Friday, April 11, 2008

FW: Guilty Siphon breaker!

a brand new diesel filter that leaked

Townsville this morning. No wind

Msgnetic island shores (just to change from engine pictures!!!)


Any one knows how many pulses a Bosch 24V alternator produces per engine revolution ? The old tachometer was using oil pump rotations and had to be replaced by a pulse-based tachometer that plugs into the alternator. Calibration was rough! How many revs does this engine sound!!!


Wet exhaust with no siphon. BAD.


wet exhaust now with siphon 65 cm above the waterline, hopefully better once  have replaced the siphon breaker.


brand new Bukh engine. The 40 years old one got killed by the siphon because of age, this one made it through the leak. Regular oil checks throughout running the engine are a must to detect warning signs early

The siphon, or more exactly the siphon breaker, It’s the guilty one in the system and my lack of systemic analysis to put the finger on the problem!. Headed out with a brand new engine this morning, did a routine oil check to only discover that water had come into the oil again. Pure Milk!! I nearly fainted. Could just have been a bad nightmare and I was just going to wake up (7am!) but it wasn’t... Arrgh.

After 4 oil changes (pump the oil completely, including the sump and run the engine for a few minutes to cycle the new oil through), the engine was confirmed to be OK. Stock up on cleaning rags, plastic bags and engine degreaser!!! Lucky the Bukh is an old really tough construction and could take a few dents for a short time (according to the agent), it did. Another guy at the marina ceased his Volvo engine for the same siphon breaker failure reason. Result: complete replacement. A Kubota engine probably wouldn’t have stood to water going in, so it was lucky. Milky Oil had clogged the oil pressure gauge so it took a clean with kerosene to get it running again but all came up fine after the cleaning and 150$ of oil for flushing, spent in one day! Boats.

What happened on the KUNA: relative height of exhaust siphons


Explanation: The way the siphon breaker was set with the previous engine (just 6 inches above water line, just after the water pump and before the block inlet) seemed to just work OK for 16 years. So what changed ? The waterline. The boat is fully loaded with camera gear and 700 L of water, the siphon was not high enough and the breaker valve failed as it stuck to the top and didn’t let air in when it should have. A better alternative is to have a permanent hole on the top of the siphon and hook it to a small pipe which lets water down wherever convenient. If there is water coming out of that little pipe, it means the breaker hole is working OK. It is also a way to monitor that cooling water is running through the engine It is now placed above my head, but the siphon breaker model shown needs replacement due to valve failure!

Shame 3 knowledgeable diesos had checked the whole system after the installation before we headed out, not pointing that detail out! Bugger!


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