lower unit oil

[striperguy]

Pulled plug on lower unit to inspect the oil. The magnet on the end off plug had very little if any shavings on it, but the oil looks gray and kinda milky. is this ok or is there a problem. thanks

 

[achris]

Re: lower unit oil

Gray and milky could be a problem...

Do a crackle test for water... If it crackles you need to pressure and vacuum test to find the leaky seal and replace it (or all of them)...

Chris..........

Crackle test: Get a tablespoon and put some of oil in it. Put a flame under the spoon. If there's water in the oil, as it reaches boiling point it will make crackling and popping noises, hence 'crackle test'.

 

[striperguy]

Re: lower unit oil

Done the crackle test and it popped and cracked, does this mean seals are bad. When i put it in gear there is a rumbling noise could this be because the seals are shot. thanks

 

[22E6441]

Re: lower unit oil

Not necessarily.

Change your oil and make sure you get a new o rings for the fill and drain screws (if yours is like mine).

Run it a few times in the water and check the oil after each run. If it's milky again within a few runs you've got some serious leakage somewhere. If not, maybe it was just a bad o ring on the fill / drain screws. Sometimes it's that simple. This is very wishful thinking.

 

[achris]

Re: lower unit oil

Done the crackle test and it popped and cracked, does this mean seals are bad. When i put it in gear there is a rumbling noise could this be because the seals are shot. thanks

If there is water in the oil it means one (or more) seals are leaking. My preference is to re-seal the whole box. It takes very little extra time to do them all, and it's just not worth not doing them....

Your rubbling noise is something else. It could be a bearing or the gears. You won't know until you pull it down (which you have to do to replace the seals anyway)...

Chris......

 

[Nial]

Re: lower unit oil

Last time i changed my gear box oil it was a real milky colour but the seals looked like they were as old as the gear box (35+ years). I scraped the hardened rubber o-rings off replaced them with some new ones and also used some liquid gasket stuff. I'll probably drop the oil just as winter starts and hopefully it was just a dodgey o-ring last time cause i hate to think what's involved with the seal around the prop...

 

[striperguy]

Re: lower unit oil

thanks guys, if the gears are bad is it cheaper to rebuild or buy another lower unit. thanks again

 

[verado7]

Re: lower unit oil

a little milk is normal - it happens from condensation - see in the summer the leg gets warm from the sun and outside air temp. then you dip in the water and you get condensation (water) that will turn the oil a cream color - if you had a serious leak you would see plain water run out the hole with the oil - also if the drain plugs arent real tight there will be some intrusion - just follow recomended drain intervals and if you do decide to apply pressure to test - be carefull it doesnt take much to create a problem that didnt exist .