Water Pump

[blmacias]

I just installed a water pump kit on 2003 yamaha 90hp I bought from Boats.net. The kit is OEM and it doesn't pump water when it is idling. It pumps good when I run the engine above 1500 rpms. It almost seems like it is getting air locked at idle (idle is @800 rpms) and pumps no water. Does anyone know what is going on or has anyone experienced this after a water pump install?

[Ken]

blmacias,
Are you testing the water pump with the earmuffs on the motor on the driveway? If so, you need to put the boat in the water and check it there. Sometimes the earmuffs won't seal well around the water intake, and the impeller will suck air.
What are you gaugeing the water pump performance with - the side discharge? Water pressure gauge?
If you are using the side discharge (pee stream),
you might want to disconnect the hose from the nipple connector and tape it over the edge of the
lower cowling - sometimes debris will collect in the nipple and restrict water flow.
I just did a water pump repair on my C115 last week, and the pump was slow to prime using the earmuffs - took about 10 seconds for the "pee-stream" to appear, and at idle, the stream was weak. Then I put the boat in the water and ran it - it primed immediately and the pee stream was strong at idle.
Good luck [img]smile.gif[/img] ,
Ken K

[Hamfisted]

So you're getting little if any water flow out of the tell-tale hole at idle? When you put the water pump back together did you spin the driveshaft clockwise while you were tucking the impeller into the housing? What direction did the impeller blades end up pointing? If you got them in counterclockwise it won't pump for crap at low speed. There's also the waterpump housing base O-ring seal that likes to pop out of position as you're putting it back together. I usually silicone it in place before I put the housing back on.
Those are just some things to look at.


Mike

[Ken]

blmacias,
I remembered another item that might cause your symptom, although doing a water pump repair
has nothing to do with it. It's the pressure control valve, aka pressure relief valve, poppit valve.
If you are getting a lot of water dumping out of the relief holes at the top of the upper casing at idle, then that is an indication that the PCV is stuck open. Remove and clean away the debris/corrosion and replace spring if broke.
Also, inspect end of valve and seat for cracks.
You want the PCV to remain closed until the water
jacket pressure exceeds 20 psi - it it's stuck open, then you will not have much pressure at low speeds, and probably not enough at high speed to cool the motor.
Hope this helps [img]smile.gif[/img] ,
Ken K

[blmacias]

Ken, my boat has a water pressure gauge which I have been recording the water pressure readings. The readings have all been while the boat was in the water. I can be running and pump will be pushing 15lbs. or more but, when I get to the ramp to load on trailer it will only push 2 lbs. at idle or nothing will come out of the pee hole. I have been revving the motor up to 1500 rpms in order to get at least 8 lbs. of pressure when I'm idling. I'm going to check the nipples for debris. This thing has me baffled.

[blmacias]

hamfisted, It is a possibility that the o-ring could have rolled out of its channel. I didn't rotate the shaft because I marked its position so I could stab it in the motor easier. I installed the impeller in the metal enclosure just like the original impeller and then ran it down the shaft. I may have to remove the lower unit again and check the o-ring.

[blmacias]

Ken, where is this pressure control valve located? This is my first water pump I've installed and it was fairly simple.

[Ken]

blmacias,
I've never thought about installing the impeller in the metal housing cup and then sliding down over the driveshaft - but, the normal sequence for installation is as follows (this is for my 2000 C115 - yours should be the same):
(1)gasket
(2)impeller plate
(3)woodruff key
(4)impeller
(5)three washers (two flat and one wave)
(6)spacer (nylon)
(7)collar (retainer ring)
(8)impeller cup and housing assembled together
with two o-rings
You can look up the exploded view of your water
pump in the online catalog above.
You want to tap the collar down on to the nylon spacer to within 0.080 inch, and then install the cup/housing/o-rings assy. Flip the nylon housing upside down and install the small o-ring. Hold it in place with marine grease. Then install the metal cup into the nylon housing and make sure it indexes properly so that the output of the cup lines up with the output of the housing. Then place the large o-ring in it's channel around the cup and hold it in place with grease.
Now, slide the assy down over the drive shaft. Make sure you have a little grease on the impeller and the inside of the cup. While pushing down on the housing after it makes contact with the impeller, rotate the driveshaft clockwise and at the same time rotate the housing/cup ccw while pushing down - the paddles of the impeller will bend back away from direction of spin.
You can have someone get down at eye level and make sure the paddles are pointing backward to clockwise spin of the driveshaft, and check the large o-ring to make sure it is still in it's channel of the nylon housing before you make contact with the impeller plate.
Line up the dowel pins with the holes in the housing.
For my first water pump, I actually put a large hose ring clamp around the impeller blades and got them started in the right direction before pushing the housing/cup assy down.
Don't worry about the position of the driveshaft - when you install the lower unit just make sure the shift rod is in neutral (turn the prop shaft - the drive shaft should not turn) and make sure the remote shift handle is in neutral. If the lower unit will not travel that last inch, have someone turn the flywheel just slightly so that the splines of the bottom of the crank will line up with the driveshaft. I have to do this every time I stab the lower unit on my C115.

The "poppit valve" is located toward the bottom of the exhaust plate. It is under the dome shaped metal cover held in place with two bolts. It has a rubber hose attached to it.
You need to get yourself a Yamaha shop manual to help guide you with procedures like this. Can order online at www.yamahapubs.com.
Good luck - and let us know how you come out.
Ken K [img]smile.gif[/img]

[blmacias]

Ken, thanks for all your help. The 2003 90hp tlrb 2 stroke doesn't have all the washers and o-rings your 115 has.
1. The only O-ring is the one which keeps the water from going down into the lower unit bearings which I replaced.
2. Followed by a gasket
3. Spacer channeled housing plate (O-ring above is on this housing that has to be tapped into place)
3. Followed by gasket
4. Followed by a metal outer plate
5. Followed by another gasket
6. Followed by woodruff key
7. Folowed by impeller
8. Then metal insert cartridge
9. Then plastic housing held by 4 bolts covering all of above.

I did notice the rubber hose attached to a small housing which is screwed near the water pump. This seemed strange to me because it runs up the cowling but, then exits and is plugged. Do you know what this hose is supposed to do? Is this hose the one which controls pressure that allows the pressure control valve to open and close at 20psi? I am going to check this hose and housing. I am starting to get a feeling that the PCV may be my problem because, the impeller I took out was not worn. I am ordering a repair manual today.

[Ken]

blmacias,
That hose near the water pump is the speedometer hose. It feeds water pressure from the leading edge of the lower unit to tubing that you route up to the console speedometer.
Boy, I just looked at the diagram of your motor in the online catalog (above) - I stand corrected.
Heck, your water pump is more complicated than mine! Geez - wouldn't it be nice if the maufacurers would standardize on things like WATER
PUMPS!
Ok, the PCV valve is located at the TOP of your motor assembly - take a look here - item #39:

http://www.boats.net/yamaha/partsyst...mponent=368576

Sorry for the confusion .
Keep us posted on what you find out,
Ken K [img]smile.gif[/img]

[blmacias]

Ken, Mike, Success is so sweet!! I found my problem. It was a piece of gasket stuck in the PCV. I also blew all the hoses and nipples including the hose leading up to my pressure gauge. I'm pushing 12 to 15 psi at idle. Thanks, for all your help guys. Mike I do have an AIM account. I will get back with you on that info.

[Ken]

blmacias,
Glad you got it fixed - and I'm glad it wasn't the water pump.
By the way, what kind of pressure gauge do you have? And you are reading 12-15 psi at idle, what are you reading at WOT?
Thanks [img]smile.gif[/img] ,
Ken K

[blmacias]

The pressure gauge is Yamaha OEM. It was installed when I repowered my Dargel Scout Shallow Running Boat. I'm guessing WOT means Wide Open Throttle. If it is then I am pushing about 9-12lbs at 5200 rpms with the jackplate all the way up and the trim is level. The shallow blaster cavitation plate is skimming the top of the water when I'm running in a foot of water. In the Intercoastal when I had the jackplate half way up it pushed 14-18lbs at 5200 rpms. At idle 800 rpms it is pushing 8-10lbs. I noticed the trottle was sticking at 1200rpms so that is why I noticed 15lbs pressure yesterday. I sprayed it with WD-40 and now its idling at 800rpms and 9-12lbs pressure.

[blmacias]

Sorry, Ken but I still contradicted myself on the last reply. So many rpms and so many pressure numbers at so many intervals with jackplate up or jackplate down, in the water, with ear muffs. Its mind boggling. Omit the last sentence on my last reply which states the wrong PSI @ 800 rpms. I am getting 8-10lbs PSI @ 800rpms.

[Ken]

blmacias,
Thanks - it is amazing that at 5200 rpm you are getting enough water cooling at 9-12 psi.
I am just now installing a water pressure gauge on my C115 that is six years old now. I have had a water temp gauge all this time, but after reading other owners' experiences with the pressure gauge, I now realize that the pressure gauge is the best indicator of water pump performance. And since my Yamaha shop manual gives me no clue as to what psi to expect, I have been inquiring to find out what others are getting at idle, mid-range, and wide open throttle
(aka WOT).
It's pretty obvious that with your motor in the up position on the jackplate, the water pump is sucking some air, but evidently not enough to cause the motor to overheat.
Good luck [img]smile.gif[/img] ,
Ken K