Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Water Pump Impeller on Mercury 40

Posted by burtim on 05/25/10 - 1:49 PM
#1

I've got a 2001 Mercury 40 HP 2 stroke on my 13. After several weeks of normal operation, I noticed the "tell tale" water flow was reduced to a trickle from what has been a normal rate of "pee". All of the shops I called laughed at me when I asked if they could look at it before Saturday. I have never disassembled the lower unit myself before, but I have assumed the impeller is in need of replacement. I went ahead and purchased a new impeller for my engine regardless. Based on the information I have just outlined, can anyone give me a brief step by step of where to go from here to get my motor back up and running (hopefully) before the big weekend?

I appreciate your help!

Posted by Joe Kriz on 05/25/10 - 3:26 PM
#2

Before replacing the impeller, I would check to see if the tube has any debris in it.

Take the tube off and see if you can blow through it. Sometimes a small pebble or a bee will block the tube.

Posted by HarleyFXDL on 05/25/10 - 5:12 PM
#3

I agree with Joe, Take a small wire and run it up the tube. I've cleared many tubes this way. Most of the time I find motors that are run in salt water will have the corrosive material within the engine loosen up and lodge itself in the hose.

Posted by awayland on 05/26/10 - 3:47 AM
#4

I used a straightened out paper clip to clear mine while running it. If it's not overheating you may just have a minor clog. But do learn how to change your impeller it's invaluable knowledge.

Posted by Jet Wrench on 05/26/10 - 4:10 AM
#5

Same thing happened on my old Honday 10HP. Just needed to probe/clean the outlet. Worked like a champ.

Posted by burtim on 05/26/10 - 7:15 AM
#6

Thanks guys. I'm going to replace the impeller partly because I haven't done that yet and I purchased the boat two years ago from someone else. I'll clean the tubes out as well.

I figured I'd pick up a manual for the motor and learn how to do the important stuff. Since boats are more a hobby than a requirement for me, I can enjoy taking the time to do it right. This is opposed to car repairs, which I am beginning to dread. They always seem to come when you don't have the time or money to take care of them!

Posted by Derwd24 on 05/26/10 - 8:01 AM
#7

That's for sure!

Take a look at this first video, it's for gearcase removal on a Merc. Yours might not be identical but this may help a bit:

www.themarinedoctor.com/videos/remove...vecase.wmv

And here's one on changing out the pump. Again, not identical but it may help:

www.themarinedoctor.com/waterpump.wmverpump.wmv


Posted by burtim on 05/27/10 - 6:37 AM
#8

Thanks for the video links. I looked previously and those are the best ones I have seen on the subject.

The local parts shop had Clymer engine manuals at half price. I picked up one of those too.

Posted by CES on 05/27/10 - 6:52 AM
#9

I replace the impellor on my 40hp yami every other fall just for preventive maintenance, it's part of what I do to get it ready for winter.

When you install your impellor, make sure the rubber vains are pointed in the correct direction and also apply a small amount of grease to it as well. His is to help prevent damaging the impeller he first time you start it up.

Edited by CES on 05/27/10 - 6:53 AM

Posted by John Fyke on 05/31/10 - 5:35 PM
#10

I have seen several times where some bugs have nested in the pee drain. Also check your thernostats while your at it. When is the last time your impeller was changed?

Posted by burtim on 07/07/10 - 4:39 PM
#11

I just thought I would post an update in case someone else has this problem in the future. To recap, my tell-tale water stream got to be a drip-drip instead of a continuous flow on my Mercury 40 HP two stroke.

I took apart the lower unit to inspect the impeller and replace it with the standard kit of parts from Mercury. I was surprised at how new and good looking everything was inside. Nevertheless, I proceeded with the replacement. Since everything looked so good, I assumed the impeller was not the problem. Others suggested the tell-tale drain tube might be blocked. I disconnected the tube and tried to blow air through it. Sure enough, it was blocked. I used my compressor and blew through the outlet fitting back toward the motor with the tube disconnected. Sure enough, it was a small maple tree seed! I re-assembled and saw the motor pee like a race horse.

Back to fishing!

Posted by CES on 07/07/10 - 7:07 PM
#12

Great news!! If you haven't replaced your impeller for some time, it was probably a wise choice to have replaced it when you did.

Thanks for the update.

Posted by Ric232 on 07/07/10 - 7:52 PM
#13

I carry a 1-foot piece of heavy monofilament line (from my lawn edger) on the boat. I used it more than once to unclog the tell-tale. Much safer and more effective than wire.

Posted by MW on 07/08/10 - 3:23 AM
#14

Replacing the water pump is the best insurance that you can get on an outboard, GOOD JOB !