exhaust water leak HELP!!!

[tazzvon]

Let me start with the fact that i just bought this boat and am having trouble identifying the engine. i know it is a Mercruiser. The serial number i found looks like 4773902 but this would make it a 140 1972-1978. Not only was i told it was an 84 or 85 but the 140 does not resemble the engine i have so i am thining it is a 470 1982-1984. I do know the outdrive is a Mercruiser with S/N A322340 which also leads me to believe the engine is a 470 82-84. Anyway, i just replaced the impeller in the outdrive for the salt water pick up and replaced the exhaust bellow between the gimble and the bell housing. all was good except know I notice a leak inside the engine compartment at the transom plate. I believe it could be where the inside exhaust elbow connects to the bell housing inside the transome plate hole. If I am correct how could this happen unless there was a block in the outdrives exhaust and if there is a block where would it most likely be. If I am incorrect does anyone have any ideas on what the problem may be. Thanks for all help.

 

[Don S]

Re: exhaust water leak HELP!!!

If the water is coming into the exhaust tube where it hooks to the transom shield, it's always under water when the boat is just sitting in the water. Even with a new exhaust bellows, there is water in it.
However, that is not usually the cause of 99% of the leaks. What is the cause is the ujoint bellows. When water gets into it, it will drain into the engine compartment, and into the outdrive and the gear lube becomes milky. Time to pull the drive and check for any water in the bellows. If there is, replace the bellows, along with the gimbal bearing and ujoints since they now have had water as a lubricant.

 

[thrasher]

Re: exhaust water leak HELP!!!

I second Don's suggestion. I think you have a hole or incorrectly fitted drive shaft bellow. Once you get a hole in this bellow, it allows water into the bellows and the water will come out the transom end and will also damage the coupling on the drive shaft and the water will also try to get inside the outdrive and damage that.. Time to pull the outdrive (6 nuts, plus remove the pivot for the trim RAMs and it will pull off) and have a look inside.

Gary

 

[tazzvon]

Re: exhaust water leak HELP!!!

Thank your for the responses but i guess i forgot to mention that i have not put the boat in the water yet, i have only run it in the yard with a set of ears on it. after checking to make sure it was not the incoming water so i think that only leaves the exhaust elbow where it bolts to the gimble inside the engine compartment. if this is the case, everything iread say i have to remove the engine and outdrive to get this elbow off. Is there ANY chance of replaceing this elbow without removing either of them?

 

[Don S]

Re: exhaust water leak HELP!!!

The same thing can happen when running on muffs. What you have to do is LOOK and see what is happening. We can't.
Start it up and look for the leak. Use mirrors and flashlights if necessary.