Yanmar 3YM30 Help

Sep 24, 2020
5
Marlow Hunter 31 Redondo Beach
Just had my yanmar serviced (oil, filters, impeller, etc.). 300 hours and running well. After first trip out since service, I decided to recheck oil (cold and warm) and just make sure everything was in order. All is good.

Except, I noticed a black zip tie that snapped...looked like it was retained near/around the exhaust elbow and the coolant reservoir. Mechanic said he didn’t notice it, but doesn’t think it’s needed.
My only thought is that - as my floating dock condo (it’s a 2015 Hunter) - it’s a cramped engine bay and perhaps one of the exhaust hoses was getting too close to the elbow and the zip tie was there to keep it off?

Any ideas?

bonus question - what’s this clear pvc tube for that you see just below the elbow? It appears dry but seems to lead/drain to the sail drive/bilge.

I’m new to diesels - my prior sailboat had a kicker outboard and that was it. Trying to learn as much as I can so I can enjoy the boat but also be safe and keep her in great condition. Thanks in advance for listening and for any ideas.

jeff
 

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NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
That zip tie holds the engine to the boat!! Ha just pay attention to your engine and you will see. Sail relax and be observant. Before I leave I always look at my engine. After about 15 minutes I look at my engine. If I’m still motoring after 30 minutes I look but am not happy. And if I have to power all day I check every now and then. Point being is just keep an eye on things and you will see what needs to be done.

Good luck!
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Uuhhhh, wouldn’t both ends of the strap be retained if it had been set/tightened? One end is attached, the other end would have been in the “jamb cleat”
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Photo is a little hard to see but from what I can see, the clear vinyl tubing is the sea water supply to the mixing elbow.

Mixing Elbow.jpeg


If, and only if this is correct, I would advise getting to your boat within the next five minutes and closing the sea water thru-hull if you haven't already closed it as a regular safety procedure. Next, I would not start the engine again until you have replaced it with a proper hose for below water service such as a wire wound wet exhaust hose. Cheap, clear vinyl tubing has no place on a boat, let alone below the water line.

As far as the broken zip tie goes, you're the best judge to determine if it was intended to keep an unknown hose away from the mixing elbow. Take a look when the engine is in gear and idling. This should be about as rough as the engine runs. See if there's any chafing problems. Maybe next try running the engine up to full RPM in gear and see if any problems exhibit themselves.
 
Sep 24, 2020
5
Marlow Hunter 31 Redondo Beach
It’s a sail drive...so there’s no typical thruhull for cooling. There is a small shut off valve on the SD unit for when you need to replace the strainer for the seawater that comes in from the sail drive unit.
Based on researching other posts, I think this could be an engine coolant drain tube...
 

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RoyS

.
Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
Zip tie found a concern? You are in a different universe than I am. I keep a small container below that I call the "Lost and Found". Into that container go all kinds of loose items discovered adrift on board. My boat is forty years old and things turn up that may have been lost when Eisenhower was President. Anyway, when something is discovered missing on the boat, the first place I look is the "Lost and Found."
 
  • Helpful
Likes: jssailem
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
It’s a sail drive...so there’s no typical thruhull for cooling.
In looking at your engine, you've got to wonder what keeps your rubber exhaust hose from bursting into flames. Hot diesel exhaust (around 1,000 deg. F.) enters the elbow and requires cooling water to cool it ............... lots of cooling water.

DSC00493 Detailed.JPG


Above is a discarded mixing elbow which I sectioned some years ago. It shows the route of exhaust gasses and sea water. The sea water has cooled the glycol coolant in the heat exchanger and its final job is to cool the hot exhaust gasses before being discharged overboard. Yours is the same until someone with a 3YM30 offers up an alternate flow pattern.

Based on researching other posts, I think this could be an engine coolant drain tube...
Yes, of course it is. It's either a drain tube for glycol coolant or a heat exchanger sea water drain. How is that possibly a hazard to your boat ? It has nothing to do with with the cheap, clear, vinyl hose carrying sea water to your mixing elbow. Right now, it's sitting there planning how to sink your boat :yikes:. This is what you want carrying sea water anywhere in your boat:

Sea Water Flow.jpg

If your engine mixing elbow is below the water line, you'll want a vacuum breaker to avoid filling your muffler and cylinders with sea water. Mine is well above. All hose fittings SHOULD be double clamped. Yanmar fittings are too short to double clamp hence the single clamps here.

Please get yourself a shop manual for the Yanmar 2YM30 and read it cover to cover and don't put it down until you have it memorized and understood. There may be a copy sitting in this site under boat modifications.

Ignorance is NOT bliss in boating.
 

NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Photo is a little hard to see but from what I can see, the clear vinyl tubing is the sea water supply to the mixing elbow.

View attachment 185300



If, and only if this is correct, I would advise getting to your boat within the next five minutes and closing the sea water thru-hull if you haven't already closed it as a regular safety procedure. Next, I would not start the engine again until you have replaced it with a proper hose for below water service such as a wire wound wet exhaust hose. Cheap, clear vinyl tubing has no place on a boat, let alone below the water line.

As far as the broken zip tie goes, you're the best judge to determine if it was intended to keep an unknown hose away from the mixing elbow. Take a look when the engine is in gear and idling. This should be about as rough as the engine runs. See if there's any chafing problems. Maybe next try running the engine up to full RPM in gear and see if any problems exhibit themselves.
That hose is not clear. It looks to me like a proper reinforced black hose that has faded grey. My guess. Watch you engine and you will figure it out. Just make sure wires aren’t hanging on the engine or in the belts.....
 

senang

.
Oct 21, 2009
304
hunter 38 Monaco
That clear vinyl hose is most probably coming down from the siphon break in the seawater hose going from the heat exchanger to the exhaust elbow. That siphon break should be high above the engine in order to keep it well above the waterline (also when boat is heeled). The siphon break valve occasionally will leak saltwater that you don’t want to drop on top of your engine. The other end of that hose goes somewhere in the bilge to get rid of the small quantities of saltwater.