing it. Won't really know until it is torn down. Any suggestions are welcome.

And thank you everyone!

 

[Trav]

It is tapping it is probably because the ball end was coming loose or is missing. Use a magnet and see if you can catch the end. I would fix it if nothing else got damaged. Check it against the other one to get an idea if it is just the ball.

 

[paulo57509]

The push rod end is a bit blurry to determine failure mode. However, it appears to be a classic case of fatigue - origin, propagation and fracture areas are evident.

 

[doitmyself]

I fished the bottom half of broken rod out with a magnet. I think the bend occurred afterwards when trying to start the engine and the rod wedged in the compartment while getting pushed up and down.

Any advice is welcomed. The question is why was there "tapping" noise when the valve lash seemed o.k.? Is the camshaft lobe worn? What else do I look for?

Would it be bad to just install a new pushrod, adjust the valve lash, and give it a go? Removing the engine and tearing into it is SO much labor (for me). Thank you everyone. FYI - rod is about 3/16 inch diameter.

 

[ZX11Rebel]

You might remove the other push rod and install it where the broken one was and check for a stuck valve, or bad camshaft lobe lift, etc. If it checks Ok, buy a new push rod and put it back together. You could try to send Kawasaki the bill!

 

[doitmyself]

I installed a new push rod - local John Deere Dealers keep them in stock @ $11 ea.(hmmmm, what does that suggest?). Everything visually looked o.k..

I adjusted the valve clearance to .005 and it started and ran fine. After warmed up, the tapping noise was there again. What does that mean and/or how do I proceed? What changes when warm to cause the tapping noise? Valve clearance too loose or too tight? Something else, requiring engine tear down - I.E., bad cam shaft, tappet, etc.?

Thanks.

 

[Tman220]

Things like pushrods don't just break for no reason. You found the result of a problem and fixed the result of the problem, not the cause of it. I'd be worried about valves and valve guides at this point.

The ticking could be a valve hanging open and the resulting hammering due to that.

 

[spasm3]

How hard is it to pull the head and check the valve seat?

 

[ZX11Rebel]

According to the Kawasaki manual, you are supposed to remove the cylinder head and clean combustion chamber every 300 hours. It also calls for lapping the valves into their seats at the same time.

 

[paulo57509]

To cause that kind of bendage, I would say there was hard piston/valve contact.

 

[doitmyself]

Things like pushrods don't just break for no reason. You found the result of a problem and fixed the result of the problem, not the cause of it. I'd be worried about valves and valve guides at this point.

The ticking could be a valve hanging open and the resulting hammering due to that.

Thank you everyone for helpful comments. I rechecked the valve clearance after my last post and found it changed several thousanth's over spec., so I readjusted it back again, warmed it up with better results, but not perfect. I readjusted the valves one more time just a wee bit tighter than spec., put in one grade heavier oil (10w30 to 40) and called it good.

This is my workplace Gator and I have to consider my time involved. Too bad it's not winter. The Gator is 10 years old, maybe about 1200 hours. Local estimates are upwards of $600 - $800 to have the engine torn down and repaired. A new engine is about $1300. I think I am going to run it until it dies, and then reassess the solution.

Thanks again for the timely help. A DIYer wants to believe that parts swapping will fix a problem not addressed, as Tman220 point out above.

 

[Trav]

I fished the bottom half of broken rod out with a magnet. I think the bend occurred afterwards when trying to start the engine and the rod wedged in the compartment while getting pushed up and down.

Any advice is welcomed. The question is why was there "tapping" noise when the valve lash seemed o.k.? Is the camshaft lobe worn? What else do I look for?

Would it be bad to just install a new pushrod, adjust the valve lash, and give it a go? Removing the engine and tearing into it is SO much labor (for me). Thank you everyone. FYI - rod is about 3/16 inch diameter.
View attachment 218026

I did not expect that, the break is so clean. I have seen a few bent pushrods and pushrods that fell off the rocker arm but non that snapped like that. On aluminum heads and all aluminum engines valve clearances increase when at operating temp but running too hot can increase that even more. Check the rocker arm and adjuster for wear, check for broken or weak valve spring that could cause the valve to bounce and check the cooling fins for debris or clogging that could cause temps to increase.