Water Leak under cowl 150 HP

[arriva2001]

Hi,
I've been paying a little extra attention to my Force 150 lately, as I'm questioning some of what the former mechanic was doing to take care of it. He removed the thermostat which caused an overheat problem for me. I have another thread about it if you are interested in the outcome.

Anyway.... I noticed that there is a water deposit stain under the cowl. From the water deposit stain area, it looks like it's coming from the top of the Exhaust manifold maybe where the gasket is located. I circled where it seems to be originating from. You can see in the lower left of the picture that the water deposits are kind of all over in there...but that appears where it starts.

I run the engine and I can't really see any liquid water so I don't know for sure where the leak is.

A couple of questions. Is there anything I can do to stop this mysterious leak that I can't find? Can I tighten down the bolts in hope that maybe one's just too loose so the gasket isn't quite seated all the way? or can I put some sort of sealant around the edges of the gasket so it stops leaking? Or do I have to remove the entire manifold and replace the gasket (this option scares me a bit, because those bolts are hard to get to near the bottom, and I'm not even sure how I would be able to get to them especially if they are even a little rusted.

I was thinking about those products that people put in radiators to stop leaks...that cause the gaskets to swell. Is there something similar I could use here?

Or if the thing isn't wet inside after an afternoon of boating...what's the harm in leaving it alone as long as I monitor the situation to make sure electronics aren't getting wet or something. Maybe the leak was really old and the mechanic torqued the bolts before and it fixed it? Not really sure.

Here's the photo so you can see what I'm talking about. There's quite a bit of hard water deposits in there...so this must have been either a very small leak for a very long time...or it was a pretty big leak.

 

[pnwboat]

Most of the leak stop products for automotive cooling systems are designed for a closed pressurized cooling system. Most outboards have an open cooling system and is not pressurized. The only pressure is created by the water pump, and it's not that much compared to a closed cooling system. I doubt that you will find these products useful in your situation.

Worse case scenario, you have to replace the gaskets. The lower bolts on the 150HP motor are a bear to get to. You can remove the lower cowling bolts and shift the lower cowling a few inches away from the exhaust cover, but it's still tough to get to them.

It's also not uncommon to snap a few of the bolts too. That brings up a whole new can of worms as you have to drill the bolt out and re-tap the hole. Depending on which bolt it is, it may be almost impossible to get a drill in there.

 

[jerryjerry05]

If you can't find it?? you sure it's still leaking?
​You run with the cover off??
Test it with the cover off and see if it's still leaking?
​Usually the water leak comes with exhaust leaking into the cowl??

I had a problem with a gasket giving out.
I smeared sillycone all over it and it stopped the leak.
Way better than pulling the motor and maybe fixing the leak?

​Tightening bolts that are almost 30 years old?? Not sure I'd do much to it??
The exhaust bolts are a bit stronger than the ones they used on the 85/125 but can still twist off easily.