Tech Tips: Differences Between Diesel Rebuild Kits

No matter how you look at it, rebuilding your diesel engine is a big job. It can even seem downright stressful trying to pick the right rebuild kit. In-frame, out-of-frame, and engine re-ring kits are just some of the terms used. What do they mean? What are the differences between them? All these questions and many more will be answered in this post!

2250115-C15 CATERPILLAR C15 OVERHAUL REBUILD KITHighway & Heavy Parts is dedicated to providing you with as much knowledge as possible when it comes to rebuilding your truck’s engine. If you'd rather watch our video explaining this topic, you can watch it here

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Primary Differences Between In-Frame, Out-Of-Frame, And Re-Ring Kits

Knowing what you need is critical for getting the correct engine rebuild kit. Most commonly, when customers ask for a rebuild kit they are referring to an in-frame kit. But, just like diesel engines, rebuild kits are a dime a dozen nowadays. Getting the right, complete kit for your specific needs is just as important as choosing the correct model. 

An engine overhaul kit can mean different things, depending on who you talk to. Luckily, our ASE-certified staff can help you out make sense of everything. Unlike our competitors, we like to use the term “rebuild” as opposed to “overhaul” when talking about engine kits. 

Diesel Engine Rebuild Kit Guide


Re-Ring Rebuild Kits

If damage is minimal, or you just want to take care of a potential problem before it happens, our diesel engine re-ring kits are the way to go. An engine re-ring rebuild kit is used when the rest of the bottom-end is in good and usable condition.

Cummins ISX Non APR Inframe Re Ring Rebuild Kit New-1Make sure your pistons, crankshaft, and overall state of the engine are all in good condition as these kits only provide you with, in most cases, new piston rings (more info below). Here is a perfect example of a Detroit Diesel series re-ring kit. 

Contents Included In A Re-Ring Kit

As previously mentioned, a common re-ring kit comes with new rings, head gaskets, oil pan gaskets, and cylinder liners. Unlike the other diesel engine rebuild kits on this list, they will not come with pistons. This is often referred to as a “pistonless” kit. 

Why Should You Choose An Engine Re-Ring Kit?

Keeping your old cylinders may be an option if an engine “refresh” is all that’s needed. If there hasn’t been any physical internal damage such as a valve hitting the cylinder head, there is no need to physically replace the pistons. If it ain’t broke, don’t fix it, right?

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In-Frame Engine Rebuild Kits

An in-frame rebuild kit is what most people think of when talking about an overhaul diesel engine kit. It has significantly more parts than a re-ring kit but still doesn’t require taking the engine out.

4376175 CUMMINS ISX APR INFRAME REBUILD KIT NEWLike with any other truck parts, make sure you get the right kit for your specific make and model. Most in-frame engine rebuild kit parts are not interchangeable between different engines. Not sure which in-frame engine rebuild kit is right for you? No problem! Our experienced staff will happily help guide you in the right direction. 

In-Frame Kit Contents

In-frame rebuild kits will contain everything needed to do a complete, frame-on engine overhaul. Kits come with rings, seals, rod bearings, main bearings, required gaskets, and hardware. Of course, this depends on both the manufacturer and engine type you have. 

Additionally, the in-frame kits we sell on Highway & Heavy Parts will come with an upper engine gasket kit, saving you the money and hassle of having to buy them separately. It’s one of the many things that helps up stand out in a crowd. 

Choosing The Right In-Frame Rebuild Kit

There is a reason why most mechanics, owner-operators, and fleet managers choose this type of kit over the rest. It includes the most common parts that fain on diesel engines while not giving you anything you might not need. 

Most engines can be saved, given that the block is in good shape. Sleeves, pistons, rings, and gaskets are all items that can be replaced. By going with the right in-frame rebuild kit, you can get your truck back on the road that much quicker.

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Out-Of-Frame Engine Rebuild Kits 

Unlike the other two options on this list, out-of-frame rebuild kits are the most comprehensive, and often the priciest.


But for those who want or need the best, this kit is the one to go for. It helps repair current problems and prevent future ones from happening. 

Out Of Frame Engine Rebuild Kit Contents 

Out-of-frame engine rebuild kits will come with everything an In-frame rebuilt kit contains such as cylinder liners, pins, ring sets, rod bearings, thrust washers, plus more. Gaskets included in this kit will come as an upgraded series and not just the basic ones. Increased durability and reduced wear and tear is the name of the game.  

Each kit will vary slightly by manufacturer and the engine type you have. However, we include the best of the best with every frame engine rebuild kit we sell at Highway & Heavy Parts. When pulling the engine, you have more access. Therefore, can access more gaskets and critical parts such as front and rear crankshaft seals.

Why Go With An Out-Of-Frame Kit?

If your diesel engine has to come out, why not benefit from this situation and replace all worn and damaged parts? Trust us, the few extra dollars you spend on a quality out-of-frame kit now will end up saving you more money and headaches in the future. 

An out-of-frame engine rebuild kit is worth every penny. While everything is taken out, replacing all internal components, even if they don’t look to have much wear, is ideal. The next major engine overhaul may not come for hundreds of thousands of miles, make the best of a bad situation.

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Final Words

Highway & Heavy Parts has a wide selection of engine rebuild kits for you to choose from. From simple re-ring kits, to complete, out-of-frame kits. We strive to offer a solution for all your diesel engine needs. 

Our experienced, ASE-certified staff has is ready for any questions you might have about diesel engine rebuild kits, or any other parts needed to get your truck back on the road quickly. Give us a call at 1-844-304-7688 or request a quote online today!

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