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Hello, We are running W12V32’s, and one of our engines starts to “use or lose” HT water when the engine load goes down below 80 percent. The HT water level in the expansion tank drops by approx. 5 gallons per hour. We cannot find any leaks in the cooling system, and all the valves appear to be fully operational. There are no signs of HT water jacket leaks at the cylinders via exterior inspection and no signs of water in the oil sump.
I can only speculate that the water is going into the cylinders, but my cylinder temps are not showing any variations and are perfectly in range and perfectly consistent with our other engines.
When blowing down (purging) the engine during engine offline periods, no noticeable water is expelled from the purge cocks.
Another interesting thing is that when the engine load returns to levels at or above 80 percent, the issue resolves itself within 24-48 hours. It always takes 24-48 to return to normal. In other words, the HT water levels remain constant in the expansion tank when the engine runs at 80 percent load.
We are not in a position operationally to shutdown the engine and do bore scopes to see if water is in the cylinders at this time.
Does anyone here have any ideas on why this could be happening? Or what else we can troubleshoot?
More than likely you have an exhaust seat leak. We have not been able to trace it to a cylinder by trends. The only thing you can do is shut it down and borescope.
Our engines are new and we’re new to the Wartsila world. We are suffering some of the same issues. We are leaking exhaust gases into the cooling water as well. We detect carbon monoxide in the expansion tank. Wartsila has been unable to identify exactly which head is leaking, because apparently the leak is minor. They also borescope, but they won’t tell us what they are borescoping and what they are looking for. Jeremy you mentioned borescoping the head/cylinder. Can you elaborate on what you are looking for when you borescope?
We had the bubbling issue with varying degrees of severity. In the worst case in the summer at full load it was almost disastrous, as the entire system got aerated and temps just kept climbing until it shut down or was unloaded. It was due to the cylinder head to PCC surface condition. We ran the Wartsila cleaning tool (with felt) on it, but the surface was still not clean (due to corrosion issues). We learned that we could use sandpaper on that tool, and we re-surfaced it. Afterward…no bubbles whatsoever! Did the bubbling get worse after some maintenance, like after pulling prechambers? We had actually expected the answer to be exhaust valve seals or head gaskets, but turned out to be neither. We have (5) 20V34SG engines, approx. 10,500 hrs in 7 yrs.
There are typically 2 scenarios: The first scenario is exhaust gas in the cooling system. This is typically caused by a PCC seal leak or cylinder head gasket leak. We have found major gas leaks are due to a PCC seal leak, either by PCC studs breaking or as Stephen mentioned poor sealing surface. We have also found the stiffer bronze seal rings are less forgiving to surface imperfections and don’t seal as well as the copper seal rings. These types of leaks can be found by using a jig with clear plastic tubing that attaches to each cylinder head vent tube. When you run the engine the leaking cylinder will be blowing lots of bubbles through the vent tubes.
Due to the excessive amount of exhaust gas that enters into the system you may see a drop in your coolant level, but this is due to coolant overflowing back to your maintenance tank due to being displaced by the exhaust gas in your system.
The second scenario is an exhaust seat leak. You will have glycol consumption, but little to no exhaust gas entering your coolant system. This can be found by borescoping the cylinders and looking for coolant dripping or residue on the exhaust seat pockets.
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