2007 3.0 mercruiser Water Leak

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
This engine starts to overheat when @ or above 4200 RPM. I watched the engine while at this speed and noticed water gushing from the Stearn starboard lower end of the engine. The bilge pump would also start pumping. I do not have a good maintenance manual, but this looks like a large manifold cover that is bolted on. Any thoughts on how to repair it or where the water is coming from? It is difficult to get to. I hope that the engine does not need to be pulled. This is on a Freedom 241DLX I/O Pontoon.

Thanks
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,322
Re: 2007 3.0 mercruiser Water Leak

http://www.boatfix.com/merc/Servmanl/13/13covr2.pdf
This is for the GM 4 cylinder. You have to narrow it down by looking to see where it comes in. pics would be useful. water inlet hose is usually on the port side so if it`s a gusher of a leak I`d check for a popped out core plug from faulty witerization.
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,320
Re: 2007 3.0 mercruiser Water Leak

if your saying you have water leaking from just under the intake manifold then you have a cracked block my friend.
 

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
Re: 2007 3.0 mercruiser Water Leak

Here is a pic, it is right behind the starter.
 

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
Re: 2007 3.0 mercruiser Water Leak

Hope the pic shows up this time. Took the pontoon out today and kept the rpm at 4000 with no problem.
 

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
Re: 2007 3.0 mercruiser Water Leak

Hope the pic shows up this time. Took the pontoon out today and kept the rpm at 4000 with no problem.
However, at over 4200 water starts to gush out right behind the starter..​


CIMG3917-1.jpg
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,320
Re: 2007 3.0 mercruiser Water Leak

There is a core plug up in there behind the coupler.... I'd suspect that's whats leaking because the blocks typically do not crack back there. Bad news is the engine needs to come out to fix it.
 

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
Re: 2007 3.0 mercruiser Water Leak

I have been going to various repair shops with the photo and that is what I am being told. If I use the boat at low speeds, do you think that the plug could fall all the way out and do more damage?​
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
Re: 2007 3.0 mercruiser Water Leak

If it is a core plug, then water is going to be coming in the boat at ALL speeds and all rpms - not just high speed.
 

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
Re: 2007 3.0 mercruiser Water Leak

Sounds right, but I took it out for about four miles yesterday and kept it under 4000 rpm. Engine temp stayed around 165 and no water in the bilge. However, if I crank it up over 4200 rpm, water starts pouring out of the cover. Could the core plug just be leaking at high pressure??
 

Schmoe

Petty Officer 2nd Class
Joined
Feb 10, 2004
Messages
117
Re: 2007 3.0 mercruiser Water Leak

No. It would leak regardless of rpm setting.
 

ronmax99

Cadet
Joined
Feb 10, 2005
Messages
20
Re: 2007 3.0 mercruiser Water Leak

Well I am resigned to the fact that we have to pull the engine. We should be able to do this next week and I will update this post with the results. Thanks for all the help.
 
Top