disaster situation in my 500hp's !! help
 

:(

hello dear friends.. i need help...

i have a 2000 fountain lightning with 500 hp's.
i replaced the manifolds 3 weeks ago and while there,decided to get the heads off and send them to get checked and gone through..boat has 90 hours....salt water used...

they came back telling me that the valves were needed to get sone as they were pitted... went to check it out and yes they were... they needed to clean some and replace a few and re-do some seats..

put all back in the boat and went out last week...great run !
this week,great run...on the way back into the marina,i was at idle going to my spot and one motor stalled as i was looking in the engine bay ! my firnd was at the controls ..at idle ..... i was looking for any signs of water leaks etc...all was fine...i figured it stalled as it was running a little low at idle..
i restarted it and went back to what i was doing...stalled again !!!! i started it again and as i was going back, i heard this all fo a sudden loud knocking sound..in one shot ! knock,knock,knock ...oh my god...shut the motor off !

too compression test and one cylinder has zero..a few 80-80-150....
took off both heads that same afternoon.

the seats have broken like glass !they are spread in a few cylinders..poked into the piston surface....on a few pistons....did some damage to the head surfaces as well...

how in hell can all these seats desintegrate like this ????

that machine shop are really good usually..they do lambos for me ,ferraris heads and blocks...

did they use bad quality seats ? were the valves badly seated and broke the seats ? was the mixture bad and hurt the seats ? too lean,rich ?hell, i am lost here and cannot understand how ?
they are closed for another 13 days...so i am trying to find the cause....

the other motor sounds fine... i will yank the heads off as well...wont take a chance and hopefully, there is no damage there..will take compression monday...but still, wont take a chance these seats break and might as well get them checked or changed now...

had this happen
 

I had this happen to me before.It took me several rebuilds to figure it out.What I found was a lean condition which caused the heads to get so hot the seats fell out on a few holes.Once I fixed that motor,the other would do the same.I did both motors 3x each until I figured out my problem.My problem was low charging voltage at high rmps.When wide open,the electric fuel pumps werent getting a full 12+ volts,only 9.So my fuel pressure was low when it needed to be high and created a lean condition!
Another boat I had did something similar.One of the float valves in the carb stuck shut which caused the engine to run on only half the carb and with a singal plain manifold this created a lean condition.The seats didnt come loose but it did tulup the valves because of the heat! hope this helps.

Reversion can cause this problem. Dripping cold water on hot seats and valves is never a good thing. Can your engines be reverting? Is the idle too low? Too low of an idle can cause the engine to revert water.

i never let of the throttle...when i slow down...as a precausion..even though i have flaps on the pipes...and there was no water in the cylinders when i took out the plugs...

one thing i can think about is that motor was running rich...

I was looking at buying a pair of 500hp's a few years back that had aluminum heads on them. The reason the heads were replaced was because the original iron heads kept dropping the valve seats. He said no matter what they did they could'nt keep the new seats in the heads. If it were me I would give some serious thought to replacing the heads, might save you some grief in the long run.

that doesnt make sense....once valve seats are well installed, they never fall off !@

Did you replace the original valve seats?

i was told they replaced a few .... now they may have used cheap quality ? or non marine ?
now that motor was running rich ,...can that destroy seats ?

i will check the other motor tomorow...that motor was not running rich ..lets see if there is any damage or lost compression due to premature damage of those seats...

Did they magnaflux your heads, are you sure there are no hairline cracks, if it's a reputable shop I doubt they put all the seats that fell out wrong.

Which manifolds did you replace????? exhaust manifolds or intakes??????

The valves most likely became pitted beacuse of cracked Gil manifolds leaking water.

Also, there are 2 kinds of reversion. The water that gets forced up the exhaust from a wave is one. The other type is caused by cam overlap causing water get sucked back up idle. The 500hp's had some issues with reversion at idle and changed risers because of it. The lower the idle rpm, the easier it is to suck water back up the risers.

Was this after your 45 minute WOT run from the post in the Fountain Owners page? One of my friends ran an entire poker run WOT on a pair of carbed HP500's in a 35 Fountain and literally beat the valves right out of the heads (or more appropriately right into the heads)! Those engines only had 35 hours on them. That might have contributed to your seat failures.

I guarantee the ones that fell out were the ones they replaced. I'd be raising hell with them on this. I had one drop and it f*cked the whole engine up.

new intakes,new exhaust manifolds on my boat...

i wished i knew which were the old / new seats to compare...

maybe they used cheap seats for cars or something..

Maybe not the proper press fit on the new seats.

Steve,
There is no real difference btween the seats for "cars" and those for marine use. At least not if you use a high quality seat manufacturer. If I remember correctly from the last set of those heads I did, the seats are an unusual size and material. I think I had to special order them. Your shop might have cut the heads for a larger seat instead, which is perfectly acceptable and done all the time.

A lot of the manufacturers are starting to use powdered metal seats and they are available in the aftermarket. I am not comfortable with them yet and will not use them. Ford had some problems with them in some of thier engines with the seats shattering into pieces :( Also, like someone else mentioned, if the seat was not installed with enough press fit, it can come loose too. Too much press fit can cause problems also, stressing things.

Hope it didn't do too much damage.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

ok..here are the news :

both motors running on 91 octane ,full tanks the day before...
both motors had the same head jobs...a few seats on each head...same shop.
the starboard motor compression was taken today.exactly 170 all over...all identical. not one has damage to a valve or seat. i never did put the heads back to the original motors..we mixed them up not knowing which head came from what motor...
the star motor is perfect still after running the same amount of time as the port side...same fuel,same everything..

now the port motor, on both heads, seats came apart....both heads ! the other motor, zip !

the port motor was smoking a little when being started...running rich...carb was leaking some fuel we noticed...

that is the only diff. with both motors...one running very rich.

i always checked the temp,pressure,oil temp.etc.... was very carefull the during those rides since we put all back together....

why does on motor with the same valve job/seats stay perfect and the other fall apart on both heads ?

damages:

cylinder liners all scratched up with the metal pieces..
lots of metal punched into the piston top...
for sure valved bent...
heads have minor damage...

tell me that one seat fell out, or one on each head ...but at least 2 on each head ?

and the other motor is perfect as it had gotten the same tratment ?

i am sure the running rich had to go with it ??? can it ?

hell, i am lost of ideas here !

Running rich won't do that. Sorry to hear about your troubles.

StevemamanFountain, you never answered this question...

Two valves on each side of motor sounds like a two plain mainfold.This means four of the eight are conected threw the manifold and use the same fuel supplied threw the carb.This means one problemmore than likley starting at the carb.make sure the carb is working.With a two plain manifold,the fuel is spread evenly threw the engine,Half of the carb feeds 4 cyclinders and the other half feeds the rest.If you have a total of 4 cyclinder bad,your problem is fueling,probably lean.also when if only one seat fell,once it breaks it can travel to the other three threw the manifold and distroy those cyclinders aswell.Like I said before,ive had this happen and it was a lean condition. Check and see if the four cyclinders are connected together by the manifold!

no ,not after that run... the i went out for another run after that...maybe 25 minutes at the most..not pushing it that bad... upon reentry at the marina at idle, after 5 minutes at idle... knock knock !