Water on top of pistons and rockers

[Lou C]

Wow that is really odd. Never saw that before. Every OMC parts catalog I have ever seen, has had them. Either they replaced the Y pipe with a Volvo one due to corrosion, or there was a slip up on the OMC production line and they were left off a number of units. Even to the end of OMC Cobra production with the joint venture with Volvo drive they had them in the catalog here's a 1998, last year made:

EXHAUST & COOLING - 1998 OMC Stern Drive 5.7 572BPBYC | Crowley Marine

 

[jeremiah89]

I measured 14 1/2 inches i used this picture as a reference i measured from the water level on the picture to the top of the transom then from the top of the riser elbow to the stop of the transom subtracted the 2 and got 14.5

 

[Lou C]

If it were my boat I'd look into removing the exhaust bellows, and adding a flapper valve over the gimble bearing exhaust opening.

 

[jeremiah89]

Wow that is really odd. Never saw that before. Every OMC parts catalog I have ever seen, has had them. Either they replaced the Y pipe with a Volvo one due to corrosion, or there was a slip up on the OMC production line and they were left off a number of units. Even to the end of OMC Cobra production with the joint venture with Volvo drive they had them in the catalog here's a 1998, last year made:

EXHAUST & COOLING - 1998 OMC Stern Drive 5.7 572BPBYC | Crowley Marine

Do you know if there is a universal kit i can install?

 

[Scott Danforth]

bottom of the elbow crook? not top of elbow

 

[jeremiah89]

bottom of the elbow crook? not top of elbow

It's a 3 1/2 inch pipe so it would be 11"

 

[jeremiah89]

If it were my boat I'd look into removing the exhaust bellows, and adding a flapper valve over the gimble bearing exhaust opening.

I'll look into it I'm very mechanically inclined but just not on boats lol

 

[Scott Danforth]

It's a 3 1/2 inch pipe so it would be 11"

thats 3" under spec. put a few heavy folk in the back and your sucking water when there is a wave.

suggest weighing the boat and comparing to spec weight.

 

[jeremiah89]

thats 3" under spec. put a few heavy folk in the back and your sucking water when there is a wave.

suggest weighing the boat and comparing to spec weight.

If it's overweight what do you suggest?

 

[Lou C]

Ok judging by your pic you’re not sitting low in the stern, mine sits lower, the waterline on mind is right at the top of the part of the transom mount that moves side to side. As in right under the trim piece that says OMC on it. You seem to be an inch or so higher. I measured my static water line and it was 14”. So I think you’re ok there but need something to keep water from rushing up the exhaust.

 

[Lou C]

Do you know if there is a universal kit i can install?

It’s what I said earlier. I’d pull the drive then get a snap ring pliers. Remove the snap ring that holds the aft end of the exhaust bellows in the pivot housing then take off the clamp on the front end of the bellows on the gimble housing. Then pull out the exhaust bellows. Now install an exhaust flapper of the right size on the exhaust opening on the gimble housing. I’m not sure but it’s prob 3.5” in diameter, measure first. Just like the ones you see on inboard boats with thru the transom exhaust.

 

[jeremiah89]

It’s what I said earlier. I’d pull the drive then get a snap ring pliers. Remove the snap ring that holds the aft end of the exhaust bellows in the pivot housing then take off the clamp on the front end of the bellows on the gimble housing. Then pull out the exhaust bellows. Now install an exhaust flapper of the right size on the exhaust opening on the gimble housing. I’m not sure but it’s prob 3.5” in diameter, measure first. Just like the ones you see on inboard boats with thru the transom exhaust.

Thanks for your help man!

 

[Lou C]

You’re welcome! Hopefully that solves it. On my boat I have the OMC 4.3 V6 which originally had the one piece batwing manifolds. In the 15 years I ran it with them I never once had a hydrolock from water coming up the exhaust. The only time I had water in a cyl was due to a blown head gasket. I switched the exhaust to the 2 piece style in 2017 when I did a top end overhaul and with the new exhaust same thing no hydrolock the past few seasons.

 

[Lou C]

3-1/2" to 4" I.D. External Flapper - Hardin Marine (hardin-marine.com)

something like this, if its the right size, you have to measure the opening in the gimble housing. I know the Y pipe is 3.5" at least it is on mine.

 

[jeremiah89]

3-1/2" to 4" I.D. External Flapper - Hardin Marine (hardin-marine.com)

something like this, if its the right size, you have to measure the opening in the gimble housing. I know the Y pipe is 3.5" at least it is on mine.

Thanks alot!

 

[PITBoat]

I have no internal flappers left, but in 2019 put a piece of 3" rubber pvc pipe cap over the opening where the exhaust bellows would go (cut with a hacksaw so it's hinged at the top). Note, it's not directly on the pipe, but fitted over a short portion of the exhaust bellows and secured with a hose clamp. It fit perfectly like that, but would be too loose w/o the piece of bellows.

I'm not recommending that, just saying I've got it, and it has worked fine so far. My brother chopped the throttle once not long after I put it on, but w/o any bad results. I wouldn't be too enthused about backing down fast, but that's prob not a good idea anyway.

My long story is that I had an original (batwing) exh manifold overheat due probably to rust restriction. In the process of replacing those with a newer style riser setup, I found that there were no flappers. Now I wondered if there were flapper chunks blocking the exhaust, so I got an inspection camera and inspected, both the U-pipe and the drive as best I could w/o taking it (the drive) off. I found at least one piece of flapper. It was in the drive I think.

I needed to cut my brand new exhaust bellows for some reason, probably to aid that inspection, and I just added the fabbed up flapper mentioned above after that.

It can be done by manipulating the drive (over and up) so you can get in there.

I can see water into the cylinders through the exhaust, but how is it getting on top of the heads? And if it's on top of the heads, how's it not getting into the pan?

 

[Lou C]

Sometimes it seems as if you don't have water in the oil in the pan because it doesn't get into the dipstick tube until it gets really bad. What's happening is that there really is water in the oil and when it gets to the top of the engine, since the oil up there is cooler than in the pan and rest of the engine, the moisture can't boil off totally and condenses on the cooler rocker arm parts. If it were a one time thing and you ran it hard the moisture might totally boil off but if it is happening repeatedly then the first place you see it is under the valve covers due to the cooler temps.
The flappers in the Y pipe vs the flapper on the gimble housing have pros and cons. The ones in the Y pipe are more work to install and if you have an overheat they can block the exhaust or be hard to remove. But you still have the full exhaust bellows which actually protects the driveshaft bellows above it in the event of an overheat. The one on the gimble housing is easier to install or replace, and might work better at keeping water out, but if you had an overheat, now since you don't have a full exhaust bellows the hot air coming out due to the loss of cooling water could partially melt the driveshaft bellows. So there are pros and cons to each, but some kind of flapper is better than none. That's why I never understood Volvo's policy of removing them.
BTW if you have melted flappers on any I/O you really should consider splitting the drive and replacing the water tube grommets, these can melt from the hot air going through the drive in a bad overheat.

 

[PITBoat]

Sometimes it seems as if you don't have water in the oil in the pan because it doesn't get into the dipstick tube until it gets really bad. What's happening is that there really is water in the oil and when it gets to the top of the engine, since the oil up there is cooler than in the pan and rest of the engine, the moisture can't boil off totally and condenses on the cooler rocker arm parts. If it were a one time thing and you ran it hard the moisture might totally boil off but if it is happening repeatedly then the first place you see it is under the valve covers due to the cooler temps.
The flappers in the Y pipe vs the flapper on the gimble housing have pros and cons. The ones in the Y pipe are more work to install and if you have an overheat they can block the exhaust or be hard to remove. But you still have the full exhaust bellows which actually protects the driveshaft bellows above it in the event of an overheat. The one on the gimble housing is easier to install or replace, and might work better at keeping water out, but if you had an overheat, now since you don't have a full exhaust bellows the hot air coming out due to the loss of cooling water could partially melt the driveshaft bellows. So there are pros and cons to each, but some kind of flapper is better than none. That's why I never understood Volvo's policy of removing them.
BTW if you have melted flappers on any I/O you really should consider splitting the drive and replacing the water tube grommets, these can melt from the hot air going through the drive in a bad overheat.

Ah. I suppose once it's in the cylinders, it could seep past the rings eventually if it's not running too. My understanding of all the pathways is a little incomplete.

I guess I was lazy about the flapper thing, or just wanted to get it done w/o waiting on more parts. I'm not sure when mine departed, but I wouldn't be surprised if it was before I got the boat. The pins were still there, I'm pretty sure.

I'm not 100% certain now what I found was flapper since it was hard and broken, not melted.

 

[jeremiah89]

Thanks for the help everyone. I put the flapper on the exit of the exhaust where the exhaust bellow would usually go. Went out Sunday about 20 miles with no issues with water in the motor just a few carb issues.

 

[Lou C]

That sounds good! Keep us updated....