Water Flow Problem

Pat310

Had an overheat issue this past weekend. 2003 310FV with 5.0MPI’s. As soon as i throttled up outside the no wake zone the starboard engine alarm went off. Shut down immediately. Engine cooled down below 170 and started back up. Went down to 150 right away. Throttled up again and temp began to climb so shut down and headed in on port only. Today went to boat and same result. Water pressure on starboard fluctuating 3-6 psi at 1000 rpm temp 151. Pressure drops to less than 1psi at 2000 rpm and temp starts climbing. Idle back down, psi back up temp back to150. Any thoughts?

Pat310

BTW water pump impeller done in October

Ian

Impeller spinning on shaft like a spun hub in an Alpha? Seems okay low revs, wind it up and the friction of the impeller vanes exceeds that of the shaft.

Ian

Belt isn’t slipping on the pulley?

captkevin

Salt water or fresh water? What drives do you have?

captkevin

bravoitis

Ian

He has B3’s, got the same vessel.

Pat310

Bravo 3’s. Belt is good. Raw water cooled in salt water. New transom assembly 2 years ago. I also have flush kit installed and flushed soapy water thru the drive with lots of bubbles coming out back so no clog between water pump and drive. Mechanic going to check impeller. I was thinking maybe sucking air somewhere in the system?

aero3113

I’m thinking it’s your impeller. If it doesn’t fix it, how old are your manifolds, risers and elbows?

Pat310

@aero3113 second season with Sierra manifolds and elbows. Hopefully just an impeller. Thanks

earl1z19

The impeller might be new but what does the inside of the pump look like? Excessive wear will allow the water to essentially cavitate around the impellor and result in low flow.

davidbrooks

Other than the obvious impeller check.  I would also check if there is an obstruction.  A lot of time water flow can get restricted in two places.  The first is the power steering cooler.  I would pull hoses off one at a time and back flush with a water hose.  Second place is related to the bravoitis comment.  That is where water is coming in through the transom assembly.  A lot of times that doesnt get replace as it is a real PITA.  So over time it get restricted.  When this happened to me mine was about the opening of a bic pen.  Be careful trying to get the fitting off from inside the engine bay.  Those bolt snap pretty easily and cant be drilled out without a right angle drill.

Pat310

Thanks @earl1z19 I was thinking the same. I assume the cavitation would increase with rpm?  @davidbrooks the hose that comes thru was brand new 2 years ago. Blockage would explain temp going up with rpm increase but not the drop in water pressure, no?

aero3113

Also, check the intake on the drive for anything blocking it. I just saw that you flushed and saw bubbles but one side can still be blocked if something is stuck on it.

davidbrooks

@Pat310 I can't comment. I don't have any experience with that. My gut says don't rely on those old analog gauges though. I love my Rhinda for times like this. If you have replaced the pressure sensor I don't think they are expensive and it would give you peace of mind.

Pat310

@aero3113 I thought the same so put on my mask and scrubbed the intakes with stiff brush. @davidbrooks i am getting pressure readings from vessel view mobile and i did swap sensors from side to side just to make sure readings were true

Pat310

Ok for future reference. Could not duplicate problem at dock. Pulled water pump apart all good. Pulled boat out of water today and found hose from drive to transom assembly had come off at transom assembly. So every time I accelerate and transom assembly lost contact with water, no pressure and overheat. Hopefully can get hose back and clamped without removing drive and bellows. Thanks to all

aero3113

WoW, first I’ve heard of that happening. 

Pat310

First time my mechanic has seen it in 40 years