neil jameson
Recruit
- Joined
- Jan 10, 2004
- Messages
- 5
1994 V6, 4.3l LX 4 bbl.<br />I purchased this boat in August 2002 with 70 hrs on it. It seemed to run great and all appeared OK. In Nov 2002 I got rain water in no 5 cyl through the carb. I found it within 1 week. (went to start it and it would not crank (at all, yes I was lucky). I took out the plugs and cranked engine to get it all out. Next trip I found water in the crankcase oil so went back to the ramp and had the oil changed. The engine appeared to run great, marine mechanic gave it a clean bill of health. (40 psi oil press and 140 degree F) <br />I checked no 5 cylinder a few months later (as we had a big rain storm) and forgot to put the spark plug lead back on. I ran the engine for about 3-4 hours before finding that. The engine seemed to run fine after that.<br />I did not observe water in the crankcase oil again, I checked 10-15 mins after starting every trip. I did however, have milk build-up in the top of the valve covers (found by removing the hose to the flame arrestor) and in the hose to the flame arrestor. I cleaned this out several times and thought it was due to the wet weather and the boat being outdoors and under cover sweating. I also noticed slight steam rising from the oil filler cap (with the cap off). I winterized the motor by removing the block drain plugs, manifold/riser drain plugs and hoses to the block. I didn't fill with antifreeze as we live in Jacksonville, Florida and it does not get real cold, but does sometimes have frost overnight. On the real cold nights I put a light bulb inside the motor cover. <br /><br />We moved house and the boat has been in a garage since July 2003. <br />In Nov 2003 the engine seemed to be loosing power and as risers and manifolds were original (almost 10 years) and there was continued milk in the valve covers along with slight steam from the oil fill cap. I decided to go ahead and change both exhaust manifold and risers. <br /> <br />I completed a compression test and got 2 cylinders at 190psi, 2 at 180 and 2 at 175 psi. I figured this was acceptable. I even did it again hot, found them 5 psi higher. <br />I went ahead and replaced the exhaust manifolds, risers gaskets. I thought with the good compression that it was probably the risers. <br /><br />I put it all back together and ran it. I then saw a rusty line between the head and the intake manifold and also drops of water under the block water pump.....back into the garage.<br /><br />I removed the exhaust manifolds/risers and then the inlet manifold. The gasket had a couple of spots that looked suspect, rust stains. As I was in this far I decided to remove the heads and have them pressure checked. They checked out, no leaks and they were flat.<br />I replaced the head gaskets with original Mercruiser gaskets, and replaced the intake manifold all with new gaskets. I took considerable time to ensure all surfaces were 100% clean prior to re-assembly. I had a friend from the mobile workshop at work (Master Mechanic) supervise putting the heads and intake manifold back. He said all looked Ok. We also measured how far each piston rose up the bore, all measured the same. Each bore looked real clean, with no scores, scaring.<br />I put the exhaust man, risers, carb etc back on. I also replaced the water pump. <br />I will be using the boat in salt water considerably in the future, so with all the new parts installed I decided to put a heat exchanger on the block only. Raw water still circulates through the manifolds. <br />The kit came with a replacement 160 degree F thermostat to replace the original 140.<br /><br />On Saturday I ran the motor on the garden hose and once the timing was set got the motor to run. It seemed fine......<br />I noticed the heat exchanger block side water level dropping (approx 500ml in 10 mins) and considerable steam from the oil fill cap. This was more when I reved the engine. I let the motor cool overnight, topped it up again and ran again Sunday (hoping it was an air bubble). The level dropped again and now I have milky oil in the crankcase. I did not observe any steam/gases coming from the heat exchanger fill cap. The motor run at 160 degrees F and 40-45 psi. <br /><br />Can you please offer any advice - were to go next?
<br /><br />Chris.........