Raw water cooling

Seastoke

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On my D6 370 the water goes out through the exhaust , so how can I tell that the two engines are being cooled.
 
Assume the exhausts are underwater or you have outdrive legs so you can’t see water flowing out? That being the case, if there aren’t tell-tales installed and the strainer lids aren’t see-through then you could try what we used to do on our KAD32’s as part of our start up routine on a previous boat, which was to touch the front plates on the raw water pumps to see if they are cold when the engines are running. Check them before you start so you can tell the difference and give them a minute for the water to flow and to cool them. We could do this safely on our engines but not sure if that is the case on the D6. Keep well clear of belts and moving parts!

Aside from that the obvious is to watch the temp guages carefully as she warms up.
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An option would be to fit one of these:

SM007D

Yes, perhaps should have mentioned that seeing as we fitted one following a forumite being unaware of an over-heat whilst on the flybridge. As an aside, the unit is currently showing a sensor error on the port engine so I need to fix it!
 
If you have clear lids on your seawater strainers you can generally see the water flowing through them.

A cheap laser thermometer allows you to check your engines and exhausts for hot spots and compare twin engine installations https://www.amazon.co.uk/Etekcity-L...pY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

You can get exhaust sensors either alarms or the one shown above by Greg2.

How old is your D6 when was the last time you inspected the water injection bend after the turbocharger?
 
If you have clear lids on your seawater strainers you can generally see the water flowing through them.

A cheap laser thermometer allows you to check your engines and exhausts for hot spots and compare twin engine installations https://www.amazon.co.uk/Etekcity-Lasergrip-Non-contact-Thermometer-58°F-1022°F/dp/B01I4TB2IM/ref=sr_1_3_sspa?crid=77UVQ39732IC&keywords=laser+thermometer&qid=1651487747&sprefix=lazer+thermometer,aps,157&sr=8-3-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyV1M3UzJLSTRaNFEzJmVuY3J5cHRlZElkPUEwNTMwMjUxMzJZWlVZTzc4N1Y1SyZlbmNyeXB0ZWRBZElkPUEwNDM0OTcwMTk3R0pQOVE0VUtZQyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

You can get exhaust sensors either alarms or the one shown above by Greg2.

How old is your D6 when was the last time you inspected the water injection bend after the turbocharger?
2008 how do you inspect , and is it because of water getting in the engine
 
When my Stbd engine overheated due to a fouled inlet fitting I fitted both exhaust temperature alarms and flow switches.

I will be fitting similar to my next boat, although the monitoring system I fitted on the last boat was a bit OTT. I will design a simple alarm box looking at both the temperature and flow warnings.

I did try a small flow switch on the stern tube cooling line, but a pal who did this had problems with the strainers within the flow switches plugging with fine debris, which would also compromise stern seal cooling. So I used a full bore (32mm / 1 1/4") flow switch from Aqualarm. Cooling Water Flow : AQUALARM, Warning Systems For Land And Sea
 
After 12 years or so the injection elbow starts to corrode and fur up partially blocking the water flow, increasing the back pressure, so reducing the cooling effect.

These are photos of my injection bends, the old and the new. My engines are Volvo Penta TAMD 63's about the same a literage and size as yours.

You can see how the water passages are starting to be heavily occluded by the corrosion and the furring up.
 

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On the D6 you need to keep a close eye on the seawater intercooler and the oil cooler which are both raw water cooled, and check for any leaks. If you are seeing crusting of the joints ordrips and leaks you need to investigate these and repair or replace the parts.

The raw water system can be circulated with Rydlyme to remove scale especially in the coolers to improve the water flow.
 
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