Sportmaster-leaking at overflow

[KevinGa]

After a recent change of lower unit fluid, I have noticed the last couple trips to the lake that after loading my rig, I see a small trail of fluid coming from the tiny overflow hole at the top starboard side of my sportmaster (2000 Model/225PM). Was too much fluid added? Should I drain off an ounce or so? Is there possibly anything else wrong other than it being too full? Thanks, KevinGa

[Greg Moss]

Shift shaft seal is bad

[us1]

Also it could be a two-cycle oil build up if you are running to rich. It will drain down and pool in the shift shaft cavity. Smell it and see what it is.

[KevinGa]

I am running Pennzoil 100% synthetic in my motor (225PM stock). I have been supplementing my fuel tank with 1 oz of oil for each gallon of gas. My motor is still oil injected so this is in addition to what is being injected. Come to think of it the color of the oil running out of my sportmaster is the same color as my Pennzoil. I had Merc Hi Performance gear oil replaced. I do not recall if it is the same color as my Pennzoil or not. I will check tonight when I get home.

[Euroski]

I had the same problem and replace the shift shaft seal. But I did notice a few weeks later on a hot day and doing some long running at full speed some fluid started to come out. Only thinking this " which could be dangerous" That the long runs caused the gear oil to heat up from the exhaust going through the housing. In turn gear oil expanded some and had to come out somewhere. If so I think it may just be a little too full. Next time I change the gear oil I think I am going to put the top plug in after the oil stops dripping out....

Any other theroies Hasn't leaked since that day

[us1]

Smell the oil, it is a dead give away.

[Greg Moss]

The hiper Merc gear oil is the same color as the penn. 2stroke oil. John there is no way the exhaust oil would still be blue and it can not get to the shift shaft seal area there is a metal boss cast into the exhaust hoousing infront of the water pump and in the same area on the lower unit. Euro The heating of the gear oil is right but it is from the load of the gears and the bearings instead of the exhaust. The oil will get heat from the exhaust but it is minor. A bravo drive with the exhaust going through the transom and none of it going throught he outdrive will get up to 250* from load of the gears and bearings. If the shift shaft is leaking (have it pressure tested) check the shift shaft they are not hard steel and will get a ridge around them that will not let the seal seat properly.

[MadMat]

us1, I reckon yall get some funny looks if ya go round sniffing people's gearcases.

[us1]

I did not see him say it was still blue, when I break-in a motor on the ramp with it full rich loading up mine leaks black oil out there all the time. Maybe mine is coming down from on top?

[Greg Moss]

John I run my motors rich all the time and they drip oil out of the prop shaft bearing carrier and the outlets above the antiventaltion plate. I think he is saying the oil is blue because he is using the penn snth. which is blue so is the hiper Merc gear oil. If it's coming from the weep hole in the front starboard side of the lowerunit it has to be gear oil exhaust oil has no way to get there. And do you get funny looks when you smell other peoples lower units? LOLOL Greg

[us1]

Yes, if the oil is blue it is definitely not burnt two-cycle oil. I've always loved sniffing a good rear end.

[gtsmpuc]

I think it would be very hard for gas/oil mixture to get there. Also the gear oil will have a thicker residue than the mixed stuff. My did it and had to change the o-rings.

[ChrisH]

They'll bleed off the excess lower unit lube when over-filled. When the lube warms up and expands, it'll pass the excess out the drive shaft seal.

Bet it quits after a few times to the lake....;)

[Greg Moss]

Who the hell ever told you that? If there is not the proper gear lube in the unit first thiing to go will be the upper driveshaft bearing after that the gear set. those things are meant to hold a certain amout of gear oil and if filled properly and pressure test correctly it wil and I repeat WILL not LEAK.I f your mech. told you that you REALLY NEED TO FIND A NEW ONE!!!!

[KevinGa]

Well I just got done sniffing my lower unit. I had a very small bit of oil left over. I think it is definately foot oil. The foot oil does not have near as strong an odor as the Pennzoil synthetic. Amazingly both oils are almost identical in color! I trust my mechanic (yes, I have to use one of those - I can't do everything myself) and he told me that he probably did not drain enough out after filling. He said to drain a bit and it should be fine. Thanks for all your help! I learn something everytime I post something!

KevinGa

[Greg Moss]

Fire your mechanic!!!!!! That unit should not leak period!!!! If you drain some oil out it will not lube the driveshaft bearing and it will cost you more than a shift shaft seal.
Fire your mechanic or have him call me I'll tell him he is full of-- well you know. If mercury didn't want that thing that full they would of put the top hole down further.

[RayBishop]

Mercury says to fill until lube runs out of vent plug, then drain about 1 oz. to allow for expansion...

[KevinGa]

Where is this seal and what does it look like? Is it a small gasket or something that can easily be replaced if I know how to remove my lower unit?

[Greg Moss]

The shift shaft is the small splined shaft at the front of the lower unit. There is a housing the seal is pressed into that unscrews and you can pull the housing and seal of the shaft. Be careful and hold down on the shaft so it will not come out. Kevin I have build more lower units than I care to think about and would never let one go that does not hold pressure and vaccum. The shift shaft seal is a weak point in the sealing of the lower unit and if I ever see a unit leaking I tear it down and fix it. those things are supposed to be air tight no lube should come out. The tool for changing the seal is not to much money you may want to but it. The seal and bushing number is 23-77631A2

[Liqui-Fly]

Run Pennzoil Synthetic and had it puddled up by the bearing carrier. Got scared, brought it to a mech...he pressure and vacuum checked it,,gave me a funny look and sent me home with my case. LF

[Superdave]

My nderstanding from Merc is that the lower unit should hold approx 15psi. The shiftshaft seal is designed to relieve higher pressure. When the sun, or a long hard run heats the gear oil up it has to have a relief for the built up pressure. If you look close at all the lower unit seals you will notice the lip faces in on all of them except the shift shaft seal. Also, if you put 20psi, or so on the housing, and all the seals are good you will notice the shift shaft seal will almost always leak first.




That's my story and I'm sticking to it!

[ChrisH]

Greg,

Every spring and fall this same topic comes up on the BFHP over, and over, and over again. 99.99% of the time the cause is the same!

First time boaters always freak when it happens. My lower unit does it almost every time I change the fluid and I've NEVER found water in it later in the season!!!! It even did after it was freshly resealed!!! I change my lube at least twice a year.

I'm no expert, but I have been around.

BTW, I'm not the dumbass you might think I am

[mxz]

Same thing happens to my CLE after I change the lube. Just like ChrisH said, even after I got it resealed and pressure tested by two different mechanics. Never any water when I drain it.

[KevinGa]

I normally change the fluid myself, twice a year as well. I had my mechanic do it because he was also in the middle of checking many other things on my motor. I consider myself to be a novice compared to many of you guys - I have only owned 3 bass boats with 150xr2, 200 carb, 200 Optimax, 225 Promax. All Mercury. I have never had a lower unit do this. Maybe it is just a coincidence that the first time was also a time when it was not myself changing the oil.

Here is what I plan to do:
1. Drain all oil
2. Install oil myself
3. Run motor on lake
4. Check for leaks

If steps 1-4 do not work I will be posting here again for help.

[Greg Moss]

I Don't think your a dumb ass. I know that if the unit is sealed right and the lube is at the proper fill level it will not leak. I have 4 lower units for my boat and I will tell you none of them leakat the shift shaft seal. If the unit is building that much heat that it has to push lube out then there is something needing attention inside of it. Super dave the seal may be designed to hold a set pressure I am not sure what it is but the reason it is installed the way it is because water will puddle up on top of the seal and the way it is put in will keeep the water from seaping into the unit as the temp changes after being run. The seals on the other shafts are back to back one that keeps the oil in and one that keeps the water out. the reason for two seals on the driveshaft and prop shaft is because of the rotation of the shafts. guy's I have years of experience building lower units from small jon boats to Blown bigblocks and would just like to help you Guy's do things to help keep you from tearing up your equipment. No lower unit no matter who the manufacture is should leak unless there is something wrong.

[Greg Moss]

That is a good idea but I would drain the lube and take it to some one (your mech.if he is close) and have him pressure test it it is quick and easy to do. As soon as he pumps pressure in it itwill bleed off. Also alway replace the washers around the fill and drain screws, I always use the ones OMC has the mercury ones are cheap cardboard the OMC ones are nylon and will out last the Mercs The number for the OMCs are 311598

[us1]

Greg’s right , none of mine leak.

[Greg Moss]

Some of you made me feel guilty especially Chris about the thinking he was a dumb ass I no way think that ,like I said all I want to do is keep you from having problems. I went back and looked at the service manual to check what mercury says is proper fill procedure, Fill from the fill to the vent until no air bubbles out with the lube, put vent plug in and put fill plug in. The note says IMPORTANT: make sure you do not lose any more that 1oz of lube.That means not to drain it but be carful to not lose anymore lube when removing what ever you are using to put lube in with and puting the fill screw it.

[ChrisH]

Greg,

Sorry I got my feathers a little ruffled...

This was my second season (~70 hrs) on my current lower unit. It is a 200 housing that's stuffed with CLE heavy duty internals. Tony Reynolds of Reynolds and Reynolds Racing built it for me. I ran Bakers "Rapid Red" lower unit lube in the original CLE and it ruined the all bearings as well as pitting the shafts (saw them myself). When Tony built my new gearcase, he put all new shafts, bearings, and seals in it and used the original gears as they were in good condition yet.

After my first run on the lake, it "bled" off excees lube like the CLE always did.

I've heard of this happening over and over and apparently others on this board have experienced the same thing.

I run a 260/Ally Grandsport @ 100+. It will generate heat in the lower unit, (remember the 10% loss from the crank..it's a right angle gearset that is not 100% efficient--it does "consume " some energy and convert it into heat, vibration, noise,....etc)

Thanks for your concern, I now believe you meant no disrespect.

I've been told "absolutes" so many times, I tend to take all of them "with a grain of salt."

[jay j]

you probably just over filled it and excess builds up and
comes out the weep hole. mine has done the same thing. a couple trips to the lake and it will be ok.

[MERCMAN]

john , your not wrong about the oil leaking. the offshore midsections can leak and build over rich motors oils around the shift shaft seal(and drip out the side). but the bass or production midsection is sealed off. so half right , half wrong , no so bad! talk to you soon!

[russell]

Check your seal I just replaced one on a new case that was upside down. And blowing the prop shaft seals out of the case.
The seal will relieve excess presure when over filled ( that is why there is only one seal set to keep water out not presure in) It will hold presure to the spec.

[russell]

Check your seal I just replaced one on a new case that was upside down. And blowing the prop shaft seals out of the case.
The seal will relieve excess presure when over filled ( that is why there is only one seal set to keep water out not presure in) It will hold presure to the spec.

[Greg Moss]

Seals are designed to crus when installed to seal the outside of them. The seal size of the shift shaft seal is .004 crush. some of rhe aftermarket seals have a housing that is cut to small and will crush the seal to much and egg shape it. even if the seal is new if the seal is crushed to much it will leak. also look at the rubber of the aftermarket seals the have delaminated on me also. the rubber does not cover the entire inside of the metal seal and will pell off the metal housing. After I found these problems I contacted the aftermarket parts company and they paid me alot of warranty time for fixing them. I now only use Mercury shift shaft seals. The shift shaft seal will not leak if it is good and installed properly.

[RULE-1]

Mine did the same thing after changing the Fluid. It's just over flow. I've run mine for 50 hours since with no problems.
There is not a problem. :D

[bb21xd]

I too have a Sportmaster that has a leak at the overflow. Yesterday after pulling the boat out of the water and trimming the engine up to put the motor toter in place I found a slight amount of gear oil (sulphur smell) had run out of the overflow hole. I drained the gearcase this morning and the oil is dark emerald green (no sign of water contamination). I connected my Stevens gearcase pressure tester to the case and pumped it up to 10 psi. It has held exactly 10 psi for 6 hours and the gauge needle hasn't budged yet. The Stevens gearcase vacuum tester is next.

[Bruster]

Man, I got my azz kicked for saying that. I insisted you could not overfill the gearcase. Must be the engineers don't know what they are doing.

[bb21xd]

After 8 hours at 10 psi the gauge is still showing EXACTLY 10 psi so as of 3pm EDT the Stevens vacuum tester is in place and there is -15 in Hg showing on the gauge starting. Report coming in 8 hours!

[bb21xd]

After 14 hours on the Stevens Instruments vacuum tester at 15 in Hg I'm calling my lower unit not leaking. Evidently the tiny bit of oil that came out of the overflow was forced out due to too much pressure and NOT due to any seal that might be leaking. This theory fits with the condition of the lube oil as it shows no signs of water contamination.

Thanks for everyone's ideas and comments.

[russell]

after 14 hours on the stevens instruments vacuum tester at 15 in hg i'm calling my lower unit not leaking. Evidently the tiny bit of oil that came out of the overflow was forced out due to too much pressure and not due to any seal that might be leaking. This theory fits with the condition of the lube oil as it shows no signs of water contamination.

Thanks for everyone's ideas and comments.

the shift shaft seal will let out excess oil as the gear oil heats up. It should stabelize and and stop check it for water a couple of times if you see any replace the seal. Happens all the time
russ