Exhaust mixing elbow extension on Yanmar 3GMF

[Garbonzo]

OK, we have a Yanmar 3GMF that we have to put an extension on the exhaust elbow, because it is to far below the waterline for the normal high rise mixer to keep water out. Exhaust run was not well designed and when loaded to cruising weight we got problems. Tried to use a 12 in iron pipe between the elbow and the mixing riser and it works great for a little while, but then the vibration cracks it in short order.

Any good economical ideas. Sitting at anchor in Boynton Beach.

Thanks.

 

[Ralph Johnstone]

we have to put an extension on the exhaust elbow, because it is to far below the waterline for the normal high rise mixer to keep water out.

Something not right here. You rely on the hose configuration AFTER the mixing elbow (exhaust loop) to keep the water out.

 

[Garbonzo]

Yep, like I said exhaust run was not well designed, and in the middle of the ICW We are trying to fix and we did manage to install a flexible exhaust hose that will work for now, and yes we will redesign the piping when we return to the yard.

Apparently, the exhaust outlet WAS above the waterline and had a small riser right there, but now it is just below the waterline.

Thanks for the drawing, we are kinda constrained by the engine room and aft cabin layout, which is why we are putting the loop between the manifold elbow and the mixing elbow for now.

 

[Ralph Johnstone]

Apparently, the exhaust outlet WAS above the waterline and had a small riser right there, but now it is just below the waterline.

I've got the same arrangement with no extra consideration for the fact it belches out about 5-6 cm. below the water line. Above or below the water line, all the same thing. The deck height exhaust loop protects the engine. Or am I missing something here ?

we are kinda constrained by the engine room and aft cabin layout, which is why we are putting the loop between the manifold elbow and the mixing elbow for now.

There is nothing, absolutely nothing, like working with stiff, 2" exhaust hose in a tight, confined space .

 

[Garbonzo]

And that is the truth. I presume that the loop is not high enough and allows water to siphon back into the exhaust. Caught it very soon, and in fresh water, so no harm done. But man what a kerfuffle it caused.

This old Yanmar is one tough beast. Having not run for 20 years, and started right up. Had to switch alternators (to a Compass Marine solution), replace the gaskets in the heat exchanger, redo the fuel line and put in a couple Racors and now resolving this unexpected exhaust issue. Pushes this Colvin Gazelle at 6-7 knots easily with only 24 hp. The restoration continues.

This is a great group. Thanks.

 

[Ralph Johnstone]

This old Yanmar is one tough beast. Having not run for 20 years, and started right up.

So I guess we can write off all this crap about careful annual maintenance on our engines if yours performs that well after 20 years of neglect ?

What I could be doing with all that extra free time I previously spent on maintenance..

 

[Garbonzo]

So I guess we can write off all this crap about careful annual maintenance on our engines if yours performs that well after 20 years of neglect ?

What I could be doing with all that extra free time I previously spent on maintenance..

I will have to say, while the engine did sit for 20 years, it appears it was well fogged, and the whole boat was shrink wrapped for that whole period. Sitting in the humid atmosphere of mid fla. didn’t help and took a bit of a toll on the rest of the boat, but after 5 months of dedicated effort, she in the water and running.

gotta save up for sails now..

 

[Garbonzo]

1984 Colvin Gazelle

 

[Ralph Johnstone]

it was well fogged,

A diesel engine can't be fogged as the engine will launch itself by burning the combustible fogging material. I have been looking for years for something to use but nothing to date.

If your previous picture is the boat which contains the engine, I could see myself being broke and destitute in very short order with all of the work I would undertake to return it to its original grandeur.

WHAT AN ABSOLUTE BEAUTY ! ! !

 

[Garbonzo]

A diesel engine can't be fogged as the engine will launch itself by burning the combustible fogging material. I have been looking for years for something to use but nothing to date.

If your previous picture is the boat which contains the engine, I could see myself being broke and destitute in very short order with all of the work I would undertake to return it to its original grandeur.

WHAT AN ABSOLUTE BEAUTY ! ! !

Fogging can happen if you pull the decompression levers while you turn over the engine and spray fogging oil in the intake, and then stick a rag in the intake.

 

[Ralph Johnstone]

Fogging can happen if you pull the decompression levers while you turn over the engine and spray fogging oil in the intake, and then stick a rag in the intake.

I can see it now ........................ standing in front of the running engine, barefoot with a rag between in my teeth and a fogging can in my mouth. Squirt the fogging can into the air intake, open the decompression levers with my toes, jam the rag in the air intake with something and hope nothing goes wrong.

What you say is absolutely true, in theory, but I'm going to pass that one by right now while everything on me is still intact .

 

[RoyS]

If you put a rag in the intake, tie the start key to it.