Mercruiser Lower Unit Tips at Sterndrives.Com

Hi! My name is Ed and I have some great tips about your outdrive or lower unit. If you don't find your answers here then please email me and I will get your answer for you. You may also call 954-480-9647 ( there may be toll charges!).

Read your Manual! It may sound boring... actually, it IS boring. Your Mercruiser manual does have some basic maintenance tips that you should know. I also encourage owners to get to know their mechanic. Have a good certified Mercruiser mechanic go over your drive and engine with you. It's worth $50 to $100 and can save you problems and money in the long run.

Keep your boat stored out of the water. This is always good advice for several reasons. First, you don't have to worry about the dam thing sinking while your sleeping. Second, you won't get barnicles and crud growing all over everything and third, your outdrive components won't be destroyed by corrosion and galvanic corrosion.

Change your outdrive oil and engine oils frequently. Can you believe that I have had owners tell me that they didn't even know that the lower unit is filled with oil? Well, it is. And not just any oil either. Use the specific oil that the manufactuer recommends.
Older and newer "R" and "Alpha" drives can use Mercury Marine's Premium Blend Lower Unit Oil but they now say it's better to use the green looking stuff called High Performance Blend. All the Bravo drives HAVE to use the High Performance Blend or they will experience clutch problems. The newer Generation 2 Alpha's also use the High Performance Blend.

Check the drive oil after EACH use.
Sure the stuff stinks and your wife won't come near you if you smell like drive oil but all it takes is one trip fishing with a bad oil seal and,KaBOOM! Just take a little time and after the drive has cooled and the engine is off, remove the side vent plug with a large screwdriver and see what the lube looks like.
It should NOT have a burn't smell.
It should NOT be white and milky looking.
It should NOT have sparkly metal flakes.
If you suspect a problem... get it looked at QUICKLY! Don't wait till next week or a $400 repair bill could turn into $2,000 nightmare real quick.

FIX IT NOW !!!
If you EVER have ANY problem with your drive unit, get it looked at immediatly.

Think about it. If water is in your drive, then it will rust. Rusted bearings and rusted gears are considered unusable and they WILL destroy themselves with little use.

Perhaps the most common problems I have run into are shifting problems. You know... when your with a bunch of girls and your trying to impress them and when your coming up to the dock at your local waterfront bar your engine stalls while shifting and you slam into the new 85 foot yacht with the Dolphins football team on board. Happens all the time!
Well, Most shifting problems are actually not in the drive unit at all. The shift cable assembly which goes from the engine to the drive may be too stiff from water leaking around a seal or such. The engine stalling is NOT the engine's fault nor is the shift interuptor switch faulty (in most cases).
The important thing is this... GET IT FIXED!
See, if you don't fix it then you will ruin your shift clutch and then you will really be crying.

Here is a good one. Store your drive in the DOWN position. In the water or out. If you store the drive in the up position then you will deform your outdrive bellows, your trim cylinders will eventually sieze and if you're in the water, barnicles and growth will cover the ram rods.
Full tilt is really for trailering use.
Also, water will puddle in the housing in front of the prop and will corrode and possibly crack the lower unit housing. That would really suck.

Keep your prop in good shape. Bent or damaged props ruin bearings and seal. Bad props will also really really slow you down. Pull the prop off at least twice a year and grease the prop shaft with some good grease.

Shift Cable Replacement Instructions and Tips!
Bellows and Gimbal Bearing Replacement Procedures and Tips!
Water Pump Replacement!
Great Exhaust Tips and Replacement Procedures
New! Try our new Mercruiser Information Bulletin Board.