Lower Unit "leaking"

[chris in houston]

Recently replaced impeller and gaskets on pump. The housing and bottom plate looked fine and smooth.

When on muffs, water spurts/dribbles out of the interface between the top of the lower unit and the rest of the engine. This happens before I start the engine, and leaks in proportion to the garden hose pressure on the muffs. Keeps leaking after starting engine. Might have done this before I replaced the impeller, but I never looked.

Seems the entire cavity that the water pump sits in must be filling with water from muffs for this to be happening. Is that cavity supposed to remain dry?Is that a problem? If so, what needs fixed?

PS: I did not apply any sealant to the top of the LU before rebolting to engine. Should I? I doubt this is the problem, but just thought I'd ask. Without it, seems that same cavity would eventually fill up with lake water from inward leakage.

Thanks in advance for your help!

 

[Texasmark]

Re: Lower Unit "leaking"

So what. Run it and check your pee stream and listen for any overtemp alarms. Enjoy!

Mark

 

[will941s]

Re: Lower Unit "leaking"

The mating surface between the lower and the mid is designed to go without sealant. No need for it, the parts are made to be submerged in the water. As for the water coming from the mating surface, may need to be addressed. When the water pump housing is completly sealed to the base and all the o-rings and gaskets are functioning properly, as well as the inlet tube from the water pump housing to the powerhead, water should be completly contained when it's running on muffs. You should'nt see any water coming from anywhere other than the pee tube, the exhaust ports, prop hub, and the relief hole in the side of the lower unit. As for what your describing, sounds like you need to remove the lower again and inspect the waterpump to see what has failed. You may have great pressure at idle but at higher RPM's the motor may not get enough water to properly cool the engine.

 

[chris in houston]

Re: Lower Unit "leaking"

Update: I just put on muffs, turned on spigot, and a little drippage came from the top mating surface of the LU with engine off.

However, when I started the engine, water started spurting up like a drinking fountain around the shift shaft. The drippage from the top of the LU turned into a weak spray.

Definitely seems there is a leak on the outlet side of the pump. I will remove LU and report back. DANGIT!!!!!

PS: do I put in neutral before LU removal, or forward?

 

[Texasmark]

Re: Lower Unit "leaking"

Update: I just put on muffs, turned on spigot, and a little drippage came from the top mating surface of the LU with engine off.

However, when I started the engine, water started spurting up like a drinking fountain around the shift shaft. The drippage from the top of the LU turned into a weak spray.

Definitely seems there is a leak on the outlet side of the pump. I will remove LU and report back. DANGIT!!!!!

PS: do I put in neutral before LU removal, or forward?

F is the preferred gear as the shifter is all the way to one end (convenience) and the prop is engaged so that when you attempt to stab the drive shaft spline into the mate on the bottom of the engine block, you can rotate the shaft, via turning the prop, and effect a mate.

Mark

 

[chris in houston]

Re: Lower Unit "leaking"

UPDATE: Today I muffed LU, turned on water, started engine, and saw that a stream of water was coming out of a hole in front of the engine midsection and squirting onto the shift shaft where it is exposed just above where it re-enters the lower midsection (I'll call that the "first squirt hole"). Water also was girgling out around shift shaft and there was a weak spray from the LU/Midsection mating interface.

I removed the LU. Water pump and water tube connector looked fine and in place, and water tube interior looked fine (no obvious breaks or separation; I used a flashlight). Looking up into midsection, there is the water tube end and, next to that, the drive shaft "tunnel" (where the drive shaft resides when the LU is installed). Toward the bottom of the drive shaft tunnel was the first squirt hole (from above). Opposite the first squirt hole was a second hole (I'll call that the "second squirt hole") in the bottom of the drive shaft tunnel; that hole led to the plenum where the water tube resides.

So with engine off, I pressed my garden hose nozzle into the water tube and squirted until engine filled and pee stream started. I noticed that water was squirting out of the second squirt hole, across the drive shaft tunnel, and thru the first squirt hole and out onto the exposed shift shaft.

Obviously, when the LU is on, the stream from the second squirt hole is hitting the drive shaft, filling the space around the water pump, and eventually supplying the water that appears as the leaks described in the first paragraph above.

So, is this normal? Am I simply torturing myself? Or is there a problem? I'm fearful that enough water is "leaking" that engine cooling will be compromised. Fine Mercury geniuses, help!!!!

 

[will941s]

Re: Lower Unit "leaking"

Any area should'nt be filling with water around the water pump housing, esp not coming from the shift shaft hole. Idea #1 The seals on the lower portion of the water pump assembly are leaking. #2 The rubber ring that fits on the top of the water pump housing around the drive shaft is'nt there. #3 the water pump base plate is'nt sealing, or the cup is defective. #4 Where the tube goes into the powerhead, the o-ring is broken or missing (have to remove powerhead to replace). When you did the service, did you replace the whole thing, or just the normal things (base plate, impellar, cup, gaskets)? Sometimes you have to replace the whole assembly every so often to prevent water leakage. Also, what is the model and the year of the motor?

 

[chris in houston]

Re: Lower Unit "leaking"

it's a 2000 ELPTO 60HP Tracker Merc, 3 cyl 2 cycle. I replaced impeller and gaskets between base plate and housing. I did not see a rubber ring around drive shaft (your item #2), but I don't see one shown in complete kits either. I believe my pump assembly is functioning and not leaking, but will probably try installing a new one before worrying about the upper water tube seal.....pulling the powerhead sounds like a big job!

I am thinking the upper Water Tube seal is the culprit, given the results of my garden hose test with the LU off.

 

[will941s]

Re: Lower Unit "leaking"

May be the problem. I saw on here once that a guy changed his o-ring with a flashlight and ALOT of extensions. Worked for him. Just keep poking around and the problem will present it's self.

 

[pinellas50]

Re: Lower Unit "leaking"

I responded to your question in my post. http://forums.iboats.com/showthread.php?t=371604

It kind of sounds like you are dealing with 2 different issues there. One at the water pump and mabey another up higher. But I'm not sure if your motor is set up the same as mine so I am guessing more than anything else.

Was all this going on before you changed the impeller?

 

[chris in houston]

Re: Lower Unit "leaking"

Just got the boat and decided to change impeller to ease my mind. I hadn't muffed it before I changed the impeller. That's when I saw water coming out the shift shaft and adjacent hole.

 

[chris in houston]

Re: Lower Unit "leaking"

I called Merc hotline. They said my "leaks" are normal. 5% of the water goes out tell-tale, the rest comes down exhaust and water tube chambers. The cavity the water pump resides in is supposed to fill and flow out as I witnessed.

So I have been worrying for nothing.....can't wait for warm weather so I can spend time fishing instead of tinkering!