Bent Valve/push rod?

[Burlsube]

I took my "new" 88 in for a few repairs (mainly a general tune up) and the mechanic called and said the reason why it was running so poorly is that it seems to have a bent valve/push rod.

The engine was recently rebuilt but only has a handful of miles on it.

Has any one experienced this? I thought that only happened on high horsepower engines?

[I Leak Oil]

Ouch! Sounds like you need to take it to whom ever rebuilt the motor. If it's only one I'd say it was either like that before the rebuild and the shop didn't pick up on it (get a new shop) or perhaps the pushrod wasn't seated correctly, rocker arm not adjusted correctly or maybe something dropped into the cylinder and has had a colision with the valve.

[Burlsube]

Yeah. It was rebuild by Vermont Engine. I believe RN uses them to do their engines. It was supposedly a new engine, so I believed all of this would have been sorted out. It was one valve, so I hope it is anomaly. Looks like I might need to put up my RRC to pay for this one...

[SafeAirOne]

It was one valve, so I hope it is anomaly. Looks like I might need to put up my RRC to pay for this one...

Replacing one valve pushrod shouldn't be that tough. It only involves removal of the rocker cover and rocker shaft. Not much of a teardown, unless more disassembly was done during troubleshooting.

[I Leak Oil]

It's not under warranty???? I'd be standing on someones desk until they made it right.

If it's just the pushrod then it's really easy as Mark said. If it's also a valve then the head needs to come off and some work might need to be done with it depending on the damage.

[Les Parker]

Have you ben in contact with the initial rebuilder?
It would be more correct to follow that path and give them the chance to put it right before building up a head of steam.

[Terrys]

It's hardly a catastrophic event, and fairly common. Perhaps and old 7:1 pushrod got mixed in. They are slightly longer than an 8:1. Perhaps a sticky valve snapped back. Whatever they cause, the part is cheap, and it doesn't take an hr to replace.

[Burlsube]

That doesn't sound too bad then.

The rebuilder said there is no warranty since I am not the original owner.

I'd give it a whirl, but I dont have anytime in the next few weeks.

[I Leak Oil]

That doesn't sound too bad then.

The rebuilder said there is no warranty since I am not the original owner.

I'd give it a whirl, but I dont have anytime in the next few weeks.

With just a few miles I would have figured they'd still stand behind their work but I guess that's a thing of the past. Give the job a shot. It's not that bad and you're bound to learn something about this new to you vehicle.

Terrys, I'd respectfully disagree that a bent valve or pushrod is common on a fairly fresh rebuild. There's just no reason for it unless something wasn't put together right, barring any other monkeying around with it. Not something you'd plan on happening on a professional rebuild job.

[Terrys]

Terrys, I'd respectfully disagree that a bent valve or pushrod is common on a fairly fresh rebuild.

Actually, all I said was that it was fairly common, but I didn't say it was common on a fresh rebuild, nor did I say anything about a bent valve. Who knows what the OP means by a "few" miles, if he didn't have the engine rebuilt himself. That aside, a freshly done head would presume valve guides were replaced, which may be tighter than normal. The reason a pushrod gets bent to begin with is most frequently a valve snapping back, as opposed to simply closing by spring relaxation. Snapping back can be from a sticking valve stem, or very advance ignition detonation, something entirely out the hands of the rebuilder.
If you, or anyone for that matter, has occassion to pull the rocker shaft, take all your pushrods out, and line them up and with your plam, roll them across a flat surface. You will be surprised to see how many are not straight. I have pulled some that were so bowed that the middle of the rod was in the same plane as the ends, i.e., they won't roll 360 degrees.
Also, it takes a VERY bent rod to reduce valve travel to the extent it will be detected in rough running (these are plodders, not Lamborghinis), and that's not likely to be missed by any engine rebuilder.