I see a spin on oil filter which means to me no oil cooler at all. I suspect sky high oil temps causing bearings to be destroyed leading to pistons hitting the heads and broken rods exiting the side of the pan.

Don't think a good oil is going to fix poor engineering

exactly !!!! B/S setup and you were lucky for a while...as soon as you turned the key the pin was removed...need more oil, cooler, decent lines, etc...

Not sure on this setup but some people spin a filter on there during tear down to stop the oil from dripping on the floor. Before you crucify someone get all the FACTS not our own assumptions.

Point taken, Red, but from the looks of all those holes in the oil pan, I think putting a filter on there is not going to do much to keep oil from leaking out of that engine! ;)

You can see the oil cooler and line in pic #2 on the first post.

Agree, brings us back to the bypass issue.

see what looks to be a cooler...I'm thinking was not hooked up...buy hey lets not jump to any conclusions...bottom line is this, it spun more than 1 rod bearing, no question, ran till destructed...reduced to door stop material...

I would like to see what the main brgs look like, if it was indeed an oiling issue the mains would show the lack of oil to some extent, and if they look decent then we can lean towards detonation. But lets not rule out rod bolt failure, leading to oil loss at the rods in question, then the snowball effect at 4900 RPM, then the inevitable. Forensic engine CSI can lead us down many paths, I know that if I was running at 4900 RPM with the design of my boat the wind over my ears, I would not hear a rod knocking till the engine quit(blew up) So this motor had to make some noise before it blew!

I have purchased a bunch of new and used parts from the OP and spoke with him on the phone a few times. He is not the type of guy that would run without an oil cooler. Now it does look like a stock merc cooler, was it cooling enough? Not sure if OP has oil temp gauge?

the blue crank says it all, lubrication failed first...

While it's hard to dispute that the hydrodynamic film broke down, I think it's a jump to say that the cause is the lubrication system. This failure could very well have been caused by overpressurization of the chamber (due to detonation or otherwise) leading to extrusion of the bearing material or fatigue and spalling of the same. If the bearings are compromised, the presence of lubrication oil is no longer sufficient to keep the asperities separated, which can lead to heat-bluing as we see here.

So, the hydrodynamic film failed... but what was the root cause? How do the other bearings look (as asked before)?

I agree with Nauti.. Crank jounal for #1&2 7&8 seem to be ok (from what I can see), So It seems the Oiling system was still working, I'm not a professioal engine builder but if I was to guess, the oil film was compromised by detonation or rod bolt stretch/failure/fatique Just what I can see from the pictures the brg material does not appear to be paper thin, and the big end of the rods in pic #4 are not dark blue. I don't know?

look at the rod laying in the pan, blue as well, as far as other bearings, not going to tell much as metal was flowing everywhere at that point, if was a rod bolt failure( and have had those) does not blue up parts, just cuts loose quickly, and if it detonated so bad as to kill the oil, the tops of the pistons would be killed, only damage I see is from the pistons hitting the head from the bearings being spun and continued to run, this thing had to have been struggling for a while before just gave up...

I'm with Nauti and abones, like from the beginning. The mains will tell the tale but I'll bet detonation killed this motor.

I didn't hear a thing when I did almost this exact same thing to one of my motors two years ago. I noticed a little loss in speed, looked down and saw OP falling, chopped the throttles and turned to look behind me, saw a big ball of blue smoke. Too much timing, not enough gas, boat had been running out west at high altitude and was tuned for such. Worked good for 5500' ASL, not so well for 250"ASL

I thought I would post a couple of pic's of a piston that was removed because of Detonation and a broken ring landing. Both engines ran fine, perfect oil pressure but had a lot of blow by. Notice scratching on the skirts of the pistons when they rock back and forth. Even if the piston kissed the head they will still have scratch marks in the bores and side of pistons.. I ran these engines lean, mis calculation on my primary jetting. These engines had over 100 hours on them. Brand new 502's....

bingo!!!!

Auto engines are typically built with tighter tolerances that can hold high RPMs for a short time, but not so much on long extended runs at the rev limiter.

Block adapter and oil cooler were removed during tear down. I just spun a filter on to keep it from dripping on the driveway while taking the rest apart.

Definitely was a stock oil cooler. I also believe everyone to be correct on the issue of the 11 lb. bypass. I found other issues as well like the wrong flywheel was installed, wrong pushrods (rockers were hitting valve spring retainers), exhaust valves/ports rusty (you know what causes that), as well as a leaking intake.

The biggest problem for me is that I had absolutely nothing to do with putting this together. All work was done for the previous owner by a shop that I will not name but they are in New Jersey and have been in business a while. I had even called them after buying the boat and they confirmed they did the engine work and that all was on the up and up with what the original owner was telling me.

Honestly get a ZZ502 and drop it in with a marine oil pan etc. It will run like a raped ape.

Wannabe

Make sure you have the right exhaust for that cam that comes in the ZZ's, and also replace the afore-mentioned bypass valve.

Sounds like it was a ticking time bomb. You pulled the pin the minute you started it up. That sucks. :mad: Good luck with the new build.

ok, with the cooler issue addressed, I've seen a few engines from merc with the std relief spring in place, so I don't think thats a total killer, the small pan and the combo of the spring and assuming you had no oil temp gauge, thinking oil just got overheated and died, also if the carb ever flooded and fuel got into the oil would kill so quick make your head swim...I know happened to me...I have a 482 short block if that would help, just out of machine shop assembled...good luck Rob

Thank you but I have a new engine that is going in the boat today actually. And NO, not another automotive 502 crate engine. Also changed flywheel and pushrods on the other motor. New exhaust all the way around and large oil cooler. Oil temp gauges too.