There’s a lot that can go wrong under the hood of your car, but if your engine is fundamentally compromised, you’re probably on the hook for a large bill. In the article below, we’ve outlined how an engine works, how to know if yours is bad and what your options are for getting back on the road.
How does a car engine work?
Put simply, an internal combustion engine (the kind in most automobiles) combines fuel, air and spark to produce a series of small, controlled explosions. These small explosions are contained within the cylinders of your vehicle's engine, and each time the explosion occurs, a piston in the cylinder is driven up and down. These pistons are connected to a crankshaft, which is in turn connected to the vehicle's transmission and from there to the rest of your drivetrain.
This process repeats itself thousands of times a minute while your car is running, with various engine components and systems working in harmony to propel your vehicle down the road. However, should one of these components fail, it can cause a domino effect that can damage and even ruin your engine.
For example: If you have a failing gasket, your engine will slowly lose oil. Over time, the amount of oil in your engine is significantly reduced, and this lack of lubrication can lead to the internal components of your engine heating up past their design thresholds. Left untreated, this overheating can cause everything from warping to major engine damage.
Symptoms of engine failure
Because your engine is so integral to your car’s functions, engine failure can affect many different systems and show itself in many different ways. Still, there are several common symptoms that you should look out for if you think your engine is failing:
- Check engine light: Most modern vehicles utilize a check engine light to let you know that one of the engine’s many sensors has detected a problem. This could be a small issue (like a loose gas cap) or a major one, like engine failure.
- Decreased performance: This can mean a lot of different things, from decreased fuel efficiency to failure to move your car at all. If your engine is running rough or not behaving normally, it’s a good idea to get it checked out.
- Knocking: One of the most common symptoms of engine failure is a knocking or thumping noise coming from your engine bay. A similar sound can be caused by fuel burning unevenly in a cylinder, but one more serious cause is a failing engine bearing.
- Grinding: Grinding noises can come from a lack of lubrication between critical engine components, and they generally mean that something’s either not where it’s supposed to be or not receiving proper lubrication.
- Increased exhaust: A sudden increase in the amount of exhaust your engine is producing usually means something is burning that shouldn’t be. You may be able to tell what’s burning by the color of the new smoke.
- Black smoke is a sign that too much fuel is making it into the engine.
- Blue smoke generally comes from burning engine oil.
- White smoke comes from burning antifreeze or coolant.
- Oil or coolant leaks: Oil or coolant spots on the ground under your vehicle could be a sign of engine failure. If a leak is caught early enough, it may not be an issue, but if your car has been leaking for months, the lack of fluids may create other problems.
If you suspect you have major engine issues, visit a mechanic you trust to find out exactly what you're dealing with. Qualified mechanics will run a full diagnostic scan on your vehicle and perform a thorough visual inspection to determine what the cause of your problems is. If your mechanic tells you that your engine is seriously compromised, you'll generally be presented with two options: an engine rebuild or an engine replacement.
How much does it cost to rebuild an engine?
In general, engine rebuilds are less expensive than engine replacements. Costs vary widely depending on the type of engine you have and how much work it needs, but an average price is anywhere from $2,500 to $4,000, according to the National Automobile Dealers Association (NADA).
If you elect for a rebuild, your mechanic will disassemble your vehicle's engine, inspect the damaged components, and reassemble the engine with new or re-machined parts to replace whatever was causing the issue. There are a lot of intricate processes involved in a rebuild, but by the end, your engine should be back in working order and nearly good as new.
On the downside, this process can take up to two weeks, and it can have a drastic effect on resale value since many people do not want to purchase a vehicle that has a rebuilt engine. While this mentality isn't necessarily fair, it is often a reality.
How much does it cost to replace an engine?
If you choose to install a replacement, your mechanic will purchase another engine and swap it out for your old one. Engine prices vary so significantly from manufacturer to manufacturer that it’s hard to pinpoint prices, but your mechanic should provide you with an itemized quote showing the cost of the replacement engine and what they’re charging for labor.
If you’re buying a new crate engine from the factory and having it installed at the dealership, expect to spend anywhere from $4,000 for a four-cylinder engine to upwards of $10,000 for a high-performance engine. However, most prices are somewhere in the middle, and buying new isn’t your only option.
If you want to save money, you can find a cheaper mechanic and have them install a remanufactured or salvaged engine instead:
- Remanufactured engines have gone through a more stringent rebuild process to make them almost as good as a newly built engine, and some even come with warranties. Again, costs will differ, but installing a remanufactured engine will often split the difference between the cost of a rebuild and installing a crate engine.
- Salvaged engines are pulled from used vehicles in junkyards. They are often the cheapest option in this scenario (with some engines costing only a few hundred dollars), but they might have other issues from previous use or neglect.
You can theoretically source your new engine from almost any vehicle or maker, but replacing your engine with something different may require more time and money. One possible exception is if your automaker uses the same family of engines across multiple vehicles, like with Chevrolet’s LS series of engines found in many of the company’s trucks, SUVs and performance cars. Different engines in the same family will have different characteristics, but swapping them is often easier than replacing one with something more exotic. However, it’s still generally easiest to replace your engine with an identical model.
If your engine is covered by a warranty, then the cost to rebuild or replace it may be negligible. Your engine is a part of your vehicle’s powertrain, which means it’s covered for a certain amount of time or miles by most factory warranties and extended warranties. To see if your engine is still under warranty, check with the manufacturer or your extended auto warranty provider.
How long does it take to replace an engine?
In terms of labor, an engine replacement can take your mechanic anywhere from 8 to 20 hours, depending on your vehicle. At a rate of $100 per hour, this means you could spend $800 to $2,000 on labor alone, and some mechanics charge even higher rates. In 2017, AAA found that repair shops in its network charged between $47 and $215 per hour.
Replacing an engine is a considerable undertaking, and you may be without your vehicle even longer than the time your mechanic actually spends working on it. Time spent sourcing a new engine, replacing your old one and testing the replacement generally translates to anywhere from three days to a week in the shop, maybe longer.
Is it worth rebuilding or replacing an engine?
Given the high costs of rebuilding or replacing an engine, there’s a certain point where they no longer make financial sense. In some cases, it’s more cost-effective to junk your car and buy a new one rather than fixing it.
If you’re unsure whether a rebuild or replacement is worth it, think of your repair bill in terms of the value you’re getting back. Think about how many years of driving will you get out of your car once it’s fixed and how much you can sell it for when you’re done with it.
- How long do you plan to keep your car for? If your car’s other components are wearing out, spending a lot of money on the engine might not guarantee much more time on the road. You should also factor your plans into which repair option you choose. A salvaged engine generally won’t have as many miles left as an OEM, remanufactured or rebuilt engine. If you plan to sell the vehicle immediately, a replaced OEM engine will always fetch more money than a rebuilt one, too.
- How much is your car worth? If your vehicle is only worth $3,000 in good condition and it's going to cost $4,000 to replace the engine, you may be better off writing your vehicle off as a loss. However, if your vehicle is worth $30,000 and it's going to cost the same $4,000 to fix, replacing the engine may be a better choice.
Frequently asked questions
- How long is an engine supposed to last?
- There is no set rule for how long an engine is supposed to last. Some engines may last over 400,000 miles with proper maintenance, while some engines may only last 100,000 miles with the same level of maintenance.
- What do you do after replacing the engine?
- Once your engine is replaced, you'll want to take it easy for the first thousand miles or so to break it in. From there on, just keep up with scheduled maintenance, including changing your oil regularly.
- Do extended car warranties cover engines?
- Yes, extended auto warranties generally cover engines. Some specialty warranties may only cover specific systems, like electronics, but most basic vehicle service contracts start with at least powertrain coverage that includes your engine. If you want to be certain, check the terms and conditions of your extended car warranty to determine if the engine is listed as a covered component.
- Does car insurance cover engines?
- No, car insurance won’t cover your engine unless the issues were caused by an accident or another covered event.
- Article sources
- ConsumerAffairs writers primarily rely on government data, industry experts and original research from other reputable publications to inform their work. To learn more about the content on our site, visit our FAQ page.
- National Automobile Dealers Association (NADA), “Will the Engine Break the Bank: How Much Does It Cost to Rebuild an Engine.” Accessed September 14, 2021.
You’re signed up
We’ll start sending you the news you need delivered straight to you. We value your privacy. Unsubscribe easily.