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Old 03-13-2022, 10:48 PM
GoreMaker GoreMaker is offline
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Default What is this broken piece?

Found this in my oil pan. Cannot figure out where it broke off of.







The radius is too small to be from the mains or the cam tunnel. It's just about right for the distributor hole, but I can't spot any missing bit from that in the block. Oil pump looks intact. Too wide to be from either end of a connecting rod. Looks to have some wear on the outside like something spins on it or it spins in something. It's cast iron, not aluminum. I have the block pretty much apart except for the crank, rods, pistons and cam. I'm very confused...

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Old 03-13-2022, 10:59 PM
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Its a piece of a harmonic balancer. Probably happened in the past when someone didn't properly tighten the balancer down.

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Old 03-13-2022, 11:05 PM
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OH THANK GOD!

You're totally right. It's not from the harmonic balancer that I just removed, that one's intact. But it looks exactly like that part of the snout that rides on the front seal. Must've been from an old one that was removed by a previous owner and that piece has been living inside the oil pan ever since.

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Old 03-14-2022, 06:30 AM
25stevem 25stevem is online now
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It can’t be from a balancer snout, they are not funnel shaped and taper down like that!

Is it magnetic?

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Old 03-14-2022, 07:36 AM
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It kinda looks like a stock balancer piece to me looks like mine when it broke



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Old 03-14-2022, 08:39 AM
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It absolutely is, it looks identical to the shape of the snout on the balancer I removed

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Old 03-14-2022, 09:17 AM
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If you plan on reusing the crankshaft in the engine, I strongly suggest having it mag tested to make sure it's crack-free. Generally speaking, if a balancer isn't torqued properly (particularly to the point it breaks), it can't dampen harmonics correctly, which forces the crankshaft to dampen them. That can then lead to fatigue/cracks in the cheek area where the journals meet the counterweights over time.

I also see the "77" on your block. It it happens to be a 500557 casting, they have the thinner main saddles, which may have also been affected by having to absorb the harmonics. I'd suggest having it mag tested too for piece of mind.

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Old 03-14-2022, 09:36 AM
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Quote:
Originally Posted by Rocky Rotella View Post
If you plan on reusing the crankshaft in the engine, I strongly suggest having it mag tested to make sure it's crack-free. Generally speaking, if a balancer isn't torqued properly (particularly to the point it breaks), it can't dampen harmonics correctly, which forces the crankshaft to dampen them. That can then lead to fatigue/cracks in the cheek area where the journals meet the counterweights over time.

I also see the "77" on your block. It it happens to be a 500557 casting, they have the thinner main saddles, which may have also been affected by having to absorb the harmonics. I'd suggest having it mag tested too for piece of mind.
Very true, the 6.5 diesels have a habit of slipping the rubber on the harmonic balancers when they get older. If you don't catch the problem as soon as it happens, the crank will break. When the ring slips it makes noise from the ring hitting the pulleys, and timing cover.

There are a ton of 6.5s that break cranks due to this problem, so many in fact, that the after market now offers a forged crank for these engines.

As has been mentioned also, the block main webs also break in them due to the slipped balancer problems. There are blocks that GM cast for these engines that are weak like our 557 block is. Casting numbers to avoid, if you ever rebuild one of these engines.

As recommended, check the crank and block for cracks as long as you're pulling the engine down anyway. It may save you grief down the road.

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Old 03-14-2022, 09:43 AM
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Quote:
Originally Posted by 25stevem View Post
It canít be from a balancer snout, they are not funnel shaped and taper down like that!

Is it magnetic?
it can & is from a balancer snout, these balancers are tapered down just as shown!

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Old 03-14-2022, 09:50 AM
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I'm planning on a new rotating assembly anyways. Not a stroker, just sticking to stock displacement. But I'll definitely have the block magnafluxed, I was planning that anyways since the engine's been run with NO PILOT BEARING for an undetermined amount of time and the shaking on acceleration was horrendous.

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Old 03-14-2022, 11:20 AM
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Funny you should mention no pilot bearing, there was an exhaustive discussion about that very subject recently on here, link :

https://forums.maxperformanceinc.com...=pilot+bearing

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Old 03-14-2022, 12:59 PM
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Quote:
Originally Posted by Rocky Rotella View Post
If you plan on reusing the crankshaft in the engine, I strongly suggest having it mag tested to make sure it's crack-free. Generally speaking, if a balancer isn't torqued properly (particularly to the point it breaks), it can't dampen harmonics correctly, which forces the crankshaft to dampen them. That can then lead to fatigue/cracks in the cheek area where the journals meet the counterweights over time.

I also see the "77" on your block. It it happens to be a 500557 casting, they have the thinner main saddles, which may have also been affected by having to absorb the harmonics. I'd suggest having it mag tested too for piece of mind.
If it tests OK, and you plan to use it...I'd take a cartridge roll and de-burr ALL the sharp edges in the bottom end of the block, especially the oil feed holes on the main saddles and the dowel pin holes.

IF, IF all the reading I've done here lately, it is best to use the roll pins (spring pins) in the thin blocks??? Anyone???

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Old 03-14-2022, 01:03 PM
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Roll pins work well, especially under 6k rpm. Some rebuilders with lots of experience with 557 blocks use extended solid dowel pins, they do a better job of keeping the caps situated without inducing too much stress on the main webs. The real trick is to make sure the holes for the dowel pins are the right size to accommodate solid ones. If they press in too tight, then they add stress at that location and increase the chance of cracking the block.

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Old 03-14-2022, 01:04 PM
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Quote:
Originally Posted by 78w72 View Post
it can & is from a balancer snout, these balancers are tapered down just as shown!
The broken piece had a dash of blue paint on it. So it had to be a semi-external part. Balancer piece makes sense.

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Old 03-14-2022, 01:07 PM
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Yep, that was my thought as well initially. But being unable to find any broken piece anywhere in the removed components had me really worried. It makes sense now that it's something that broke on an old, previously-replaced component. I wonder how many decades that piece has been rolling around in the oil pan.

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Old 03-14-2022, 02:05 PM
mgarblik mgarblik is offline
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I have found an amazing amount of stuff in Pontiac oil pans over the many decades. Here is a short list. 1. Tons of plastic cam gear teeth 2. Push rod pieces, some as long as 4-5 inches, 3. Various nuts and bolts, typically oil pan bolts or other short ones 4. magnetic screwdriver bits, several, rocker arm nuts and pieces of guide plates. 5. Lots and lots of RTV globs 6. Ends of valve cover oil drippers. 7. Oil pump pick ups 8. Pieces of the windage tray. 9. Ends of valve springs 10. Front oil gallery plugs

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Old 03-14-2022, 02:53 PM
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When I was 16 years old a friend knew where there was a 389 short block that someone wanted removed from their carport. I of course went and picked it up. It had a box of parts too. In the box was a pair of '65 GTO valve covers. One had a hole from a pushrod. I had those repaired and re-plated. When I took the short block apart I found two pushrods wrapped around the crank somehow (I don't remember exactly how). Someone had revved that thing to the moon I guess.

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Old 03-14-2022, 05:50 PM
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Quote:
Originally Posted by mgarblik View Post
I have found an amazing amount of stuff in Pontiac oil pans over the many decades. Here is a short list. 1. Tons of plastic cam gear teeth 2. Push rod pieces, some as long as 4-5 inches, 3. Various nuts and bolts, typically oil pan bolts or other short ones 4. magnetic screwdriver bits, several, rocker arm nuts and pieces of guide plates. 5. Lots and lots of RTV globs 6. Ends of valve cover oil drippers. 7. Oil pump pick ups 8. Pieces of the windage tray. 9. Ends of valve springs 10. Front oil gallery plugs
How many oil pump pickups??? close guess....

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