Water in oil

[ajgaines]

The previous owners killed the A4 by getting water in the cylinders/oil. I got a rebuilt A4 and replaced it. After a few months I noticed water in the oil again and had to remove the engine again. The guy who fixed it up said there were no cracks in the engine.l after magnafluxing it. I had previously changed the entire exhaust hose and hot exhaust thinking the issue was the check valve in the exhaust line failing(which it did) and allowing water to backflow.

Now I'm trying to pin down what could possibly have caused it now so that it doesn't happen again because I'm guessing that was not the issue. I tried to draw the system here


The things I can think of are...
Antisiphon valve between the engine and the hot exhaust entry failure(it seems to be failed). Could this allow full backflow into the engine?
A small hot exhaust clearance because it is in the Catalina 30. There's only about 2 inches above the water entry point on the hot exhaust instead of 4 inches recommended by moyer But this doesn't seem to be an issue for other cat 30 owners.
The muffler. Maybe there's something inside that blocks the opening? I am about to remove it so I can better inspect it.
The amount of rise on the exhaust hose. Can the hose be so high that the engine can't push the water out? I made it so the hose went about as high as it could go so water wouldn't back flow from outside.


Does anyone have any other things I should check? It's also not coming from the fuel as I have a fuel water separator.

[ndutton]

Here's where I see a red flag:

The guy who fixed it up said there were no cracks in the engine after magnafluxing it.

Don't much care what somebody else says, need to make sure myself. To that end, a cooling system pressure test is in order.

[ajgaines]

They were 2 separate engines. You don't think a faulty antisiphon valve could have filled the muffler with water? I checked the muffler just now and the level was just a bit higher than the longer exhaust end

[ndutton]

Of course it makes perfect sense to be certain all the exhaust components are in good operating condition, anti-siphon included.

In a separate unrelated study I actually measured the residual water height inside the waterlift after shutdown on my Catalina 30 = 2¼" of water above the bottom of the waterlift. That calculates to roughly a quart. The results were consistent regardless of engine RPM at shutdown.

However, there is no downside to a cooling system pressure test.

[GregH]

Since happened with 2 engines, is there any possibility that this could have been cause by too much cranking and the water intake was open?

[ajgaines]

Since happened with 2 engines, is there any possibility that this could have been cause by too much cranking and the water intake was open?

I'm starting to think that this must have been the case. But I was very particular at ensuring it wasn't open until the engine was running. But there may have been once or twice where I didnt realize it was open

[ajgaines]

I reinstalled the engine with everything hooked up and started it up. I ran it about 2 minutes and then removed the hot exhaust section to look inside. Immediately I saw that there was moisture inside, especially along the top of the exhaust manifold. I looked inside the water lift muffler and the water level seemed to be right at the level of the stanpipe going out the exhaust.

So this led me to believe the only 2 possible options is that water is back flowing from the water entry into the hot exhaust pipe(jumping up 2" somehow) or there is actual water somehow making its way into the cylinders themselves.

So I ran the engine for about 10 minutes with the hot exhaust removed and the exhaust water just flowing into the bilge. I figured that was enough time to dry out everything and if there still was moisture then it was certainly coming from the cylinders. When I shut it down there was still moisture on the inside.

So is it normal to have moisture there? I would have assumed that that should be a dry environment in the hot area and any condensation would come with the cooling of that hot air.

[gregsails]

I think the block should be pressure tested first