How about sludge build up? A guy at the lake has a pair of 2003 525's which he has owned since new. He has been religious about changing his oil every 10 hours or so.The boat has aprox 250 hours on it and he decided to rebuild the motors. What he found in the oilpan and pickup filters was astonishing and does not make sense. There was lots of sludge.The first 8 years , he used Merc oil and most recently, switched to a synthetic blend. What would cause this sludge situation?

Excessive oil temp will cause the oil to "gel", for lack of a better term. It won't all come out when the oil is changed and can build up in the pan.

Slightly off topic but here goes.

What sea water temp are you guys seeing on your 525's?

My Smartcraft SC-1000 gauge reads 148-150* pretty consistently, regardless of the air, water temp, or RPM. I thought this motor has a 160* t-stat? All my other my other efi/mpi motors ran around 170-175*.

I recently changed the gear oil in my truck. Was running short on synthetic and added some different brand regular gear oil to the synthetic bottle. I squirted it in and some had gelled in the bottom of the bottle. Leary of the switch now

somebody please tell me what blue printing is...seems like a useless buzzword to me. Ballancing and following specs I understand. Where the fuk is the blueprint?

I read a lengthy article regarding oils a while back, after we tore a few engines down with a bit of sludge sitting on the bottom of the pan. According to the article, it mentioned the sludge can be from the additives added to the base stock, to make the oil a multi weight. They said it was mainly from the breaking down of that particular additive, which is mainly an issue when running a conventional, non synthetic, multi weight oil, such as a 10w40, 20w50, etc.

I have recently switched to full synthetic to since I am running 20w50 in my engines. At 10 bucks a quart, and 22 quarts for an oil change, I don't know how much longer I will run it. I cant attest to any change in sludge, as the engines haven't been apart. I do know when I was running 20w50 conventional, I had some sludge in bottom of the pans.

I think blueprinting means that you've gone over all measurments and aspects of the build. Things like measuring and recording deck height, piston to wall clearance, bearing clearances, PTV clearance, guide clearances, etc. All the things most good engine builders do, not just mercury racing.

This is the million dollar question. Just pulled the motors out this fall with 640 hours on them still running!!! Port had all the seals still in place. Starboard had the heads done at one time. Would still push a 38 sonic 75. But they were tired!

I guess I would consider those a given for any builder. Even a standard rebuild...irritates me when I hear it for some reason. End of rant

Back to 525s. With the low seat pressure I can see spinning them faster as a big problem. I want to know what tore up the hbeam rod 8 that eddie pictured! I don't think the rod snapped...something else failed causing that carnage.

I used straight weight conventional all year 50W (granted only about 50 hrs) but you saw those pans nice and clean.