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Mercury 9.9 not peeing (but impeller tested good)

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bcontento

Contributing Member
I have a 90's Mercury 9.9 that stopped peeing reliably (would sometimes). I started getting steam out of the weep hole. I pulled the lower unit off to check the impeller and flush it out. Our lake is pretty mucky so I figured some junk got sucked in. Pulled it apart and the impeller is perfect and the key is in place. I flushed it out and I tested the unit in a bucket. When I put it in neutral and spin the driveshaft clockwise with a drill, I get water pumping. Figured I took care of it. I reassembled it to the motor, but still not getting any water out of the weep hole, just steam after it heats up. I had the LU off 3 times trying to figure it out. I tried to make sure I got the tubes lined up right and everything.

Last time with it off, I put a rubber tube onto the copper water tube inside the shaft. When I blow through it, I hear it and feel it coming out of the weep hole but if I plug the weep hole while blowing, I do hear air escaping inside the shaft somewhere else. Is that normal? Could the pump be working but the water escaping into the shaft somewhere before getting to the block?

Any suggestions on next steps for testing or repairing would be greatly appreciated!
THanks all
 
I a relative newbie... I put my '87 Merc 8 hp in garage six week ago after a successful day. No fish, but motor ran well and peed fine. All told motor ran start stop 30 minutes while I kept checking tell tale. Tis was a test running.
After six weeks, I started in a full tub of water and it did not pee after several attempts. Never let it run over 10 seconds from a cold start.
Tube from thermostat outlet is clear. I pulled the cover, discovered there is no thermostat in the engine. I started to see if water was circulating up - 10 seconds, no water flow. I've checked the lower screen intake and do not see any clog. I bought it as a fully rebuilt in March. Only had it in the lake the once described above.
Thanks

Is my next step to drop the lower unit to check the impeller?
 
The answer to the first poster (the second needs to start his own post) is that the impellers on those are different from the usual OB setup. (The water pumps are centrifugal types vs. the usual positive displacement types)

You need to install the entire impeller kit with the seals that go above and below the impeller or they don't pump correctly.

Jeff.
 
Thanks Jeff. I appreciate the reply and the hijack redirect. LOL

I did install the 2 little seals (new) and a new key when I opened it up the first time. Like I said, when I spin the drive with a drill and the LU in a bucket, I get water out of the top of the pump. I think the issue is above that.

When I blow air into the copper pickup tube inside the leg, I get air out of the weep hole but if I plug the weep hole and blow, I HEAR air escaping inside the leg. Is that normal or is there a failure inside there somewhere letting the water escape before reaching the powerhead?
 
bcontento said:
I have a 90's Mercury 9.9 that stopped peeing reliably (would sometimes). I started getting steam out of the weep hole. I pulled the lower unit off to check the impeller and flush it out. Our lake is pretty mucky so I figured some junk got sucked in. Pulled it apart and the impeller is perfect and the key is in place. I flushed it out and I tested the unit in a bucket. When I put it in neutral and spin the driveshaft clockwise with a drill, I get water pumping. Figured I took care of it. I reassembled it to the motor, but still not getting any water out of the weep hole, just steam after it heats up. I had the LU off 3 times trying to figure it out. I tried to make sure I got the tubes lined up right and everything.

Last time with it off, I put a rubber tube onto the copper water tube inside the shaft. When I blow through it, I hear it and feel it coming out of the weep hole but if I plug the weep hole while blowing, I do hear air escaping inside the shaft somewhere else. Is that normal? Could the pump be working but the water escaping into the shaft somewhere before getting to the block?

Any suggestions on next steps for testing or repairing would be greatly appreciated!
THanks all
Click to expand...

I believe that engine "P"s from the thermostat housing, if the thermostat is not functioning correctly, it wont P , put your hand on the exhaust plate and water cover while it running and see if it gets hot.
 
It does P from the thermostat housing...but there is not thermostat in it. Does it REQUIRE a thermostat? I know that in the deep south, we take them out of the old car engines often because the motor doesn't need to generate heat...it's already hot before we start! Engine does get hot quickly.
 
ok, well I've removed the lower unit like 5 times. This time, I hooked up water to the copper pickup tube inside the leg and got great water out of the P hole. If I put my finger over the P hole while doing that, I get stronger back pressure against the water line but water was coming out somewhere still inside the leg. I pulled the waterpump apart again, reseated the impeller, bushings and key, put it in a bucket and drove it with a drill. Again, I got water out of the pump but I don't know if it was strong enough. I put it all back together making sure the pump and the pickup tube were lined up, hung the motor in a bucket and fired it up...NOTHING.

Stumped.
Do I NEED a thermostat for it to pee correctly (backpressure, etc)? It ran before correctly without one so I'm guessing no.
Is it possible that the copper tube is partially seated so that I do get water on the hose or air if I blow through it, but the water and air escapes elsewhere if I plug the P hole.
If the tube needs to be reseated, can it be done without removing the powerhead?
What are my next steps?
 
Yes the copper tube can be put in from the bottom no problem. Is the water in the bucket above the waterpump by 6"?? You are not using muffs correct?
 
So it is still stuck in the pump housing? Do not use a pliers you could kink it, just gently wiggle it until it comes out. I usually replace that grommet because it could split or sometimes it is just easier to cut the tube out. Then put the tube back in the powerhead and reassemble everything making sure the tube lines up in the housing grommet.
 
The copper tube does not attach to the pump housing directly. There's a small rubber hose attached to the pump housing then another piece of rubber hose that acts as a union that pushes over a flange on the copper tube when you install the lower unit. The copper tube is inserted into the power head and that's the connection I'm worried about. I'm wondering if I can pull the copper tube out of the power head and insert it back with a new grommet.
 
bcontento said:
The copper tube does not attach to the pump housing directly. There's a small rubber hose attached to the pump housing then another piece of rubber hose that acts as a union that pushes over a flange on the copper tube when you install the lower unit. The copper tube is inserted into the power head and that's the connection I'm worried about. I'm wondering if I can pull the copper tube out of the power head and insert it back with a new grommet.
Click to expand...
No you cannot replace the powerhead grommet from the bottom.
 
Appreciate the replies! Do you think based on what I've described that it's possible that that grommet and connection is bad? Even though I have good water flow hooked up to a hose or air?
 
It could well be the grommet.

If you pull the lower unit again try "gently" to pull/push the water tube and you notice "some play" then the grommet is probably shot.

You state your motor is a "90's". If it was built before the first half of 1994 you can't pull the water tube out because there is a grommet (cover/plate) with a couple of screws that attach the upper end of the water tube to the powerhead and the tube has a bit of a lip/flair at the top. But if the grommet is bad that (connection) will have some wiggle room.

If it's a 1994-and-a-half or later the tube simply presses into the grommet and the tube is held in place by a (flair) in the tube about half way down the leg. The (wide spot in the tube) stops the tube from falling out as it butts up against the guide hole in the leg which is large enough to pass the tube but not the flair (if you get what I'm saying). In this case, if the grommet is gone you will be able to push the water tube (up) and get some play, but it shouldn't come down any further - the flair is up tight against the guide hole to prevent the tube from (falling out).

Whichever model year you have, the power head needs to come off to get at the grommet. If you go that route, get yourself a new power head base gasket as well - they are only a few bucks and rarely survive the (separation).
 
Great info. Thanks. There is no play in the tube any direction. It is a '95.

I'm going to be really pissed if I pull the power head for no reason!

If while blowing air into the copper tube I plug the weep hole I hear air escaping somewhere is that expected or a possible symptom?

I know it's hard to maybe describe, but his strong should the water pumping from the pump be on a drill test? It's not like it shoots a couple of feet on the air. It pumps out a couple inches.
 
bcontento said:
Great info. Thanks. There is no play in the tube any direction. It is a '95.


If while blowing air into the copper tube I plug the weep hole I hear air escaping somewhere is that expected or a possible symptom?

I know it's hard to maybe describe, but his strong should the water pumping from the pump be on a drill test? It's not like it shoots a couple of feet on the air. It pumps out a couple inches.
Click to expand...

Anyone with any other thoughts on these questions?

I put the thermostat in and of course, still no peeing.

On a side note, I've got it starting and idling better than it ever has (all be it just for a few seconds since no water)
 
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