Yep I snagged the pair of Mike in the swap shop, was that a good guess? He thinks they arent actually Merc but just have stickers on em, but were on a 540 with 650 HP so should run fine for me even if eventually they get stroked.



I see you're running a serpentine belt system. Its not the one on CP which looks real nice but $$$. Do you who makes it?

Heard back from the company that make Evapo-rust and Thermocure, its actually CRC, the lubricant / anti-corrosion spray. Their tech department said
"For your application, we would recommend Thermocure. One bottle will treat up to 3 gallons. While we cannot say if the product will remove the scale, we can definitely say it will remove rust from the cooling system. It will not harm rubber, plastic, aluminum, brass components. It is safe in the cooling system. It works best when the engine is run so that it gets heated and there is circulation in the cooling system."

So I figure to plumb the coolant lines in a loop, fill em up with Thermocure, run it a few minutes up to temp, let em marinate for a couple days, and repeat until they're clean. Then do the same with a descaling product, and as a last step use distilled water flushing between runs a few times before moving to antifreeze. Will report results in the spring.

The only fabrication I had to do was to move the PS pump. I made a mockup of a bracket out of PVC (Azek) and had a local aluminum guy fab it. Had to move our forget outward. Other than that, hook it up and enjoy the good life. I'm a religious flusher with CMI's so I was fine with a half system.

sfguy........Looking straight ahead at your stb. engine is the power steering pump all the way to the right?.........

In that picture it's ALL THE Way on the left, ie it is as far starboard as you can get. You can only see about half of it because the photo cuts it off.....

sfguy, I know this is a post about cooling but I want to ask about your power steering. Do you have full hydraulic steering or still running "stock" stuff? Also, without a pump on the port engine, does it run a little higher rpm at wot than the starboard? I have no idea how much hp it takes to run a pump. Just curious if it is noticeable.

I have full external steering. It should be illegal for any performance boat over about 24' to leave the factory without external steering. It's wonderful and easier on swivel seals I've heard.

Most boats only run one pump on the starboard motor. No noticeable difference in performance, idle, etc.

My PS pump is odd - I think it's an older Hardin or Latham pump, but the guts are just GM Saginaw pump ( I know because I rebuilt it last year unfortunately ).

I definitely want to add a 2nd power steering pump. Blew a fuel pump on the stbd motor on Labor Day 2021, was drifting towards a dock and ended up busting a steering cable trying to turn the drives. Not fun losing steering when an engine goes down.

You're telling me. Shattered a rocker 19 miles from home and OF COURSE it was the starboard motor on the hottest day of the year. Long ride home without PS and docking was unpleasant when I got there!!

Must be that it doesn't take much hp to operate I guess. I know that my starboard engine actually ran my steering and the port pump just ran a loop. I too have full hydraulic steering and this year I bought the "combining valve" and will have both pumps running. Thanks for your reply and info.