water jacket leak, need advice!

so a couple weeks ago i had an impeller go out(less than 20 hours on it) and it blew pretty much all the blades off while out on the water. Needless to say the boat got over heated. The temp guage got to 200 by the time i got it back to the dock.

I replaced the impeller, cleared all the lines and went ahead and replaced the thermostat also. The boat runs at like 142 degrees now which is perfect.

The problem I now have is that at rpms over/around 3000, water starts to leak out of the water jackets. It is coming from where the lower half of the jackets in the part where the exhaust leaves the engine. I thought it might be a bad gasket but I look on the floor in the bilge and there are a bunch of metal flakes that have chipped off the spot where its leaking. The spot is in the middle of one of the tubes coming out of the engine(i think they are headers) and is not where they bolt together, its like a crack in the metal. I dont have the 400 bucks to replace the jackets, will this ruin the motor? The leak is more like a drip, not a huge flow of water. It never did it before though.

Any advice is greatly appreciated

Water jackets are the passages inside the motor to circulate water so if you had a damaged jacket you would have a damaged block.
Then you have the freeze plugs from where they drilled the waterjackets and plugged the holes but to me it sounds like your talking about a cracked manifold.

Btw if it is the exhaust manifold you could have cracks on the inside also and could be leaking water in your heads.

Check your oil ASAP... Praying that it's not chocolate milk in color.

Also, there are not typically headers on an inboard boat engine..... but exhaust manifolds. It's not uncommon for the manifolds to need to be replaced after 10 or 15 yrs of use, especially if the boat has been in salt or brackish water. The problem would appear as Brock described above.

(Message edited by bill_airjunky on July 30, 2009)

sorry for the confusion, after reading the posts, the leak is in the exhaust manifold on the drivers side only. There are two halves to the manifold (top and bottom) and the leak is in the bottom part, but not where the bottom butts up to the engine, its actually in the manifold itself.

They are VERY corroded, but at 179 bucks a piece in the skidim.com catalog, and me being totally broke, will it mess things up to keep running it? It only drips at high rpms.

How do I know if it is leaking into the heads and im guessing that would really mess things up. The boat has never been used in salt or brackish water, but the boat is 23 years old.

Is there a way to check for water in the oil without draining all the oil or do I need to drain it all and buy new oil?

Just check the dipstick, if the oil is clean then your good, if milky chocolate color you have issues. Here's the deal, salt or brackish water has nothing to do with it. It's attrition, 23 years of water running through iron causes rust and corrosion that's all. There's no fix at this point they've rusted and flaked enough iron off to wear through and eventually, probably sooner than later you'll have a major break through or collapse. Check boat salvage places as they part out boats and engines, might get lucky.

I've never seen the manifolds cause catastrophic failure. But I imagine it can't be good to run that way forever. I think I'd put it on your list for the winter & make it happen.

You don't have to overheat a engine to crack a manifold.If your impeller was bad running without circulation will cause a crack within a few minutes.If you get a crack on the exhaust side it could spit cold water on your hot valve causing some major damage.

I guess that could happen, but the flow of things is generally the other direction. It's a winter job IMO.

yeah i am hoping its a winter job. It makes me nervous though. I guess I wont be running weight the rest of the summer, or at least not the amount I have been.

wire brush the crap out of the spot, wipe clean, and try jb weld.i have a spot on one of mine and it has held so far.