1977 120 hp mercruiser leaking gear lube from behind the prop

[dissturbbed]

1977 120 hp mercruiser leaking gear lube from behind the prop where the exhaust flows out. I have replaced the shift shaft seal, the small oil seal near the water pump, water pump itself, and one of the upper seals drive shaft seals where the drive connects to the upper half. This stopped the gear lube leak coming from the small vent hole but now there is a new leak coming from behind the prop. Where else could this leak come from?

http://i297.photobucket.com/albums/mm229/dissturbbed/009_zps3ff094a4.jpg

 

[Bondo]

Ayuh,..... Welcome Aboard,.... My guess is the prop shaft seals,....

A pressure test is the best way to know for sure,...

 

[dissturbbed]

Ayuh,..... Welcome Aboard,.... My guess is the prop shaft seals,....

A pressure test is the best way to know for sure,...

I checked the front prop seal and couldnt find any oil leaking, is there a rear seal?

 

[500dollar744ti]

Do the pressure test, you won't have to check anything more because it will show you exactly where the leak is coming from.

If I had to guess, I would think the quad ring between the two halves is pinched or broken on the inner side and lube is dripping down the exhaust channel.

 

[dissturbbed]

Do the pressure test, you won't have to check anything more because it will show you exactly where the leak is coming from.

If I had to guess, I would think the quad ring between the two halves is pinched or broken on the inner side and lube is dripping down the exhaust channel.

Where is the quad ring? First i heard of that one. If it is the oil seal where the drive meets the upper half i have already replaced that one, however i did not replace the second one above that, could it be that seal?

 

[dissturbbed]

I would like to do a pressure test but don't have the time to order or put one together. Would like to have it fixed by friday if thats possible since i have all the parts ready to go.

 

[Bondo]

Where is the quad ring? First i heard of that one

Ayuh,.... Portside, 'tween the lower unit, 'n upper unit,.....

Have ya had the lower unit off the upper unit,..??
Didn't ya replace the quad-ring puutin' it back together,..??

 

[Bondo]

I would like to do a pressure test but don't have the time to order or put one together. Would like to have it fixed by friday if thats possible since i have all the parts ready to go.

Then take the lower unit off, 'n Look for the oil trail,....

 

[dissturbbed]

Then take the lower unit off, 'n Look for the oil trail,....

Will do Bondo, nothing but fun putting that lower unit back onto the upper. I was hoping it was the other seal on the upper part of the stern.

 

[500dollar744ti]

I wouldn't run that thing without pressure testing to be sure it isn't leaking. Even if you find where the leak is, in order to be sure you fixed it, you have to pressure test it.

I adapted a fill hose fitting for the drive oil to a standard automotive radiator pressure tester. It works perfectly for pressure testing the drive. you don't need anything fancy.

Take one of these (lower unit gear lube filler) and remove the clear hose from the metal fitting so you just have the metal fitting.

Then take one of these (car radiator pressure tester) and disconnect the hose from the cap that goes into the radiator.

Then take the lower unit fitting and put the hose from the pressure tester on it and clamp it. Now you got yourself a drive pressure tester. Pump it up to about 15psi, let it sit and make sure the pressure stays for a good long time. If there's a leak, it will immediately start dropping and you will probably hear the hissing where it's leaking.

 

[dissturbbed]

I wouldn't run that thing without pressure testing to be sure it isn't leaking. Even if you find where the leak is, in order to be sure you fixed it, you have to pressure test it.

I adapted a fill hose fitting for the drive oil to a standard automotive radiator pressure tester. It works perfectly for pressure testing the drive. you don't need anything fancy.

Take one of these (lower unit gear lube filler) and remove the clear hose from the metal fitting so you just have the metal fitting.

Then take one of these (car radiator pressure tester) and disconnect the hose from the cap that goes into the radiator.

Then take the lower unit fitting and put the hose from the pressure tester on it and clamp it. Now you got yourself a drive pressure tester. Pump it up to about 15psi, let it sit and make sure the pressure stays for a good long time. If there's a leak, it will immediately start dropping and you will probably hear the hissing where it's leaking.

This is exactly what i needed, thanks a million 500dollar744

 

[500dollar744ti]

I'm not Bondo, but you're welcome.

 

[Bondo]

This is exactly what i needed, thanks a million 500dollar744

I'm not Bondo, but you're welcome.

Ayuh,.... Nothin' like a live chat, with edditin',....

 

[dissturbbed]

Ayuh,.... Nothin' like a live chat, with edditin',....

yea yea yea