Hello all,

I am not in SOCAL (wish I was), but am still hoping for some west coast help on the east coast.  I have a (new to me) 73 CV-19 Glastron Carlson. I am a newbie on jets, although I've been around stern drives & outboards for half of my 52 years ....but this jet drive is a new animal to me.
 
This boat will idle all day on the trailer with a water hose connected at 160*. But when I put her in the water, and engage the jet drive at idle, it will peg the temp gauge at 220 after travelling maybe 200-300 yards at no wake speed to get out of the marina. When I get it up to 3000 to 3500 RPM's it will drop back to 180*. But if I idle it down to no wake speed to approach a dock....the temp hand pegs again FAST! It also puffs considerable steam (white smoke) out of the exhaust discharges when it's this hot approaching a dock.

 I have checked the compression twice, and it only varies by 20 lbs from hi to low (165 to 185lbs on Olds 455 with 425 "B" heads). I am running a CP Performance 180* marine t-stat. For the upcoming Memorial Day weekend, I am considering backing down to a CP 160* t-stat --or-- removing the t-stat and just running a Mondello reducing washer. I have had 3 new marine t-stats in her. I have replaced the water temp sending unit, and had 2 known good water temp gauges in her....all with the same result.

The Berkeley jet drive was rebuilt last year by the previous owner, so I don't think (hope) it's a water flow problem. This one has be stumped! Does it sound like a possible bad water pump on the engine? (it still uses the stock Olds engine water pump) But I don't see how...as it runs cool on a garden hose. I would think if it was a bad water pump, she'd run hot all the time. It's very much acting like a faulty or stuck t-stat. But what are the odds of 3 bad t-stats in a row?!! I'm also wondering if it's maybe a water flow issue <?> Any help on this will be VERY much appreciated!!  It really has me baffled!