Yanmar 2QM20 Exhaust part - help

[hertfordnc]

It was a gorgeuous day, three guys underway for an overnight sail around Albemarle SOund. All trips for me begin with a bridge opening. We were approaching the open bridge, past the point of no return when there was a distinct and unpleasant change in the engine sound. A quick peak over the stern- no water discharge. Sure would love to shut it down but I really need to clear this bridge first and I can't anchor underneath it. We cut the engine after the bridge and tried to get a sail up. We weren't really ready to sail so that was a bit hectic as some things were still battened down from recent storms.

Anyway, we sailed across the river and dropped the hook. Didn't take long to find the problem.

See the photo. What is that big hunk of iron with a water line going to it and what does it do?

Thanks

[Giulietta]

Hert..

I think your water pump impeller is damaged..happens frequentely on Yanmar, and I allways carry one or two spares (relatively cheap)...and easy to change..

The cooling water pump intake has a rubber impeller, that has a brass or steel fitting tthat attaches to the engine...that ruibber will in time lose the bonding (vulcanisation??) and the center of the impeller rotates but the rubber impeller does not...

Open the water intake (make sure you close the intake valves), and look at the impeller..without letting the engine start, crank it up and see if the impeller rotatates..if it doesn't..there you go...

If it does, then its somethng else.

Alex

[hertfordnc]

I always carry spare impellers. We checked that first. Then we followed the path of the cooling water by handcranking the engine and we found it running out of the big rusty thing in the picture. The hole in the bottom is about three inches across.

There is a water line that goes into the top of the big rusty thing with the hole in it.

In the photo I have unbolted it from the exhaust manifolt but I ran out of time to get the hose off and I could not get it out enough to photograph the hole.

Thanks

[Rockter]

That is the exhaust elbow by the looks of it. They should not be too expensive.
Hert : pls be careful, that is an obvious one. The water line going into it is to cool it. The water line carries your coolant supply after it has cooled your motor.

[Giulietta]

Hert, Ah..OK..

Maybe then the heat exchanger is pierced?

The heat exchanger is a part that has cooling water inlet and outlet on one side, and then sea water inlet/outlet on the other side..

Appart from that, sorry but I can't help anymore. Give Yanmar a call..I call them once in the US and they were really helpfull with me..and I did not buy the engine from them..they have a tchnical department that has really nice folks working there...they helped me right away.

My prevuous engines had a sacrificial anode built into a bolt that you would put inside the exhaust section on the heat exchanger..Yanmar engines (at least mine), doesn't have anodes or any sacrificial itemns in the exhaust system...which I found weird...that is why I called them...but hat is the way they make them. They said because I have a saildrive and the rest is plastic...well..not really sure in the long run...time will tell

[hertfordnc]

OK, this is starting to make sense. There is some confusion about nomenclature and function that I am trying to clear up.

I googled around to figure our what I was dealing with and found conflicting terminology.

Some refer to an exhaust elbow, a U-shaped thing of light construction that goes near the discharge to keep water from backing into the engine.

Some places showed an "exhaust riser", made if cast iron, coming from the back of the manifold and pointing up into a U- to keep water from backing into the engine.

I don't have that. My exhaust riser points down and goes directly to a very heavy hose and over the side. There is no U-shape to prevent water from coming in but it is a couple feet down from the engine to the discharge.

Thanks

[Giulietta]

Hert..if you go to VETUS dot com, you can find around page 168 or so of their catalogue several water locks and mufflers...see what system is yours.

But now..I'd really give Yanmar a call...it's easy and they solve the problem right there and then...they are really nice..and may save you a lot if you have something wrong in there...

No matter what we can say and help here (there are some really good experts here), nothing beats Yanmar...

[trantor12020]

hert, what you have there is a mixing elbow. is comes in straight length that angles down 45deg or an inverted U. normally the mixing has two chambers, one for the exhaust gas and another for the colling sea water. both are mixed before leaving the elbow to the exhaust hose. your mixing elbow could be corroded such that it blocks the water flowing and also restrict the exhaust coming out. replace it with new and that usually solve the problem.

[AUBERGINE]

TRANTOR IS correct i have same motor and replaced same part this year, its called an exhause mixing elbow and its about 90 bucks, get the gasket also ... its copper. the 45 degree elbow screws on to the thing you unbolted, if you cant unscrew it because of rust ask the parts guy for that piece also. so you need 3 parts. bolt the base peice to the manifold and then screw on the elbow with some thread teflon tape. then clamp the exhause hose to it then to the muffler that was my sequence should be same for you.

BTW i am fixing my old engine and i have a push pull stop lever that i dont know how it works can you tell me how you shut down? is it a pull swtich or just throttle back. also do you key start yours or push button start yours.

[camaraderie]

Ditto the two last posts. It also looks rather clogged with soot and you may have had restricted output. Did you unbolt it from the engine or did it fall off?? Hope the former or you have a bigger problem with the bolts and threaded section.