'88 100 hp merc. leaks gear oil when engine is tilted up

[holbs]

Well pretty sure Ive been taken advantage of by trusting someone to be telling the truth.(I just bought this boat 3 days ago and its an 88 skeeter bass boat) but i noticed that when i put the trim up that i have a small amount of gear oil coming out of where the water intake is at the bottom of the lower unit.(where you put the earmuffs on when running motor in drivway. Im thinking seal kit and how difficult is this to replace? I do have some experience working on vehicles whether its my snowmobile car truck ect.

 

[emckelvy]

Re: '88 100 hp merc. leaks gear oil when engine is tilted up

Sounds like leaking driveshaft seals.

Raise up the motor for access to the L/U then place the remote control box in Neutral.

Unbolt the lower unit and remove; pull the bolts holding the water pump assy together and then the water pump base is accessible for removal.

The seals are pressed into the pump base; before driving the old seals out with screwdriver or other suitable tool, note the orientation of the seals so you get the new seals' lips facing the correct way.

You can get parts diagram for your motor at www.mercurypartsexpress.com or http://www.dougrussell.com/partscatalog/collections/index.cfm?fuseaction=collectdetails&colid=01

You may as well replace the impeller at the same time. There will be some gaskets to replace also.

Note the biggest challenge may be if some of the bolts are stuck. If it's a fresh water motor it should come apart easily. If she's a Salty Dog, you'll probably need a carefull application of heat from propane or equiv torch if bolts don't loosen with normal force. Don't reef on them unless you like drilling stainless bolts out of aluminum !!!

Use a coating of Permatex #3 gasket dressing on the bolt threads holding the base down. Use anti-sieze or a waterproof grease such as Sta-Lube boat bearing grease on all other bolts and it'll come apart easily for servicing in the future.

Lightly coat the impeller with Vaseline or grease before installing; turn clockwise as you install.

Put a coating of grease on the driveshaft splines prior to installation; be sure there's no grease on top of the driveshaft though.

HTH & G'luck..........ed

 

[holbs]

Re: '88 100 hp merc. leaks gear oil when engine is tilted up

Thanks for the great info! where I get the gasket kit from quickest im guessing mercurypartexpress.com which being at work i dont have the serial number and im eager to get the gastkets here. Just to double check that i explained correctly when the engine is all the way down it doesnt leak but as soon as you go up to a 45* angle it starts leaking out of the the bottom hole where the water is sucked in.

 

[holbs]

Re: '88 100 hp merc. leaks gear oil when engine is tilted up

Just wanted to update everyone to my lower unit learning class. Its seems Emckelvy hit the nail right on the head! After removing the water pump assembly I could see what you were talking about. Theres a rubber seal on the shaft and a metal sleave that alson slides over the shaft and that sits in side the pump base. Every thing looked fine but as i was cleaning the crap out of the pump base the metal sleave fell right out in my hand. After to looking at it it has a lip on it that makes the seal and thats where my leak is happening. When i put it back inside the pump base is sort of snapped into place and seated nicely. Also now as much as i tried to remove it it would not come out of the pump base now that it was sitting correctly. I put it back together,(resiliconing the pump base) and tilted the motor up and voila!, there was no oil leaking, but that was short lived after fishing all day sunday the sleave must have popped back out of place cause she is leaking like a siv again. No problem though my new seals will be here in a few days.(I hope) Again not to get to over excited like the job is said and done but i feel real confident that once those new seals are in i wont be seeing any oil. Thanks a lot for taking the time emckelvy to spread your knowledge to a newby like myself!
-Jason