Water In Both Cyl Banks and Pan

[Tiki Tom]

I have a 2002 Volvo Penta 5.0 GL-B I/O that has run fine several times this season, including the day problems started. Boat is on the Texas coast, runs in saltwater and is thoroughly flushed every time the lower unit gets in the water. Was not anywhere near freezing temps last winter or any other. Went out fishing early last weekend and motor ran fine - started right up, good oil pressure and temp, ran well at idle, low rpm, and cruise, although perhaps a barely noticeable trace of roughness on the way in at cruise. Ran again during flush and no problems. Went to start again late in day and had ugly loud noises from what I now know was hydro lock, but at the time thought was a starter problem as after a couple of short tries the starter bendix would not engage and the starter just spun freely. Replaced the starter today and more noise/hydro lock. Removed spark plugs and water drained out of one plug on each cylinder bank. Cranked engine over to clear water and water came out of at least two cylinders on each bank. Pulled oil dipstick and level is at least two quarts above the normal level, but no water or milky mix visible on dipstick, just normal brown oil.

Based on reading a number of threads, primary suspect seems to be exhaust manifolds and risers and/or their gaskets. However, the risers and manifolds were replaced on the advice of my mechanic 3 years ago (37 months to be exact) although they were not leaking at the time of replacement. I have been even more fanatic about flushing since then to try and prevent or delay as long as possible corrosion problems. I believe, but am not sure that OEM risers, manifolds, and gaskets were used particularly as parts cost for those items was $1000. So three years to failure when the originals lasted six or seven years without failure seems a short life. Plus it seems very unlikely to me that both sides would develop serious leaks at exactly the same time as seems to have happened here. I read on one thread that intake manifolds are known to develop leaks below the thermostat, but I am not clear if such a leak would get into the top of the cylinders like this has.

I have oiled all cylinders to delay corrosion but have not removed manifolds or risers since my DIY experience is that with 20 bolts to remove, one will snap off at the same torque all the others come loose at, and turn a bad situation into a disaster. So I am looking for advise on the most probable cause and best next steps to take to confirm and correct the problem at minimum risk.

Many thanks for your thoughts and suggestions.

 

[Tiki Tom]

Re: Water In Both Cyl Banks and Pan

Update:
Pulled a riser and maniford off with no drama. Water passages have some deposits and scale, but nothing visible that looks bad enough to be a hole through the jacket wall. Manifold has Barr Marine OMC-1-914035 cast into the side. Is that an OEM part or aftermarket? Have to go out of town for a couple days, will pull other riser and manifold and try to leak test the manifolds when I return.

 

[Tiki Tom]

Re: Water In Both Cyl Banks and Pan

Update:
Leak tested manifold with water, no leaks to exhaust side visible. Pulled off a valve cover, looks good, no rust or signs of water under on top of valves.

Still like to have thoughts or suggestions. Looks like removal of thermostat cover will be next, followed by intake manifold if thermostat area looks ok.

 

[Don S]

Re: Water In Both Cyl Banks and Pan

To be in all the cylinders, it has to be getting in from either the exhaust (Steep ramp and above elbows possibly??????) or through the carb (rain and un-covered)

As far as water in the oil, it would have to be milky after that much running. And could be the intake manifold passage or a cracked block.
Drain the engines cooling system and block off the exhaust and water in and pressure check it.

 

[Tiki Tom]

Re: Water In Both Cyl Banks and Pan

Update:

Thanks for the suggestions, Don. Steep ramp and above elbows not a factor as boat is stored on a lift and so has not been on a ramp. Storage slip is covered and engine cover has been down so rain in intake also not a source.

Plugged cooling intake and exhaust hoses and did a rough pressure test, but not able to drain block and do a proper pressure test as block drain connections are blocked or clogged. Rough test seemed to hold but was probably only pressurizing exhaust side of thermostat and not the full block.

Removed thermostat cover and discovered that the intake manifold water passage appears to be a bronze insert in the cast iron (?) intake manifold. A section of the about 1/8 inch thick cast iron "skin" over the bronze passageway insert has broken off around the front of the thermostat area disclosing the green and bronze insert piece. Looks like at some point water got between the insert and manifold and corrosion caused the "skin" to crack and pop off. The insert had been sealing to the thermostat housing so there was no water leakage to the outside of the engine, but I am wondering if since the insert to manifold joint or seal was broken if that could cause leakage at the manifold to cylinder head joints so that water could get into the cylinders via the intake passages somehow and into the pan via the pushrod area under the intake manifold.

The bronze insert was a complete surprise to me and is not a manufacturing technique I would have expected, but then this whole problem continues to baffle me. Any more thoughts, experience, or suggestions greatly appreciated.