Help: Metal in Oil Pan

[George Bongert]

Originally Posted by kchampagne

Hello all! Quick background - I purchased a 65 GMC Suburban 2 weeks ago. I was told the 305 was rebuilt approx. 10,000 miles ago. The engine was running rough and was told it was the carb. I installed a new carb but still was running rough. Pulled the valve covers and found 2 bent pushrods, 2 loose push rods, and 2 stuck valves. Everything else looks new. I pulled the oil pan off to see what was going on below. Everything looks good and cranks smooth, but I found these 4 clips/retainers attached to the magnet in the bottom of the pan. I apologize up front for being inexperienced, but I have no clue what these are? Is it a sign that the engine needs pulled and completely rebuilt again? Is this something I can fix while the engine is still in? I really appreciate any input you can provide. Thank you.
Ken

Greetings fellow club member!

I hate to have to tell you this--but I do believe it would be in your best interest to tear the engine down again. what you have found in the oil pan are broken wrist pin retaining clips. This type of clip is most commonly found in agricultural or industrial type engines employing "full floating" wrist pins. Most automotive engines use wrist pins that are press fit to the connecting rod and do not use retaining clips of any kind.

[FetchMeAPepsi]

Another thing you might think about since you have to pull the engine anyway is just pulling it and setting it in the backyard under a tarp for spare parts. You can find a replacement 305 for about $100-300 bucks and you'll be in better shape. I bought a spare for Cecilia when I got her just in case something like this happens. Parts for a full rebuild are hard to find. Might be the cheaper route!

[kchampagne]

So here is a photo of the piston with the floating wrist pin and broken retainer/lock clips. Snap rings probably would have been better.

[bigblockv6]

That's the problem, why did whoever rebuilt the engine useing u joint retainer clips? Snap Rings are normally used on these engines. I have bought 1/2 a dozen V6 piston sets over the years, one factory and the rest aftermarket yet all came with real snap rings:

[BobBray]

Because he lost the little envelope with the snap rings in it! My guess is the grove in the piston was not wide enough for the U-joint retainers and they did not fully seat.

Sorry, that engine should come apart again. Also need to find out why the valves stuck. Might not be too bad, but you don't know until you get inside of it. Sorry to hear of your troubles, sounds like a nice wagon.

[bigblockv6]

Bob, you're right, the snap rings that come with the pistons are much thinner than u joint retainers. Can't believe someone would compromise such a critical part in assembling an engine.

[bigblockv6]

Here's a pic of the correct snap rings that come with V6 piston sets. What I've noticed is not all my V6 piston sets came with the snap rings. It could depend on the manufacturer as well as being old NOS stock sometimes it may get removed for something else

[Clyde]

I have seen over a dozen different types of retaining rings for wrist pins. I have seen where the same piston manufacturer has used two different types during a production run. I have seen and used the type that looks like the snap ring for external u joint that was used in the above piston with the broken snap rings. Under light load conditions like the V6 and under 4500 -5000 RPM's most any snap ring will work if installed properly. If the rod is bent or the wrist pin bushing is wearing out then that will put an extra load and can break a snap ring.

[bigblockv6]

Best to use what came from the factory, I've only seen the ones I posted on factory as well as aftermarket pistons. Pistons for these engines are the same way too. OEM pistons are less prone to expansion while aftermarket pistons were prone to expansion and would score the cylinder walls, that was a real problem with these engines.

[abus319]

Ken
Sorry to see you having troubles of this sort.

Since there are bent push rods and other issues as well as the clips, the engine needs to be pulled. There will probably be metal particles piled up in in places in the oil galleries.
It needs to be completly disassembled, cleaned, measured and inspected.

Do you have any paperwork on the rebuild or the shop name?