Well , the nightmare for many finally happened .

After the storms cleared the (full service) yard put all the boats in the marina back over and never told me what they were doing , had they done so I would have been there to assist and make sure everything was OK .

Next morning the boat is submerged at its slip (salt water) . The yard had it back out and were working on it 5 hours before they even called to let us know what was going on. I can't fault them for that tbh. They had it running again within 24 hours.


Problem is it's a very low hour ('98/'00) FWC Merc 502 mag mpi and we all know they don't make them like that any more . Of course the entire boat will have to be rewired as nothing electrical can ever be trusted again after that but the yard owner is talking about a total re-power because he says that engine harnesses are no longer available. I did a cursory check on one well known Merc parts site and sure enough the engine harness is NLA so I'm sure the rest of the harness forward to the helm is NLA too .


A suitable 'new' re-power is going to be one of these super computerized nightmares with emission equipment and then transom cutouts probably won't line up then either (exhausts) amongst other things . The yard also happens to be the Volvo distributor/agent.


We'd really like to keep this engine package if we could . What do you guys think the possibilities are ?


Thanks a ton.

Why did it sink if the storm's had past ? Id start by putting an ad in the wanted section for the harnesses, so many of these were upgraded to Holley / EFI / Whipples there has to be some around you'll just have to dig, Id also call all the US builders.

^^^
That's a great suggestion and I thank you for it. Funny how the obvious sometimes isn't !

The reason it went for a swim still isn't conclusive (the weather was fine at that point and the marina was calm.)
So far from what I've heard , they put the outdrive back on to seal the gaping hole in the transom plate with the engine out and backed the boat down into the water on the trailer and supposedly they saw water (don't know how fast) coming from somewhere on the transom plate , as in a possible perforation.They didn't make it sound like it was the steering shaft bearing/seal.

The engine to helm harness is available from michigan motors for 300$.
Genuine MerCruiser Instrument Wire Harness - 9-pin, 20 ft. - Michigan Motorz LLC https://share.google/wlDs91xBtPuKF2tK7
If you have a mefi 3 ecm, I have virgjn charging starting harnesses, efi harnesses and ecms, nla available new though
The sensors are all available too everywhere, smitty

Did they not plug the water pickup through the drive? Yikes

Their guy is pretty competent so I would imagine he had that covered . I can just imagine his reaction when I double check with him ..lol

Thanks for that very valuable lead. I will investigate a bit further but it could be extremely helpful .

I feel your pain.

The boat & instrument harness are still available no problem https://www.mercruiserparts.com/812475a20-harness-assy however as pointed out the engine harness are NLA

Also I am not a fan of the catalyst engines. Mercury Racing does have something that has become my go-to in these situations. The 520 EFI is non-catalyst, FWC, with conventional pedestal mounts. The only complication is it is DTS (digital throttle and shift). Which in your case might not be an issue as you might be replacing controls & cables anyhow.