Water in Oil

Have a 89 with dual 5.8l. Ocas

Have a 89 with dual 5.8l. Ocassionally my stern will have water in oil to point where it smokes and eventually won't turn over. Remove old oil and replace runs great. How is this getting in? During heavy winds the outdrives receive heavy wave action. Is there anyway that this could drive water up into engine? Is it possible that bad or nonexistant exhaust seal assy (or something else) would allow this?

Are you talking about water in

Are you talking about water in the engine oil or the sterndrive? If it's the engine do you know if it gets in even if the boat has been sitting a while or is this only after it has been run. Also is it just one engine or drive?

Engine oil in only one. The st

Engine oil in only one. The stern that gets heaviest wind/wave action. Doesn't seem to get in when running only if sitting for a while.

"I suppose it's possible f

"I suppose it's possible for serious wave action to push the water up that far. I've heard of it happening to some coming down off plane quickly or even being towed backwards. There are flapper valves in the exhaust Y pipe that's supposed to prevent that from happening, maybe yours are missing? Quite often they will break off and fall down the exhaust pipe, some have seen them when they remove their drives in the fall. See the pic below and item and item # 51 in the red circle. 5.8 Exhaust

Thanks Bob. It could be that c

Thanks Bob. It could be that coming off plane quickly was doing it. Is it possible to get at these when boat (Avanti 2950) is in the water or do the drives need to be off.

You can get to them normally w

You can get to them normally with the boat in the water as long as the boat isn't sitting too low as the water will come up those pipes. See if you can determine where the waterline is inside the engine compartment and then have a look where that lines up on the Y pipe. You will have to remove the flex hose from the y pipe to the riser and they are just inside the y pipe. If yours are missing or stuck in the open position (they should always return to closed once the engine is shut off (no exhaust pressure)it could be anywhere down the exhaust or possibly previous owner never replaced or ???

Last question. If the outdrive

Last question. If the outdrives are at maximum up position the prop is mostly out of the water. Would that not prevent water coming up the pipes?

"I would say it would prevent

"I would say it would prevent a lot of it but not necessarily all of it. Most of the exhaust bellows today actually have slits cut in the bottom of them to allow backpressure to escape, better idleing, etc. When you raise the outdrive the bellows is stretched then and those slits open all the way, whether that would be enough water pressure to push it up or not I don't know. I think it would definitely reduce it considerably. I would still check if the flappers are inplace and (Flapping) if in fact this is the way the water is entering."