Mercruiser Engine Rust

[Scottd21]

Hi I recently bought a 2001 Sea Ray bowrider that has a 7.4 MPI Mercruiser engine. The previous owner had a water leak and while I have had no issues pertaining to that, there is some build up of rust.

I am attaching some pictures to get an idea and opinion on how bad this is and how you would recommend treating it.

Thanks,

Scott

[FAST FRED]

Use a couple of brass brushes to remove rust prime & paint.


No big deal.

[Sailmonkey]

Nothing there but deferred maintenance. Like the previous poster, wire brush and paint. I’ll add a good bath with soapy fresh water too though.

[Scottd21]

Okay thanks guys. What about rust removers such as Rust-Oleum or inhibitors like Corrosion X? Not needed if I just use the wire brush and paint?

Scott

[jimbunyard]

If the leak was around the t'stat housing, as it appears it was (and that was the primary place) you'll never get to half of the places that are rusted without removing it.

To do it so it stays done, if it were me I'd remove the housing (should just be two bolts and a bunch of hose clamps, take it off and then you can wire brush or, as I prefer, sandblast it to get a good surface to paint.

You'll also be able to get at the areas behind the housing on the intake manifold that are likely rusted as well, and check the condition and operation of the t'stat while you're there. I'd pull the intake hose on the circulation pump and clean and paint that too; the corrosion there looks pretty bad.

Places that I can't get all the rust off, I use rust converter, and then paint. Though some might say that it shouldn't be used on high heat areas, I've never had a problem with it

[Scottd21]

Hey that’s extremely helpful! Thanks for all the information!

Scott

[jphillips]

Use some Ospho after wire brushing. It will do a great job for paint prep. Read instructions and use carefully it is a mild phosphoric acid.