A damaged or faulty engine can cause various issues for your daily driver. If it’s beyond repair, the next best solution is to replace it, but don’t expect to be rid of all problems once you have a new engine under the hood. Some issues can crop up after replacement.

Common Problems After Replacing the Engine

Some common issues you might encounter after replacing the engine include fluid leaks, electrical issues, strange noises, and performance trouble. A couple of these problems arise because of faulty or improperly installed components.

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: The smart thing to do is to take your time and make sure you install every component right. If the engine you’re installing is a used engine, go ahead and replace the rear crankshaft seal and pull the valve cover to see if the engine is badly sludged up. And on a used engine, if it has a timing belt, go ahead and replace the timing belt while you’re at it, and the water pump and thermostat as well.

Fluid Leaks

If there’s a damaged gasket, you might encounter oil leaks after the replacement. Some symptoms to watch out for include oil spots under the car, a lingering burning oil smell, and excessive smoke coming out of the exhaust pipe.

If the vehicle is equipped with an automatic transmission and the torque converter’s weight is resting on the front pump seal (where you can’t see it), you may have a badly leaking torque converter seal when you’re done even if there was no leak prior to removing the engine. It’s best to replace the transmission pump seal while you have the engine out to prevent a transmission leak you didn’t have before.

Oil leaks can accelerate engine wear and tear because there won’t be enough lubricant to reduce the friction between parts. Leaks can also cause issues in the radiator, air conditioner, rubber hoses, and seals, so it’s best to resolve them.

It’s also worth checking the coolant, transmission fluid, and power steering fluid to see if there are any leaks when the engine has been replaced. Any leaks need to be dealt with before you call the job finished, whether you caused the leaks or not.

It’s always a good idea to replace the heater hoses and the radiator hoses when you replace the engine, not to mention replacing the oil cooler (if it has one) because of metal from the previous engine that might still be in the oil cooler. If the cooling system had a lot of rust in it, replacing the radiator and flushing the heater core is a good idea.

Electrical Issues

Replacing the engine involves disconnecting and re-connecting the wiring harnesses, ground connections at the block, positive connections at the starter and alternator, etc. Any mistake in the process could lead to electrical issues, such as a no-start or no-crank condition, blown fuses and malfunctioning components.

Pay close attention to wire harness routing and make sure none of the wires are chafing against sharp edges, near or on the exhaust manifold or in danger of being sliced by the fan belt or pulleys.

It’s always a good idea to replace the heater hoses and the radiator hoses when you replace the engine, not to mention replacing the oil cooler (if it has one) because of metal from the previous engine that might still be in the oil cooler.
–Richard McCuistian, ASE Certified Master Automobile Technician

Weird Noises

You know what your engine sounds like when you’re starting or driving your car. If you hear anything unusual, like engine knocks or a whistling sound after engine replacement, don’t ignore them. Some GM vehicles require the starter to be properly shimmed before it will work and sound right. Listen for belt noise or or bad bearing noises from the pulleys and components driven by the belt.

Illuminated Check Engine Light

The check engine light illuminates to indicate emissions and fuel injection issues but it won’t always illuminate even if there’s something you overlooked, so don’t depend so heavily on this light to flag any and every issue. If you notice that it turned on after installing a new engine, it might be pointing to problems with the engine or its related parts.

Rough Running

Expect the engine to idle smoothly about 750 rpm to accelerate smoothly and maintain speeds without surging, skipping, or detonation/labor knock.

Lack of Power

If something went wrong with the replacement, the engine might not perform as well as it should.

Various issues can cause it. For example, dirty fuel and air filters can result in the engine not getting enough fuel or air. This leads to loss of power, causing the vehicle to shake, stall, stutter, or struggle to climb uphill.

How to Prevent Problems After Engine Replacement

engine replacement inspection — To prevent the problems listed above, make sure to break the engine in, ensure engine compatibility, follow your maintenance schedule, and monitor engine performance and fluid levels.

To prevent the problems listed above, make sure to break the engine in, ensure engine compatibility, follow your maintenance schedule, and monitor engine performance and fluid levels.

Break the Engine In

Breaking a new engine in is essentially conditioning it before driving long distances. It also allows the piston rings to sit correctly on the cylinder wall to prevent uneven part wear, increasing the engine’s longevity.

The break-in period is within the first 1000 miles, but different car makers have varying distances.

Breaking the engine in involves using the car sporadically at lower speeds and RPM. Experts recommended a maximum of 3,500 rpm and 90 mph.

Ensure Engine Compatibility

Make sure the replacement engine is compatible with the other components within your vehicle. Incompatibility can cause some parts to fail or get damaged.

Your owner’s manual has detailed information about your engine’s specifications. You can use those details to ensure you buy a compatible engine.

Pro Tip: The vendor who is selling you the engine can, with your vehicle’s information (VIN, etc), look up which engines are compatible with your vehicle.

Professional mechanics know what to look for in replacement engines to ensure compatibility. So, if you leave the task to them, rest assured that they’ll get a new engine that fits your ride.

Follow the Maintenance Schedule

Your owner’s manual details your ride’s optimal maintenance schedule, and it pays to commit to it.

Routine inspections can help you catch potential problems early, preventing breakdowns or accidents caused by malfunctioning or worn-out components. In short, if you’re on top of your maintenance schedule, there’s less chance of issues arising after engine replacement.

Monitor Engine Performance

Keeping track of your engine’s performance should also be a priority because it lets you determine if the engine and other related components are working optimally. It’s also a great way to nip issues in the bud.

In other words, pay attention to anything that doesn’t feel right about the way the engine sounds and performs and don’t put off having it checked if you feel or hear something that might be a problem.

Check Fluid Levels

Make sure you check your car’s fluids regularly. This includes the oil, coolant, transmission fluid (if your vehicle has a transmission dipstick; many late model vehicles don’t), and brake fluid. As mentioned, leaks may damage the engine and often stem from components that are worn out or not installed properly.

Parts to Check After Installing a New Engine

checking car engine and parts under the hood — Many of the issues that happen after engine replacement stem from faulty parts.

Many of the issues that happen after engine replacement stem from faulty parts. So a good way to prevent them altogether is to examine the parts for signs of wear, tear, and damage during or after the installation process.

Here are some of the parts you should check:

Besides checking for wear and damage, double-check each part’s placement as well. Problems can crop up if a component is displaced or not installed correctly.

How Much Does It Cost to Replace the Engine?

It costs around $4,000 to replace a four-cylinder engine and $10,000 for high-performance ones. The total bill depends on the type of vehicle you’re driving and whether you’re looking for a new or used engine.

How Often Should I Replace the Engine?

Changing the engine depends on its condition. Manufacturers design vehicles to last up to 200,000 miles. Some can handle that much mileage, while others break down sooner. The general rule is: “If it ain’t broke, don’t fix it.”

Where to Get High-Quality Engine Parts for Your Vehicle

Some problems might arise after replacing the engine, but they’re typically easy to solve. Serious issues can develop, however, if you opt for engine or engine parts with low-quality pieces. Lucky for you, CarParts.com can keep you from that pitfall.

We have a wide range of replacement engine parts tailored specifically for your ride. Enter your car’s year, make, and model into our vehicle selector to browse for compatible products. Then, use our search filters to view the parts that match your preferred brand, price, features, and specs.

All our engine parts come with a low-price and lifetime replacement guarantee, helping you get the best value for your money. Order now, and we’ll deliver what you need straight to your doorstep in as fast as two business days.

Shop now, and don’t miss out on the best deals on the market!

About The Authors

Reviewed By

Richard McCuistian

Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Written By

CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.