yanmar diesel 4jh4 hte I did a stupid thing

[jimbeam]

I did a very stupid thing. I started my engine and forgot to open the seawater intake. Engine overheated and black smoke. limped back to marina and realized it was closed so I opened it and burst the exhaust pipe just below mixing elbow. It is a round gray plastic piece and is pretty large. I can't find the part anywhere and I don't even know what it is called. Anyone know what this thing is? it's all plastic and gray. Kinda looks like a large muffler. Part does not show up on any engine diagram for the 4jh4 hte. I know I got to change the impeller and make sure it did not get destroyed. Talk about screwing up. I'm probably gonna pay thru the nose for this.

jimbeam

[danstanford]

Trying to imagine how opening the thru-hull would impact the muffler unless she was running when you did that.....and that the impeller was still pushing enough water through the heat exchanger to get to the elbow and muffler.

Perhaps the muffler has overheated and burst due to the extreme heat due to no water flow to cool the exhaust.


At first thought, opening the seawater thru-hull was coincidental to the muffler problem.

I forgot to open mine once and over heated but the overheat alarm warned me before too many bad things happened and I just had to replace the impeller and find all the pieces of vane in the system.

[Rumrace]

The exhaust connection is or should be silicon or TPU. It’s at its temperature max when the engine is pumping water.
Contact the boat manufacture to find the part. It’s not a Yanmar part on pleasure craft.
You should have an alarm and if you don’t they are easy to make with a few parts from the electronics store.
Lots of us make mistakes get home safe is All that counts. I print lots of boat parts but can’t help you on silicone and my TPU can’t handle the heat If you get stuck I can print a mould you can take to a caster. Better you find the part.There are large silicone hoses you could substitute a piece. 4 new clamps wash the fibreglass around the port if any it’s like likely loaded with exhaust acids

[Sailmonkey]

Does it look like anything at this link?

https://www.google.com/search?q=vetu...&bih=552&dpr=2

[jimbeam]

That is it, a waterlock. Thanks sailmonkey

[RaymondR]

Did it myself a couple of times before I learned to take the ignition key out and hang it on the valve handle any time I shut the water off.

[grantmc]

Waterlocks are designed to 'fail'. They melt with hot gas. The idea is that the waterlock is cheap and motors aren't. People will notice the issue before the engine is damaged. And yes there are many assumptions in such a design, but for a typical little keeler with an engine underneath the cockpit floor, if the water lock fails you'll be quickly aware something awful has happened as there'll be massive amounts of steam and in fact it has the appearance of a smoke from a fire. Actually it's just the residual water in the lock being ejected under pressure, as steam, where the melting has occurred.

Downside is of course that when the water is coming through again, the water isn't being ejected back in to the sea. I guess without realising the issue you could be pumping a great deal of water in to the boat.

OP I would also replace the exhaust hose connecting the motor to the waterlock as it will likely also have been degraded.