Mercruiser 4.3 EFI water intrusion issues

[jeremyk2000]

This is my first post, but this forum has been SUPER helpful for me over the years in doing my own boat maintenance and repairs. Don S. has helped me on numerous occasions over the years! RIP. Thanks to all who help in this forum! I try to do as much as I can myself, but I do have mechanics in to do things that scare me and I don't fully know about even after reading up on them.

So now to the issue(s). I had a little bit of water in the remote oil filter when I changed the oil in the fall. At the same time, I was just having starting issues with this engine. The manifolds/risers were replaced two years ago and they had to come off due to other work last fall. Upon inspection, they were clean, no rust spots in exhaust passages and the water passages were also looking fine. Plan was to run boat a few times and change oil.

Ran boat July 4, first time out due to other issues - boat only put in water on the 1st. Already off to a very bad season. Loud sounds coming in from the day, first issue was cracked U-joint bellows, took on water had to get emergency pulled. That annoyed me because I had a mechanic change it last season. Friends and I changed it this time around. Changed bellows and gimbal bearing.

Boat back in July 18. I am based in CT, we went over to Long Island for the day, 45 minute cruise. Docked boat went into town for about two hours. Boat starts right up, cruise back no issues. Next weekend try to start same engine that had a little oil in it and starter was really being challenged. Take plug out port side towards transom about 4-5 ounces of water comes out, a little on the other two. The starboard side ones out, not a ton of water but plugs all rusted and looked to be a little water on the plugs anyway.

Take manifolds/risers off. Water in exhaust both sides.

Now I am getting to the point where I need help so I had a mechanic come down and I explained the above. He says tuliped valve and I need a new block. Keeping in mind I have not taken the heads off and inspected inside I just wanted to get thoughts. He says after water gets in the engine it is junk anyway. I suppose true? It cranks now that plugs are out and I cranked out water and dumped two bottles of wd40 into the valves. I also changed the oil and cranked it as well.

Just wondering if there is any chance I should dig into this more or give up and listen to him. Would be great if I can replace head gaskets if that is what it is and be OK. I have no idea if this tulip theory makes sense based on the above or if a blown head gasket makes sense so wanted to see what you all thought. This boat did overheat once about 3 years ago when a piece of the raw water plastic casing broke and completely ate the rubber impeller. Freak accident. No other overheating or odd operational items have occurred other than the non-start issue which I noted above.

Mercruiser 4.3L EFI
Year 2000
Serial # OL623728

 

[Bondo]

Ayuh,..... Welcome Aboard,.... Has the motor been run, since the incident,..??
If not, do it,... Right now,... Gotta burn out the saltwater,....

I don't buy the tuliped valve theory as the cause,.... not sayin' it don't have a bad valve, but it ain't the cause,.....

I would drain the block, isolate the blocks water system, 'n pressure test it to find any leak,....
Then do a compression test on the cylinders,....
With that info, a battle plan can be developed,....

 

[Scott Danforth]

if its a tuliped valve you only need a valve job and a new valve. not a new block

find a different mechanic

however if you do not get that motor running ASAMFP after ingesting water, especially salt water, then you will need a new block AND heads

since your motor has now had salt water in it for a month, you may be SOL

as stated above. stop typing. get the motor running on muffs

then pressure test the cooling system and do a compression test.

 

[tpenfield]

. . . find a different mechanic

This ^^^

 

[Lou C]

Agree with all of the above. I’m in the same salt water boating areas as you on the Long Island side of the Sound…
I had a similar problem past overheat followed by blown head gaskets & water in 2 cyls & oil. Got the water out & changed oil while the boat was still on the mooring and had it towed in & put in the trailer. Got it home did diagnostics found normal to high comp test results & combustion gas in the cooling water. Took it apart found both HGs blown. Took heads to machine shop after examination found cracks in exhaust seats on both heads (overheat) and the cooling passages had gotten eroded by years of salt water use (15+). So replaced with reman heads, new gaskets & head bolts. Total cost $750 for parts. Still running fine 5 seasons later. Getting the water out is critical. I changed the oil 3/4 times to get it all out.

Take all the plugs out, squirt the cyls with fogging oil and see if it will crank over.
What I did was run it only long enough to change oil; then drain water & change oil each time.