Cooling System Question

[Joe R]

Guys,

Went to change out the thermostat in my 1999 Suzuki 115 2 stroke engine. Easy job. Did notice something which I have a question about: the space in the engine where the thermostat sits (housing?) looked pretty rusty. I cleaned it up as best I could, but it’s showing rust. The question is, is this normal for an engine of this age (I estimate 500 hours of run time tops)? It has been used in the salt, so I expect signs of wear, but it was surprising to see all that rust. I know the engine’s cooling system is completely separate from the internal engine components, but are there things I should be concerned about given the condition of that housing? By-The-Way engine runs fine - I'm more concerned with the next 250 hours or so of run-time.

Joe

[DaleH]

I'll start ... where's the "rust" coming from? From that I mean (and I am most familiar with OMC/Bomb products) I'm used to t-stats that are stainless and blocks that aluminum?

Put a magnet on the old t-start, if carbon steel it will be ferretic ... that's probably your answer. I'd be very surprised of any '99 vintage OB with plain ol' steel parts in it, but I've been surprised before.

[Joe R]

Dale,

the thermostat itself looks OK -- its the water jacket (not sure if this is the correct term for an outboard) I am concerned with. Basically, I see lots of rust in the area of the powerhead that houses the t-stat. Let me see if I can post a digital image later tonight -- might help.

Joe

[Joe R]

Dale,

I now understand what you were talking about with respect to the old tstat. Basically that could be the source of the rust, even though it may not be that rusty - I get it. I'll try the magnet tonight. So, is it unusual to see rust in that housing? Seems as though there would be some given that saltwater is the cooling element.

[DaleH]

Another thing I just thought of Joe, stainless steel is truly only stainless in the presence of oxygen, plus there are various grades, some more resistant than others.

Being installed in the water system, it's more likely that you saw stainless steel "staining" versus corroding like a carbon steel fitting would. You can also see this type of staining on SS bolts holding on rod holders and other deck hardware.

[Joe R]

Old Thermostat and housing.

[Joe R]

having trouble attaching JPEGs. went to manage images and followed directions. both images less than 1MB. Any advice?

Joe