4.3 big problems

[richardson61]

looking for a little advice here, we have a 93 Sea Ray with a 4.3L merc. Had problems earlier in summer, ended up taking to marina had 3 bad valves and a cracked head. Valves where replaced as was cracked head and valve job done on both heads. Boat ran great for four weekends, best its ever run. Two weeks ago girlfriend had it out, started fine took off across lake and after 2 or 3 mins made "lots of bad sounding nosies" according to her and quit. Motor had seized up wouldn't turn over or nothing.

Following weekend I drain about 2 gallons of water out of oil first clue there was big trouble, pulled all plugs got it to crank over a few times lots of water in cylinders. Pulled heads and found one of the valves (the smaller one not sure if that is intake or exhaust) had dropped into the cylinder. Cause all kinds of trouble to top of piston, valve broke in half, knocked 2 holes in top of head, and bent push rod.


I have two questions

1. Could anything besides the valve retaining clip failing cause this, little concerned about taking it back to same marina for repair. Assuming if its an error on the rebuild it would be the machine shop that redid the head and not the mechanic that put it back together?

2. Has anyone ever heard of www.michiganmotorz.com or www.rapidomarine.com both have pretty good pricing on rebuild marine motors?

 

[Bondo]

Re: 4.3 big problems

Ayuh,... Long before I would start Blaming the Machinest, or anybody,....
Was the Original Problem found,..??
I don't mean the Wasted head,+ Valves,.. I mean the Cause of it's Failure,..

The reason I ask is,... It's probably that Same Issue again....
It sounds like a Lean condition that caused Detonation, which destroyed the valves, causing all the other damage....

Has the Fuel filter been Inspected,+ changed,..??

Btw,...
Raul at Rapido has alot of Fans here at iboats,...
Quite a few guys have bought motors from him...

 

[180shabah]

Re: 4.3 big problems

lots of bad sounding noises - that is what a dropped valve will sound like.

And also, need to address the water in the oil, before you destroy another engine. What is the age/condition of the exhaust manifolds/elbows?

 

[richardson61]

Re: 4.3 big problems

Well I was assuming (and I know what that will do to me) that the original problem was solved when we took it in the first time, but thats a good point. Yes both fuel filters where replaced prior to the valve work. I there is a problem with it running lean that would continue on with a new long block i'm guessing?


The exhaust manifoilds are original so 16 years old, that was first thing mentioned as a cause of the problem. That being a craked exhaust manifold, but after pulling the one head and seeing 2 nickel sized holes around the spark plug area I figured thats where the water got into the oil. I've been told they are difficult to determine if they have cracks and need to be pressure tested?

 

[richardson61]

Re: 4.3 big problems

Could that lean condition or a detonation problem cause the valve to drop like it did?

 

[JustJason]

Re: 4.3 big problems

Could that lean condition or a detonation problem cause the valve to drop like it did?

Not likely in a non-interference engine. Does the valve still have a stem on it?
Any chance you could post some pictures of the valve, the piston, the cylinder head and the spark plug for that cylinder?

 

[richardson61]

Re: 4.3 big problems

I can take some pictures when I go back up this weekend and post them.

The top of the piston was marred up but no holes in it, the cylinder wall appears to be fine. The valve broke off with maybe half inch of stem on it still, the rest of stem is still stuck in the head. The head has to small holes about dime or nickel size that are located around the spark plug area. The spark plug itself was destroyed flattedn down and all the threads that were expose inside the head chewed up.