Lower Unit Oil

[zippy83]

Re: Lower Unit Oil

The proper way to change gear oil is when the LU is still warm. The oil flows a lot easier minimizing retained fluid the particles are still suspended in the fluid instead of falling out of suspension and collecting in recesses and such that don't drain when the fluids are cold. Make sure you have a magnetic drain plug as well.

If the inside of your LU is that dirty, fill it up and run it for a couple of days before changing it again. Once clean it will stay that way unless you have mechanical tolerance issues or the fluid is contaminated. I change my LU oil every October. Most years there is still a tinge of green left in the oil even after 200-250 hours of use

That is one mistake I have done before I started to drain the old fluid and that is I did it while the LU was cold. I did notice that the drain plug is not magnetized though. I will go to my local Mercury dealer to see if they can get me a new one. I guess I could run it a few times if the weather gets better soon, and then replace the oil again alonf with the new drain plug.

 

[JimS123]

Re: Lower Unit Oil

Probably just a waste of time at this point. You verified there is no water in it, so its good to go for the winter. If you are really concerned, run it a couple months next summer and THEN change it again.

 

[zippy83]

Re: Lower Unit Oil

Roger that !!!!
Thanks

 

[Home Cookin']

Re: Lower Unit Oil

I wouldn't keep changing it; not only is it a waste of time, money, and more oil to the hazmat folks (never throw it away in the trash) but you have some wear on your fittings. I had a lower plug screw get crosswise or something and you don't want to be there.

Some people replace the rubber gaskets on the screws when they change; it's a good idea but not the end of the world if you don't.

 

[zippy83]

Re: Lower Unit Oil

I wouldn't keep changing it; not only is it a waste of time, money, and more oil to the hazmat folks (never throw it away in the trash) but you have some wear on your fittings. I had a lower plug screw get crosswise or something and you don't want to be there.

Some people replace the rubber gaskets on the screws when they change; it's a good idea but not the end of the world if you don't.

I recycle the oil, learned long time ago to never throw it in the trash or dump it in the toilet..

I got a bunch of the rubber gaskets they were 50cents so I just got a dozen so I have them in the boat in case I or someone out there need one or two. However I just orderd the magnetic lower plug since I dont have one to begin with.

 

[Home Cookin']

Re: Lower Unit Oil

You can replace yours with the magnetic and not change the oil; just leave the top screw in tight. The drip or two that you may see is all you need to verify that your oil is fine and doesn't need changing any more. Go baotnig instead!

 

[limitout]

Re: Lower Unit Oil

just put ear muffs on the motor put it in gear idling (to stir up and suspend any particles in the oil) and after about 15 minutes its going to be warm enough to change even in winter time.

if the oil is new just catch it in a container then pour it through a coffee filter and reuse it if you don't want to waste it (not much in there anyways) to refill it put the new oil in hot water for about 5 minutes so its more "fluid" and its easier to refill.

as to the magnet plug, you need to make sure there is no difference in that plug and yours, sometimes there are different sized threads or clearance issues to consider so be careful when deciding on your own to add parts that were not designed for your motor. the magnet is helpful but not necessary.

 

[zippy83]

Re: Lower Unit Oil

You can replace yours with the magnetic and not change the oil; just leave the top screw in tight. The drip or two that you may see is all you need to verify that your oil is fine and doesn't need changing any more. Go baotnig instead!

I may be better off by replacing it just for the practice of it....

 

[zippy83]

Re: Lower Unit Oil

just put ear muffs on the motor put it in gear idling (to stir up and suspend any particles in the oil) and after about 15 minutes its going to be warm enough to change even in winter time.

if the oil is new just catch it in a container then pour it through a coffee filter and reuse it if you don't want to waste it (not much in there anyways) to refill it put the new oil in hot water for about 5 minutes so its more "fluid" and its easier to refill.

as to the magnet plug, you need to make sure there is no difference in that plug and yours, sometimes there are different sized threads or clearance issues to consider so be careful when deciding on your own to add parts that were not designed for your motor. the magnet is helpful but not necessary.

This motor only takes about 8 - 10 oz of oil. I got about a gallon left so I think I should be ok if I drain it... As for the pluggs I talked to the Mercury Parts guy and he said that Im good since my engine is a little bigger, if it was a smaller outboard like a 25HP it wouldnt have enough clearence. From the looks of it this bolt is only 1/4" longer then the original one.

 

[zippy83]

Re: Lower Unit Oil

ok so this went from bad to worst... Today I decided to replace the bottom bolt with the magnetic one, at the same time I wanted to chenge the gear oil one more time. I put the ear muffs on ran the outboard for 15-20 min.. waited untill all the water came out and drained the oil. The oil came out milky, Im not sure what happend there some water came into the lower unit from the looks of the gear oil. I also noticed while the outboard was running that the water that was comming out of the prop or near it was kind of white.

I am a little confused on what could gone wrong, 2 weeks ago when I started this thread the old LU oil came out dirty as it should. I am going to take the lower unit apart and look at the gear housing seal and the water pump. I might just replace that darn tning while Im at it. I just hope that there is no crack in the lower unit somewhere.

 

[tazrig]

Re: Lower Unit Oil

Did you use the correct crush washers? (they go on the fill and drain plugs) Before you start pulling the lower end apart I would go to your local auto parts store and borrow or rent a pressure tester and see if the l/u holds pressure or not. If it holds pressure than it was just your washers.

 

[zippy83]

Re: Lower Unit Oil

Did you use the correct crush washers? (they go on the fill and drain plugs) Before you start pulling the lower end apart I would go to your local auto parts store and borrow or rent a pressure tester and see if the l/u holds pressure or not. If it holds pressure than it was just your washers.

I used the yellow rubber washers that I got from the Mercury dealer. Those washers were very tight to put over the bolt.. I made sure that it is on very tight. I guess I could go and rent the pressure tester, but even if the washers were off by a fraction the ear muffs were nowhere near the bolts..

 

[tazrig]

Re: Lower Unit Oil

You did the yellow washers correctly. (remember to use new ones every time you take out one of the screws) My next guess would be water pump seals and gaskets. I can't think of a reason why the seal in back of the prop would just suddenly go unless you or the PO put on the prop and way over torqued the bolt bending the plate in back of the prop and breaking the seal. I would, in this order, do the following:

1. pressure test the l/u per the manual and see if it's holding pressure. if there is no apparent leak on the l/u casing (check in back of the prop too) then:

2. take apart the water pump assembly and re-assemble per manual paying close attention to the seals and gaskets.

3. re-pressure test and if you still have a leak then replace seal in back of prop and check to make sure the plate on top of the gasket isn't warped. If it is replace that too.

 

[Sea Rider]

Re: Lower Unit Oil

Usually you order a general kit and change all related water pump and LU's lower seals and gaskets in a one time job, it's useless to change upper or lower parts and that's it, unless you like playing being mechanic and working double....

Happy Boating

 

[zippy83]

Re: Lower Unit Oil

You did the yellow washers correctly. (remember to use new ones every time you take out one of the screws) My next guess would be water pump seals and gaskets. I can't think of a reason why the seal in back of the prop would just suddenly go unless you or the PO put on the prop and way over torqued the bolt bending the plate in back of the prop and breaking the seal. I would, in this order, do the following:

1. pressure test the l/u per the manual and see if it's holding pressure. if there is no apparent leak on the l/u casing (check in back of the prop too) then:

2. take apart the water pump assembly and re-assemble per manual paying close attention to the seals and gaskets.

3. re-pressure test and if you still have a leak then replace seal in back of prop and check to make sure the plate on top of the gasket isn't warped. If it is replace that too.

Roger that I will do that this weekend..

 

[zippy83]

Re: Lower Unit Oil

Usually you order a general kit and change all related water pump and LU's lower seals and gaskets in a one time job, it's useless to change upper or lower parts and that's it, unless you like playing being mechanic and working double....

Happy Boating

Sounds like a good idea but the water pump dosent need to be replaced every year, at least not according to the owners manual.

 

[zippy83]

Re: Lower Unit Oil

You did the yellow washers correctly. (remember to use new ones every time you take out one of the screws) My next guess would be water pump seals and gaskets. I can't think of a reason why the seal in back of the prop would just suddenly go unless you or the PO put on the prop and way over torqued the bolt bending the plate in back of the prop and breaking the seal. I would, in this order, do the following:

1. pressure test the l/u per the manual and see if it's holding pressure. if there is no apparent leak on the l/u casing (check in back of the prop too) then:

2. take apart the water pump assembly and re-assemble per manual paying close attention to the seals and gaskets.

3. re-pressure test and if you still have a leak then replace seal in back of prop and check to make sure the plate on top of the gasket isn't warped. If it is replace that too.

Tested it out last night and it is not holding pressure. Took it apart saw where it was leaking it was right under the water pump, got the upper housing kit and replaced every seal I could find. Ran it for 10 min and changed the oil agaain. This time it came out nice and clean.

Thanks Tazz