Posts Tagged ‘marine longblocks’

I love my boat but the engines are on their last leg. Should I try and upgrade with new engines, or just sell the boat and start over?

This is one of the most common questions boaters are faced with today when its comes to replacing the engines in older model boats. There are a number of factors to consider when replacing the engine, so this Selection and Shopping Guide will help you drill down to see what option best fits your boat’s situation. It’s important to realize how the 2010 Marine Engine EPA regulations changed the overall topic of replacing the engine, so this is something every boat owner needs to be aware of.

• 1) Do you want a complete Bobtail Engine, Power Package Motor or just the Longblock?
• 2) Do you want a New Marine Motor or Remanufactured?

*SHOP ONLINE*
BOBTAIL ENGINES	POWER PACKAGE (PAR PAC) ENGINES	LONGBLOCK ENGINES

Selecting the Correct Model of Marine Engine for Beginners and/or Novice Boaters

There’s no shame in finding it difficult to distinguish one model 454 Marine Engine from another. Over the years the various marine manufacturers have changed both V6 and V8 engine models so many times it can be difficult even for Marine Engine distributors to properly identify the correct engine model for a customer. Typically, verifying the Engine Casting Number (link to block casting number location) along with the Cylinder Head Casting Number (link to head casting number location) is the best way to identify your Marine Engine correctly. Providing customers with solutions is where PPT stands above the other Marine Engine suppliers in providing technical assistance and information to help you properly determine the correct motor model for your application. PPT maintains a A+ rating with the BBB for one simple reason; WE TAKE CARE OF OUR MARINE ENGINE CUSTOMERS! Don’t be fooled by other Marine Engine retailers advertising 7 year warranties or 30% better fuel economy; those are simply gimmicks. The bottom line with Replacement Marine Engines is that you get what you pay for.

Marine Engines Technical Library

Topic: Replacement Options

Question: Why is it so difficult to find a remanufactured marine shortblock? I see plenty of new and remanufactured longblocks but not any shortblocks.

Response:

There are a variety of options to be considered when replacing the engine in marine applications. Depending on the severity of the issue that’s driving your need to replace the engine here are a few things to consider. You can also read our technical articles regarding overall repowering options to research the advantages versus dis-advantages of drop in bobtails versus longblocks. 

Definition: Shortblock 

• Shortblock’s have been offered in the past as either new or remanufactured product.
• Shortblock’s include the block and rotating assembly but NOT the cylinder heads.
• The primary purpose of Shortblock’s is to offer the “cheapest” engine replacement option.

Definition: Longblock (read more on the terminology of longblock versus bobtail, etc.)

• Longblock’s are currently offered as either new or remanufactured product.
• Longblock’s include the block and rotating assembly AND the cylinder heads.
• The primary purpose of Longblock’s is to offer the “most cost effective” engine replacement option.

Summary Explanation

It’s important to remember that cheaper is not always better when repowering your boat. Whether you consider new or remanufactured the better option to consider would be what offers the best value. While shortblocks are almost always going to be cheaper on the front end versus a longblock they may not necessarily be cheaper in the long run. This leads us to the overarching reason of why the Marine Industry has all but moved away from offering the shortblock engine options. Warranty cost is a huge factor that the manufacturers are building into the up front cost of the products when they are sold. The more complete the engine is when sold to the customer the less likely it is that the customer will experience warranty related issues. By far the vast majority of warranty problems customers experience when repowering is caused by something they install improperly, installing incorrect accessories, etc. With this in mind it’s important to realize that one of the driving factors determining the longevity of any replacement Marine Engine is the marine cylinder heads they are equipped with. The cylinder heads are a huge factor in dictating the overall performance which also has a huge affect towards the engines suseptibility at ingesting water. Another extremely important factor is the condition of the valve seating, etc which affects both performance as well as the water ingestion and reversion characteristics.

Last but not least is the manufacturers ability to test the product which is being provided to the customer. In the case of a marine shortblock the product cannot be fully tested for compression, fluid leakage, performance, oil pressure, etc. Even in the case where test heads are installed for the purpose of test running the engine the performance, compression, head gasket leaks, etc being verified are not valid for the actual engine that ultimately gets installed into the customers boat. The reason being since the heads have to be removed on shortblocks after testing and ultimately get repalced by whatever the customer choose to install.

Final Conclusions

Our best recommendation is to pay a little extra up front and purchase a true Marine Longblock. The up front cost difference is really not as great as one would think because the testing required for shortblock’s requires more labor at installing and then having to remove components. Therefore some of the cost saving you would expect are in fact eaten up by additional labor cost. This small up front cost of the longblock buys you exponentially lower industry reported warranty rates versus that of the shortblock’s. In our experience, in the longrun we’ve found the longblock will generally cost even less than the shortblock.

SHOP FOR LONGBLOCK’S NOW

Question: What’s the best direction to go when replacing the old Mercruiser 3.7L/470 marine engines?

Unfortunately there is no single good option for this when looking at a complete re-power. The 470 was originally developed by Mercury Marine specifically for it’s purpose; to power boats. The inline configuration allowed for easy draining, a single intake/exhaust manifold was cheaper than two, etc. The engine was also a large displacement engine for its size and therefore made a tremendous amount of torque because of the stroke and displacement. On top of this Mercury utilized their die casting expertise to produce a light weight aluminum block and combination with the existing Ford cast iron 460 cylinder head.

To go up in Hp you will have to go with the typical V-Configured  350 engine which will also require a different drive ratio and propeller. With any changeover to the V engine configuration be it V6 or V8 this will also require completely rebuilding the stringer system in your boat. Many customers ask about replacing the 470 engine with the current 3.0L engine since they are also are an inline configuration. The problem with this is that the 3.0L makes approximately 135 Hp & 180 Lb-Ft of torque where the 470 made 190 Hp and approximately 275 Lb-Ft of torque. The 3.0L engine is simply too small and does not make enough torque.

Recommendation

Therefore the prevailing direction for 99% of boat owners in this position is to go with the remanufactured 470 longblock. The remanufactured longblocks are of a very good quality and have a 24 month warranty. This is important versus rebuilding realizing this was not a standard automotive product and therefore most local rebuild shops do not have the experience to produce a comparable, good quality product.

In some cases certain customers really love their existing boat but prefer more horsepower/torque. If this is the case for you it may be worth the time and investment to investigate changing over to the larger displacement “V” configured engine, however in 99% of the instances the only viable option comes down to replacing the longblocks or simply changing boats.

Installation Drawings for reviewing specific dimensional differences (open is separate windows)

470 (1976 Model) Installation Drawing (Select Link)

470 (1978 Model) Installation Drawing (Select Link)

3.0L (Inline 4 Cylinder) Installation Drawing (Select Link)

4.3L (V6) Installation Drawing (Select Link)

5.7L (V8) Installation Drawing (Select Link)

Tech Tips (Select Link)

Remanufactured Longblock Product (Select Link )

GM produced 2 different 3.0L model marine engines up through 1994. They were both 3.0L Marine Engine models but had different cylinder heads which is where they got the different performance levels; 120 (large oval port head) and 140 Hp (small rectangular port head). They however do range the ratings on them so you could have one version that was previously rated the other version in previous years. Starting in 1995 all that GM produces is the 140 Hp longblock. The new 3.0L longblocks are offered to be used as a replacement either way for which ever version of the engine that you have.

Since the 3.0L marine engines are not used in automotive applications there aren’t enough cores to support a good remanufacturing option in our opinion. Regarding this particular engine we only supply new longblocks which do not require a core deposit. There are several other benefits in this case with the 3.0L being that this is the exact same engine which is/was used by Mercruiser and Volvo Penta to build their respective products.

Another great benefit with the new longblock is that General Motors began supplying the engine with a new electronic ignition system to address the historical issues this engine suffered with head gaskets failures due to detonation. Therefore with the new 3.0L longblocks you get the new longblock assembly but also the water pump, distributor, coil, ignition module, plugs and plug wires.

If you need more than a longblock you will have to begin looking towards a complete turnkey engine known as a bobtail engine.

Installation Drawings for reviewing specific dimensional differences (open is separate windows)

3.0L (Inline 4 Cylinder) Installation Drawing (Select Link)

Tech Tips (Select Link)

New Longblock Product (Select Link )

Topic: 3.0L (120/140) Replacing Your Marine Engine Longblock

New and Remanufactured Longblock……Pricing

Question: How do I replace my damaged longblock with a new marine longblock or remanufactured marine longblock?

Response:

Since 3.0L marine engines are not used in automotive applications there aren’t enough engine cores to support a good remanufacturing option. We only supply new 3.0L longblocks which do not require a core deposit. The other benefit of the new engine is that it includes the new electronic ignition system that GM released in the mid-90’s to address several of the ongoing quality issues that plagued this engine over the years.

There are two (2) solutions to this common problem of replacing the 3.0L marine engines, however, there are many factors affecting the final direction to proceed with. Up through 1991, the engine was produced with a two-piece rear main seal and a 12-3/4″ flywheel. Then in 1992, the engine was produced with a single piece rear main seal. Finally in the year 2000, GM upgraded to a 14″ flywheel which is how the engines are currently being produced.

Solution 1:   Marine Engine Repair

• If your existing engine was built before 1992, you will need a 12-3/4″ flywheel that matches the two-piece rear main seal, so that you can re-use your existing coupler and starter.
• If your engine was built between 1992 & 2000, you can re-use the flywheel on your existing engine.
• If your engine is not an OMC Cobra engine vintage, it will require that your existing coupler be re-machined to allow it to fit up properly to the 1 pc rear main seal configuration 12-3/4″ flywheel. We can help with this as well.

• If your engine was built after 2000 you can use the flywheel that comes with the new or remanufactured longblocks.  We have an option for a 12-3/4″ flywheel to go on this engine as well.
• If your engine was a large port engine, or the 120 hp built up until 1994, you will also need the exhaust manifold conversion adapter which converts from the old style oval port head to the higher hp rectangular port head, which is the only head being produced today.  
• #gm181base (1991 – Current Engines)

Solution 2: Marine Engine Repair

Another option is engine conversion kit that can be used with your existing Mercruiser or OMC Cobra/Volvo SX 3.0L engine. These kits include an engine, flywheel, exhaust manifold gasket, fuel pump, and coupler as a complete kit.

• #301201P_2M – Mercruiser (1968 – 1990)
• #301201P_2 – OMC Cobra/Volvo SX (1986-1990)

Select the following links to view the mentioned products:

GM 3.0L 4 Cylinder New Base Marine Engine