Merccruiser taking on water.

[acebailey]

I have a 1986 thundercraft bowrider,with 175 hp merccruiser.
The boat is taking on water, and the water is oily and gasy. Would this happen with a leaking exhaust bellow? Nothing is leaking from the motor inside that I can see. I am going to remove the lower unit this week, and just wondering if that would be the cause.

 

[tpenfield]

More likely a cracked cylinder head, if the oil & gas are coming from the engine and not from residual fluids in the bilge.

 

[acebailey]

Hooked it up to muffs, wasn't water leaking from anywhere. Checked oil, nice and blackish still. If it was cracked head the oil would be baige color.

 

[Grub54891]

Did you run it on muffs? If you didn't you won't see any leaks.

 

[Eric 3.7LX Alpha 1]

The exhaust bellows is below the water line/ Every time you shut off the engine it is full of water. If it has a crack in it, it would not enter the boat from there.

 

[poconojoe]

A damaged or disconnected exhaust bellows will not cause your boat to take on water.
Mine popped off the outdrive side a few years ago. I left it. Didn't want to hassle getting it back on.
It's now acting like an exhaust tube.

 

[Rick Stephens]

The driveline bellows is more likely a cause.

 

[poconojoe]

I have a 1986 thundercraft bowrider,with 175 hp merccruiser.
The boat is taking on water, and the water is oily and gasy.

Could the oily and gassy appearance of the water just be from accumulated crud in the bilge over the years? The boat taking on water and sort of rinsing a dirty bilge?

Hooked it up to muffs, wasn't water leaking from anywhere. Checked oil, nice and blackish still. If it was cracked head the oil would be baige color.

So, if your oil doesn't have the "milkshake" (beige) appearance, that should be a plus.

Oil, nice and blackish? It should be amber and clear, no? When was it last changed?
...Just sayin'

What about the taking on water situation?
Did you find the source?
How much water comes in?
If either your u-joint bellows or that little shift cable bellows fails, your boat can sink.

Is your boat on a trailer now?

Does it leak into the boat while sitting in the water and the engine not running? Or does it only leak when the engine is running?

I think you need to determine whether the water is coming from the engine raw water cooling system, or from the hull.

 

[acebailey]

Could the oily and gassy appearance of the water just be from accumulated crud in the bilge over the years? The boat taking on water and sort of rinsing a dirty bilge?


So, if your oil doesn't have the "milkshake" (beige) appearance, that should be a plus.

Oil, nice and blackish? It should be amber and clear, no? When was it last changed?
...Just sayin'

What about the taking on water situation?
Did you find the source?
How much water comes in?
If either your u-joint bellows or that little shift cable bellows fails, your boat can sink.

Is your boat on a trailer now?

Does it leak into the boat while sitting in the water and the engine not running? Or does it only leak when the engine is running?

I think you need to determine whether the water is coming from the engine raw water cooling system, or from the hull.

Hi thanks for the reply. The boat is out of the water now. I will remove the lower unit and check all the bellows. Its hard to diagnose the boat because I'm not near the water.
The boat started leaking as soon as it went in the water. It was clean water, about 2-3 inches an hour. After a while the water looked oily and smelled. Didnt find any water leaking from the motor anywhere. Couldn't see where it was coming from.
So it definitely wouldn't be exhau
st bellows causing this? I have manually checked it and seems fine.

 

[Rick Stephens]

It would not be the exhaust bellow.

If you take a rag and soak up some of the oil floating in the bilge, if it smells like gear oil then you have a leak at the u-joint bellows and a drive lube leak at the yoke. No other lubricant smells like gear oil, so that's a dead giveaway.

 

[JHinMT]

My 4.3l mercruiser shed both water shutters, one jammed in the y-pipe just inside the transom and wore a hole through the y-pipe. Cold water leak into the bilge when the hull was in the water, but nothing running on muffs. Clean water though, no gassy or oily stuff.