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Old 28-08-2008, 18:24   #1
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Boat: Pearson 303 (1985) - Loreley
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Yanmar 2GM20F mixing elbow replacement

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.

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Old 28-08-2008, 18:31   #2
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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.

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Old 28-08-2008, 18:59   #3
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Replace the whole schmeer....You'll thank us in the morning.....
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Old 28-08-2008, 19:32   #4
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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!

Our boat is our bedroom, the world has become our living room.

Greg & Jill Delezynski
Cruising aboard Guenevere
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Old 29-08-2008, 07:56   #5
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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.
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Old 29-08-2008, 20:06   #6
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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:

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Old 30-08-2008, 04:44   #7
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Originally Posted by CS27 View Post
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.

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2gm, 2gm20, elbow, yanmar

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