Hey all, I'm new to this forum, although not altogether new to it's contents... I have a 1995 Mercruiser 4.3lx 4bbl v6 I/O. I've had it out three times this year, only to come home and find milky oil on the dipstick.
I pulled all the spark plugs and did a compression test. On the starboard side I had roughly 150 psi to all cylinders. The spark plugs looked as they should. On the port side I found water on all three plugs, with compression as follows, front to back: 175 (water sprayed out when I released the pressure), 120ish, 145ish. All three cylinders had some amount of water in them, with the most in cylinder 1.
I tore it down and replaced the head gasket, both intake gaskets and manifold gaskets. After changing the oil twice, I still have slightly milky oil, this has cleared up a bit with the engine running about 1000 rpm in the driveway on muffs. However when I turn off the engine and quickly drain the cooling system, then remove the spark plugs, they are wet and the cylinders have water in them. I suspect the milky oil originated from water leaking past the rings, as when I drain the system and pump the water out of the cylinders I don't notice an increase in the milkiness of the oil. Compression now is 1: 150,3: 150,5: 120(rapidly leaking to 0). inside the exhaust ports of the manifold I see a layer of milky oil/fuel dimpled with water droplets.
When I changed the head gasket I couldn't really see any signs of water leaking into the cylinders. The intake gaskets both had some breakdown near the cooling ducts, but given their lack of proximity to the intake I doubt this is where water was entering the cylinders. I've been working on this for two days, and I have exhausted every forum and post I can find that even resembles some of these symptoms. I cannot fathom how so much water can be found in the cylinders immediately after the engine was running (albeit a tad rough). Could a cracked head be spraying water into three cylinders at once? and what could have triggered the sudden change in compression to cylinder 5? As things are, the engine is hard starting, but runs quite well warm, I'm tempted to go ahead and use the boat regardless of these issues, and carefully ensuring the cooling system is drained and cylinders dry after each use.... Thanks for your help!
I pulled all the spark plugs and did a compression test. On the starboard side I had roughly 150 psi to all cylinders. The spark plugs looked as they should. On the port side I found water on all three plugs, with compression as follows, front to back: 175 (water sprayed out when I released the pressure), 120ish, 145ish. All three cylinders had some amount of water in them, with the most in cylinder 1.
I tore it down and replaced the head gasket, both intake gaskets and manifold gaskets. After changing the oil twice, I still have slightly milky oil, this has cleared up a bit with the engine running about 1000 rpm in the driveway on muffs. However when I turn off the engine and quickly drain the cooling system, then remove the spark plugs, they are wet and the cylinders have water in them. I suspect the milky oil originated from water leaking past the rings, as when I drain the system and pump the water out of the cylinders I don't notice an increase in the milkiness of the oil. Compression now is 1: 150,3: 150,5: 120(rapidly leaking to 0). inside the exhaust ports of the manifold I see a layer of milky oil/fuel dimpled with water droplets.
When I changed the head gasket I couldn't really see any signs of water leaking into the cylinders. The intake gaskets both had some breakdown near the cooling ducts, but given their lack of proximity to the intake I doubt this is where water was entering the cylinders. I've been working on this for two days, and I have exhausted every forum and post I can find that even resembles some of these symptoms. I cannot fathom how so much water can be found in the cylinders immediately after the engine was running (albeit a tad rough). Could a cracked head be spraying water into three cylinders at once? and what could have triggered the sudden change in compression to cylinder 5? As things are, the engine is hard starting, but runs quite well warm, I'm tempted to go ahead and use the boat regardless of these issues, and carefully ensuring the cooling system is drained and cylinders dry after each use.... Thanks for your help!
