1979 Merc 260 - closed cooling system - SE106 outdrive
End o last year, found water in oil after many hours run time... found small amount the year before, but dismissed as fluke.
Boat ran fine for a few months (May - July), oil was normal (no foam) but I kep losing coolant. Strange. I assumed into the bilge, but was wrong. After a few long days fishing in early July, I found the bilge covered in oil and the oil pan over full (half of it water).
Assumed it was head / gasket problem, but puzzled by smooth running. the started thinking it was passive intrusion, after I shut it down... But the exhaust mani's are new. Went with the heads... When I called for a new gasket kit, the folks at Go2 Marine suggested I check the exhaust mani's for leaks, before I tear into heads. Easy enough.
Found Don S. sticky on acetone test - super handy. But, no leaks in mani's.
Read recent sticky from Don S. on "Water in my Oil - Arggg" Darn strait, ARRGG! After reading, I was convinced I had a cracked block. Decided to pressure test. With exhaust manifolds off, I rerouted the heat exchanger tubes directly into the Intake manifold, closing the system. Removed thermostat and pressure tested to 15 psi. Pressure held steady. I even pulled the oil drain plug hoping to see water drip out. Nothing - no sights no sounds.
Now what?
I am interested in replacing intake, distributor and carb with newer stuff (edlebrock combo and thunderbolt IV). Would give a chance to visually check for cracks at valves - but pressure test should have indicated trouble, right?
Should I replace head gaskets and test the heads while they are off? (assuming I can find someone local who can test them)
Any suggestions? I was almost happier with the notion of a craked block...
As always, thanks for your thought and opinions..
J.
End o last year, found water in oil after many hours run time... found small amount the year before, but dismissed as fluke.
Boat ran fine for a few months (May - July), oil was normal (no foam) but I kep losing coolant. Strange. I assumed into the bilge, but was wrong. After a few long days fishing in early July, I found the bilge covered in oil and the oil pan over full (half of it water).
Assumed it was head / gasket problem, but puzzled by smooth running. the started thinking it was passive intrusion, after I shut it down... But the exhaust mani's are new. Went with the heads... When I called for a new gasket kit, the folks at Go2 Marine suggested I check the exhaust mani's for leaks, before I tear into heads. Easy enough.
Found Don S. sticky on acetone test - super handy. But, no leaks in mani's.
Read recent sticky from Don S. on "Water in my Oil - Arggg" Darn strait, ARRGG! After reading, I was convinced I had a cracked block. Decided to pressure test. With exhaust manifolds off, I rerouted the heat exchanger tubes directly into the Intake manifold, closing the system. Removed thermostat and pressure tested to 15 psi. Pressure held steady. I even pulled the oil drain plug hoping to see water drip out. Nothing - no sights no sounds.
Now what?
I am interested in replacing intake, distributor and carb with newer stuff (edlebrock combo and thunderbolt IV). Would give a chance to visually check for cracks at valves - but pressure test should have indicated trouble, right?
Should I replace head gaskets and test the heads while they are off? (assuming I can find someone local who can test them)
Any suggestions? I was almost happier with the notion of a craked block...
As always, thanks for your thought and opinions..
J.
