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Ziggy · 15-06-2014, 20:01

I tried to remove and replace the U-type mixing elbow on my 3YM20 (see the picture below). But even with a 2' wrench, I still wasn't able to budge it. Is there a trick to it? Do I need to remove the manifold, put it in a vise, and take a torch to the elbow? I'm afraid of breaking something by using too much force on the engine.

gamayun · 15-06-2014, 20:29

I removed mine from the bolts on the one end and the hose clamp on the other, then took the whole assembly to a shop that used a big-a$$ pipe wrench and vice clamp. It still required about all this guy's weight to make it budge.

**roverhi** · 15-06-2014, 20:53

I tried removing the one on my 3GM30 which looks the same as yours. Couldn't figure out how to get a proper grip on it to unscrew it. Finally called mechanic. He had a huge vice on his truck. With the vice, a huge pipe wrench, heating it cherry red with an acetylene torch, and a lot of muscle, got it loose. Even for the mechanic, it wasn't easy.

Ziggy · 15-06-2014, 20:55

Quote:

Originally Posted by gamayun

I removed mine from the bolts on the one end and the hose clamp on the other, then took the whole assembly to a shop that used a big-a$$ pipe wrench and vice clamp. It still required about all this guy's weight to make it budge.

Do you recall if the thread was righty-tighty or lefty-tighty?

Ziggy · 15-06-2014, 21:00

Quote:

Originally Posted by roverhi

I tried removing the one on my 3GM30 which looks the same as yours. Couldn't figure out how to get a proper grip on it to unscrew it. Finally called mechanic. He had a huge vice on his truck. With the vice, a huge pipe wrench, heating it cherry red with an acetylene torch, and a lot of muscle, got it loose. Even for the mechanic, it wasn't easy.

Lovely! This for a part that's supposed to be "cleaned or replaced" every 250 hours...

capn_mark · 15-06-2014, 23:00

Yup, ditto on my 3GM30. Wouldn't budge, so I removed the bolts and took off the whole manifold. I took the whole assembly to a muffler shop because I figured they would have the right tools. Took 10 minutes, and I gave him a case of beer. It would have been impossible to unscrew the elbow while on the engine. Sorry, can't remember if they were left h threads tho. Good luck!

gamayun · 16-06-2014, 00:00

They were righty-tighty bolts....I have a 3GM30F.

Ziggy · 16-06-2014, 04:00

Quote:

Originally Posted by gamayun

They were righty-tighty bolts....I have a 3GM30F.

Gamayun,
Thank you. Actually, my question was about the thread on the elbow itself, where it screws onto the coupling nipple. Looking at the new one, it seemed the thread might be lefty-tighty. If that's the case, I was tightening it with a 2 foot wrench. But there's no indication in the service manual of anything weird like that.
Z

**Hudson Force** · 16-06-2014, 05:09

I agree with the earlier suggestion of removing the mixing elbow assembly at the gasket to the manifold. Once this is out, then it can be dealt with easier in a vise.

jimbunyard · 16-06-2014, 06:34

Looks like regular thread to me.

Try heating the top (female) flange of the elbow with a mapp gas torch. Acetylene would be better but mapp gas might work. Neverseize the crap out of it when you put it back.

um saudade · 16-06-2014, 07:33

As far as I know all the small Yanmar mixing elbows are left hand thread into the elbow and the stainless adaptor is a left by right nipple that should in theory allow the removal of the elbow in situ. This is seldom the case as the threads are pretty cooked together.

If you still think it to be right hand thread talk to the local Yanmar guy and have him set us all straight. I have never seen the adaptor go bad so just take it out carefully.

The apaptor does allow the removal of the hardware going into the elbow all in one place only as all the other joints are right hand thread and will not loosen as the adaptor is removed from the elbow.

Take the assembly off the manifold. I find that the judicious use of the torch at the left hand thread will usually free it up to where a reasonable size wrench will complete the job. (I think I normally use a 36 inch pipe wrench for this but you may get by with a 24 inch pipe wrench or a suitable spanner. I think the flats on the stainless nipple are about 2.25 inches and most 18 inch Crescent wrenches won't open that far.

Good luck.

**a64pilot** · 16-06-2014, 07:43

When you put the new one in, I'd use this to help avoid this in the future

Specialty Lubricants - Anti-Seize : Permatex® Nickel Anti-Seize Lubricant

Badsanta · 16-06-2014, 08:17

If memory correct the double threaded joint is left and right. In theory you could turn the joint only and it would either tighten or loosening either end without removing the elbow or flange. This is seldom the case. Remove the whole unit and take the stress off the manifold. I then used a vise and wrench but had no difficulty and used no heat.

gamayun · 16-06-2014, 12:04

Quote:

Originally Posted by Ziggy

Gamayun,
Thank you. Actually, my question was about the thread on the elbow itself, where it screws onto the coupling nipple. Looking at the new one, it seemed the thread might be lefty-tighty. If that's the case, I was tightening it with a 2 foot wrench. But there's no indication in the service manual of anything weird like that.
Z

Yep, I misunderstood. Actually, I should have paid attention to this when they took it off at the shop, but I don't know. Any Yanmar shop could answer this for you.