I finally got around to pulling the motor from the boat and pulling the pan to see what I have going on. Some of you will recall my earlier thread detailing my issues with excessive distributor gear wear.



http://www.offshoreonly.com/forums/g...illet-cam.html

After investigating, I took a screwdriver and turned the oil pump, only to find it very rough to turn and on the verge of locking up.

First thing I did was pull one of the main bearings (#2). This is what I found:



If you look closely, you will see that the bearing was burnished shiny. No real grooves that you can feel with your finger. Fortunately, the crank journal does not appear to have any damage. I will obviously have to pull the rest of the rods and mains to check them, but it is obvious that some very fine grit apparently went through the motor.

Pulled the oil pump and opened it up, and found this:





It looks like some serious trash went through those billet gears! But where did it come from? The screen should have picked up anything big enough to do that kind of damage, at least in my thinking. I will check the valvetrain out very closely to look for signs of needle bearings coming out, but I may have found the culprit:



This is a closeup of the inside of the intake port for the oil pump pickup. If you look closely, you can see an area where it looks like the weld may have burned through. Right now I am wondering if a piece of slag developed there and broke off. Here is the outside of the pickup welded to the pump:



That is the best theory I can come up with right now, and it would explain all the wear on the distributor gear. However, I am wondering why the oil filter wasn't able to catch all of that stuff. I cut open the filter from the initial breakin as well as one that had about 20 hours on it (also documented in another thread). Here is a shot of the inside of the first filter:





Looking closely, you can see a lot of fine black grit with the consistency of valve lapping compound. Did this stuff come from the distributor gear, or somewhere else? It almost appears that it might have clogged the filter media, which might explain if it bypassed and got into the bearings. I used the correct GM melonized gear with the cam as specified for a billet grind.

I am also using a thermostatic sandwich adapter like they sell at Jegs. This thing uses a bimetal strip that covers up a hole between the inlet and outlet chambers going to/from the cooler. Best I can tell, when this passage is open, the pressure transferring across the passage prevents all or most of the flow of oil through the cooler. Has anyone else used one of these things? Wondering if this could have contributed to my issue if it caused excessive back pressure and popped the 30lb bypass on the filter pad in the block. I do not recall ever seeing any drop in oil pressure when running the boat, and oil temps never climbed above 225*.

Sandwich adapter:



I guess I'll know more when I tear into the engine the rest of the way, but right now I am scratching my head a little bit. I would feel better if I could determine for sure what went through the bearings and where it came from. Any input is appreciated!

I and a couple others I know run the Jegs sandwich adapter. Never have had any problems. Mine bypasses the coolers not the filter. What filters are you running and do you have the blocked plugged or running the 30# relief valve?

Correct, Rookie - it appears that it is intended to bypass the cooler, not the filter. I was just wondering if the small bypass opening coupled with cold, heavy (20W50) oil could have build enough flow limitation to kick in the block bypass. I'm running the 30 lb bypass in the filter pad on the block. I am seriously considering eliminating the bypass to force ALL of the oil to pass through the filter and/or cooler, but the sandwich adapter makes it impossible to put a very big filter on there. The thought of the filter getting clogged and limiting oil pressure to the engine worries me, but I guess if it does get clogged with debris I have bigger problems anyway. Are you running the bypass on yours, or do you have the block bypass plugged?
I did notice when I took the filter off the last time I changed oil that the bimetal strip assembly had fallen out of its groove and was no longer in place to provide a positive seal on the bypass passage. The effect here would be to bypass or partially bypass the cooler all of the time, although I never saw excessive oil temps. If I use it again I am going to JB weld it up in there, or use a punch to keep it in place.

I was toying with switching to one of the Mocal sandwich adapters - just hate spending another $200 if the one that is on there is not my problem.

Thanks for the reply. Now I just need to figure out what got into my oil pump - and where all that crap came from that went through the bearings.

I was running a Purolator high flow filter.

My block is plugged. I run Mobil 1 filters and Mobil 1 V-Twin 20w-50.
Don't use JB weld center punch it.

And as you already stated if you are plugging filters the bypass is the least of your worries.

Not absolutely sure that the filter was plugged, but you can see the black crud in the bottom of the filter canister. My suspicion is that this is the stuff that went through the bearings. The big question is where did this stuff come from? I would expect that I would see a lot of shiny metal fragments from the distributor gear - it was a GM melonized gear. I guess it could be stuff left over from machining that didn't get cleaned out from the block, but that seems unlikely to me.

Has anyone else seen anything like this?

I would think the crap was probably left in the oil passages from rebuild...were ALL the block plugs removed and block cleaned with cleaning brushes ?? when I bought my 251 engine was new...well it lasted about 5 hours...crap from the oil passages clogged the main bearing passage..don't have to tell you what happened then...I use a block cleaning brush set that looks like a gun cleaning set....long handles, diff sizes to swab out ALL passages...looks the crap got into pump, started the chain reaction and everything went south after...

I don't think the weld is your problem. That looks good to me. Just a nice full penetration weld.

Nice documentation. Good luck. I'm betting that something somewhere wasn't clean and the debris was in the engine at startup. Keep us informed.

Dan

EZ, the engine was professionally rebuilt by a local machinist. I wasn't there looking over his shoulder to see that all the block plugs were pulled and rifle-brushed, but I would be surprised if it wasn't done. He has an excellent reputation and is meticulous.

Dan, I know what you mean, but something definitely went through the pump. Only thing I can think of that is big enough to cause that much damage and would make it through the pickup screen would be roller bearings from the rocker arm trunions or roller lifters. I would think that I would see a lot more evidence of failure if that was the case. I guess I'll know more when I pull it down the rest of the way.

Thanks for the replies.

It also looks like the dist. needs to go deeper in the block.

Not what you want to be doing with a new motor that you just finished installing. My sympathies.

Dan