Mercruiser, Marine Engine, Mercruiser Part, Marine Part, Marine Engine Part


Your Best Source for Marine Parts at the Best Prices!

** Offering the option between Original Equipment, Direct Replacement, and Performance Marine Engines and Marine Parts**

Welcome to the Monthly Technical Tips Newsletter. In conjunction with our goal aimed at serving the retail customer, the purpose of this newsletter is to further assist customers in understanding the basics of the marine products they purchase and own. Your feedback is greatly appreciated and helps us to continue providing you with helpful information. Please feel free to respond back to us and let us know if this type of information is valuable to you, as well as suggesting future topics you would like to see included . We will also use this newsletter to offer extended discounts to our "preferred" customers.


It doesn't take long when looking at the price of new boats that one wants to start investigating the alternative option of replacing or repairing your existing marine engine. In the past the thought of taking on a project this size has been a daunting task to the layman. This newsletter covers the options of marine engine long blocks versus complete bobtail marine engines, and provides crucial information at helping you to determine which product is actually best for you.

Engine Rotation - No matter whether you choose a long block or complete bobtail engine the rotation is a crucial piece of the puzzle that needs to be known. Rotation with marine engines is always viewed from behind the engine looking towards the flywheel. Standard rotation (left hand) means the flywheel is turning counter clockwise looking at it from the rear. Opposite rotation engines (right hand) were common years ago however are not regularly produced today as the later variety of transmissions; the later model Hurth & Velvet Drive have negated the need for this as the gears can rotate either direction without a problem. 


Long block


This term generally refers to the cylinder block and heads as well as the required internals of the engine. Generally marine engine long blocks do not include the intake manifold , engine circulating pump , or flywheel . Depending on the brand of the product the "tin ware" (oil pan, valve covers, timing chain cover) may or may not be included. Much like the flywheel, since the tin ware is not considered a "wear" item some manufacturers do not include this with their marine engine long block products. (Not including the "Tin Ware" is normally associated only with remanufactured long blocks.)


Common issues that arise when replacing a marine engine long block are whether the intake manifold will match, making sure the flywheel is correct, making certain the ignition system matches properly, and making the necessary adjustments for electric versus mechanical fuel pumps . With marine engine long blocks there are either remanufactured or brand new options however the prices are actually very close to the same for either option.

When it comes to the specific product your needs have to be evaluated since many design changes have taken place over the years including rear main seals changing, mechanical fuel pumps being eliminated, cylinder heads changing, etc. The following links address the specific changes that have taken place over the years and will provide you with the much of the necessary information to help you determine which product you require.

 - 3.0L Engines

 - 4.3L Engines

 - Small V8 Engines

 - Big V8 Engines


Bobtail Marine Engine


This term generally refers to a complete new engine as required to complete a "drop-in" replacement project. Depending on the manufacturer of the product in question these products generally come complete with fuel, electrical, cooling, and exhaust systems as well as the engine mounts. This level of "completeness" yields it ready to drop right in when replacing a "used up" engine.


When it comes time to investigate this option there are several things to consider; first and foremost is the age and condition of the engine being replaced. If the engine itself is bad, but the Exhaust   and or Cooling systems are in relatively good shape it can be a good option to simply replace the long block instead. However, unless you intend to complete the work yourself one must always consider the labor associated with switching the attaching hardware over from the old engine to the new one. If the determination is made that the complete engine needs to be replaced one may want to consider a complete bobtail marine engine. When replacing a complete bobtail marine engine you will need to determine if the existing coupler can be used and if the existing sterndrive or transmission will couple directly to this. In many cases if the engine is more than 10 years old you will likely have to change out the engine harness connection plug as these have changed over the years. It is also common to have exhaust changes since the exhaust systems have changed from 3 inch to 4 inch. There are several different manufacturer options as well as even the option of changing from one to the other if it makes more economical sense.


Volvo Penta


Technical Information Library


Wednesday, February 15th, 2012

Alphabetical List of Articles