New Guy with some ?'s on a Base Gasket Leak 150 x-flow

[skimmabird]

Hello folks, I have recently bought a old project boat that came with a 1989 150 Crossflow. I have put about a hundred hours on the motor since bringing it back up to snuff with a carb rebuild, l/u reseal, water pump, head gaskets, diverters, stats & poppets. The motor holds between 100 & 105 psi in each cylinder. Basically it seems to be a very nice running smoky old loud 2 stroke. I basically got the motor for free because the last owner bought the boat without the engine running & then sold it to me in the same state.

I have the dark exhaust ooze running down from just above and behind the two steering pivot arm bolts that go through the upper mount. I pulled the lower cowl, checked the three long bolts that go through the adapter into the powerhead. I also checked the front nuts and bolts and the two rear. They are were all snugged up like I think they should be. There isn't a fuel leak washing grease and grime down the exhaust housing. There isn't any seepage from the outside of the base gasket and powerhead from the separating line. The leak is more apparent idling for a while in the water rather than the muffs, I assume because of backpressure. When I split the lower I reused the old inner exhaust housing gasket, but it seemed supple to me. It had a tiny bit of sag in it but looked fine, any shot that could be the problem?

I'm pretty familiar with the old 90 deg. OMC's whether looper or crossflow but haven't had a need to do anything to one in 20 years until this motor. For the life of me though I don't remember seeing the base gaskets leak like this. Though it looks like the powerhead has never been off and judging by the other work I've done to the motor it's probably the 23yo base gasket. Could I have something more or worse going on than just a leaky base gasket? Or am I overthinking this?


Thanks

 

[keefallan]

Re: New Guy with some ?'s on a Base Gasket Leak 150 x-flow

When that gasket leaks(from the exhaust area), you get exactly what you are describing. I know, I've had a couple of issues also. When I lifted the powerhead, I could see where it leaked. The irony was that it didn't leak for 3 weeks. So if you pull the powerhead, clean the surfaces, and put on a new, high quality gasket, you should be fine.