wiped cam lobe on briggs and stratton engine

[The motor guy]

So what causes this to happen after about 600 hours? Maybe the last 25 hours it wouldn't want to restart when hot. You guys told me that was excessive valve lash and I believe it now. The valve lash was about 4 times larger than what it should have been. Will that cause a camshaft to fail? I'm just assuming it's one cam lobe wiped out because the exhaust valve still opens and closes normally. I'm not sure if they use plastic gears and lobes or not like on the old flathead briggs. This is a newer ohv briggs. I haven't taken it apart yet, but I'm guessing one probably broke off.

 

[Elkins45]

It’s more likely to be the tappet or the pushrod than the cam lobe.

 

[oil pan 4]

Lots of dirt for me. I need to check my Honda gx390. One tappet had a weird pattern worn into it. Need to check it now that it has some hours on it.

 

[The motor guy]

It’s more likely to be the tappet or the pushrod than the cam lobe.

I didn't see anything wrong with the pushrod. maybe I didn't fit it back into the tappet right? Or it fell out?

 

[oldcodger]

I have seen several cam lobe failures that looked to me as if the heat treatment was off.

 

[The motor guy]

Lots of dirt for me. I need to check my Honda gx390. One tappet had a weird pattern worn into it. Need to check it now that it has some hours on it.

What do you mean dirt?

 

[Exhaustgases]

And have you reset the adjustment? And then tried it?

 

[The motor guy]

And have you reset the adjustment? And then tried it?

What do you mean? The exhaust valve was set, but nothing moves the pushrod on the intake valve.

 

[jeepman3071]

Poor materials used in the camshafts.

 

[fantastic]

Lack of oil lubrication, overheating the engine, & the list goes on. 600 hours out of a residential B&S engine isn't too bad?

 

[thastinger]

Are you sure the valve seat is still in place?

 

[The motor guy]

Are you sure the valve seat is still in place?

Don't I have to take the head off to see that?

 

[thastinger]

Don't I have to take the head off to see that?

unless you have a bore scope. I assumed you would be removing the head(s) anyway.

 

[The motor guy]

unless you have a bore scope. I assumed you would be removing the head(s) anyway.

No I was going to take the engine off and remove the bottom case to see the cam.

 

[fantastic]

No I was going to take the engine off and remove the bottom case to see the cam.

You'd need to remove the heads to see the valve seats.

 

[The motor guy]

You'd need to remove the heads to see the valve seats.

I was assuming it was a cam issue. Could be either.

 

[fantastic]

I was assuming it was a cam issue. Could be either.

That's right, Rule out both by taking a peek.

 

[oil pan 4]

What do you mean dirt?

I got an early 2000s gx390 for $50 that burned oil. The last guy that had it attempted to change the air filter. When he changed the filter I'm guessing the o-ring stuck the the old air filter and got thrown out with the filter. So the engine was just breathing dirt for who knows how many years. I changed the oil 3x before it wasn't jet black after a minute of running. Then last year I rebuilt that engine to use as a pressure washer, but the cam might be toast. I needed to get my pressure washer going so I didn't replace the cam.