I have a 1990 Mercruiser 3.0. I was out on the water on Sunday, boat ran great was out for about three hours or so, No strange noises or anything never even ran at WOT-lots of no wake area and just cruising. I retrieved the boat and pulled the plug and motor oil begins to flow out. I closed the drain and cleaned up the oil real quick and dragged her home. I wound up draining about 2 quarts of oil out of my bilge. You might ask how I did not notice this and I will respond "good question" I feel like an idiot.
I found that the oil was coming out of the breather hose that comes from the valve cover to the spark arrestor. There was no water in the oil so the level had not gone up. The dipstick read nothing after I realized I had the problem. I did some research and found that my symptoms were blow by. The amount of oil leaked is more than I have seen anywhere on line but the situation is the exact same. Got the boat home and yesterday went out and a compression test. All cylinders are between 145 and 155 psi. I started the boat up and rand it up to temp. The blow by did not happen but I didn't give it more throttle seeing as I was on the muffs. From what I have read it presents itself at higher rpms. From there, ran a leakdown test. All cylinders were less than 20% except 2. There is a steady flow of air from the carb when I hook up the hose 0 pressure builds up; This indicates to me that the rings are OK but that an intake valve is stuck open. Now questions.
1. Is the amount of oil that was in my bilge blow by? Seems like a lot from what I've seen in other posts.
2. Is it even possible to have a good compression reading if a valve is stuck open? How am I getting 150 psi on #2 cylinder if it won't hold 50 psi on my air hose?
3. Have I interpreted the results of the leak down properly?
4. Is it possible that motor pumped all that oil from the pan into the valve cover through the intake valve and still ran? Seems like oil would have fouled the carb and stalled?
Looking for any opinions/knowldege on this. I'm going to pull the cover and likely the head today so any thoughts are welcome as soon as you have them.
Thanks a ton guys!
I found that the oil was coming out of the breather hose that comes from the valve cover to the spark arrestor. There was no water in the oil so the level had not gone up. The dipstick read nothing after I realized I had the problem. I did some research and found that my symptoms were blow by. The amount of oil leaked is more than I have seen anywhere on line but the situation is the exact same. Got the boat home and yesterday went out and a compression test. All cylinders are between 145 and 155 psi. I started the boat up and rand it up to temp. The blow by did not happen but I didn't give it more throttle seeing as I was on the muffs. From what I have read it presents itself at higher rpms. From there, ran a leakdown test. All cylinders were less than 20% except 2. There is a steady flow of air from the carb when I hook up the hose 0 pressure builds up; This indicates to me that the rings are OK but that an intake valve is stuck open. Now questions.
1. Is the amount of oil that was in my bilge blow by? Seems like a lot from what I've seen in other posts.
2. Is it even possible to have a good compression reading if a valve is stuck open? How am I getting 150 psi on #2 cylinder if it won't hold 50 psi on my air hose?
3. Have I interpreted the results of the leak down properly?
4. Is it possible that motor pumped all that oil from the pan into the valve cover through the intake valve and still ran? Seems like oil would have fouled the carb and stalled?
Looking for any opinions/knowldege on this. I'm going to pull the cover and likely the head today so any thoughts are welcome as soon as you have them.
Thanks a ton guys!
