1995 Force 120 no water pumping through powerhead

[beepx2]

Good day, Force-mates

I acquired a 1995 Force 120 25" shaft, condition unknown with a project boat I recently bought. My mechanic (45 years experience on all brands, trained outboard mechanics) looked it over and suggested I get rid of it and buy another brand, rather than put any money into it, since I was planning long ocean trips. So, of course I've gotten it running, intending to do some lake day trips.

New plugs installed
compression equal across all cylinders.
engine starts and runs fine in the driveway.
I tried muffs and a plastic tub - no water comes out the telltale, even when engine warm.
thermostat works fine, opening at 130. tested in teacup
pulled lower unit, impeller is soft, pliant, like new, no cracks
I pumped water up the inlet tube, and at first it leaked out everywhere, but eventually got to where it will spout out the thermostat mount hole. When I pour water into the thermostat inlet hole, it does not back up. it drains out.
Reinstalled lower unit and ran it a few minutes with muffs and in a bucket to warm up - no water. I pulled the thermostat housing. thermostat is open, but there is no water in there. When the engine is running, there is water jetting forward out of a hole in the midsection near where the tubing for the speedometer exits. So that tells me the impeller is building pressure, but the water is not going up the tube. Since this is a 25" extra long shaft, there is a spacer between the lower unit and midsection, and a rubber coupler that connects the top of the water pump housing to the inlet tube. I recall this coupling is only about 3" long so one theory is that the coupler fell off, or is too short, and the water pump is just filling the spacer with water, and it is spraying out the nearest hole. I'll pull the LU and double check this. I also notice exhaust pulsing out of the space around the sacrificial zincs. and out of the thermostat housing (!?). So I'm also wondering if there is a blown gasket somewhere, pressurizing the water jackets with exhaust and preventing the water from entering. I have ruled out head gasket because the compression is even. I'll post what I find with the coupler, but any other ideas?

 

[jerryjerry05]

Pull the lower unit.
The impeller shouldn't be soft and pliant. Replace it.
Everyone I have seen(hundreds) is stiff and not easy to install.
Old piece of hose, cut off end and run the hose up the pickup tube and run it.
Running in a bucket: the bucket needs to be DEEEP at least 4" over the cavitation plate. The pump/impeller won't work unless it's under water.
Muffs: tape them in place, and make sure the water pressure is high. Weak stream = no cooling.

 

[beepx2]

Thanks for the response, Jerry. Having slept on it, my current thinking is that I installed that rubber coupler wrong, so that the water is exiting the top of the pump, but not going up the tube. I recall mounting it to the tube, seeing an o-ring on the tube and pushing the coupler firmly up until it hit a stop. I must have left a gap. I will measure everything this time.

When I held the old impeller and the new one in each hand, they look and feel exactly the same. The PO must have replaced it recently. I'll pull the LU today and have another look. maybe just replace it anyway. Pressurized water is squirting out the back of the midsection when running, so the impeller is definitely getting water and building pressure. I'll report what happens.

 

[beepx2]

Well, I was right about the gap. My mistake was putting the coupler on the water tube, then installing the lower unit with the 5" spacer in place. The hole in the spacer is smaller that the outer diameter of the coupler, so as I tightened the bolts on the lower unit, it pushed the coupler about three inches up the water tube, leaving about a 2-inch air gap above the water pump outlet. All back together now. Will try to start it tomorrow and see if it is fixed. Been making too many rookie mistakes on this project - need to slow down and focus more.

 

[beepx2]

Success! Got it all back together on the third try, fired it up and it pumped water out the thermostat hole. So I reinstalled the thermostat, ran it again and water comes out the telltale. Weakly unless I rev a bit above idle, then strong when it revs. Got to check/change the lower unit oil and troubleshoot the panel-mounted remote control next. I suspect there may be some salt deposits inside the cooling passages, as the boat was kept on a trailer and fished occasionally in salt water only. My usage will be mostly fresh water, so I'm hoping over time that crystals/deposits will dissolve and wash away.

 

[jerryjerry05]

No such thing as salt deposits washing away.
There are some things that will help dissolve them.
Big bucket: couple gallons of vinegar and box of baking soda.
Run the mix through and let it set. Run it and repeat 4-5 times.
That might help, maybe not.
The one sure way is take it apart and use a screwdriver.
IF??? you do take it apart??? it will probably leak at most screws going through the cooling system.
Just leave it. It will last a long time.

My neighbor had a 40Yam on a pontoon.
NEVER flushed after use. 8-10 years of salt corrosion and sand and crud building up. One day he says the alarm is going off.
Removed the exhaust chest cooling system. The crud was about 50-60% blocking the passages. Long skinny screwdriver did the trick.

 

[beepx2]

Got it, thanks! Hoping for first shakedown run with this boat in the next week or two. Never ending list of things to check or get sorted. OP had the wrong thrust washer, (it was too big, did not nest in hub of propeller) Just got the new one.

 

[beepx2]

Final follow-up on this: Motor pumps water fine now, and is running great. My problem was the plastic sleeve or coupler which slides over the outlet tube on top of the water pump was falling off, or not sealing well to the water tube extending down from the midsection. I put the lower unit on and off at least 5 times before it all went back together perfectly, I used a ratchet strap to install the lower unit one click at a time while peeking into the gap with a flashlight to make sure the parts all joined together correctly before final tightening of the bolts. I wasted a lot of time and risked overheating the motor before figuring this out, but now it's fixed. I ran the motor in a tub with water and vinegar a couple times for good measure. Thanks for the guidance guys!

 

[beepx2]

Just though I would check in with some update on this motor. We are old friends now. Every time out something has gone wrong and the motor has shut down. But I have always had my tool box and able to get it running again and home. Here's a list of what went wrong, and how I fixed it.
1) at cruising speed, dropped to one cylinder. hard to start. Float bowl had come unscrewed and fallen off of bottom carb.
2) would only hold full throttle for a few seconds then die. Found the gray cheapo fuel line inner liner was crumpled up and restricting fuel flow. replaced with rubber fuel hose, replaced fuel filter
3) fuel leaking from bottom carb when motor tilted. O-ring from float bowl to carb crimped and leaking: Gasket in rebuild kit didn't fit (too wide to fit in recess in carb body. Ordered some square-section o-rings to the proper size.
3) hit a pile of rocks, chewed up new-looking aluminum prop: Mounted SS prop from a 100hp Merc I had as a spare motor.
4) runs for a bit then slowly die at idle: Rebuilt fuel pump, membranes in old one were super stretched out. Had to lower idle speed after doing this.
5) weak starting due to battery cable ends corroded: Soldered new copper connector ends on battery cables

I love how easy this old engine is to diagnose and fix. I'm glad I didnt junk it when my mechanic recommended I do so. I've had the lower unit off at least six different times now. I've repainted the motor and it looks great. Boat max speed is 36mph, cruises at 25mph. Haven't run it since hooking up the new tach, so I'll see what RPM it tops out at. BTW running it in a tub of vinegar mix flushed out an amazing amount of crud and deposits or whatever. I've run the boat in fresh water only now, and no problems with cooling. Thanks to Jerry and people on this board.

 

[jerryjerry05]

It's the little things that make us drink!!(not any more, sober 34)
Glad it's the little things. Glad I can help.

 

[topgun3690]

I love how easy this old engine is to diagnose and fix. I'm glad I didnt junk it when my mechanic recommended I do so.

The lack of respect for these old Force/Chrysler engines is actually a good thing IMO......makes it affordable to repair, replace, and maintain.

 

[jerryjerry05]

You can def buy em cheap.