cooling system - steam and possible debris?
 

I ran my boat last weekend and it ran better than ever. However, I was getting tons of steam off the back of the boat after high-speed runs. The majority of it looked to be coming from the exhaust, and maybe some from the drive after getting hot and coming off plane. The back of the boat looked like a steam bath for the first few minutes while cooling down.

The previous weekend I ran the boat in an area that had tons of algae and weeds, so I’m wondering if the cooling system might have a bunch of crap in it. Is that likely? I don’t have a sea strainer, and I’ll never go back there again. While I was running the stern drive looked like a giant salad shooter throwing green crap out the back of the boat.

Anyway, I want to resolve this steam problem. I don’t (knock on wood) have any water in the oil, so I’m hoping it’s not a head gasket. So I guess I’ll start by assuming it is a bad water pump impeller, but if that looks fine, then I’ll assume there’s crap in the cooling system that is restricting water flow.

I guess I’ll start with a new impeller and back flush the oil cooler, but as far as cleaning out the exhaust system water jackets and the engine block, I’m a bit unsure of what the best way to do that is? Any advise would be appreciated, and let me know if I might be overlooking something else.

The engine is a 454 with Gil Exhaust.

Thanks,
Steve

Re: cooling system - steam and possible debris?
 

I should also mention that the drive is a Bravo 1 with the high water pickup. I'm not sure how likely it is that weeds would get sucked into the cooling system.

Also, I'm ashamed to admit I ruined a prop the previous weekend by getting into shallow water, so I'm wondering if that could have caused some crud to get into the cooling system. (Muddy bottom with small rocks.)

-Steve

Re: cooling system - steam and possible debris?
 

Bump - Anyone?

Re: cooling system - steam and possible debris?
 

If there was a problem such as blockage or bad water pump impeller wouldn't your engine water temp guage be reading Hot? Is the steam a bad thing? I see boats doing it all the time including mine... Just wondering.

Re: cooling system - steam and possible debris?
 

Change the impeller, you should do it every year or two anyway. Backflushing th oil cooler is a good idea. Or remove the hose and check for blockage. If it's a used boat, you'll probably have impeller chunks from the previous owner. The only other place I've seen blockage is the hose from the thermostat housing to the exhaust/risers. Check your manifolds and risers for equal temps, both while warming up (thermostat closed) and fully warm (thermostat open). An engine with a blocked manifold will stay cool but steam a lot from the one overheated manifold.
You can also open the drain plugs on the bottom of the block to flush out the sand/rust/gunk that accumulates there.
Gary