1986 Mercury 150 XR2 Waterpump

Hi all,
I am brand new at this so if I mess up please be patient and help walk me through it.
I have a 1986 BassCat Pantera with a 150 XR2 Mercury outboard and my water pump is getting weak I think. Here is what it does. when you are running down the lake it will shoot a good stream out however at idle or just trolling it barley comes out and sometime it dont.
My question is does this sound like I need to replace the waterpump?
And if so is this a big project or somthing I could handle myself? I have changed the waterpump in smaller engines like a 50 hp mercury but never in one this size.
If I take it to the pro's what kind of price should I expect for them to do it?

Thanks to everyone and God Bless

Re: 1986 Mercury 150 XR2 Waterpump

At idle does the pump randomly seem to open up and push a lot of water out or does it stay a dribble or nothing at all?

If it will eventually start pumping heavy at idle, then it sounds like normal thermostat operation to me.

The water output will go from nearly nothing to a full hot stream when the thermostat opens.

RC

Re: 1986 Mercury 150 XR2 Waterpump

Replacing the impeller/water pump every few years is considered normal maintenance by many, whether the pee stream is failing or not. I think that it is better to be proactive on cooling related maintenance than to wait for the motor to overheat. Others will disagree and prefer to get the most use possible out of the impeller/water pump before replacing it.