replacing yanmar 2gm20 mixing elbow

[don z]

the last time my yanmar 2gm20 mixing elbow clogged, i had the yanmar guy change it. this time, i want to do it myself. if i remember correctly, the union between the elbow and the exhaust manifold is the kind of two-directional screw that pushes the parts apart or pulls them together as you turn it with a wrench. when installing a new mixing elbow, do the threads need to be coated with pipe dope or tape? if so, what kind? also, what about the little elbow fitting that connects the raw water hose to the elbow? does it need to be pipe doped, and with what kind. lastly, can these things be cleaned out? if so, what's the best way?thanks!

 

[s sauer]

Exhaust Elbow

For do-it your self work, 1st make sure you can get into the space above & behind the engine to do the removal, particularly if you are a big guy.To remove the flexible hoses, start by using a little 'PB Blaster' on the exhaust hose sealant connection to the bottom uf the 'U' shaped portion of the exhaust elbow; same thing for the flexible hose connection at trhe nipple into the 'U'. Use a couple thin screw drivers to work down into the joint without tearing the hose.Second, remove the four bolts that connect the flange on the upright 'elbow' to the back of the engine exhaust manifold. Scrape off the old compressible gasket material and get a new one for the re-installation.The flange and upright elbow connects to the 'U' shaped water inlet chamber with that thin walled left hand-righthand threaded stainless connector. If they were put together with anti-sieze compound they may actually come apart ok.If not, you may want to take the whole 3 part asembly to an automotive shop where they'd have large enough vise and wrenches to separate the three pieces.At that point, the flange and elbow are usually re-useable; the left hand-right hand connector is reuseable if it isn't damaged in removal. The brass nipple on the 'U' shaped water inlet chamber can easily be cleaned; however, the two sided compartments of the 'U' shaped piece can be heavily coked up. I used a chisel and commercial grade wire brush fitting on a variable speed drill to clean one out. It may be cost effective to buy a new one.Put all metal pieces back together with antisieze compound on the threads. Use an appropriate (temperature range) gasket sealer on the hose connections, and a new exhaust gasket on the flange at the exhaust mainfold. Putting it back is the easy part! Good Luck!

 

[Warren Milberg]

Nice post, Stewart

I have yet to do this task on my H28.5 Yanmar 2GM20F, but expect I will need to do so some time in the future. As I know you have an H28.5 too, how did you manage to gain access to the starboard/aft end of the engine in order to use the tools to remove/replace the elbow?

 

[John11936]

elbow

I changed my mixing elbow a couple of years ago on my 28.5 Had to remove the board between the starboard lazert and aft compartment. Then remove to panel of aft engine compartment. You will have to cut the sound insulation on this panel on both corners. Easey access, and had no problems changing the elbow.