Found Rust on engine. Advice on how serious and how to treat?

[burrben]

Hi all. Last time I was able to take my boat out or really look at her was 3 weeks ago, as my wife gave birth 6 weeks early. I went there to check the battery yesterday and found some large rust spots. I'm new to boating (1st boat) and I've only had her out twice now. I'm looking for advice on how bad it might be and how to treat it. If possible I'd like to DIY, as $$ is quite tight.
It's a 2003 Tahoe 220 with a Mercruiser 5.0 V8 220hp. Thanks so much in advance!

 

[tpenfield]

Re: Found Rust on engine. Advice on how serious and how to treat?

I would assume that the rust/flaking in the first picture did not happen recently, but has been on-going for some time (?). anyway, what you show is fairly typical of an engine that had some water sitting on the manifold. The question would be if it is from an active leak or if rain water or something got into the engine bay.

The surface rust spots can be fixed up and painted just like any other rusty metal. the one in the first picture is more 'interesting' and would be worth running the boat some more to see if there is an active leak.

FWIW - many folks do some paint touch-up periodically on their engines, so a little rust here & there is common. the more heavy metal flaking, not so much.

 

[81 Checkmate]

Re: Found Rust on engine. Advice on how serious and how to treat?

Salt water boat?

 

[garbageguy]

Re: Found Rust on engine. Advice on how serious and how to treat?

+1 on what tpenfield said. Pic 1 shows a kinked hose - can't tell exactly what it is, but should be looked at. Maybe a couple pics from further back showing more of the engine?

 

[Scott Danforth]

Re: Found Rust on engine. Advice on how serious and how to treat?

looks like rust streaking from a leak.

the one hose does look kinked.

 

[scoflaw]

Re: Found Rust on engine. Advice on how serious and how to treat?

Looks more like heat shield material than a hose.

 

[burrben]

Re: Found Rust on engine. Advice on how serious and how to treat?

The kink is the heat shield. It is a salt water boat (brakish), but it is kept on a trailer under a cover. Some rain water did get on the boat when I first bought it, so maybe that's it.

How should I clean and fix? I was thinking about a wire brush, then some Naval Jelly, then High-Temp rustoleum black paint.

 

[Volphin]

Re: Found Rust on engine. Advice on how serious and how to treat?

I'd run it and check for leaks. If none are found, use a wire brush on the end of a drill and clean it up. Touch up with gloss black engine paint.

 

[81 Checkmate]

Re: Found Rust on engine. Advice on how serious and how to treat?

The kink is the heat shield. It is a salt water boat (brakish), but it is kept on a trailer under a cover. Some rain water did get on the boat when I first bought it, so maybe that's it.

How should I clean and fix? I was thinking about a wire brush, then some Naval Jelly, then High-Temp rustoleum black paint.

Thats why i asked if it was a salt water boat.....It looks like the metal is eaten away more than just rain water or just plain old water...Caused by a salt water leak of some sorts...maybe not now but one time or another. Check for leaks before proceding.

Wire wheel all rust...then get some of that rustoleum rust remover stuff...works very well. It will turn the carbon steel black, when you see that it's good to paint.