Technical Information Asked Questions

What are the specifications for my MerCruiser engine?

A general listing of specifications is included in our MerCruiser product section. Your owner's manual also includes some specifications. Additional technical information can be found in the appropriate service manual for your engine model, or you can check with your local authorized MerCruiser dealer.

I need to replace my existing engine. What will fit?

Due to the large number of different engine/boat configurations and the changes made to engine packages over the years, we suggest you contact your dealer, engine power center and/or boat manufacturer for specific guidance in your case.

How do I obtain horsepower curves, torque curves, or fuel consumption data?

Horsepower and torque curves are not published because they are considered confidential company information. Fuel consumption data is not published because it is affected by factors beyond our control, such as boat hull type, temperature, humidity, altitude, gear ratios, propeller, etc. In some cases, fuel consumption or other performance data is available from your boat manufacturer for a specific boat/engine combination.

I want to upgrade to a new-style sterndrive with my existing engine and transom. Is this possible?

There are many factors which determine the proper sterndrive for a given engine. A different sterndrive may physically bolt to your existing transom assembly, but it may not be a good match for your engine and boat. An Alpha Generation II sterndrive will not fit where an R/MR/Alpha I drive was used. Alpha and Bravo series sterndrives cannot be interchanged. In some cases it is possible to interchange members of the Bravo drive family. We recommend contacting your dealer or engine power center for specific guidance before undertaking any type of sterndrive replacement, upgrade, or repower.

I want to upgrade to a newer engine and use my existing sterndrive and transom, what will work?

There are many factors involved in replacing your marine engine; newer current engines will not directly backfit to older style sterndrives and transoms. We recommend contacting your dealer or engine power center for specific guidance before undertaking any type of engine replacement, upgrade or repower.

I want to upgrade to a more powerful engine. How much more performance can I expect?

This depends on many factors such as hull type, weight distribution, maximum horsepower rating of the boat, etc., and cannot be accurately determined without more information. We suggest you contact your dealer, engine power center, or boat manufacturer for specific guidance in your case.

On a hot day after I run the engine for a while then shut down, the engine won't restart or it starts and idles fine, but when the throttle is advanced the engine bogs down or quits running and will not restart. Why?

It sounds like your engine may be vapor locking. One factor that contributes to vapor lock is fuel. Fuels produced for use during the winter and early spring months around the United States are designed to vaporize at a lower temperature. This lower vaporization point can cause the fuel in the boat supply lines and engine fuel system to vaporize prior to being used. Another contributing factor to vapor lock is a restriction in airflow into the engine compartment. Make sure that lifejackets, fluid containers or other equipment have not restricted the airflow. Other items that will help to reduce vapor lock are:

• Letting the engine idle for 3-5 minutes before shutting it off.
• Opening the engine cover to let the hot air escape. Note: Always reinstall the engine cover before starting the engine.
• Operating the bilge blower to remove the hot air.

If these items are OK, an authorized MerCruiser dealer can perform additional tests on the fuel and ventilation systems.

Can I use an automotive longblock or shortblock to replace my MerCruiser engine?

No, an automotive block cannot be used for several important reasons. The MerCruiser ECMs (electronic control modules) are specifically calibrated to each of our engine models. It would not be possible to determine the effect on the performance or compatibility with an automotive engine. In addition, automotive engines are not equipped to endure the high rpm duty cycles and harsh environment that marine engines see. Further, some of our engine components are unique to marine engines, such as the welch plugs, camshafts, cylinder heads, head gaskets and pistons.

My engine diesels, or runs on, after it is shut off. What causes this and can it be eliminated?

Under certain conditions, carbureted engines may "run on" after the ignition key is turned off. This condition is rarely caused by a defect in the engine itself. Usually, a combination of external factors is responsible. These factors include, but are not limited to, the type and formulation of fuel used, the boat's engine compartment ventilation system, ambient air temperatures, excessive engine compartment temperatures, how quickly an engine is shut off after running at cruise or higher rpms, elevated engine idle rpm setting, use of spark plugs with an incorrect heat range, deposits on the spark plugs or in the combustion chamber, etc. There are some things you can do to minimize a "run on" condition. Most importantly, allow the engine to idle for a few minutes before shutting it off. This helps the engine to normalize at idle rpm. Other suggestions include having your dealer verify the engine idle mixture, idle rpm and timing are correct. Try a different brand of regular fuel or try premium fuel. Use spark plugs that are in the next colder heat range. Most of these are changes that should be made by your local authorized MerCruiser dealer. Our company has provided information to authorized dealers to help them assess your situation and to correct or adjust the contributing factors.

Is there a factory authorized repainting procedure for my sterndrive?

Yes, MerCruiser has a refinishing procedure available. For best results we recommend this procedure be performed professionally.

Refinishing procedure:

This procedure should be used in refinishing MerCruiser sterndrives and transom plates. This procedure will provide the most durable paint system available in the field. The listed materials should be purchased from a local DITZLER AUTOMOTIVE finish supply outlet. The minimum packaged quantity of each material shown is sufficient to refinish several sterndrives and transom assemblies.

• 1 QT. DX-533 Alumiprep #33 metal preparation
• 1 QT. DX-503 Alodine #1201 conversion coating
• 1 QT. DP-40 Non sanding Epoxy Primer zinc chromate primer
• 1 QT. DP-401 Catalyst for DP-40
• 1 QT. DAR-9000 Acrylic Enamel-black topcoat
• 1 Pt. DXR-80 Delthane Ultra-additive for acrylic enamel
• 1 QT. DTR-602 Acrylic Enamel Reducer-temperature range 70-90 degree F.

Procedure:

1. Scuff sand to remove all blistered paint and roughen factory finish. Remove sanding dust.
2. Follow manufacturer's recommendations and instructions on the individual containers.
3. Apply DX-533 (Alumiprep #33) to clean and condition the aluminum.
4. Apply DX-503 (Alodine #1201) brush on chemical conversion coating for aluminum.
5. The DP-40 (Epoxy Chromate Primer) mixed with DP-401 Catalyst can now be applied. A .75 mil film build is recommended. NOTE: Allow 30 minute induction period for permeation of the epoxy chromate primer and the catalyst prior to application.
6. The topcoat consists of DAR-9000 Acrylic Enamel Black and the DXR-80 Delthane Ultra additive, and DTR-602 Reducer. It is a polyurethane acrylic enamel system which provides fast drying, durability, high resistance to corrosion and good color and gloss retention.
7. The type of spray gun used will determine the proper reduction ratio IMPORTANT: DO NOT use any type of aerosol spray paints, as the paint will not properly adhere to the surface, nor will the coating be sufficiently thick to resist future paint blistering. NOTE: DO NOT PAINT SACRIFICIAL ANODES.