1981 mercury lower unit ?

[mavmike72]

Leaking gear oil out speedo hole . What could this be ? Thanks

 

[mavmike72]

Re: 1981 mercury lower unit ?

140 hp

 

[mavmike72]

Re: 1981 mercury lower unit ?

Anybody ?

 

[Chris1956]

Re: 1981 mercury lower unit ?

If it is truely gear oil, supect that the driveshaft seal in the base of the waterpump is leaking, or the waterpump base oring or gasket are leaking. Replace the waterpump base, wear plate and impeller and gaskets. Clean the driveshaft and lube it before installing new base, or you will tear the new seal.

 

[mavmike72]

Re: 1981 mercury lower unit ?

Thanks for the reply . I did put a water pump on last year but nothing else . Should I buy a hole seal kit ? Where is the best place to purchase it ? Thanks alot

 

[Chris1956]

Re: 1981 mercury lower unit ?

Just replace driveshaft seal kit for now. propshaft seal is a bear to replace.

BTW - verify your motor's year via serial number. I thought 1979 was the last year for the Merc 140HP IL6. You will want the right parts.

 

[mavmike72]

Re: 1981 mercury lower unit ?

Tag on transom is 5741787 can you tell year off this number ?

 

[Faztbullet]

Re: 1981 mercury lower unit ?

If you motor has the speedo pick up cast into nose of lower unit I would pressure test it first as the only 3 ways gear oil could come thru the speedo hole: 1) someone drilled it out to clean debris and went to deep 2) shift shaft leaking and speedo connector is removed 3)speedo passage stopped up and froze causing crack in housing.

 

[mavmike72]

Re: 1981 mercury lower unit ?

After looking at it again its not leaking from the speedo hole . It's leaking from another hole up higher . Rite where the lower and upper meat . This hole is on one side only . I also have a longer transom saver on it too . U think I had the motor up to high making it leak ?

 

[carholme]

Re: 1981 mercury lower unit ?

Your s/n is a 1981.

140 140 6-cyl 5625108 - 1981 USA

From here:

Mercury 2-takt, R6, 6-cyl, 80 - 150 hp, produktions?r, modellguide

The hole you are referring to is probably the drain hole which allows water to drain, preventing freezing and rupturing the case. Drop the LU and see if the oil is located to the front (shift shaft) or around the driveshaft area.

Gerry

 

[mavmike72]

Re: 1981 mercury lower unit ?

I lowered the motor last night and this morning it was dry as a bone under it .

 

[carholme]

Re: 1981 mercury lower unit ?

If the oil was enough to leak out of the drain hole, either the shift shaft seal or the seals under the water pump have failed. If and when you run the engine again, make sure you check for the same leakage after you run it. And it would be wise to see how much you have lost before running it again. It would be bone dry if the freeze cavity emptied, it is just waiting for another load when you run it.

Gerry

 

[mavmike72]

Re: 1981 mercury lower unit ?

Is their anyway I can pressure test it myself ? Thanks for the help guys .

 

[mavmike72]

Re: 1981 mercury lower unit ?

I just found a video on how to do it .

 

[Chris1956]

Re: 1981 mercury lower unit ?

Are you positive it is gear oil? 2 cycle motors leak 2 cycle oil out of there routinely.

 

[MH Hawker]

Re: 1981 mercury lower unit ?

I would sure run a pressure test first, because a lot of 2 strokes do leak a bit of un burt 2 stroke oil out.

 

[Chris1956]

Re: 1981 mercury lower unit ?

Crap, just smell the leaking fluid. If it stinks like rotten eggs it is gear oil. If it smells like gas or oil, it is 2 cycle motor oil.