Thread: 95 mariner 150 cooling water

Originally Posted by dfar

That impeller needs to be replaced. It is not pumping water as it should and could fail at any time. Probably already has hairline cracks developing in the bent areas of the blades. Save your motor and replace it. Just make certain that the blades are bent in the correct direction or it will not work and motor will overheat.

I DON'T see the flat wear plate from under the impeller in the picture. ??????? Was it missing??? Will not pump water without it.

I can't tell if the color change on top of the blue base around the drive shaft is worn from the impeller running against it. But if it has you will need to replace that as well as needing a new wear plate.

The pee holes are notorious for having bugs building nests in the end of the outlet. Run a piece of wire up inside it to clean it out.

Dfar please read whole thread. Wear plate was there. Discoloration is from gasket being stuck haven't finished cleaning it up yet.Thanks for your input.

Sorry I missed that part. Hope you get it fixed soon and get out on the water.

LOL.... ok... a couple of things.

The impeller does have some age and set to it. So I would expect a weak idle flow. Go ahead and replace it. Also, you will find that the motor will not put out much water from the tell tale off of the hose until the t-stats have opened. But you should see water flowing from the prop's hub and exhaust reliefs in the lower part of the mid section within a few seconds of start-up. I think the learning curve of how it waters will quickly flatten out once you get a little run time under your belt.

As for being careful not to bend the vanes in the wrong direction.... That is about as far from true and accurate as one can get. It doesn't matter. The vanes (being flexible) will simple bend and curl in which ever direction applied. It is important that you fully seat the housing over the impeller by hand while turning the driveshaft. If not, the base of the housing can pinch the ends of the impeller vanes if tightened down by mechanical force. I apply a small amount of grease to the cup to keep the friction to a minimum while turning the driveshaft and pressing down on the housing during assembly.

Good luck with this. The Merc 2.5 ltr is a beast of an engine that is sure to put a smile on your face when it comes to life.

All done with the replacement. Took almost three minutes before a weak trickle. Increased idle speed and all looked good. Will test on lake Saturday. Heads never got to hot to touch.

That's about right. When you get to the lake, you will see that it waters better. As I stated earlier, the unlimited availability of water and the change in head pressure that occurs on the lake will make a notable difference. Be thinking of getting a water pressure gauge. They are worth their weight in gold if you are running rough water and/or a hydraulic jack plate.

Happen to have a link to a pressure gauge and maybe a temp gauge that you would recommend? Thanks

Hands down the pressure gauge. You have a warning buzzer that is preset by the manufacture to let you know if temps are critical. But before temps can become critical, a loss of pressure has to occur. The temp gauge is somewhat static and can be easily forgotten. But the water gauge is dynamic and will keep your attention during the learning curve. Once you know what to expect, a quick glance will have you taking appropriate action before overheat occurs.

Thanks just googled them and feel like an idiot. I was overthinking it. I can acquire everything from work for this. I do automated controls, so I was trying to reinvent the wheel. I still am going to look into a temp gauge I hate "binary" alarms I want real time data. Thanks again for your help.