95 Mariner Magnum 40 with ongoing water flow issues. Need next step in trouble shoot

[MikeG5903]

Serial # 0G239008
Water flow is delayed at start and poor pressure. I have to bring up the RPM to get the water to start flowing. Once flowing it stays pumping with poor pressure. Water temp is pretty warm coming out as it steams even on a hot day. I am pretty sure this motor does not have a thermostat. I had a problem about five years ago and changed the impeller that looked perfect and found I had a nest of some sort in the discharge tube between the motor and the pee hole. Started having issues again last year and changed the impeller that was perfect again. Checked the hose and it was clear. Sent air through the pee hole back and it sounded clear. I was told to check and make sure the water tube from the pump to the motor was in the bottom of the and it is. I purchased a Seloc book but have no idea what to try next. Any help would be appreciated by my sons and I.

 

[carholme]

Re: 95 Mariner Magnum 40 with ongoing water flow issues. Need next step in trouble s

Your s/n comes up as:

MARINER - ( 40 H.P. (1995 ))
Serial No: 0G239008 Model No: 7040312DD

Parts and Service Bulletin list for s/n 0G239008:

Search Results - Crowley Marine

The Mercury service manual you require is P/N: 90-814676R1. See my message to you in Notifications at the top of this page.

When you last changed the impeller, do you recall the condition of the faceplate and how scored it was.

Gerry

 

[MikeG5903]

Re: 95 Mariner Magnum 40 with ongoing water flow issues. Need next step in trouble s

It was like brand new. Most of the face plate is covered by the upper and lower gasket if i remember correctly. This is the impeller from the last change. I Keep the old to compare.