water pump woes on a Force 88 125 HP

[ahickman]

After receiving the new water pump kit yesterday, I went to work on pulling down the lower unit. Took over an hour to remove all the bolts. Very intense owing to amount of force needed to remove several bolts. They were heavily corroded and lots of aluminum oxide power flushed out. Once exposed, I could see the shaft was rusted as well. Light sanding and then I unbolted the four water pump bolts. Pulled the housing and impeller out. Pretty bad shape with lots of pitting. No wonder there was no water flow.






I was very suprised at the grooves on the lower shaft. Is this normal?


Got everything cleaned up and ready to reassemble. Chased the bolt holes with a thread to clean them out a bit. Started to tighten the four water pump bolts down to about 15 ft/lbs and the last one cut loose. Threads totally crumbled. Really wasn't a suprise, but surely was a dissapointment. Now I have to tap that hole out and re-thread it. There is not much aluminum to work with around the bolt hole. Anyone have a recommendation on what bolt/thread size I should use?

 

[Jiggz]

Re: water pump woes on a Force 88 125 HP

The proper torque for those 1/4"-20 bolts is only 70 inch-lbs! which is less than 7 ft-lbs! If you can afford it I would highly recommend getting a replacement pump housing. but if you can't, at least smooth the walls. Personally, if I have to reuse that housing, I would fill the pittings with some type of epoxy and smooth it with sandpaper. It will at least make it easier for the impeller not to mention prevent premature wearing due to rough surface.

 

[ahickman]

Re: water pump woes on a Force 88 125 HP

Jiggz, thanks for the input. I did indeed get a new housing with the kit I ordered. Can't imagine ever getting a successful positive vane pressure using the old housing. Aluminum is so brittle and easily fouled. My biggest worry now is re-tapping the one bolt. Not much aluminum on the base plate left.

 

[Jiggz]

Re: water pump woes on a Force 88 125 HP

Patience will be your best tool in re-tapping that broken bolt. I always start small and slow and progress through it. And of course, your last resort is probably the heli-coil option.

 

[Frank Acampora]

Re: water pump woes on a Force 88 125 HP

The grooves are normal. One is from the seal lip and the other is from the white plastic locating disc. Because the pump and impeller is offset, the disc locates it while bolting it back on and keeps you from side loading the seal.

Now: To the stripped bolt hole: There is not a lot of meat around it and a heli-coil will be "iffy." If the stripped hole is NOT located above the fill (or vent) hole--I forget which it is-- you have the option of drilling deeper and retapping to 1/4 - 20. Just be careful and use lots of lubricant. Deep holes in aluminum tend to gall and snap drills and taps. After drilling 3/16, tap 1/2 turn at a time then back out and go in another 1/2 turn. Repeat until the threads are deep enough to hold the longer bolt

 

[ahickman]

Re: water pump woes on a Force 88 125 HP

Ended up retapping the thread with an 8 mm x 1.00 pitch thread and got enough thread in there to take the bolt down to 7 ft/lbs. Enough to close the lock washer and start compressing the new gasket. Buckled the LU back up after struggling a bit with the splines. Took other's advice and covered the shaft and bolts with antilock grease. Just waiting on the return of my TnT pump and I can get this thing on the water!!!

 

[ahickman]

Re: water pump woes on a Force 88 125 HP

Frank,

took a few minutes today to hook up muffs across both slotted vents just behind the propeller. Turned the water on full and was hoping/expecting to see water flow out the "pee-holes" just below the cowling latch. Nothing! It did trickle out the snout, but most spewed out from behind the black muffs. I took the hose off the muffs and pushed it flush up agains the "pee-holes" and water came running out the snout. I thought the bottom vents were the main pickups for the water pump? Kinda stumped here.

 

[fgardinier]

Re: water pump woes on a Force 88 125 HP

ahickman,

Do not think that is bad. We just replaced a WP on an 88 125hp force and had similar results. But in the water it pumped really good.

 

[ahickman]

Re: water pump woes on a Force 88 125 HP

What are the grills for at the bottom for?
_

 

[Jiggz]

Re: water pump woes on a Force 88 125 HP

Those grills are actually the intake for the impeller. On muffs, if the garden hose has too much pressure there is actually less water going into the water impeller instead it ends up all over the sides of the muffs. On muffs, there is very little water coming out of the "nostrils" and more to the snout. On water, because there is resistance to the snout being submerge, more water will come out of the nostrils.

 

[foodfisher]

Re: water pump woes on a Force 88 125 HP

The hose pressure won't push past the impeller on it's own. The engine has to be running for the pump/impeller to push it up.

 

[Vintage IRA]

Re: water pump woes on a Force 88 125 HP

Got an 86 125hp that now has a fresh impeller. This is the first time I've fired the motor in a bucket of water instead of muffs.
I now have water misting out the the 2 mid-leg holes as it should. BUT, this is the first time I've noticed water running out the drain holes in the base of the water pump area near the bolt heads that hold the lower unit on. Pulled it back apart and put the garden hose on the plastic adapter that the engine feed tube goes in to see about leaks. Quickly found a hole in the Pump cover that must be there to allow the pump to self prime? Sent out a nice solid stream that would explain why the drain holes are present in the bottom of the pump cavity. Doesn't seem like the 1 hole spraying out of the pump cover could create a steady stream from all 6 drain holes below it. I then checked the plastic adapter. Fits tightly into the lower unit so I slid it out and onto the engine feeder tube. The top edge was a little
banged up from a previous owner. I took a knife and trimmed the tapered ID just at the edge to clean any burrs to help it start onto the tube when assembled. Seemed like it was a bit loose on the tube. Wondering if this might be where some excess water might be coming from. Grabbed a 1/4" O Ring at work and slid it on the tube before assembly in hopes it might slow down the water flowing out of the drain holes in the lower unit while running. Didn't seem to make a difference! Now I'm wondering if this is normal and just never saw it before because of the water muffs I've used in the past? Seems to be flowing enough water to cool? Doesn't trigger the overheat sensor as it did before. I'm guessing with the muffs excess spray I just never noticed this in years past? I'm covering the intake slots by 1/2". If the boat was in the lake I'd never know.

Any thoughts guy's?