Yanmar 2GM20F mixing elbow replacement

[dirkfr]

This is my first post, so please bear with me.
I am facing the necessity of having to replace the mixing elbow on the 1985 Yanmar 2GM20F that propels my '85 Pearson 303 when there's no wind. A couple of weep holes in the elbow and reduced raw water flow through the exhaust tell me that it's way past its life span. The double-threaded connector linking the mixing elbow to the exhaust manifold is the problem. So far it won't budge, despite generous applications of Goop and Gunk where the thread meets the manifold. Has anybody out there faced this problem and emerged victorious without seeking professional help?
Thanks in advance.
Dirk Ruemenapp, whose Pearson 303 "Loreley" is moored in Kittery, Maine.

[never monday]

the connector is stainless. Both manifolds are cast iron. The connector is also left and right thread to draw the manifolds together. Do yourself a favor and replace all three pieces.
The injection elbows now come with a raw water fitting that is straight out, not a 90* turn.

[Chief Engineer]

Replace the whole schmeer....You'll thank us in the morning.....

[Delezynski]

Dirkfr,

I am in Mazatlan Mexico and had the Yanmar shop just do a 1000 hour check on our 2GM20F. It's been about 5 or 6 years since I dropped it in. I needed a mixing elbow also. Mine was not bad on the outside, but had a LOT of corrosion on the inside. As we are heading further south I decided to replace it. The shop guy just undid the 4 bolts holding the manifold on and removed all 3 parts at once. Took it to the hop and with a bit of heat had no problem with the nut!

You need a new gasket, but for the small $ you save a LOT of time and heartache!

As long as you have that off, you might as well check out a lot of the other stuff!

We had the injectors sent off for cleaning and calibration at a local lab.
We also had the heat exchanger taken out and cleaned, the water pump">raw water pump, the fuel filters, and the valves adjusted. We also had a strobe check the actual engine speed to compare to the tach. The tacks are not real accurate and can not be adjusted, so I am making a table for mine so I can read the tach and tell the true speed.

It now sounds like a new machine!

Greg

[dirkfr]

Thanks, all!
Looks like there is consensus on including the manifold in the mixing elbow replacement project. So that's what I'll be doing.
I'll let you know how it went.

[CS27]

Being penny wise and pound foolish, I tried to clean a 4 year old mixing elbow and an 8 year old exhaust elbow (I've been told that Yanmar says the mixing elbows have an 8 year life span with the exhaust elbows being longer). Long story short, a local transmission shop soaked them in solvent overnight and ran them several times through their steam cleaner/soak tank. They came out quite clean and the shop even refused to accept any payment, but being too stupid to leave well enough alone and knowing that "the enemy of good is better" I tried to make them 'better' by soaking them in 5% muriatic acid which cleaned them well, but also removed all the outside paint and started an internal and external rusting process that is challening to reverse. I treated them with an anti rust compound that quickly burnt off (stinking up the cabin in the process) after they were reinstalled... evidently Ospho phos. acid would both treat the rust and tolerate the high temps so now I get to re & re everything again. After all this messing around including removing seized bolts and fighting an exhaust hose that melted onto the mixing elbow (tapping a long thin flathead screwdriver between the hose and the elbow was the only way to get them apart), I think you are making the right choice to follow the advice of Chief Engineer and replace all the pieces.

Best prices I could find were at:

http://www.bluewatershipsstore.com/E...nmarparts.aspx

and

http://shop.torresen.com/ships_store/

[never monday]

Originally Posted by CS27

Best prices I could find were at:

http://www.bluewatershipsstore.com/E...nmarparts.aspx

and

Ships Store Torresen

Those dealer are only allowed to sell in their areas or internationally. If you are in another area you will need to contact the local Yanmar rep.

[MangoCats]

Many years later, same problem statement... this time an '86 Pearson 303 with a big ball of corrosion where the threaded nut used to be. Wondering what the downsides of a stainless kit like this might be?

https://hdimarine.net/product/gm-kit/

[djousset]

I replaced the mixing elbow on my 2GM20F this past season and had the same question. I was advised by many, including the shop guys at the yard to go with the cast iron. Consensus seemed to be that this was not the environment for SS, perhaps because of the welds.

[MangoCats]

Originally Posted by djousset

I replaced the mixing elbow on my 2GM20F this past season and had the same question. I was advised by many, including the shop guys at the yard to go with the cast iron. Consensus seemed to be that this was not the environment for SS, perhaps because of the welds.

I seem to remember the same advice from I don't remember where... there's a lot of vibration working on those parts.

However, my Yanmar dealers are all playing "who's got this part, who's got that part" not sure how long to get them to me, weeks at least, and quoting $450+ for just the major bits, while the online stainless kit source is ready to ship, promised here by Feb 14th for less money... Tough to decide against stainless when the existing parts are a big ball of corrosion.

[Gary Mc]

It looks good to me, it is 316 SS so should last. Not a bad price either, likely less than one from Yanmar. Thinking I should do the same thing, mine is original from 84.

[Frankly]

I am about 6+ years into a 316SS ebay replacement (3GM) and a small pinhole leak in the elbow has developed. Considering that my replacement on the old CI elbows was 4 to 5 years the SS is at least as serviceable (based on a data set of one).

After I get around to pulling the SS unit will make a decision about which way going fwd. At age 80 can't hardly loose .


Frankly

[MangoCats]

Originally Posted by Frankly

I am about 6+ years into a 316SS ebay replacement (3GM) and a small pinhole leak in the elbow has developed. Considering that my replacement on the old CI elbows was 4 to 5 years the SS is at least as serviceable (based on a data set of one).

Sounds like you use yours a lot. I don't have an hour meter, but I do know we've only run about 20 gallons of diesel through our 2GM20F in the past 3 years, so... we're not out there cruising the intracoastal every day.

Replacing a part with a pinhole leak seems a lot more appealing than what I found when tracking down the smoke in the cabin to find everything corroded and cracked. I've ordered the stainless kit - time will tell, I'm only 55 so I may get to see the end of this part even with our occasional use pattern.

[Compass790]

Originally Posted by Frankly

I am about 6+ years into a 316SS ebay replacement (3GM) and a small pinhole leak in the elbow has developed. Considering that my replacement on the old CI elbows was 4 to 5 years the SS is at least as serviceable (based on a data set of one).

After I get around to pulling the SS unit will make a decision about which way going fwd. At age 80 can't hardly loose .


Frankly

Can you tell us which brand ss elbow you used/ or post a picture?. I'm just curious as i make my own. Is it a cast elbow or a welded one?
The salt water sits in the yanmar style elbows but if you make a straight pipe design with no jacket you can avoid that problem & also the problem of water dripping into exhaust manifold if it leaks.
You have to ceramic wrap it up to the water injection point
HDI marine sell cheaper ss cast 316L elbows & at your age I'd go that way.
My father raced keelers till 89 so hang in there

[Checkswrecks]

Originally Posted by MangoCats

Many years later, same problem statement... this time an '86 Pearson 303 with a big ball of corrosion where the threaded nut used to be. Wondering what the downsides of a stainless kit like this might be?

https://hdimarine.net/product/gm-kit/

Just bought the same kit last week.
Having fought with trying to replace individual pieces too many times, doing the assembly is the ONLY way to go. Yes, it'll go bad too in a number of years because the exhaust elbow on this engine model (& the 3GM) should be considered a consumable part.