Short Block versus Long Block Engines for Boats
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.
Tags: marine engines, marine longblocks, remanufactured longblocks