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Thread: Engine life on Merc 525 EFI & 600 SCI??

  1. #21
    HPBoats83
    That's kind of a long time to go on an oil change in a boat. I run the Royal Purple (full synthetic) and still change it every 20ish hours. I run the Merc Synthetic in my Volvo drive and change that when I change my engine oil at 20ish hours and stick the alignment tool in their just to make sure all is good.
    James
    The 100 hr. interval is dictated strictly by oil analysis. I don't like to cut it really close but 100 hrs. gives a really good clean analysis. It's really the best way to know the health and longevity of an engine that gets beat pretty hard.[/QUOTE]
    How do you do an oil analasys? What does that cost?

  2. #22
    HEDJUG
    There is a Donzi in our marina with a pair of 525's. The driver had two speeds, docking speed & WOT. Both engines popped before 500 hours. I don't know what failed, but I can find out.

  3. #23
    XTRM22
    Good info and I think accurate but there is a pretty big difference running 4000 rpm vs 5300 - 5400 especially with the added lift on cams run in 525 and 600 sci. Bottom ends with regular maintenance will run a while but the weak link in the higher HP - RPM motors is the valve train. I have heard of 502 mpi running that many hours but never a 500hp or 525. I would like to know if they are out there.
    Hey Andy, long time no see! how many hours were on Pams motor (the 502) before you went through it? My little 454 turned 602 hours this weekend, now it's just become a challenge to see how long it will last!
    Chuck

  4. #24
    BadKachina
    I have heard of 502 mpi running that many hours but never a 500hp or 525. I would like to know if they are out there.
    I agree. I've seen and known many people with 500 hp's and 500 efi's break around 250/300 hours. It's almost always the valve train, but I've also seen burnt pistons and blown head gaskets. I think the fuel system should be gone too as well, injectors should be cleaned and tested and the fuel pump should be replaced. Nobody wants to do maintenance until the motor comes apart. If it were me, @ 250 hours or so I would pull the heads, and go through them along with doing the fuel system. Black motors seem to run forever, but the fuel system should still be kept up on. Riser gaskets should also be changed every couple of years, it's cheap insurance. People wouldn't believe what a leaking riser gasket will do to a motor.

  5. #25
    havaduner
    forever if you dont use em...
    I guess that would count you out on that one huh??

  6. #26
    airpacker
    pulled my 500efi apart at 250 hrs. Both heads were cracked all over the place. Guides were worn, springs were soft. Replaced em with aluminums and cometic head gaskets because the OE gaskets were actually starting to leak between 3 and 5 and 4 and 6. If I had waited, the block would have been scrap due to burn through at the head gaskets. I also replace the lifters at the same time.
    Ran her to 404 hrs and now its apart for a full rebuild. The pistons were getting a little sloppy in the bores at that time.
    I run it hard. Lots of hrs at 5000rpm or better. Mobil 1 20w50 every 20hrs from new.

  7. #27
    hkunz
    Lotta drywall screws did !!!!!
    Hey, but they're stainless screws!

  8. #28
    hkunz
    I agree. I've seen and known many people with 500 hp's and 500 efi's break around 250/300 hours. It's almost always the valve train, but I've also seen burnt pistons and blown head gaskets. I think the fuel system should be gone too as well, injectors should be cleaned and tested and the fuel pump should be replaced. Nobody wants to do maintenance until the motor comes apart. If it were me, @ 250 hours or so I would pull the heads, and go through them along with doing the fuel system. Black motors seem to run forever, but the fuel system should still be kept up on. Riser gaskets should also be changed every couple of years, it's cheap insurance. People wouldn't believe what a leaking riser gasket will do to a motor.
    Even our 6.2 needed riser gaskets at 100 hours. Then the shop forgot to tighten the hose clamps, so we had water everywhere Luckily I carry a small variety of hand tools.
    Good ideas on maint - I'd rather spend a little now than a lot later.

  9. #29
    dunaholic
    I heard that neither of these motors will last if your spinning out in the reeds.

  10. #30
    Keith E. Sayre
    I know a guy that had a 28 Magic cat bought in 2001 with a 500EFI in it.
    He put over 800 hours on it without a problem, took the engine out and sold
    it to another guy with a 30 Eliminator Eagle. Still in the boat and that boat
    has 2 1/2 seasons on it too. I also know several guys with 400 plus hours
    on their 525's without problems. I know a guy with a whippled HP500EFI with
    over 500 hours on it with no problems.
    I believe that it has to do with how you maintain it and how you drive it.
    Keith Sayre

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