Is it Less Expensive to Rebuild or Replace an Engine?

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For whatever reason, you’ve found yourself in a place of deciding whether to rebuild or replace your engine; before you make any big decisions, let’s put down the wad of cash and weigh the pros and cons carefully. In this article, you’ll see that we’ve put together a guide that will help you make an informed decision on whether or not to rebuild or replace your engine. 

Deciding whether to replace or rebuild your engine requires case-by-case consideration. Lack of maintenance, a road hazard, a need for speed, or a love for a classic car can all lead to engine replacement. Wherever you’re at – we’ve made a list to help you on your way.

Though we won’t be able to address your direct concerns since we can’t view your vehicle, we can help you make an informed decision on whether to rebuild or replace your engine, in the next few paragraphs we’ll cover quite a bit, so don’t be afraid to take some notes! Let’s get into it! 

The Great Debate, Rebuilding or Replacing An Engine

If you have ever been stuck on the side of the road with a broken timing belt or a blown head gasket, deciding whether to replace or rebuild the engine was probably the least of your concerns at the time. However, once your car has been moved and is sitting in a shop somewhere, the costs begin to rattle in your brain, “How much is this going to cost me,” is probably the most common question asked at a mechanic’s shop.

While you may be hanging on to the hope that it’s a simple fix, every so often you’ll get that dreaded call where they tell you that your timing belt has snapped and your pistons are pinched, you may begin biting your lip and weighing the pros and cons. 

Well, the good news is that it’s less serious than a car accident. 

The bad news is that you are going to be counting your pennies for the next five months. 

Of course, you can also get rid of the car and start a new car loan.

But consider this, the average cost of an engine replacement is between $3,000 to $6,000. The average cost of an engine rebuild is $2,500 to $4,000. This is enough for a down payment on a brand-new vehicle, so while making your decision you must decide what is best for you, not what the mechanic wants you to do.

Let’s consider the full spectrum of pros and cons and how each particular scenario might play out below.

A Partial Rebuild

Assuming that you are frugal and like to work less and get more for your money, you’re probably leaning towards an engine rebuild at this point. Depending on the extent of the damage, the shop might be able to do a partial rebuild if the pistons look good. 

This is usually how this type of work goes; the mechanic isn’t going to know, for certain, whether your engine is completely damaged from a broken timing belt unless he pulls the head off, after he pulls the head, he can check the valve train and determine whether there is any damage to the pistons if they collided with it. This is a critical aspect of engine repair or replacement. 

Many modern vehicles have interference engines that will suffer catastrophic damage if the timing belt breaks. However, you may be lucky if your vehicle has a non-interference engine.

It is always best to double-check this list because some shops don’t even bother to look. They will tell you that the engine is bad and that it’s not worth fixing if it’s an older vehicle – this info could be completely wrong, because more often than not, older, carbureted vehicles are, in fact, easier to fix.

Taking out an engine is very involved because it involves substantial disassembly of the transmission at the mating surface. Removing the transaxle is thought to be one of the most difficult repairs in many cars. Removing an in-line transmission on a truck or a vehicle with rear-wheel drive is much simpler.

If only the head is damaged, the mechanic simply has to remove some hoses, ducts, and bolts to expose the head bolts. These are special one-time use bolts that stretch as they are torqued. Always ensure that a mechanic replacing the head uses new head bolts, or they may break off or get stuck, leaving you with even more problems.

One problem that is difficult in head removal is the exhaust manifold; the exhaust manifold is often rust-welded to the back of the engine, the bolts can get stuck in the head and break off. This makes it a difficult area to work on and will cause many mechanics to avoid the job or consider higher rates. This could be the end all be all when it comes to your decision – do you want to spend the extra cash? 

If you have a relatively new vehicle, you might want to emphasize that everything is in good condition and will come apart without problems. This may help you bargain for a lower labor quote or find more shops willing to take on the repair at competitive prices.

You can also save yourself money by searching online junkyard inventory to find a replacement head or engine. However,  you have to know how to find the code of your engine yourself, in many cases, to ensure that the replacement is compatible, you will have to consult enthusiasts, a technical manual, or a dealership to find out where exactly the engine code is located on your model. 

Pro tip: The engine code is just a few numbers and/or letters. On an older vehicle, the identification stickers are probably faded or damaged. In that case, you’ll have to locate where exactly it is stamped on the engine itself if you can’t determine it from the 8th digit of the VIN.

A Full Rebuild

If you do decide to fully rebuild a cruddy engine, you should ask them to hot tank it before they rebuild it. A hot tank is a dip in a solvent that restores all the metal parts to their original condition.

It will add value to your vehicle and help you notice oil leaks and other problems with less eye strain. By asking your mechanic to do this they will also consider that you know what you are talking about and perhaps lower your price.

Most people opt for oversized pistons when they have the engine rebuilt, this requires a rebore but will extend the life of the vehicle. This is especially important if the engine has a lot of miles on it. Oversized pistons help to create a little more displacement and can increase power but at the cost of fuel economy.

Most mechanics don’t do most of the engine work themselves, they will simply send your engine out to a machine shop for the rebore and hot tank, and even the piston installation. If you want to save money, remove the engine yourself and take the block to a machine shop to get the best prices.

Engine Replacement

Replacing the entire engine is usually the best option when insurance is going to pay for it. Insurance may pay for a claim when you hit the oil pan on a pothole and the engine burns up the pistons, for example. This would be an accident and would require a full engine replacement using all-new factory parts if they are available.

Engine replacement may also be necessary if you are not confident in the quality of work in your area. Not every location has the best options for car repairs or machine shops. In a lot of bigger cities, car shops don’t fix a lot of vehicles and do a lot more maintenance because everyone buys new cars or leases them.

The only other reason to insist on engine replacement is that it is a very special vehicle, or you are replacing the engine for a performance upgrade. A lot of tuners that originally had small 4-cylinder engines are upgrading to V6 engines, turbo engines, and even W12 engines to take advantage of the improved power but often at the sacrifice of weight distribution.

When an engine overheats and the head gasket blows, always be sure to have the mechanic check the mating surfaces of the block and engine with a straightedge ruler to ensure that neither is warped. If both are warped, you’ll have no choice other than a full engine replacement. 

The other advantage of a full engine replacement is that you can breathe new life into an old vehicle for less than a full engine rebuild if you purchase a low-mileage engine from a junkyard yourself. You know that the quality of the engine is good because it was assembled by the factory, best of all, you won’t have to wait weeks for a full rebuild on it.

You just have to be careful when you purchase a complete junkyard engine. You should smell the oil, check the coolant, and make sure that there was no damage to it before you purchase it. Sometimes vehicles wind up in the junkyard because their engines were run into the ground as well. We wouldn’t recommend this unless you or a friend knows how to check a junkyard engine. 


We hope that this article has helped you weigh the pros and cons moving forward with your engine rebuild or replacement. Remember to go into any mechanical situation with knowledge and don’t be afraid to show that you know what you’re talking about! As always, we’re here to help. 

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