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T

the vig

New member
Hi All,
I bought a 90 Convincer last week. It has a 540 merlin in it. I used it on Saturday and sunday morning it was hydrostaticaly locked up with water in the oil. I put it on the trailer and am running it to a mechanic today.

Any Ideas? What is perplexing is it ran perfectly on Saturday and I never ran it over 3800 rpm.
Also is there any way the seller could have known about this before he sold it to me and covered it up? I test drove it with him for an hour or so before I gave him the cash.
No sour grapes I think I still got a pretty good deal 8400.00 for the boat and trailer. Considering NADA it goes for aout 15600.00 low retail I have some room to invest some money in it.

Any help would be appreciated.
 
the vig said:
Hi All,
I bought a 90 Convincer last week. It has a 540 merlin in it. I used it on Saturday and sunday morning it was hydrostaticaly locked up with water in the oil. I put it on the trailer and am running it to a mechanic today.

Any Ideas? What is perplexing is it ran perfectly on Saturday and I never ran it over 3800 rpm.
Also is there any way the seller could have known about this before he sold it to me and covered it up? I test drove it with him for an hour or so before I gave him the cash.
No sour grapes I think I still got a pretty good deal 8400.00 for the boat and trailer. Considering NADA it goes for aout 15600.00 low retail I have some room to invest some money in it.

Any help would be appreciated.
Click to expand...


my buddy has a chris craft and had a bunch of work done(new motor ect...) he went out for a test ride for a while and everything was peachy..... a couple days later he took it back out and it "siezed" as he put it. it wouldn't even turn over. he took it back to the guy that replaced the motor and he found that the screen that is in the water intake for the cooling was clogged- it had warmed up and sucked water in the motor untill the piston chamber was full hence the motor not turning over..... it's pretty hard to compress water if you know what i mean! he pulled the plugs out and turned the motor and released the water out of the chamber and a few minuites late we were on our way back to the lake! of course he replaced the screen! just thought i'd give you a heads up! sounds similar to me. you will get this from running the boat in shallow water or in a river w/out the motor up high enough.....-ross
 
thats too bad man. i have seen engines run with a couple cylinders full of water as you described. they were just down on power.

how did it run when you tested it?
 
illMATTic said:
thats too bad man. i have seen engines run with a couple cylinders full of water as you described. they were just down on power.

how did it run when you tested it?
Click to expand...

matt.... how can a motor run w/ a few cylinders full of water????? water will not compress..... that will make the crank stop right in it's place! i'm not a mechanic-i'm a electrician but have built and raced many sleds!!!! just got rid of 4 that i used to race! i know how a motor works and this does not make any sense.... not unless the pistons that were bad had a big enough hole in them to release the pressure. also i'm talking about a i/o.....:poke:
 
ross said:
matt.... how can a motor run w/ a few cylinders full of water????? water will not compress..... that will make the crank stop right in it's place! i'm not a mechanic-i'm a electrician but have built and raced many sleds!!!! just got rid of 4 that i used to race! i know how a motor works and this does not make any sense.... not unless the pistons that were bad had a big enough hole in them to release the pressure. also i'm talking about a i/o.....:poke:
Click to expand...

think about how the water got in there in the first place. :cool:
 
the vig said:
Also is there any way the seller could have known about this before he sold it to me and covered it up?
Click to expand...

Yes the seller could have known and covered it up. And yes it could have just happened the Saturday when you used it. Their are a stack of reasons why you could have water in the engine. After the test ride with the seller did you pull the dipstick to see if water was in the oil ??

Proving who's fault it is will be a waste of time and a long road to nowhere.

Was the boat you bought red ??

Water in oil

1- leaking intake gasket
2- leaking head gasket
3- leaking manifolds
4- cracked block
5- cracked head or intake
6- leaking oil cooler
7- The cam "BUMP STICK" is to big for wet exhaust and you are having reversion this is a common problem for those that do not know about overlap on marine engines

A engine will not run with water in the cylinders it will bend a rod or bust the starter right off trying to crank it. A engine will run if its leaking just a small amount of water just enough that it can burn it off but it will smoke like a steam engine and foul the plugs.
 
i know if the head gasket is leaking enouph to let water it it wont hold compression so no matter how much water is there is will still do the compression stroke it will just push the excess out the bad gasket. My wifes car kept saying it was overheating becuase gases were getting into the coolant lines and tricking the gauge sensors.
 
wizard8575 said:
i know if the head gasket is leaking enouph to let water it it wont hold compression so no matter how much water is there is will still do the compression stroke it will just push the excess out the bad gasket. My wifes car kept saying it was overheating becuase gases were getting into the coolant lines and tricking the gauge sensors.
Click to expand...

:thumb: Good comment I have also seen this happen on a 350 just forgot about it.
 
Thank you all

I took it to a mechanic, and as suspected, there was water in 2 cylinders.
One on each side.
After deliberation, I have decided to pull the motor and go through it. My feelings are if the water got in even if it was just a leaky manifold and an isolated problem, I dont have enough history to know how this happened. I am suspecting a major overheating. Also if the guy was deliberately covering up a known issue it makes me leery to put in money knowing there may be other hidden items that could cause me grief right after buying new heads etc....
It isfor these reasons I am leaning toward buying a new 540 merlin shortblock and rebuild. At least then I know where we started and if there is a problem, I know I cant blame not knowing about it.

Thanks for all the insight if you have any more Id appreciate it.
 
the vig said:
I took it to a mechanic, and as suspected, there was water in 2 cylinders.
One on each side.
After deliberation, I have decided to pull the motor and go through it. My feelings are if the water got in even if it was just a leaky manifold and an isolated problem, I dont have enough history to know how this happened. I am suspecting a major overheating. Also if the guy was deliberately covering up a known issue it makes me leery to put in money knowing there may be other hidden items that could cause me grief right after buying new heads etc....
It isfor these reasons I am leaning toward buying a new 540 merlin shortblock and rebuild. At least then I know where we started and if there is a problem, I know I cant blame not knowing about it.

Thanks for all the insight if you have any more Id appreciate it.
Click to expand...

Do your homework before you buy a Merlin block or heads. I know of a few new merlin blocks with machining flaws and other problems. Dart Big M blocks seem to be the choice of those in the know lately. My friend has a Dart Big M (540) and after 2 seasons with 1100 HP he has had NO issues. He runs his stuff hard....
 
If your problem is water reversion, or cracked manifolds, you will STILL have a problem!
You MUST address the problem first! Diagnosis and repair before you rebuild, or you're
wasting your money!
 
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