I have a 2005 Sundeck with 5.0L...

[DestinEd]

I have a 2005 Sundeck with 5.0L MPI and Bravo 3 that I bought 2-1/2 years ago and it had new manifolds, risers, and elbows (all Merc parts) installed by the marina where I bought it.  About 3 weeks ago I noticed when the bilge pump ran there was a bit of oil in the water and around the same time it started kind of hard - like my old Chevy when I had too much advance on the ignition, but it started.  I charged the batteries and then checked the charging system and it was fine.  A week later it started hard again and there was some oil in the bilge so I decided to check the engine oil - water for sure in the oilpan.  Some milkiness and it was almost a quart over full.

Called a few mechanics and they told me 2 months to even look at it since they're so busy.  I'm good with car engines and still learning the weirdness on these boats, but I decided to have a look at this so I pulled off the risers and elbows.  Port side fine, nothing odd at all.  Starboard side bad, inside of the exhaust parts rusty where the carbon should be and small amount of water visible in the manifold which is still on the engine.  Pulled the even side plugs and certainly there was some water in 2 and 4 but all showed an orange hue I think indicating water had been in there.  Gaskets looked like they were all sealing fine and it seems really unlikely for water to get into the exhaust due to these gaskets leaking.  Really odd thing I want to mention is that on the Port (leaky) side the upper gasket was installed with the restricting hole in the rear and the Starboard side it was in the front - my understanding is that it must be in the front, correct?

My first thought was that the riser or elbow had a leak/crack so I plugged the water holes with wine corks (worked surprisingly well), put them in a position where I could fill them with water and after 24 hours no water in the exhaust areas.  I decided to stop removing parts and ask for help before continuing at this point.  It seems that it could be a bad manifold, leaking intake, or cracked head.  Its hard to say if the oil in the bilge and water in the engine are related - but it did all seem to start over the last 3 weeks more or less.

I also would like to know how likely is catastrophic engine damage at this point?  I started it 2 times when I'm guessing there was some water in there but no loud bangs - there was a ping that sounded like spark knock once but it started and sounded normal.

Thx, Ed

[wingless]

Nothing in the description sounds like engine failure.

Removal of all the spark plugs, followed by adding engine oil into all openings, followed my manually rotating the crankshaft will help to lubricate things like piston rings that are probably rusting from the water.

Cranking several cycles before replacing the plugs to purge excess oil to not hydrolock the engine is required.

My experience w deteriorated exhaust parts was that the SOLID wall thickness between raw water and exhaust gas at the gasket surface would suffer from the salt water corrosion. There would be a thick wall, but not solid. The deteriorated region of the gasket surface would have a subtle visible difference after the gasket material was scraped away. That region would fall away with light tapping.

Were the raw water passages filled w/ corrosion? Are these OEM Mercruiser parts or another brand?

[DestinEd]

Wingless, thx for responding. I've put oil in the cylinders a couple days back and cranked it over. These parts all have Merc P/Ns on them and I believe they are OEM - not sure if aftermarket can use the same P/N.

I wasn't having any overheating issues at all and religiously fresh water rinse the engine after each outing. The passages were at least 80% open and I cleaned them up to improve flow now.

Last winter I had the injectors serviced, put new plugs, wires, rotor and cap and it was running quite well until this. It feels like the longer it sets more water leaks in because if I shut it off for an hour or 2 no real issue. If it sits for days that is when it started hard.

I'm curious if it is designed for all the water in the exhaust below the elbow to leak out naturally or is it stuck in there? In other words, is the water getting in there while it's running or after it's shut off?

Ed

[DestinEd]

What kind of problems would it create to have that upper "dry joint" gasket in backwards where the restriction was in the rear rather than the front? Any overheating of the manifold possibly?

Ed

[wingless]

It is interesting that those two year old raw water passages have 80% open despite being flushed after every usage.

My raw water passages look brand new after four years of salt water usage.

On mine I drain the salt water, flush w/ fresh water, soapy water and Salt Away, then drain bone dry, ready for the next usage.

This difference indicates to me that the flushing is not effective on your engines.

Regarding drain down, mine was designed to retain salt water 24/7/365 in the bottom half of the exhaust manifold. That aligned w/ the sea water level, draining down to that level through the dripless shaft seal cooling tube.

The Bravo 3 pickup on your boat is different, but it is likely that the system will drain down to the sea water level, probably also somewhere in the exhaust manifold.

The OEM elbows on my exhaust have Mercruiser embossed text and the manifolds have Mercury Marine embossed text.

[wingless]

IMO there would be negligible effect from having the gasket resistor hole rotated 180°. Always install per the instructions.

[DestinEd]

OK, so you are flushing them much more effectively because I don't drain them and haven't used Salt Away. I run it up to temperature while feeding it fresh water for at least 5 minutes. I guess I should have mentioned that the boat hangs on a lift so would that cause it to drain down lower that sitting in the water?

If salt water was left in the lower 1/2 of the manifold it seems like it would corrode much faster than dry. And I don't see Mercuiser on any of the castings but I'll check again on the manifold.

Thx again.

[wingless]

My parts are different, 7.4L vs 5.0L, so the markings are probably different.

The prior replacement parts were different, they only had the embossed logo on the elbows, not on the manifolds, but the manifolds had the Mercruiser P/N embossed text. These all were always purchased from a Mercruiser dealer in sealed OEM Mercruiser cartons.

Don't know about the raw water path on Bravo 3. The "easy" test is to disconnect the raw water hose from the exhaust and see what drains out of the exhaust and what drains out of the hose.

This Mercruiser elbow drain might be useful to improve the flushing.

https://www.mercruiserparts.com/862210a01-elbow-kit

It REALLY bugged be to throw a large amount of cash at my engines every 3-5 years, discarding / replacing what had been beautiful parts because they degraded into a dangerous-to-my-engine mass of corroded cast iron.

[DestinEd]

So, it seems like biting the bullet every 3-5 years is common - does it mean the manifolds only or also the risers and elbows? Manifolds aren't terrible alone, but the whole group ends up over $1500 parts. Damn!

If that is what needs done I'll get started pulling the manifolds soon...

[wingless]

In my case, it was toss the manifolds, risers and elbows on two engines, parts cost about $5K, plus a healthy workout moving all that cast iron.

Much happier now that my redesigned system looks to be good for the life of the engines.

[Smils]

Hi Wingless, If I recall correctly that you wrote in an earlier advice that after modifying your manifold drainage you undertake fresh water flush followed by a soap water rinse and then Salt Away - and believe you have come up with a lasting solution to manifold replacement. I would really appreciate if you would please inform me why including the soap rinse and what soap to use. I have purchased the Salt Away and ready to go - also what ratio of salt away as I read a Council blog where they commissioned some scientific testing of the product to prevent corrosion on mechanical road plant, which came up tops but, but I believe used a 10% rich mix. As previously, and in anticipation, thanks for the great advice - much appreciated. Regards, Smils

[DestinEd]

So, I found time to remove the exhaust manifold and did a leak test on it using wine corks again. After 2 full days not a drop of water inside the manifold and water level consistent. A mechanical suggested I probably have a blown head gasket.

When I get the intake off, I think there is a possibility that the crossover is leaking into #2 and for sure 2 & 4 has more corrosion in the exhaust port with 6 better and 8 nothing hardly at all. Either way, I think the head comes off because I'm worried about the rusty valves sticking - right?

[wingless]

Smils, YW, thanks to you also.

The flushing and draining procedure I developed was created as a hopeful attempt to resolve the horrible problem of having to discard obscenely expensive exhaust parts every few years. It was a guess.

My practice is to drain, fresh water flush, soapy water flush, Salt Away flush, then drain bone dry until next usage.

The soap I use is the same I use for washing the boat and washing my car. I use Turtle Wax Zip Wax Car Wash & Wax.

https://www.turtlewax.com/our-products/quick-and-easy/turtle-wax-zip-wax-car-wash-wax/

Not sure what is the 10% rich mix. My Salt Away mix tool has a tall clear cup. I put about 1" of car soap in (per engine) for that step and 3/4" of Salt Away in (per engine) for that step.

As had been stated, I was discarding my OEM Mercruiser exhaust every 3-5 years. My last annual disassembly for internal raw water passage inspection after 4 years of usage revealed the parts to still looking brand new.

[wingless]

DestinEd. there are many symptoms of a blown head gasket, including the coolant in the oil that exists on your engine.

When the heads are off, inspect the valves. Assuming the head is good, do a valve job if required. Replace the valves, if required.

[DestinEd]

Yes, seems like the plan. I just wish it wasn't so damn hot right now because it is miserable working outside with 92 and nearly 100% humidity. Would be a great time to have a boat...