Killed my 97 Challenger, anyone know why?

[scooper77515]

Ran fine for 6 hours, idled through a no-wake zone (been here 20 times today), gunned it to take off, and engine seized, felt like I sucked something into the impeller. Got out, didn't feel anything, towed back to the dock, got home, and found this in the pistons...

Any ideas what happened?

Did I lose oil to this cylinder?

 

[robin savell lloyd]

what does it look like to you scott? I am not sure by photo is it a rave that let loose or is that the piston that is broken up on the top of the piston?

 

[scooper77515]

Chunks of cast aluminum. Top of piston and head are scarred from this stuff bouncing around in there before it seized.

In the pile is a small chunk of heavy gauge wire in a U shape. It looks like a heavy staple that you would use to nail cable to a house, even though that is not what it is, just looks like that. I wonder if something down below the piston let loose.

This is the same cylinder that has been screwing up and melting my RAVE valves for the past 2 months, but RAVE is all clean and in good shape, since I cleaned them all yesterday, even though the guillotine does have quite a bit of carbon build up on it from only 5-6 hours driving today.

I pushed on the piston and it moved about 1/8" downward, but I think it was just floating in the cylinder and not attached to the crank. Not sure at this point, got home just before dark and didn't have much time to mess with it.

Piston does look whole, but scarred badly from the metal chunks.

 

[robin savell lloyd]

Do you think it could be a piston pin clip?

 

[scooper77515]

I am looking at the "Inside the 787" thread to see if that is what it is. That is what I am thinking...

EDIT--I don't see the top of the pistons in that thread. So still won't know until i pull the engine and check it out.

 

[robin savell lloyd]

I hope you are back and runing soon

 

[scooper77515]

By looking at the manual, I am thinking that the "circlip" that holds the piston pin in let loose, and probably the piston pin came out a bit and took chunks out of the block.

Just my guess, at this point...

I can't wait to get this thing busted open. It has GOT to be a total mess inside there...

 

[vilord]

Well here's hoping the crank and bottom end are okay... then you'd just need to order new cylinders and pistons... at least the whole engine is cheap for this boat, you'd be SOL if you had a Merc right now!

 

[shockerfd]

Sorry to hear that. Welcome to my world.

 

[scooper77515]

I am very sore from working upside down and over the side from a ladder just pulling the head. Even just for the 2-3 hours I worked on it last night.

Would it be easier to pull the entire engine out from here on until i find my root problem?

Will likely be needing to pull it anyways, to repair or replace it...

Any tips, pointers, or warnings of common mistakes before I do this?

All help and suggestions will be appreciated.

 

[derek]

try a magnet on the pieces. that looks like hunks of cyl sleeve. something gets loose it will break off pieces of sleeve. moot point actually, the motor has to come out. even if the bottom end is fine and you just need cyls and pistons, you have to get ALL of the pieces out of bottom end or it is gonna happen again within 30 seconds of start-up. i would even split the cases to be SURE there is nothing left inside. tiny bit of Permatex #2 gasket sealer on the faces when you reassemble. now i see why you wondered about swapping a 4-stroke into it. a carbed 951-maybe-but you still are stuck with a big motor and a small pump-if you can hook the 2 together.

 

[scooper77515]

Chunks

It appears to be cast aluminum, and is not magnetic. The little C-shaped chunk on the right IS magnetic.

Here is what i found on top of the cylinder.

Would it do anymore damage if I rotated the engien enough to open that cylinder to see what it looks like all the way down, or should I just disassemble as it is to minimize damage...even though I am already shopping for New and/or rebuilt motors...?

 

[Gunsrunner]

Looks BAAAAAD!!!
I would pull the motor, i have done it twice now and can have it out in 3-4 hours. Much better than hanging upside down!!!:rofl:
You will also have a good chance to clean up bilge.
Can not tell you what that staple looking piece of metal has come from, had a motor(787) apart twice now and have not seen anything like it!
SBT do replacement motor for $875 and you can get long block for around $300. This is what i did and now i have two spare motors rebuilt and ready for any mishaps, i can have a new motor in and running in 2 days.
Is there any scoring of the bore that you can see?
Reading post again i think you could be right about circlip but the ends should be closer together even if it has been squashed. If that is what it is you will have to pull the motor because the roller pins could have fallen out and will be in the bottom. they are hardened steel and have to be removed!!
Again much easier working on a work bench!
1. undo carbon ring seal under PTO cover.
2. remove pump and drive shaft.
3. remove carbies to one side.
4. undo exhaust at join to water box.
5. undo electrics starter, magneto, leads.
6. undo engine mounts and lift motor slightly
7. undo oil line and block off.
8. remove engine

 

[scooper77515]

Thanks for the condensed version of removal Gunsrunner!!! I won't get a chance to do it today...dad just called and his brake calipers are frozen, and we need to get his car on the road before he goes to work in the morning. But I am keeping the boat home this week and will get some time to work on it in the afternoons.

The metal ring is not whole. It appears to have been pinched out of shape, then sheared off in half , so the other half (or halves) is "elsewhere".

BTW...in this pic, it shows that this is the same cylinder that has been melting and blowing past my RAVE valves (see the blown oil on the top of the engine). One time it even melted the threads on the top of the guillotine to the plastic piston, and the cap, springs, etc.

Was this a warning of bad things to come? Be nice to catch this early next time and fix it before it is totalled.

 

[vilord]

You say that it got hot enough to melt the threads on the guillotine... maybe the housing the raves was in was damaged allowing combustion where it wasn't supposed to be (in the exhaust port/rave) and the extreme heat just did it in...
it could be that the aluminum chunks are from the exh manifold, that would explain how they got on top of the piston...

 

[scooper77515]

Well, one day I was out running it and all of a sudden it wouldn't go above 3k rpms, so I idled it back to the dock and found the front RAVE assembly melted. Took it home, and the plastic "piston" that screws on to the guillotine had melted onto the guillotine, and when I finally got it off, it took half the threads off. So, I guess the entire assembly got hot enough...

While I was waiting for parts, I ran the raves off my XP on the challenger with no problems, no melting, no blowby, and none of this maxing out at 5000 until I blew out whatever it was I was blowing out by bouncing off the rev limiter. (sometimes it would not go straight to 6500, but would stop at 5000, but if i put it to the rev limiter in neutral for about 5 seconds then put it in gear and gunned it, it would take right off).

When I get the time this week, I will start tearing down and report what I find.

 

[factory81]

Thats hot...I bet my boat looks something like that or worse. Just waiting on a mechanic to get back with me.