Tineriver40
Recruit
- Joined
- Apr 14, 2020
- Messages
- 1
2001 Mercury 15hp 4stroke. I had just returned from a water test to ensure the carb rebuild i just completed had worked out, and everything seemed to be working just fine while on the water. Decided to change my oil after testing the carb rebuild and noticed it was frothy/milky coming out into the drain pan. Back of valves looked all nasty with milky oil all over them from what i could see with my flashlight. Drained the oil, pulled the head and thoroughly cleaned everything. Reassembled with new oil and filter. Head gasket looks fine to me, as does the head with no crack from what i could see. Ran it on some muffs that night and it ran/idled great. Took it back out on the water the next day and when i turned the throttle it produced very little power. Rpms were not sufficent either, but it would still spin up pretty high. Tell tale was streaming fine but there was excess water coming from the exhaust and prop. And as expected with all that going on there was more engine vibration than normal. With the boat back on the trailer i pulled the dipstick agin and there i saw the same frothy/milky oil as before just not as bad.
At this point I've drained the system and pulled the head again. This time i noticed after pulling the valve cover that most of the froth and milky oil was concentrated to one spot; the passage from the head to the breather. So there is water in my oil, or so i believe due to it coming out first when i pulled the drain plug. Checked my compression before draining and it was 60psi on the top cylinder and 20psi on the bottom, way off from spec i know. Im not sold on the fact that my cheap gauges always give me the best reading but when testing them with my compressor dialed down they seemed to be working. I know head gasket and or crack in the head can result on these symptoms but i don't think thats it, unless there is a crack in a water chamber underneath the valve bowls that i cannot see. I also realize that overfilling the oil can cause this, but i rechecked levels after both oil changes. There is always the option to take the head and have it checked by a shop, which i might end up doing any way. The thing that worries me the most is the froth concentration from the head to the breather. Id love to hear any and all suggestions as to what the culprit could be.
This motor has been pushing my 16ft RiverHawk skiff since 2016. I bought the motor i a sort of "salvage" condition; as in i payed a guy a couple bills for a pile of boat parts (everything except the lower unit was disasembled). He claimed "everything should be there", and he wasn't too wrong. The issue was that not everything in the pile was functioning or in working condition. After my deal with him i would end up needing a new coil pack, water pump kit, prop, carb kit, total gasket kit, oil/piston rings and every filter/hose/fitting/plug that it required.
After some time i managed to get everything i needed and ended up with a fine running motor. All this is to say i have a lot of experience with this motor, but thats just from the process of assembling it and a knack for mechanics.
At this point I've drained the system and pulled the head again. This time i noticed after pulling the valve cover that most of the froth and milky oil was concentrated to one spot; the passage from the head to the breather. So there is water in my oil, or so i believe due to it coming out first when i pulled the drain plug. Checked my compression before draining and it was 60psi on the top cylinder and 20psi on the bottom, way off from spec i know. Im not sold on the fact that my cheap gauges always give me the best reading but when testing them with my compressor dialed down they seemed to be working. I know head gasket and or crack in the head can result on these symptoms but i don't think thats it, unless there is a crack in a water chamber underneath the valve bowls that i cannot see. I also realize that overfilling the oil can cause this, but i rechecked levels after both oil changes. There is always the option to take the head and have it checked by a shop, which i might end up doing any way. The thing that worries me the most is the froth concentration from the head to the breather. Id love to hear any and all suggestions as to what the culprit could be.
This motor has been pushing my 16ft RiverHawk skiff since 2016. I bought the motor i a sort of "salvage" condition; as in i payed a guy a couple bills for a pile of boat parts (everything except the lower unit was disasembled). He claimed "everything should be there", and he wasn't too wrong. The issue was that not everything in the pile was functioning or in working condition. After my deal with him i would end up needing a new coil pack, water pump kit, prop, carb kit, total gasket kit, oil/piston rings and every filter/hose/fitting/plug that it required.
After some time i managed to get everything i needed and ended up with a fine running motor. All this is to say i have a lot of experience with this motor, but thats just from the process of assembling it and a knack for mechanics.