[AJD1964]

A small hole maybe 3/8" in dia. was discovered in the front area of the oil pan after significant and sudden oil leak. Luckily close to home. Lost approx 1 quart. of oil.
No knocking, tapping, or misfiring. But my son, who was driving it, says nothing felt or sounded out of the ordinary and oil pressure on the gauge was good.
We are fearing the worst. Next step - pull motor? or plug the hole and listen for any issues.

Anyone seen this before? I'll bet you guys have.

1971 Lemans 350. Thanks, Tony.

[b-man]

Could be a piece of the balancer hub has broken off and somehow got launched into the front of the pan from the inside.

It could have migrated back towards the front counterweight on the crankshaft and been hit hard enough to throw it through the pan or at least pierce through enough to make that hole.

I would start by removing the harmonic balancer to investigate.

Losing a quart or two of oil isn’t anything catastrophic, people always ran these things low like that without ill effects. The engineers knew people would neglect these things and three quarts is actually plenty but not advised.

That hole could be tapped in to close it off for the most part and carefully welded up by someone with decent skills right where it sits.

You will want to pull the timing cover to retrieve any pieces that you can see and perhaps fish for what you can’t see using a magnet on a flexible extension. Having the balancer off you’ll be able to put the pieces back together to see if you found all of them.

This would also be an opportunity to replace the water pump and timing chain set and if the cover itself is too corroded (not uncommon) replace that as well.

[67drake]

What b-man is talking about happened to my ‘69 400. The engine ran fine, but when I pulled it and tore it down I found chunks in the pan, and couldn’t figure out where they came from.

http://forums.maxperformanceinc.com/...d.php?t=875282

[chiefbigb]

Removing the pan will tell all. Maybe a piece of piston skirt

[BILL BOWMAN1]

Not to hijack this thread, but this is a good reminder for me to change the balancer on my Catalina when I do the rear main this winter . it’s 51 years old!! Been lucky too long.

[b-man]

Taking the pan off means taking out the engine. Removing the pan with the engine in the car is just as much if not more work than just taking out the engine in the first place.

This can all be avoided if the damage can be seen and repaired by simply removing the balancer and timing cover.

If it is truly a catastrophic failure the engine’s coming out anyway.

[BLUE TA]

hi, I repaired a hole in my 67 elcamino pan. I drained the oil and made a small sheet metal patch and mig welded it on. worked good. but do what b man said first. you may find you need a new harmonic bal. good luck, BLUE TA

[Goatracer1]

I had a piece of the balancer key way break off and it got caught between the crank gear and timing chain. It broke the chain and caused a piston to hit and bend an intake valve. Pull the balancer at least. If you don't find anything pull the pan don't just plug it.

[steve25]

The hole looksto have been created from the inside of the crankcase unless my eyes are deceiving me.

Also judging from where it is if the motor was ever rebuilt and rebalanced I bet some of the added rebalancing weight came off some how and shot out the pan.

[sdbob]

I'd drain the oil ckg for metal first. Just to give you an idea. I'd pull motor also. I've done pan removal in A body,2nd gen. Remove engine.

[chiefbigb]

Removing the engine would be step one then repair as needed.

[track73]

I have removed the oil pan on my 79 TA twice. I didn't have any trouble.





















ta

[AJD1964]

Great responses so far! Much appreciated.
I’ll start by pulling off the timing case and looking at the balancer. I’ll drain oil and look for pieces too.

According to the previous owner the engine was redone by “Jasper” back in early 2000’s. Maybe there’s something too the balancing pieces? We’ve been playing with it since 2015. It’s been a smooth strong 350.

[b-man]

Seriously doubt a ‘puppy mill’ engine rebuilding outfit like Jasper balances anything they shove out the door.

In the unlikely chance that a piece of balancing material that was welded to a counterweight flew out under force it would most likely exit the pan directly below or inline with said counterweight, not so far forward of any counterweights.

[grandam1979]

Just pull the balancer that will tell you if it’s broke. If it’s not then its time to dig deeper.

[Half-Inch Stud]

Hmmmm, nobody said JB-Weld. Must be the Balancer collar cleaved at the Lower Timing Gear.

[Elarson]

Originally Posted by steve25

The hole looks to have been created from the inside of the crankcase unless my eyes are deceiving me.

Agree

Eric

[AJD1964]

Finally got around to looking at this. Looks like b-man was right. Broken harmonic balancer hub. Guess this motor is coming out.

[tooski]

Originally Posted by AJD1964

Finally got around to looking at this. Looks like b-man was right. Broken harmonic balancer hub. Guess this motor is coming out.

Had that happen to me. As was said earlier broke the timing chain, kissed piston, bent valve.

[steve25]

When you yank the motor look real close at the rods if they’re factory for any signs that they took a hit and now have a sharp notch in them as that will be a place where a crack could start a total failure of the rod.

If you find any you may be able to just polish them out if they’re small enough.

Otherwise replaced the rods as needed.

One thing I never noticed since after all of these decades I have never seen a failed factory balancer, but are the center hubs on them cast iron as what seems to be in this photo?