Merc Blue motor (520, 525, 540, 600)
 

Couple of questions for the gurus.

- Does a mid 2000's Merc 600sci have the same suggested refresh schedule as the Merc 525? i.e. top end done around 250 hours?

- Assume the intercooler on the Merc 600sci is cooled by raw water, not the closed loop coolant circulated in the engine. (i.e the intercooler will see saltwater when running in the ocean)

- Does the newer Merc 520 have the he same suggested refresh schedule as the Merc 525? i.e. top end done around 250 hours? Or has this been improved in the 520 engine?

- Is the Merc 540 basically a 520 with headers? Or other changes as well?

Thanks!

600SCI uses the same cam as a 500efi so valve train/top end refreshes would be the same

Does anyone know if the 600sci came with the same (not so great) headers as the 525?

And do the headers in those photo look like stock 600sci headers?

https://cimg2.ibsrv.net/gimg/www.off...4d9a80035d.jpg

https://cimg9.ibsrv.net/gimg/www.off...90e332ef5f.png
This look like the stock headers! What year is the engine? It is importend to see the end of the tubes at the head! Then you can see if newer version with cool collar design that makes much lower trouble then the first series from them! At the first ones,the outer tube is welded to then flange from the headplate.Newer headers have 0,5inch ait to the flange and only welded to the inner tube!In pic you see newer version that not this much trouble have than older versions.
Michael

Hey Thanks!

The boat is a 2005, and I believe the engine is 2005 also. Can you clarify this sentence in your reply?

Newer headers have 0,5inch ait to the flange and only welded to the inner tube!

Possible typo?

As you see in the pic from my header,you see the outer tube is not welded to the flange on the head.Tube ends a bit away from flange at the head and outer tube is weld only to the inner tube.
This header are mount on engines 2010 and newer.
I it was my engine and have the old headers style i would direct get rid of them.
To make clear,you need a pic where you can see the headers flange, that screw on the head.

Same headers on the 600sci/700sci as whats on 525efi's.