1999 Mercury 150 EFI Water pump Impeller question????

[flashmob]

My motor is giving the overheat constant alarm warning . Water pump was probably changed close to 2 years ago . About 6 months ago it was giving this warning and I noticed my water pressure gauge needle was jumping . I let off throttle and got back into the throttle and noticed the needle started reading pressure on the gauge . The needle was jumping as a rounded a corner I noticed . I have ran it a lot since that happened to it . It has ran flawless till today 6 months later I rounded a left curve and here came the constant chime . I shut it off for 30 min and fished then it ran fine another 1.5 miles and then in the next left curve it went off again . I was then a mile from the truck so I idled in and got home . My question is does this sound like an Impeller issue or something else . I forgot to mentioned it was spraying water from discharge all the time this was going on . After I let it cool off after the first time the alarm went off it started fine and started spraying water as soon as the thermostats kicked in . Any advice would be greatly appreciated. I got a fuel leaked straighten out one time on here 4 mechanics locally couldn’t figure out and I used bassboatcentral as my resource. Just let me know what you think !!!!!Thanks in advance !!!!!!

[EuropeanAM]

ANYTIME you have water pressure or overheating problems, ALWAYS, ALWAYS start at the Source: The Water Pump. Water pump should be an ANNUAL maintenance item on this engine, especially in a fishing application.

Good idea to do a complete kit this time around, then see where you are at.

Moving your thread to the correct forum for you (be sure to update with engine serial number).

[flashmob]

Thank you . I will do that first . I am somewhat mechanicaly inclined . I was just wondering how hard it is to line up the shaft and the steering linkage after everything is replaced . I am considering doing it myself and heard this is somewhat difficult. Also I saw a video that showed a marine sealant being applied before putting in the bolts before tightening up lower unit . I have never seen my tech use silicone before . Unless they were extremely clean .

[rgsauger]

It's not hard but can be a pita if by yourself. Read all the links and watch the videos about water pump replacement. You have to line up the driveshaft, the water tube, and the shift shaft. Not hard...but a pita the first time or two.

[EuropeanAM]

Silicone goes across the exhaust dam. Check out Sherm's Water Pump Instructions (reference the FAQ Section). Virtually identical to yours (only thing I'd add is DO NOT use grease on the impeller... use Dawn Dish Soap).

Avoid those tube videos... there are a LOT of them with some downright expensive errors.

[flashmob]

Thank you . I replaced it and it running great . Had it out twice with no siren alarm going off .