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Old 26-07-2020, 09:03   #46
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Re: Yanmar Tips

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Originally Posted by Wotname View Post
AFAIK, al D1-30 engines are coolant cooled rather than raw water cooled. If so, then the VP thermostat range is correct.

The advice given by a64pilot is correct and applies to raw water cooled engines only.
Thanks Wotname, Just learning and trying to understand how diesels and their systems work. So the raw water going through the heat exchange core in the D1-30, to help keep the coolant below a certain temperature and also cool the exhaust gas, would never reach a high enough temperature where the salt would separate due to overheating. Do I have that somewhat correct?
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Old 26-07-2020, 16:47   #47
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Re: Yanmar Tips

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Originally Posted by Newf1 View Post
Thanks Wotname, Just learning and trying to understand how diesels and their systems work. So the raw water going through the heat exchange core in the D1-30, to help keep the coolant below a certain temperature and also cool the exhaust gas, would never reach a high enough temperature where the salt would separate due to overheating. Do I have that somewhat correct?
I'm still learning too .

I believe you understanding as stated above is correct although I have never had to delve into the finer details of heat exchange thermodynamics. But here goes...

The cold raw water only passes once through the heat exchanger core before exiting via the exhaust injection point.

The coolant side has a temperature differential between the hot (inlet) side and the cooled (outlet) side.

So does the raw water side except the raw water inlet is the cooler side and the raw water outlet is the warmer side. I presume the designers know the flow rate of the raw water and size everything accordingly so the raw water outlet temperature remains below about 50C regardless of ambient raw water temperature. Especially as the whole idea of the heat exchanger is to cool the coolant to well below the ambient temperature of the thermostat.

As you can see, this is quite different to what happens in a raw water cooled engine where the raw water temperature inside the engine is going to be at least as high as the thermostat setting.

If my understanding is way off, someone is sure to come along and correct it
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Old 04-09-2020, 07:04   #48
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Re: Yanmar Tips

I have a 23 Glander Cay that has the engine, exhaust and exhaust pipe below the water line. The water appears to be filling up the exhaust tank and pushing back to the engine. I just blew up my new Yanmar.

Does anyone know how to solve this problem? Short of installing a check valve or vented loop?
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Old 04-09-2020, 22:45   #49
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Re: Yanmar Tips

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Originally Posted by Mikentosh View Post
I have a 23 Glander Cay that has the engine, exhaust and exhaust pipe below the water line. The water appears to be filling up the exhaust tank and pushing back to the engine. I just blew up my new Yanmar.

Does anyone know how to solve this problem? Short of installing a check valve or vented loop?

Who installed your new Yanmar?
This sounds like a failure in the exhaust design. I'd blame the engine installer. If it was you who installed it best to google marine exhaust design & see what you need for below waterline installation. The older Yanmar service manuals had exhaust design parameters in them but I have no idea about the modern ones.
You can use the google custom search on this forum to help
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Old 05-09-2020, 06:58   #50
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Re: Yanmar Tips

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Who installed your new Yanmar?
This sounds like a failure in the exhaust design. I'd blame the engine installer. If it was you who installed it best to google marine exhaust design & see what you need for below waterline installation. The older Yanmar service manuals had exhaust design parameters in them but I have no idea about the modern ones.
You can use the google custom search on this forum to help

Then engine is not installed yet, we know how it should be installed all designs show the engine and exhaust above the water line. That is not possible in this boat. At this point Yanmar suggests going with a larger exhaust tank to hold more water to mitigate the problem but it's only a bandaid. We might also extend the exhaust riser and make it a little higher but still under the waterline. This is really a boat design issue that maybe back in 1977 when the boat was made they didn't think about this.
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Old 05-09-2020, 07:21   #51
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Re: Yanmar Tips

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Then engine is not installed yet, we know how it should be installed all designs show the engine and exhaust above the water line. That is not possible in this boat. At this point Yanmar suggests going with a larger exhaust tank to hold more water to mitigate the problem but it's only a bandaid. We might also extend the exhaust riser and make it a little higher but still under the waterline. This is really a boat design issue that maybe back in 1977 when the boat was made they didn't think about this.
Many engines are below the water line.

As far as exhaust is concerned:
- loop the exhaust hose up under the stern coaming or in the lazarrette. Then down to the exhaust fitting. This will also prevent any wind waves hitting the stern at a dock from gradually filling the exhaust.
-If there is any room under the cockpit you can also make a riser coming off the exhaust at the engine, looping up to the underside of the cockpit floor, and then down to the waterlift muffler. This can prevent any water from a long exhaust hose from coming in.
-Calculate the water in the exhaust hose from the muffler to the stern loop and buy a waterlift muffler big enough to house that volume of water. Realistically, it usually comes down to the largest that fit's in the limited space you have. With the stern loop this really doesn't matter.
All basic stuff and done often.
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