im in the process of buying a 28 bertram the exaust port on the starbord side has water coming out when you give it gas at the dock but when you take the boat out and run at 3600 rpm only steam comes out what is the problem
It could be any number of things. Including but not limited to, a bad impeller, collapsed hose, blocked coolers, blocked mixer, etc., etc.
If flow goes down I would suspect a collapsing hose on the intake side of the pump but as bill said it could be a number of things incl.impeller, dirty exchanger, cooler, strainer or even something in the thruhull.
I remember some Bertram's had a 3-4 inch exhaust tube out the transom and a exhaust vent on the hull sides before the transom venting the muffler top. If you were fast enough on the throttles you could splash some water out the top of the muffler and out the side vent. During normal operation, hot air and maybe steam was normal from these side vents. Checkout the transom exhaust, at cruise you should see a nice flow of water out this tube. I had to remove this vented muffler system on a 34 when converting from LB chev gas to Cummings 5.9ta a few years ago. Ended up with 5 inch straight back with a surge tube forward. Just glued a panel behind the side vent slot that still looked cool.
locating a seawater flow switch [I recently downloaded a operaters manual from Bertram for a 28 Bertram we are still having problems with the exhaust on the port side weve done all the obvious ,and rhax for all the input ,the manual says check the seawater flow switch ,does any know wher it may be or does it really exicst.
Starting from the sea-cock, follow the hose up to the heat exchanger. I don't think there was a rule if it needed to be before or after the raw water pump. It's going to look like a hose connect with a couple of wires from it. Usually the Bertram system would just sound an alarm if water is not moving. You have not mentioned if your running hot, just water splashing out the side vent?