Broken rockerarm Generac Generator

[tuna_fisher]

I bought a toyhauler with Gen., I was told about it before purchase. The guy had attempted to weld it together, wasn't broke all the way thru. Needless to say, it didn't hold. He said it did for awhile. My question is, what could have caused this to happen? I got a rocker arm then found the push rod was slightly bent, have 1 coming. Can I just replace them, adj the valves and be done with it. I'm some what of a handy person, old school 283, 327 engines I'v rebuilt, so I can twist a wrench. But really don't want to do more than that. Suggestions ??? Generac Generator, 1 cly. Real easy to get to but only way to turn engine is to bump it, In a 06 trailer, 3600W. Thanks for any help or suggestions. Craig

[westend]

Just did a similar repair on a 26 hp Gravely--bent push rod, mashed up valve seat. Definitely pull the head, inspect, replace gasket, and torque to specs. Anything else is just asking for trouble.

If you are going to reuse valves, check stems and lap into seats for good fitment.

The small amount of time and minimal expense spent pulling the head is warranted. You won't have any clue how the lifters mate into the valve train without restoring the head to near new condition.

[MEXICOWANDERER]

A valve that has sunk into its seat will reduce clearance to minus value. If the valve spring utterly collapses tight, pushrods will bend and it could snap a rockerarm.

Not theory. I've seen it happen multiple times, automotive and small engine.

Checking for this takes experience. It isn't an amateur hour moment...

[Ron3rd]

SCClockDr wrote:
Broken rocker arm and bent push rod indicates a mechanical reason for the damage. Removal of the head would be my first move. You need to find the cause, otherwise you are dealing with a landmine.
You need to rule out a bent valve, fouled valve guide, or broken piston (top separated from the bottom).

X2, first thing I would want to know is why the pushrod bent in the first place. Not normal

[72cougarxr7]

May have just been a defective rocker, may be a valve that has buildup on the stem and is beginning to stick.
You could try replacing the rocker, and if it runs, you can fog some cleaner through the carburetor while running to try cleaning the valves.
I have done this with Chemtool or Seafoam. Amsoil Powerfoam works the best for this, but you will have to order from an Amsoil dealer.
If you get the Powerfoam, (comes in aerosol can)spray some lightly so the engine stays running for a bit, then spray heavier till the engine stalls. Let it soak for an hour or so then refire the engine. It will smoke like crazy for 10 or 15 minutes while all the carbon is blowing out and burning off.

Change the oil after all this.

[tuna_fisher]

Oh you guy's are killing me. Will take all suggestions and ck it all out. I pruned my finger instead of a branch while pruning a plant, so it will be awhile till I can get serious, left handed left finger.

[bounder39zman]

check rocker arm studs...if they back out of cyl head, will cause broken rocker arm. usually happens from improper valve adjustment procedure.

[Dave_H_M]

SCClockDr wrote:
Broken rocker arm and bent push rod indicates a mechanical reason for the damage. Removal of the head would be my first move. You need to find the cause, otherwise you are dealing with a landmine.
You need to rule out a bent valve, fouled valve guide, or broken piston (top separated from the bottom).

What the clock dock says. my bet is that there is some kind of mess in there.

[SCClockDr]

Broken rocker arm and bent push rod indicates a mechanical reason for the damage. Removal of the head would be my first move. You need to find the cause, otherwise you are dealing with a landmine.
You need to rule out a bent valve, fouled valve guide, or broken piston (top separated from the bottom).

[STBRetired]

Do you have the tools to do a leak down test? Or at least a compression test. If the results are good, you can probably get away with not pulling the head. The bent pushrod is more concerning than the broken rocker arm. A rocker arm can break from a manufacturing defect or poor lash adjustment. To bend a push rod the valve train had to hit something solid. Hopefully when he welded the rocker arm he messed up the angle and just bound up the valve spring. Stand a decent chance of no valve damage as those are fairly low compression engines. I would replace the valve retained on that valve for sure because if it was spring bound there was a lot of stress on the retainer and you would not want it to drop the valve a couple months down the road. Might be tempted to replace the spring as well. Run the lash at the loose side of the range to start. Run it through several heat cycles (run under load for 30 minutes then let completely cool down) then set lash to specs, preferably cold if they give hot and cold specs. HAving the lash too loose can lead to broken rocker arms. Might have been the root cause of the original failure.

EDIT:
On my Onan, the lash spec calls for .005 for the intake and .013 for the exhaust valves when cold. I don't have the specs for a Generac.

[tuna_fisher]

No, It looks fine, very clean. Already have a can of Seafoam to run thru the gas. I'm not replaceing the valves, unless it comes to that, just push rod and rocker arm. So far.............

[MrWizard]

you should be able to do exactly that

i would maybe leave a little extra backlash clearance

and run some sea foam or other cleaner for a few hours

then re-adjust the valve clearance

maybe pull the head and clean camber and valve seats before installing the new valves

it does sound like something got carbon build up, to put that kind of stress on the rocker arm

what does the engine oil look like ? super black ?