Yanmar Heat Exchanger

[PaulM]

Quick question. In removing the mixing elbow on my Yanmar 2GMF, for a look see, I snapped off the drain valve in the end cap of the heat exchanger . I got the end out with an easy-out. Does anyone know what size fitting goes in the end cap of the exchanger.

Thanks
Paul

[MitchM]

as i recall this valve is a specialty part . even though it looks like a standard 1/4 nut there is a long threaded specialty brass drain fitting attached to the nut. you'll need to call a local distributor like MER marine in seattle to look in the parts manual and get you the correct drain for your engine. as i recall those drain plugs are pricey about $20 apiece . yanmar HQ in ILL now refers all tech questions to your east coast or west coast distributor which is MACK BORING on the east coast. you might also try calling mack boring as their parts guys are superb..

by the way those 2GM mixing elbows have a reverse thread on them. one end is lefty loose and one side is righty loose.

[PaulM]

Thanks Mitch,
I will look in to getting the part. But, what I would really like is the size of the fitting and thread pitch. I need to clean out the threads before I put anything back. I can't run a tap in the hole until I know the size.

Paul

[Astrid]

You could probably get the thread data you need by using a thread gauge to measure the threads and try the broken fitting in your dies, if you have a set, until you find the right one, and that should tell you the stock diameter.

[PaulM]

I did contact Mack Boring. The tech there said the tread was 1/8" NTP. I compared it to the bits of the threads I remove with the easy-out (the remains of the fitting fell apart getting it off the easy-out) to the 1/8"tap. Looks right. I haven't had a chance to use the tap yet. Let you know.

[PaulM]

Got the tap in the endplate of the heat exchanger and cleaned out the threads. Very easy. The size was correct. Inserted a 1/8" brass plug with out a problem. Rather have a bronze plug so I removed the brass one.