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Basic Tips and Instructions

Here are some great basic instructions for
some of the more common service items.

These instructions should only be used as a supplemental guide
to the factory Service Manuals.

Servicing your own engine and drive is a very popular option that
many "do-it-yourselfers" perform with great success. However, you
need to take into consideration your level of technical experience,
level of patience and supply of tools.

The first thing to do before performing service on your Mercruiser unit is to properly identify the engine and drive. Every Mercruiser engine and sterndrive comes from the factory with a serial number. Older serial numbers have 7 numbers. Newer serial numbers contain a letter in the second position. Here are some examples of newer serial numbers, 0A987345, 0D123765, 0M432876, etc. Newer style serial numbers can allow us to automatically pull up your parts images. Older serial numbers are helpful but parts are still more difficult look up.

Every Mercruiser engines serial number is stamped into a small metal plate and pinned to the side of the engine block. This plate is about 1" wide X 2" tall and it is usually pinned to the stb side of the block towards the rear.

New Mercruiser Sterndrives also have serial numbers. The number is usually stamped right through the drives decals on the rear or side of the upper driveshaft housing.

Plan Ahead
Read as much about your service job BEFORE beginning. Research the tools required. Make a complete assessment of all the parts and tools that you will need. Compare the cost and risks of "doing it yourself" vs paying an experienced tech. Make sure you have a service manual. Prepare a clean and safe working area. Acquire all the proper cleaners, rags, sealants and lubes. Prepare to do the job RIGHT and don't take shortcuts.

Boats can explode. Moving parts can rip off your fingers. Hot exhaust can burn you to the bone and props can slice you up. One spark near a battery can cause an explosion. You can never be too careful. Remove the battery from the boat before working with fuel. Always disconnect the batteries negative terminal first. Clean up any spilt fuel and let ALL of the fumes dissipate before installing the battery and starting the motor. Pulleys and Belts can grab your clothes and hair. Don't wear loose clothing and keep your hair up under a hat. Always wear safety glasses. Be smart.
Change your Alpha Gear Lube
Change your Bravo Gear Lube
Why does my drive lube have white streaks?
Why does my drive lube have gray mush?
Replace Your Alpha-One Water Pump
Replace your Alpha Gen II Water Pump
Rebuild your Bravo Raw Water Pump

Troubleshoot & Replace your Alpha Shift Cable
Troubleshoot & Replace your Bravo Shift Cable

Replace your Alpha One Bellows & Gimbal Bearing
Replace your Alpha Gen II Bellows & Gimbal bearing
Replace your Bravo Bellows & Gimbal Bearing
Why does my drive "Growl" when I turn?
Water is leaking into my boat from the transom

Replacing your Trim Sender Switches
My Trim doesn't work but my Trailer Switch does
My Trim Gauge is Pegged

Rebuild your Alpha One Upper Driveshaft Housing Assembly
Rebuild your Alpha One Lower Gear Housing Assembly

Check your Engine Alignment
Check for Excessive Steering Play
Troubleshoot an Overheating Problem
Should I remove my thermostat?
Why do I overheat when going fast?
Troubleshoot a No-Crank Condition
Troubleshoot a No-Start Condition
My Engine Backfires and/or Surges and has Lack of Power
What is an Anti-Syphon Valve?
My Engine blows Steam from the Exhaust
Why do I hear a "clakity" sound while at idle?
Exhaust Manifolds...IMPORTANT Information
How do I Winterize my engine?

What is Galvanic Corrosion?
I have a Bravo III Galvanic Corrosion Problem
What is a Mercathode?
All about Zinc Anodes
How do I check my carburetor?
What carburetor do I have? A Rochester or a Mercarb?
I have water in my fuel
My fuel smells like varnish
My fuel is old
My engine has been sitting for several months without being run.

I have a Mercruiser 470, 485, 488, 190, 3.7L Engine
I have coolant dripping from the front of my engine
Can I install a regular Alternator instead of the Stator-Rotor?

Converting an OMC to a Mercruiser

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