[edwardc]

This is going to be a longish post to catch up on what's happened outside the forum, so apologies in advance.

I was in the middle of a week long cruise. The engine had been running fine for the 1 hr it took to motor into the inlet where we docked. The raw-water-cooled A4 was running at 160 deg. This is a little warmer than usual, but I attributed that to the 100 degree air temp and 80+ degree bay water temp. The head and head gasket were brand new, installed in April of this year.

After two days in port, I went to start the engine, and it started a little hard. After 3 short cranks, I turned off the water inlet and continued trying. It started , and I opened the water. It began running rough, and would not idle. I went below and found water leaking from around the manifold gasket. I shut down and pulled the plugs, and cranked it, and got a geyser of water out of #3 & #4.

Now, the two most likely causes of water in the cylinders are backing water in through the exhaust, or a blown head gasket. Since the head & gasket were brand new, and installed by a reputable and experienced A4 mechanic, I discounted that possibility and concentrated on the exhaust. After discussing the matter with Don, his conclusion was that my system had an inadequate amount of riser, and this had allowed a siphon to start while I was docked, which filled the waterlift muffler and backed into the manifold and cylinders. His recommendation was to clear the water, as described elsewhere on the forum, and, until I could rebuild the exhaust, always start with the water off, and close the water before stopping.

Well, after 4 oil changes to get (most of) the water out of the oil, I did this. When I cranked it dry, it understandably took a while to start, but eventually did and smoothed out. But as soon as I opened the water, it began to buck and sputter, and was clearly running on two cylinders! Shut down, closed the water and pulled the plugs. Water again! And a lot of it! More geysers when I cranked with the plugs out. Since the water had entered with the engine running, there was no way it had backed in through the exhaust. It must be the head gasket! A quick thumb-on-the-spark-plug-hole compression check confirmed this. I cleared the water again, sprayed oil in the cyls again, and drained the oil again.

After getting the engineless boat back to home port (an adventure in itself), I put fresh oil in it and did a real compression check. Found #1=80, #2=45, #3=40, #4=35. Prior to this, all four had been in the 85 - 90 range.

At this point, I have a call in to the mechanic, but I'm at a loss to explain what happened. I watched the him install the new OEM head, and he did a a careful clean job, and used the newer black gasket (but only one). But now it's clearly blown. Is it his fault?

Or is it possible that the original water came in as Don suggested, and that cranking it with water in the cyls is what blew out the gasket? Or was the gasket the culprit, blowing out during my 1 hr run, and letting water in after I stopped?