MD2020 High Rise Exhaust Elbow

[theoldwizard1]

Originally Posted by Dsanduril

Go over to Defender and look at all the gooseneck and waterlock mufflers that can be had in plastic/GRP for < $200. Use the low-rise elbow in hand and install one of those if you have the room to make it fit. All designed/intended to keep out water from a following sea, cheaper than the Volvo part, and probably more effective.

Yep, this looks like a good solution !

[theoldwizard1]

Originally Posted by Riddle

Use rubber exhaust hose all the way to the stern.
Then us 90 deg stainless steel welding elbows (bends) and some pipe to first go up vertically and then to a fabricated gooseneck. (Two 90 deg bends welded together) The top of the gooseneck can go as high as decklevel or just below that.
The exhaust pipe (downleg) can of course be much lower in the stern.
Backflow impossible.
It works perfect for me already 20 years

I like this idea also ! Relatively inexpensive (SS 90° and 180° exist. I would like them made from Schedule 40 or Schedule 80 or even Inconel (if not too ridiculously priced).

[theoldwizard1]

Originally Posted by TNRivers

MESA, (Marine Exhaust Systems of AL) can fabricate a custom stainless part cheaper than you can find and buy from factory parts source. Ask for Mark.

He would have to have the old part. It is in the Dominican Republic !

[Cheechako]

I just had one fabbed up years ago. They even put in a bellows for vibration. If there are short ones that are stainless maybe start with that and weld it to be high rise?

[skipper53]

Just wathe a YouTube video by Bums on a Boat trying to solve this very same problem. Search that video for their solution

[spotfire]

I'n another Volvo diesel owner who has suffered sticker shock when sourcing parts.



This company is located up here in the PNW, and they supply stainless risers Cheaper than volvo, and the last one you will need. If what you want is not on the webiste, send them a picture and they will offer a solution. Most of us up here have been pleased.



https://hdimarine.net/?s=md2020&post_type=product



Good luck.

[theoldwizard1]

Originally Posted by skipper53

Just wathe a YouTube video by Bums on a Boat trying to solve this very same problem. Search that video for their solution

That is who I am working with ! They don't have a good solution ... YET !

[coopec43]

Originally Posted by theoldwizard1

Yep, this looks like a good solution !

I really think you should get an expert to design and install your exhaust otherwise you could end up destroying your engine.

I followed this guy's (SeaBoard Marine) advice meticulously when I installed my exhaust and it works as I hoped it would.

https://www.sbmar.com/articles/desig...xhaust-system/

[Uncle Bob]

Originally Posted by theoldwizard1

Yep, this looks like a good solution !

The second diagram is how mine is fitted, works really well and if you are still concerned about following seas then a simple rubber flapper on the end of the exhaust will stop the bulk of any water attempting to enter

[jimbunyard]

Two of the problems with doing away with the riser and replacing it with a riser in another place is that you have to reconfigure the entire system, and that the volume of water contained in the system may cause backflow into the engine even without a following sea's impetus.

Couldn't find a dimensional drawing, or even a photograph of the replacement 3884165 elbow Doug recommended, but, depending on the actual dimensions, it looks to me like, with the addition of the straight boot pictured below, it might be the best solution. A source for this straight boot is

https://www.parts4engines.com/perkin...nger-end-caps/

Might also be possible, if clearances allow, to turn the existing 90 degree boot 180 degrees, put a 90 into the exhaust elbow water inlet port, and connect the two with a rubber hose.

The original 1000.00+ riser is cast iron junk, at best it should be viewed as a (very expensive) consumable. If the 3884165 elbow is indeed bronze, that alone helps make it a choice that should be considered. At around 600.00, whilst still expensive, I think it'd be hard to have one custom-made in stainless, and I don't believe they are available from stock, but would be happy to find out I'm wrong.

By the way, I made the riser for my MD2020 from 316 schedule 40 elbows and pipe, with copper tubing wrapped around it for cooling. Looks a little Rube Goldberg-y, but is works very well, you can put your hand on it with the engine under load, and it keeps the things that destroy stainless, high heat and hot salty water, from coming into contact with each other. Unless you can weld or have a friend that can and owes you a favor, this probably isn't an option, since the time required to build one makes even the 1000$ original's price (almost) competiitive. If I remember correctly, cost for materials was 150.00, but it probably took about 15 hours to build...

Couldn't find a picture of the one for the MD2020, the one shown is for a Universal M25, but the principal is the same.

[coopec43]

Originally Posted by jimbunyard

Two of the problems with doing away with the riser and replacing it with a riser in another place is that you have to reconfigure the entire system, and that the volume of water contained in the system may cause backflow into the engine even without a following sea's impetus.

Couldn't find a dimensional drawing, or even a photograph of the replacement 3884165 elbow Doug recommended, but, depending on the actual dimensions, it looks to me like, with the addition of the straight boot pictured below, it might be the best solution. A source for this straight boot is

https://www.parts4engines.com/perkin...nger-end-caps/

Might also be possible, if clearances allow, to turn the existing 90 degree boot 180 degrees, put a 90 into the exhaust elbow water inlet port, and connect the two with a rubber hose.

The original 1000.00+ riser is cast iron junk, at best it should be viewed as a (very expensive) consumable. If the 3884165 elbow is indeed bronze, that alone helps make it a choice that should be considered. At around 600.00, whilst still expensive, I think it'd be hard to have one custom-made in stainless, and I don't believe they are available from stock, but would be happy to find out I'm wrong.

By the way, I made the riser for my MD2020 from 316 schedule 40 elbows and pipe, with copper tubing wrapped around it for cooling. Looks a little Rube Goldberg-y, but is works very well, you can put your hand on it with the engine under load, and it keeps the things that destroy stainless, high heat and hot salty water, from coming into contact with each other. Unless you can weld or have a friend that can and owes you a favor, this probably isn't an option, since the time required to build one makes even the 1000$ original's price (almost) competiitive. If I remember correctly, cost for materials was 150.00, but it probably took about 15 hours to build...

Couldn't find a picture of the one for the MD2020, the one shown is for a Universal M25, but the principal is the same.

Why would you need " with copper tubing wrapped around it for cooling".

Doesn't the injected water keep it cool?


I used a Vetus Waterlock and a Vetus gooseneck and took the exhaust out through the side of the yacht (too dangerous going out through the ransom)


FIRST SHOT Water injection then into the Vetus Waterlock


SECOND SHOT Waterlock



THIRD SHOT Vetus Gooseneck and exhaust out to the side of the yacht


The other corrugated hoses are mostly cockpit drains

[Scubaseas]

The boat is in the DR. They have a low riser manifold already. They have limited funds. If they use the below water line as below all they need to do with the parts they have is buy a vented loop and some hose. all locally available and put the vented loop between the raw water pump outlet and the heat exchanger raw water inlet. If you run a hose out the top of the loop you can see if your water flow is OK just like on an outboard. Volvo recognizes this way of configuring the system. It doesn't matter where on the raw water side you have the vented loop but since their motor is at or slightly below the water line they need to follow the right side diagram.

[Scubaseas]

Looking at their video at 13:09 looks like they already have the air vent on the raw water pump to heat exchanger as I described. They state they have a water lock muffler and a previous video shows their exhaust pipe well above the waterline. So all the need to do is use the low rise elbow they already have and they're done. They need a hacksaw to cut the exhaust hose down about an inch or so. They are a lovely couple with tons of enthusiasm but not a lot of practical knowledge.

[jimbunyard]

Originally Posted by coopec43

Why would you need " with copper tubing wrapped around it for cooling".

Doesn't the injected water keep it cool?


I used a Vetus Waterlock and a Vetus gooseneck and took the exhaust out through the side of the yacht (too dangerous going out through the ransom)


FIRST SHOT Water injection then into the Vetus Waterlock


SECOND SHOT Waterlock



THIRD SHOT Vetus Gooseneck and exhaust out to the side of the yacht


The other corrugated hoses are mostly cockpit drains

The copper tubing cools the pipe before the water injection. After water injection, the exhaust is 'cooled' enough so that it doesn't melt the hose or muffler, but while the roughly eighteen inch exposed section of 2" stainless pipe shown in the example might double as a good heater in the winter, in the summer it would make the cabin unbearable. Plus there is a fire hazard; the engine is mounted such that the riser is directly under kitchen cabinetry.

The original riser was made of stainless, but there was no provision for cooling before the water injection, so they wrapped it in insulation, which seals (somewhat) the heat into the pipe and wrapping, so that when the water was injected, it was injected into the very hot piece of stainless tubing welded into the exhaust tubing as a water injection nozzle. When I was removing the riser for replacement, the >1/4" wall injection tube broke off when I tried to twist the hose off.

It is my understanding and experience that stainless steel will handle dry exhaust gases with no problem, and exhaust gases mixed with salt water at relatively low temperatures reasonably well, but at a certain temperature (can't remember what it is but it's well documented, maybe 400F?) stainless looses its' corrosion resistance. If you look closely at the picture you'll see that even though the temperature at the point of water injection in the homemade riser should be less than 200F, the water injection elbow is bronze.


By the way, have you run the engine shown in your pictures? That setup would scare the bejesus out of me; on shutdown whatever water that's left in the hose is going to run down and slosh into whatever water's left in the muffler and if there isn't enough volume to cause immediate problems, I wouldn't be surprised if exhaust valve problems manifested themselves sooner than would normally be expected.

[Scubaseas]

It would be nice to see what their "muffler" looks like and what the exhaust system looks like. As in is there a gooseneck?