lower unit leak

loganmallory

Petty Officer 3rd Class
Joined
Apr 13, 2002
Messages
77
hi. i have a 1972 johnson 25hp. please excuse lack of terminology. i have done lots of repairs to various motors for the last few years, just dont know terminology. i just got the motor this fall. after changing the gear oil, a few hours later i noticed a few drops dripping down on to the skag from the propeller shaft. i went to my local parts dealer and he gave me the o-ring and the spaghetti seal. i cleaned everything off really well, the o-ring rubber went on well, but when i went to put the long rubber on, it was really skinny compared to the old one, and was really loose in the groove, and way too long. i assumed it was just a standard cut-to-size thing, but it still bugged me how skinny it was. anyways, i put it in the river this afternoon, ran the motor for about 30mins, pulled it out, and got straight milk. by the way,the guy tried to sell me the big metal piece at the end of the shaft that seals the shaft, but as it was $140 i figured i'd try the other 2 seals first. i waited 5 hours after replacing, and no oil on the skag. whats up? thanks!
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: lower unit leak

sounds like you got the wrong seal. Even if you get the right seal, I usually use sealant between the housings. Did you put in a new lip seal for the prop shaft? Did you replace the drain and fill screw gaskets?
 

12Footer

Fleet Admiral
Joined
Mar 25, 2001
Messages
8,217
Re: lower unit leak

Here is how to determine just what is leakin where:<br /><br />Get a bicycle pump with a gauge on it, or an air hose with a gauge that you can hook to the VENT or FILL screw holes.<br /><br />Submerge the foot in a tank or garbage can (this can even be done still mounted). Charge the lower unit with about 10PSI,and look for bubbles. It's bulletproof, finds the leak every time.<br />When testing, The unit should hold 10PSI without leaking down too.
 

loganmallory

Petty Officer 3rd Class
Joined
Apr 13, 2002
Messages
77
Re: lower unit leak

hi schematic thanks for your quick reply. i don't know what the lip seal is. i did not replace the drain, fill plug seals (didnt know i could) but will tomorrow. not sure if they were leaking, but there WAS a leek from the back near the prop, cuz i saw the oil path. my dealer said i should replace the metal piece that the 0-ring fits on to, but as it was $140 i did not. is this the lip seal?<br /> tim
 

loganmallory

Petty Officer 3rd Class
Joined
Apr 13, 2002
Messages
77
Re: lower unit leak

hi 12footer. that is an excellent idea. i will find the stuff tomorrow and give it a try.<br /> tim
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: lower unit leak

Here are the leaking points on your gear box. As 12' says, find the leak before proceding. I'd advise you to use sealant along both O-rings. Especially where the spagetti seal terminates.... :) <br /><br />
lower.gif
 

loganmallory

Petty Officer 3rd Class
Joined
Apr 13, 2002
Messages
77
Re: lower unit leak

hi schematic. what kind of sealant? i have high-temp gasket maker. will this do? do you put it only along the outside edge or all over the gaskets?
 

loganmallory

Petty Officer 3rd Class
Joined
Apr 13, 2002
Messages
77
Re: lower unit leak

okay i have completely replaced and sealed everything on the bottom end including fill/drain washers and shifter pin o-ring. STILL LEAKS!! i have the o-ring and seal for the top end, and have dropped the leg. thats as far as i have gotten. can anyone PLEASE give me a detailed guide as to how i change these 2 parts? do i need anything else before i procede? the long weekend is only 9 days away and i must fish!! thanks<br /> loganmallory
 

alcan

Commander
Joined
Dec 14, 2001
Messages
2,505
Re: lower unit leak

Hi Logon<br />Now that you have your lower unit removed from the motor, you will need to disasemble it. Again. Odds are its the shift shaft o-ring thats leaking. You will need a long punch to remove and replace the o-ring and bushing. You can order one from your dealer or make one up. As for the drive shaft seal, you can carefully pry it out. I like to tap them out from the bottom with a long rod with short 90 bent on the end. You realy should have a manual, short-cuts rarely pay off.
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: lower unit leak

loganmallory <br /><br />You can procede to replace all the seals, or you can pressurize the unit and check for leaks as 12' says. Lip seals can be pryed out or driven out with a long punch. Be sure not to scar the housings. The seals should be pressed in dead straight or distortion will cause leaks. Use a sealant on the seal and housing when pressing in the seal to its bore. Red loctite or crankcase sealant work well. You can also use crankcase sealant to seal the housings together along side and on top the o-rings.
 
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