502 Catastrophic Failure!!! Why does this happen?
 

The boat ran great last year, this year first time out ran a little funny. Then was hard to start. Then wiped out the starter. Thought I had bad gas or something, added water zorb and it seemed to be running really well again.

3rd time in the water and after taking a swim break we decided to end the day with a little cruise. Ran it up to about 4900 rpm, no trim yet or anything, temp was good, oil pressure good, then pop bang smoke, not running!

Could bad fuel do this? I am just at a loss for what happened.

BTW, I did not unbolt all the connecting rods, that's what I found when I opened it up.

Well that is certainly catastrophic. Doubt bad gas would do that in a short time. Maybe over long time but that looks like a bearing spoun and locked the crank.

Wannabe

Who winterized it?

Looks like a whole lot of hot stuff, as in water doesn't lube like oil does. any signs of milkshake?

Holy schidt!! Sorry to see/hear. Are you sure your oil pressure gage was working?

How many rods did that spit? I see at least 5 and 6, but did 3 and 4 spit also? How was your oil pressure before this happened? Was it any different? There had to be some warning ahead of times. Engines don't just spit this much stuff out without warning. How many hours were on it since it was apart? I can only imagine how sickening that must have sounded when it squeeked. My condolences.

ouch!!!
looks like a new engine is needed!!

Nope, no water any place it should not have been.

The engine was getting close to 200 hours. Never run real hard. Oil pressure was great. Didn't have a tick, tap, shake or shimmy.

The only thing I saw on tear down was a little rust on a few intake runners on the heads. The only thing I can figure is water in the fuel.

Oh, and it broke #3, 5, and 6.

For what its worth, the other engine started acting funny too until I added the water zorb.

I am definitely pumping out the tank!!!

Yep, new one goes in next week. So only 3 weeks down time but it still sucks!

Starting at the beginning.......

Hard starting and wiped out a starter could have been caused by some water in cylinder. Could have bent a rod then and it finally let go.

Bad fuel could have caused detonation, bent a rod, and it let go.

A friend had an engne come apart cruising at 3500rpms and spit out the bottom without any warning. It ran perfectly fine the entire day before and right up until it blew.

What I am really wondering is since I screwed up and layed the boat up for the winter with only 30 gallons in it could that fuel have turned to water because of the ethanol? And if so, would water in the fuel do this?

Ouch, rough start to boating season, hope all goes well on new engine!

Water in the fuel would make it run poorly, if at all.

I doubt that was the culprit.

Detonation. What did the tops of the pistons look like? Any of the ring lands lifted or pulled upwards, especially near the valve relief?

Think Griff is right about the water ....sounds like you might have ingested some water and that started the whole sequence of events. Water does not compress!!!!!!How close to the water are your exhausts and do you have internal and external flappers on the boat???Don't think your ever going to know for sure now but I would be checking the other motor and take preventive measures about it possibly happening again. good luck !

Jim

Exhaust is about 6 inches above water line when not running, yes external flappers. Water did not come back up the exhaust from outside the boat. My only other question which I have been avoiding is this.....zz502 GM performance cam is what I found in this engine when I tore it down. Not real big. .527/.544 duration at .050 in. for intake is 224 and 234 for exhaust with 110 LSA.

The boat had Stainless marine exhaust with standard risers (about as long as stock mercruiser). With the 110 LSA could it pull enough water back to do this if that was happening?

Again, 200 hours on these engines. So it has been fine for a while. The only thing I changed was lowered idle from 1000 to 750 and all of a sudden I have problems.

Pistons look perfect besides the spots where they hit valves when the rods came apart.

Do you treat your fuel?
I've winterized with empty, half, and full tanks, all treated with Star-Tron; and no issues.

The one year I had ethanol fuel in the boat, and didn't know it (or treat it)...
...problems.
Had to replace F/W separators, inline fuel filters, and fuel boost pumps; as they were all destroyed by the ethanol.

Went to Wal*Mart today and cleared out their shelf again:
http://www.walmart.com/ip/Attwood-8o...itive/16351036

I've had problems with Startron and Stabil - yeh, the green E-10 stuff. With carburetors - especially billet plated one's.

Got turned on to the following by member s30 when storing boat for winter : putting some 2 cycle engine oil in fuel seperator. Run till some signs of oil smoke out of exhaust. No doubt carb is full with the mix and fogged...lol.

BTW: I run several 2 stoke engines and use 40:1 ratio, so I use that fuel to fill the seperator. A splash of Green Stabil just in case.

No problems since.

I had 2 carbs get heavily gummed (white jelly crusty substance) 2 years in a row (well used boats) and noe not anymore.

Results my vary, but mine are great now.

==============================

About the OP's motor - oh boy !

My experience, a broken starter, especially if it broke the nose, is hydrolock. Have had plenty of bent rods from it, but not engine damge like that, but then gain, never rn one after finding hydrolock until the issue causing the hydrolock was fixed.

Oh, in cars have broken starter noses with not enough starter for the engine's compression and usually not so good of battery. LOL.

Lowering the idle down to 750 could certainly cause reversion if it was on the edge. The lower the idle, the more possibility for reversion. It sounds like it may have had some water in it when you tried to start it and it killed the starter. It's also possible that it bent a connecting rod. Once it killed one rod bearing, then the other one on that journal doesn't have a chance, You are then putting metal through the oil system, which can cause others to go. Were the tops of the pistons clean, like they had been steam cleaned? That is an indicator of water
Eddie

I'm wondering if you are on to something. That cam would certainly be prone to reversion with that tight LSA. Slowing the idle down to 750 might have been the tipping point to reversion. However, this would only tend to happen at idle, not high RPM's. Perhaps as Griff suggested you ingested enough water trying to start it to damage the reciprocating assy, and it let go under load. I would check that other motor out very carefully. If it's running the same cam, consider switching it or the exhaust.

Is it the same motor that was the subject of this thread?

http://www.offshoreonly.com/forums/g...-pressure.html

Oh schit !

Good csi !

Where is the nutkick smiley when you need it ?

Lack-o-lube even turned the crank blue .

Definitely looks like Hydro lock to me..ingested water

:throw::throw::throw:

Yes, a motor can make a lot of hp on nitromethane

No, you can't just pour it in the tank and go....

Of course, when you run it 4 1/2 quarts low, problems happen.

IMO, not likely. I've had water in my fuel before. Water filled up the water sep filter and then engine would not run. Had to dump the filter abut 3x to get all the water out.

A 250rpm drop at idle could definately cause the engine to revert water more easily, especially with ZZ502 cam.

this,to me seems to be the big question

No sir, that one is currently in the garage taken apart. A friend was going to use it but we decided that it will most likely be rebuilt this winter to be a spare.

Should have added, that thread was not even about the same boat. Sorry for any confusion.

When it was hard to start to it just crank and crank and not start or was it difficult turning over and broke the starter that way?

It would spin and stop. Then spin over and stop. And if I tried giving it gas it would make a a chirp and pop through the carb and stop.

Then after sitting 20 mins it fired up like nothing ever happened.

Sounds like it hydrauliced to me.

Did u pull the heads? Maybe rotten head gaskets. I've seen it more times than a little.

Head gaskets were clean. I did have some question about one of the intake gaskets though.

This is scary to a rookie like me. How can I tell if this is happening to me?

Is there maybe a leaking exhaust riser or manifold dripping water into the cylinder