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PostPosted: Jun 25th, '18, 21:59 
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Lakes & Bays Skipper
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after a few trips back and forth from Phillip Island to Corinella to visit Phil we got confident enough to take a run offshore in the hope of catching sight of a passing whale. we were successful and the new engine head and valves are are ticking along nicely. now time to re tighten the head bolts and re check the tappets.

of course I got few snippets and chucked them on youtube

https://youtu.be/U7WC7jN_NcQ

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PostPosted: Jun 25th, '18, 23:22 
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Good stuff

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PostPosted: Jun 26th, '18, 00:31 
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Fantastic. That motor was purring. Good work.

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PostPosted: Jun 26th, '18, 14:29 
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still lots to work out its rough at idle but sweet with a higher revs. some of the roughness could be the new engine mounts they seem very flexible.

I've put a new digital temp gauge in with an adjustable alarm and it also has a second sensor which I haven't decided where to put it. solid running and the engine is sitting around 40 degrees water temp. I even splurged on a new thermostat I had been running without one but doubt it caused the last head to crack either way I'm not taking chances with the new head.

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PostPosted: Jun 26th, '18, 15:11 
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I'm not familiar with small diesels but I've been around marine and other engines for a living.

Working an engine with a waterjacket temperature of 40 degrees C is going to cause problems.

The combustion in the cylinder is trying to burn at well above 600 degrees C to be efficient, the cold cylinder and cylinder head will be quenching the combustion taking heat and power from the flame.

The thermostat will help bring the temperature up but my guess is you need to restrict the flow further.

On raw water cooled inboard ski boats, we did not use a thermostat we just throttled the water pump flow manually adjusting it to get about 80 degrees C which was rough ut worked alright on the petrol engine.

In your case I'd believe a similar restrictor on the outlet of the raw water pump would assist control. The restrictor would be set manually to raise the engine temperature a few degrees below the operating temperature per the engine specification. Then the thermostat could be put in the water outlet to provide proper temperature control.

As is, the cold engine will be effecting idle so getting the whole lot up to a good operating temperature is important.

As water flows reduce to keep the engine at temperature, the wet exhaust temperature will rise. If you can't maintain a wet exhaust (excessive steam), you may need to bypass water from the raw water pump instead of just restricting the flow.

For heavy duty marine applications, strainers and devices to keep the water in the engine clean. It does not take much to block a thermostat.

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PostPosted: Jun 26th, '18, 15:18 
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I forgot to mention working an engine with 40 degrees C water temperature will introduce thermal stresses that could cause a cracked head. The hottest part of the head near the exhaust valve is the most likely place for thermal cracks to occur.

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PostPosted: Jun 26th, '18, 21:21 
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INMA wrote:
I forgot to mention working an engine with 40 degrees C water temperature will introduce thermal stresses that could cause a cracked head. The hottest part of the head near the exhaust valve is the most likely place for thermal cracks to occur.


thanks I'll have to look into it further I believe the engine is way hotter than the cooling water. after an hour or so I can't hold my hand on the sump its way to hot. I believe the thermostat set up on this engine is installed in a by pass that cools the engine rather than allows it to get warmer. I could be wrong but even when the bypass was completely blocked by weed and other **** the engine ran similar temps but I have never had a temp gauge before so not sure.

the old temp sensor had all the pins broken off so I replaced it with a brass plug and ran a stainless bolt through it for the sensor to connect to. I might move the sensors to the block and see what its doing because definitely feels hotter than 40.

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