Volvo penta 3.0 blowing water hose off

[bigobass1]

Ibought a 2001 Seafox with a 3.0L Volvo penta outdrive.It was shot so I replaced everything except the motor with mercruiser.It has now got a water pump impeller and a raw water pump that was on the motor.My problem is it builds up to much pressure and blows off the large U shaped water hose. Like it needs to flow more water out. I removed the impeller from the raw water pump but now it runs 170 degrees at idle(it ran 125 with both pumps) and still blows off the hose anyway as soon as the throttle is increased. At idle the large hose is under so much pressure it can't be colapsed by hand. Not sure why this is happening.

 

[hystat]

I have a boat that is a mix of OMC parts (thermo hsg, etc omc) and Mercruiser drive and manifolds (dry joint even) so I had to do some field engineering... I had to drill the baffle holes in my riser gaskets to get the right flow out the manifolds and yet leave enough flow for the engine.
I suspect you may have to do the same - let more water out.

All my stuff was new though... corrosion in the riser can cause a restriction in an older setup. Also, a broken water shutter jamming the exhaust downpipe is common, but you would have just had that all open in the refit I suppose.

what ratio outdrive are you using?
Mercruiser paired the 3.0 to the 1.98 ratio so very slow turning impeller compared to a 1.81,1.65 or 1.5 used for the bigger motors