Water under the engine mounting frame

[OzDean]

I was just reading Howler's post "Water in Engine Bilge", I have a similar issue but the water only appears when the engine is running, but I can't actually see where its coming from. I have a jeanneau 43 sailing yacht, volvo penta D2-55 mounted on a fibreglass frame that is bonded to the hull. The water first appears underneath the fibreglass frame that the engine is mounted on. Then with the boats motion, the water find its way to other places further forward to the normal bilge. I thought how does this happen there are no thru hulls under the engine mounting frame and no source of water. Then on closer inspection, I discovered the engine exhaust goes down into this mounting frame into a stainless steel box about 15x15x60cm, then out of the box towards the aft. What is this box? How the hell do I get to it to see whats going on and if that is actually the source of the water? I guess it could be leaking from the exhaust connection to or from this box or the box itself. This box is within the mounting frame, the only way its getting replaced is not only removing the motor but the mounting frame that is bonded to the hull, who designs these things? I can upload photos.

[donradcliffe]

sounds like your shaft packing gland may be leaking. Photos would help

[OzDean]

Actually, I have just replaced that dripless gland thing, it is further aft and has its own little spot to leak into

[OzDean]

Photos

[wingssail]

Well, there isn't going to be any magic answer to this question. You are going to have to do the necessary and find the water's source the hard way: little by little checking and disassembling, etc.

Yes, a good possibility is the box for the aqua lift of the exhaust. Surely Jeanneau didn't put the box inside of the fiberglass engine frame before glassing that to the boat, and probably not before mounting the engine. If they got it in you should be able to get it out. (are you sure that is not possible?)

The another possibility is a leak in the engine itself which drips into the fiberglass pan then down through some hole into the bilge.

It is also possible that water is in the bilge from some other source and runs under the engine frame.

Generally the way I find sources of water in the bilge is to dry it completely then watch the bilge (closely). When you see a trickle of water you follow it back to the source. I know it is hard because you cannot see into the bilge under that fiberglass frame, but I don't see any shortcut other than living with the leak until it gets worse (it will).

[Emmalina]

More than likely your exhaust muffler. Stainless steel corrodes especially when submerged in sw all the time. Threw my stainless one away and made a glass one !

[wingssail]

Originally Posted by Emmalina

More than likely your exhaust muffler. Stainless steel corrodes especially when submerged in sw all the time. Threw my stainless one away and made a glass one !

Yeah, this is a definite possibility. My stainless steel muffler aqua lift is only 43 years old and already it is starting to show signs of corrosion and rust.

[Howler]

My guess is the exhaust mixing elbow, especially given the age and the use in salt water. Also, I’d check all hoses from the engine aft as they can crack with age. Especially check under the clamps. I know of cases where hoses cracked there where they weren’t readily visible, and slowly degraded to the point of allowing significant amounts of water to leak.

[OzDean]

Thanks for the posts. I motored for a few hours today and checked the exhaust inlet/outlet from the box. I could not see any obvious leak, but then again I can't see the whole thing. Good point wingssail about the stainless steel box being able to be removed, I had a closer look and maybe with some floor support removal I can get it out by undoing the inlet/outlet and sliding forward and up. It is the only possible source of water in the mounting frame. After motoring a few hours again today there is now about 5 litres under the engine in the mounting frame and another 5 or so that has found its way forward to the bilge. Because the design of the mounting frame has the engine drip pans higher up the salt water runs forward to the bilge rather than into the drip pans, can see this in the pics. There is actually no water in the engine drip pans. I will contact Jeanneau and see if they have a design spec.

[jt11791]

How old is the exhaust hose? They don't last forever.

[OzDean]

The exhaust hose is same age as boat 2003 vintage. It would be good if it simply was the exhaust hose connection between the motor and the stainless steel box as I can actually replace that pretty easily. I can't see around the back of it but can feel for a leak.

[OzDean]

Found the leak!! There is a small hole in the exit flange for the muffler, water mixing stainless steel box thing. So now it is time to remove it. I am assuming the inlet flange on the top screws off or am I expect to cut it off to slide the box forward? See attched picture. BTW the hole in the exit flange was where the flange was rubbing on the hose clamp on the fibreglass frame, probably because the exhaust hose from the engine to the box was 10-15mm too long and pushing the box downwards. I hope there are better designs for these things in the new boats. Back to my question, do I hacksaw or cut the flange off the top?

[Manateeman]

It sure looks like a water lift . I don’t see how you can repair it where it is now except cutting the glass and getting it out.
I’d buy two carbon monoxide detectors. You were lucky the leak pushed water out and not exhaust.
You can construct a fiberglass water lift in almost any shape and you may find a stock lift which will fit.
Any suggestions from others with the same boat?
New hoses and better clamps. What does the whole exhaust system look like ...
How about a sketch or photos.
Happy trails to you.
The manatee crew.

[OzDean]

Hey Manatee Crew, yeah water is definitely better than CO. The replacement box I am looking at is from Vetus https://www.vetus.com/en/exhaust-systems.html, although there does not seem to be one that will replace the existing box and fit in the space under the engine. The answer may be to put the box about 1m further aft along the exhaust line under the aft cabin bunk so I am hopeful that someone will be able to say they have done that and it works fine. Otherwise, I will have to repair the existing box or get one custom made, that is assuming I can slide it in/out forwards which begs the question of how to attach the inlet flange to the top? So with the boat now out of the water for winter storage it will be a project for next year.

[donradcliffe]

When I had a leaky custom box, I repaired it with fiberglass and epoxy. It lasted at least another 10 years.