I read a lot about the high maintenance needed for the "blue" Mercruiser engines.
What is actually in the maintenance schedule that differentiate them from black engines?

A link to info would do fine.

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Mostly just the valvetrain. Lots of similar threads but don't recall off the top of my head

You cant lump all the blue motors into the same catigory, they all have their own set of maint. schedules, pick one then ask the question.

Thanks,

I’m looking at 382 Fastecs from the late 1990s- to early 2000s.
One has carbed 500s, another 500 EFIs and one has 575 SC.

Details on the above engines would be much appreciated.

Both carbed and 500 EFI engines should have valve springs replaced between the 250 and 300 hour mark. The 575 SC engine is harder to get parts for..

Eddie Young is finishing up my 575's as we speak. Full head work and conversion to roller cam.

260 hours on the motors, and they were due. Glad I decided to call an end to the season when I did. Head gaskets were pushing in to the cylinders on both motors and one broken valve spring. Motors were both running strong. It's a big nut for only having the boat for 2 years, but I knew they would be due for top end refresh when I bought it. The roller cam conversion is a large chunk of the bill, but it's a no brainer to do the conversion on this engine (while motors are out).

out of those three, Id lean towards the 500 EFI, but Im sure the carb gang will correct me

I would say the hp 500's would have the least maintenance depending on hours, they haven't made them in a while. Most bang for your buck and resale I would go with 500efi.

We just pulled a guys 2000 hp 500 efi and it has just under 300 hours supposedly, one crane gold roller tip was eating itself, pistons were scuffed, was burning oil, had a nasty gouge in one main bearing , 5 other roller tips were gravelly feeling and there were some lines weraing into thge roller lifters, I say 300 hard hours dictates a rebuild unless leakdown is perfect, Smitty