Mercruiser 4.3 MPI 2005

[federicob162]

I have a preowned Maxum cuddy boat mod 1996 that I purchased on 2001. It came equipped with a 4.3 carburated Mercruiser that had some 400 hours of use. After putting some 600 more hours on it I decided to change it for a new 4.3 MPI in September 2005. The engined runned very well and I was very satisfied until 2 months ago when I began finding water in the oil. After stripping it down, the authorized Mercury found out that the block was cracked and the cooling water was getting in.

The engine so far had only 460 hours and was always well kept with periodic service and the computer does not show any recordings of overheating. The guy where I purchased this engine says that as the warranty has expired he cannot be of any help. To me this is clearly a material failure. Is there anything someone thinks I can do, besides absorbing the mishap?

 

[Don S]

Re: Mercruiser 4.3 MPI 2005

Cracked blocks are normally caused by freezing. you don't mention where you are located. Did it freeze?

 

[Bondo]

Re: Mercruiser 4.3 MPI 2005

The engine so far had only 460 hours and was always well kept with periodic service and the computer does not show any recordings of overheating.

Ayuh,... I agree,.. it's a Heat problem alright, or Lack of it,.. it Froze, 'n Cracked...

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

Sorry Don for coming back late. No freezing whatsoever in my region. I live and boat in Buenos Aires, Argentina. Boat sleeps un cvovered wharehouse and temperatures hardly ever drop below 36? F.

The computer on the engine does not register any overheating. This looks like a material or design failure to the authrized Mercury technician and to myself. Just wanted to know if you guys had heard of similar failures without accidental causes like overheating or freezing. At the same time wanted to tip other users of waht happened to me.

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

Thanks Bubba, I know that warranty is over because besides having runned the engine for over 400 hours its been running since 2005, but it looks like a material or design failure and wanted to know if any of you had heard of any similar cases on 4.3, 2005 vintage MPI.

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

As said to the other guys, no freezing and no overheating. Semms to be just an spontaneous failure. Have you heard of any similar cases. The computer log shows no overheating.

 

[Bondo]

Re: Mercruiser 4.3 MPI 2005

Have you heard of any similar cases.

Nope...

 

[GLENN M]

Re: Mercruiser 4.3 MPI 2005

just bye info you have supplied,i would say you dont have cracked block they dont just crack for no reason,i would be looking at my 460 hr old exhaust manifolds.if it didn't freeze or over heat it aint cracked.and nope never heard of them just cracking.

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

It seems i have been darn unlucky. However I did hear of more than one 4.3 block failure here but in older engines.
The official service repair expert says that he saw many failing in the same way but they were all old cabureted engines )over 10 years old or more). The replacement one (2010 vintage) they installed has a different block design. Hope is a bit sturdier. Are you familiar with this engine?

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

It is cracked allright. The engine has been stripped down and it shows a long crack on the port side of the cilinders water jacket, water through this crack and went directly into the oil pan, mixing with it and emulsifying the oil and overflooding into the bottom of the boat.
I had the same hope but if the exhaust manifolds were the culprits, the mechanic says the water would have gone into the cilinders instead of the oil pan. After seeing the crack all doubts disapeared

 

[GLENN M]

Re: Mercruiser 4.3 MPI 2005

actualy unless frozen or overheated ive not seen any that cracked for no reson,up here in vancouver b.c i see a lot of 4.3 powered boats,its a 350 minus two cyl's so its pretty reliable,seriously i would want to see those cracks,sounds fishy exhaust manifolds will cause same result water in oil and they have a service life in salt water probly somewhere around 400 hr's.

 

[GLENN M]

Re: Mercruiser 4.3 MPI 2005

we were typing same time,thats to bad but seeing is believing,i had a boat cracked manifolds poured water out distick hole and filled crank.being auto mechanic didnt even think manifolds till after dropped third motor in,funny thing i dropped second motor over the side and i had spent a long time putting it to gether and there was nothing wrong with it,wasent laughing then but my wife was

 

[Bondo]

Re: Mercruiser 4.3 MPI 2005

It is cracked allright. The engine has been stripped down and it shows a long crack on the port side of the cilinders water jacket, water through this crack and went directly into the oil pan, mixing with it and emulsifying the oil and overflooding into the bottom of the boat. I had the same hope but if the exhaust manifolds were the culprits, the mechanic says the water would have gone into the cilinders instead of the oil pan. After seeing the crack all doubts disapeared

Ayuh,... It Must have gotten cloder than 36? at some point, 'cause that's Classic Freeze Damage....

 

[Don S]

Re: Mercruiser 4.3 MPI 2005

I'm not buying the manifold problem at all. First of all, the only place that fails on a manifold in 400 hours is the joint between the manifold and riser. Since this is a 2005 complete engine, it would have had the Dry Joint type exhaust manifolds and risers, and that gasket surface would not be the problem either.
Even if the manifolds or risers did fail, water would get into the cylinders first. Then, it would have to leak past the rings to get into the oil. Not likely to happen very fast with a good running fairly new engine. Besides, the salt water would rust the cylinders before it leaked past the rings, or you would have noticed a hydrolock at some point, or slow turning because of the rust.

Those engines seldom crack, but it's possible, it is a casting, and sometimes things fail for no reason. The block may have been poured too slow in the foundry, or too cold, or heat treated wrong, or had an imperfection in the casting....... Who knows.

The block cracked, (They can see the crack) get a new block and move on, there is no warranty on a 5 year old marine engine.

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

The boat has been used always in fresh water (plenty of it in the huge Buenos Aires Delta, take a look at it in Google Earth). I will have some photos taken of the stripped engine to share, and of course just to make sure, will have the manifold inspected.

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

Agree with you Don S.
Castings may fail if not properly annealed or heat treated. I had to change the whole engine for a new one, because although I have found an assembled block, the accessories (computer, injection subassembly etc. did not fit because overall design of the block has changed since 2005.
I will try to get some photos of the stripped engine to share with you guys.

 

[federicob162]

Re: Mercruiser 4.3 MPI 2005

Not in the covered warehouse Bond -o, and certainly not while running, because the lowest reading I have seen on my fishfinder of the water was 50? F. Freezing should not be the cause. To crack by freezing I've been told, the remaining cooling water must have frozen solid inside the cooling system.