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Old 06-08-2017, 02:48 PM
197prostar'10 197prostar'10 is offline
TT Newbie
Join Date: May 2017
Boat: Mastercraft, Prostar 197, 2010, MCX
Location: Ellicott City, MD
Posts: 11
Water in the oil, overheating/overcooling, 2 dime sized broken pieces in Exh on MCX

History-- I bought this 2010 Prostar 197 with 1400 hrs in October from a ski school in Miami. Yes I live in Maryland. I skied behind it there (little bay off the canal system. Definitely salt water. Brought it home, skied about three times behind it with no issues other than loving the wake. Then my good fiend(197 owner of at least 10 years) and I winterized it. We took it out the holiday weekend and skied fine, but when I took it out afterward for a long ride, it overheated. While letting heat soak kick in, I started it at idle. The temp dropped to 90 degrees. Started to idle back... Then on plane and up went the temp again. Idled back and even just on plane and that got us back. I found a missing clamp on the strainer and tightened it down thinking air was getting in the system.

We took it out to ski the following am and got through a complete set before again it started to overheat.

Yes, at this point I wish I had checked the oil. We idled back and then it seemed to hydro lock. We paddled the rest of the way back, especially because we did check the oil-- which was foam at this point.

We noticed a steady drip/almost stream leak from the left exhaust manifold before we resorted to paddling.

I've been boating for 30 yrs but always outboards. This is my first inboard.

Ok, current problems---so in reading the posts here on overheating, off has come the left exhaust manifold/ETXCAT and there were 2 dime+ sized pieces of caste aluminum inside it. But the exhaust gasket didn't have signs of failure.

So now I've read the intake manifold gaskets fail on these.

I have changed the oil, I'll do a compression check... Any other suggestions pointers I should look for?

My skill level is I've rebuilt a few OMC v6 outboards, a few head gaskets on a few of my cars (a couple Toyota supra s a minivan...) and freshened up the bearings on one supra with the block in the car.

I think I threw out any experience I did have and kept at it instead of diagnosing.

Thanks in advance for any ideas, focus and also connection for parts like thermostats, exhaust manifold gaskets, gasket to the SS elbow and now ETXCAT s (apparently).

I'll turn it over by hand to lubricate, take compression numbers... What about this ETXCAT sitting on the floor? Anyway of testing it? The 2 broken pieces were not smooth on wither side so it's not a piston!!
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Last edited by 197prostar'10; 06-09-2017 at 03:30 AM.
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