View Full Version : water pump impeller
Anyone know what the average life span on the impeller on the water pump.I was told that it should be replaced every two years.I have a 150 xr6 thats two years old.I've installed a water pressure gauge,which i monitor while running.Its 5 to 6 lbs at wot.I would think that I should get a few years out of it,providing the water pressure doesnt drop,which would indicate the the impeller is wearing.
Trailerguy
10-25-2002, 07:36 PM
I think Merc recommends every 3 yrs., I have an old Rude that hasn't had the impeller changed in 20 yrs. I think you are on the right track by monitering it. I would think it would be most likely to fail when it was first started after being dry for a while. You might consider changing it if it's failure would be a major incovenience, such as the first day of your annual fishing trip.
BlackSilver
10-25-2002, 08:59 PM
Because it's a simple job and the impellors are cheap, I change mine every three seasons, but so far have never found one that looked particularly worn. Since you have a pressure guage, I'd just buy a spare and watch the guage.
Walk softly and carry a big fish.
Hans/MN
perchjerker
10-26-2002, 03:28 AM
I change it every 2-3 years. What happens is it will develop cracks near the hub, sometimes tiny ones. One day you might be running down the lake, miles from the rtamp, watching your gauge, then if a vane breaks you will watch your gauge go to zero. Then you will wish you preformed the maintanence on it. A spare wont do you any good miles out on the water.
For me, its a preventive maintance issue. I dont wait till there is trouble.
I've read in numerous articles where you should change it every 100 hrs. My Mercruiser has just under 800 hrs on it, and I'm on my 5th impeller so I haven't quite stuck to the 100 hr rule. Use the pre-emtive maintenance approach.
perchjerker
10-27-2002, 06:49 AM
What I do when replacing parts purely for preventative maintanence, is if the removed part looks ok, I will save that part for a spare.
Husky
10-27-2002, 08:03 AM
Tom,
5-6psi at WOT ??? OUCH!
The v6 mercs should have a MINIMUM of 10-12 psi at WOT, usually in the 17-21 psi is about right for a good impeller. Low water pressure can lead to overheating and very serious damage.
Regardless of the age of your impeller, its time for a change.
I try to change mine every other year. One thing you will notice, is that a new impeller will increase the pressure at idle and low speeds quite a bit over a worn one. Having a pressure gauge will allow you to view this first hand. The WOT pressure will also increase too.
Change it now, you've got a lot o$$ tied up in that motor and its relatively inexpensive.
Husky
Dutchman
10-27-2002, 10:29 AM
I change mine every 2 years. I like to fish shallow at times and sometimes I get hung up allowing sand and stuff into the intakes. They look pretty chewed up some years.
" Fishing is the pursuit of what is elusive but attainable, a perpetual series of occasions for hope "
SnellTier
10-27-2002, 12:21 PM
Tom,
I changed mine this year ... engine was 5 years old ... after having seen the discussions on this board. The manufacturer (Merc) recommends in the owner's manual changing it every THREE years.
I had the mechanic who changed it hang onto the old one to show it to me for my own curiousity and learning (I had never seen one). It did NOT have cracks in it, but the fins were curled and "set" from being crammed into the small area in which it operated. The mechanic told me this was typical of what he sees when he does change impellers for his customers and the "set" reduced the pushing of water through the cooling system. This means it was not as effective at cooling as it shoot have been.
From now on, I will change mine every 3 years (I only use my motor about 50 hours a year so even if the change point ought to be 100 hours of use I should still be safe).
perchjerker
10-27-2002, 12:30 PM
Sure they develop a "set". Just dont try flipping it over and getting more use out of it.
Good point Perchjerker on not flipping an impeller over. All of the marine mechanics I know have told me the same.
One thing I forgot to mention is that periodically, you should replace the impeller housing. If you notice wear (groves) in the housing, you should replace it while you are replacing the impeller.
gpbrown
10-27-2002, 05:56 PM
i change mine every three years. no problem so far..
gb
fishandhunt1
10-27-2002, 07:18 PM
Yes get it replaced I own a 93 40hp merc. the seals were leaking in the bottom end took it to my mechanic replaced all the seals impeller and housing and it only cost me $128.00 that is alot cheaper than if you get your motor hot 1 time!!!!!!! I think if you are mechanically inclined at all you could do it yourself and save yourself a few $$$ Good Luck and dont take no chances> Larry
bobco
10-28-2002, 07:33 AM
5-6 psi is bad! I second the 12psi min at WOT, my 96 150 runs at 17.5 with new impeller, dropped down to about 14 this year after 2 seasons and I changed it out. Found no real wear but was set in direction of rotation. Also check wear plate under impeller for groves or uneven wear.
Husky
10-28-2002, 08:38 AM
Tom,
After thinking about this overnight, has your water pressure gauge always read this low? It might be that you have a pinch in the gauge tubing somewhere, or a faulty gauge.
Seriously, 5-6 psi at WOT is DANGEROUS. Something, whether it is a impeller, gauge or tubing, is to blame. A cooked powerhead on a v6 is in the range of $2-4k. Better be safe than sorry.