Damaged camshaft, watcha think?

Just cracked open the top of my Husqvarna TE 610 and found this staring at me. I was troubleshooting a cracking sound under low RPM throttle coming from the engine, do you think this could cause that? I am assuming this is throwing off the valves on the intake side a bit.

The lifters look perfect, do you think this could have something to do with the valve springs being bad?

Camshaft lobe, opens the INTAKE side valves of a 4-stroke. The damaged side is the ramp down side, or the side that starts closing the valves again.

5781760478_072edab504_z.jpg

Should put an Engine specific forum on here, an engine Camshaft is not exclusive to Husqvarna so its pretty silly that the thread would be moved here.

I think a little more info would be helpful. Year, miles and type of use (hard SM vs easy DS) would go a long way. All stock parts? Prior rebuilds?

Just from what I can see looks to be surface work hardened at which point the material becomes almost like glass and breaks up. Could be result of incorrect heat-treat when new or some type of hammering/harmonic in the valve-train. High RPM valve float?

Either way that piece is complete junk and I would replace the lifter/follower for sure.

Bruce

Looks like an impact took place on it. Replace it and all the associated parts.

Retaining spring could have come loose and lodged between the cam and valve stem???

How does the valve stem look? Are both retaining clips in place?

Doesn't look like a man. defect, looks like something took a chunk out of it.. my opinion anyways.

Being on the downside, without lifter damage, makes me think it COULD be a defect. Looks porous. Any metalurgists out there??

I'd post it in engineering/technologies section. Many smart minds there. I'd like to hear Grayracer's opinion on said camshaft.

Not enough info. Roller bearing could have gone bad causing roller to skid instead of rolling across lobe profile of cam. Case hardening should be .040 deep. If this being the issue would happen within 300 miles.

Later George

Like I said, lifter and bearing are perfectly fine, no wiggle or movement at all. Only noticeable problem is this one camshaft lobe, everything else appears to be in order. The roller bearing shows absolutely no signs of damage.

The damage to the lobe seems to create a track for the roller bearing on the lifter, so I don't think it was installed defective.. could have just been shotty hardening on the camshaft lobe strait out of the factory, otherwise I would see some sign of damage to the roller bearing.

Bike is a 1995, miles are unknown, a lot of different owners before me so the exact history is unclear, I bought it in supermoto trim.

Paging Grayracer.......

SM huh? Almost looks like the valve stuck momentarily and the cam lob came down on it hard as it was coming back up. That can happen in higher RPM SM stuff where your at valve float levels in a single cam rocker system.

Seems a little strange that no other moving parts are damaged ... I'd guess if the valve itself is damaged, the engine would have a miss or something ...

Valve floating? Been hitting the REV limiter?

Should put an Engine specific forum on here, an engine Camshaft is not exclusive to Husqvarna so its pretty silly that the thread would be moved here.
The camshaft in a TE610 is exclusively Husky. Different engines are laid out differently, and each has its own idiosyncrasies. That's why there are brand specific technical forums for almost every make and model at TT. The thread was moved here because it belongs here.
... I was troubleshooting a cracking sound under low RPM throttle coming from the engine, do you think this could cause that?

The lifters look perfect, do you think this could have something to do with the valve springs being bad?

The appearance is that the hard surface of the cam gave way, and the double flat the approximate width of the roller in the rocker arm suggests that the person who suspected the roller was probably right. This was almost certainly caused by the roller seizing at least temporarily. The fact that it is on the closing side of the lobe does bring the possibility of a weak valve spring and/or valve float into the picture, though.

I have seen this MANY times at work. 90% of the time the root cause is a broken or weak valve spring. This causes the cam follower to loft over the nose of the camshaft then come crashing down on the closing side. It’s just like hitting the camshaft with a hammer. It breaks through the heat treat on the surface and the rest is history.

I have seen this MANY times at work. 90% of the time the root cause is a broken or weak valve spring. This causes the cam follower to loft over the nose of the camshaft then come crashing down on the closing side. It’s just like hitting the camshaft with a hammer. It breaks through the heat treat on the surface and the rest is history.

I am starting to think the same thing, I threw the engine back together and ran it again, the cracking/knocking sound really sounds like two pieces of metal colliding at a high rate of speed over and over again and I can imagine it being caused by the roller lofting over the top of the lobe and smacking back down onto the downward side every revolution.

ALSO, if you look close at the picture there are two spots that it is hitting, there is a small top ding and then the large one right after it almost as if it bounces every once in a while.

I threw the engine back together and ran it again.

Don't run it anymore! All you are doing is sending all that junk to the rest of the motor.

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