Blown Engine or Bad Transmission? How to Decide Whether to Fix It or Sell It

Maybe the shop just called with a number you didn't want to hear. Maybe the check-engine light has been on since last winter and the car has started making a new noise. Either way, the question is the same: put serious money into this car, or move on?

There's no single right answer. Sometimes fixing it is the smart move, and sometimes it's throwing good money after bad. Here's how to tell the difference.

First, find out what's actually wrong

Symptoms overlap more than most people expect. RepairPal notes that parts like wheel speed sensors or ignition coils can mimic transmission failure, and that a proper diagnosis can turn up a cheaper fix than a full replacement. A code reader tells you which system flagged a problem, not exactly what failed. For a decision this size, get a real diagnosis from a technician and a written estimate, and if the number is big, a second opinion.

Signs of a bad transmission

Transmissions usually give some warning before they quit. Kelley Blue Book, Cars.com, and AAA point to the same common signs:

• Slipping. The engine revs higher, but the car barely picks up speed.
• A delay when you shift. A long pause before Drive or Reverse engages, or the car doesn't move at all.
• Rough, slow, or erratic shifts. Harsh clunks, jerking, or shifting back and forth at a steady speed on a flat road.
• Sticking in one gear, or popping out of gear.
• Whining, humming, or grinding, whether you're driving, backing up, or sitting in neutral.
• A burning smell, which can mean the transmission is overheating.
• Red or brownish fluid where you park. Some coolant is red too, so have the source confirmed.
• A check-engine or transmission warning light.

Two caveats. Cars with a CVT (continuously variable transmission) and some hybrids can rev before the car speeds up, which feels like slipping even when nothing is wrong. And on a manual, slipping or grinding can point to the clutch instead. Kelley Blue Book puts a new clutch at $1,000 to $3,000: real money, but usually a smaller bill than a transmission.

Signs of serious engine damage

"Blown engine" is a catch-all for major internal damage: worn-out bearings, a broken connecting rod, a cracked head or block, or an engine that has seized. An ignored head gasket failure can lead there too. Warning signs include:

• A deep, rhythmic knock that rises and falls with engine speed. A heavy knock from low in the engine can mean bearing wear, which is serious.
• The oil pressure warning light, which means the engine may not be getting the lubrication it needs.
• Thick white smoke that doesn't clear, often with a sweet smell. Thin vapor on a cold morning is normal condensation, but Consumer Reports says billowing white smoke is almost always a sign of serious engine trouble.
• Thick blue or gray smoke, which most likely means the engine is burning oil.
• Milky oil or disappearing coolant. A frothy, chocolate-milk look under the oil cap, coolant that keeps dropping with no visible leak, or a heater that suddenly blows cold are classic head gasket signs.
• Overheating: a temperature gauge in the red, or steam from under the hood.
• Heavy misfiring and a flashing check-engine light, which signals a problem serious enough to damage the catalytic converter or the engine.
• An engine that won't turn over at all, even with a good battery and starter.

Plenty of these have smaller causes, too, like low oil, a bad spark plug or coil, or a stuck thermostat. Don't price out a new engine until a technician has confirmed you need one.

What major repairs cost: national estimates

Here's what the big jobs tend to run, based on figures from Kelley Blue Book and RepairPal. The ranges are wide because the price swings with the vehicle, whether the shop uses a new, rebuilt, remanufactured, or used unit, and local labor rates.

These are national estimates as of October 2026; your quote depends on the car and the shop. RepairPal's averages don't include taxes and fees.

When you get your own estimate, ask whether the part is rebuilt, remanufactured, or used, and what the warranty covers. Kelley Blue Book says a rebuild is usually the least expensive way to fix an engine, while a remanufactured engine costs more and is restored with new internal parts.

Is it worth fixing? A simple way to decide

Start with two numbers: the repair estimate, and what the car would be worth running once it's fixed. Use a realistic trade-in or dealer figure from an online estimator, not the private-party price.

Then apply a common rule of thumb. AAA's director of auto repair puts it this way: if repair costs exceed 50 percent of your car's value, consider a trade-in. It's a rule of thumb, not a rule. A $3,000 repair on a car worth $12,000 is usually easy to justify. The same $3,000 on a car worth $4,000 deserves a hard look.

Before you decide, run through this checklist:

• Rust. New Hampshire road salt is hard on frames, brake lines, and rocker panels. A fresh engine in a rusted-out body is a bad trade.
• Mileage and overall condition. Is the rest of the car solid, or is this the latest in a string of repairs?
• What's due next. Tires, brakes, a timing belt, or suspension work coming due all add to the real cost of keeping it.
• The warranty on the repair. Work backed by a solid warranty is a safer bet.
• Downtime. Can you get to work while the car is in the shop, and what does that cost you?
• Your loan. If you owe more than the car would be worth, read our guide to being upside down on a car loan first.

Here's how the three ways out usually compare:

Fix it, sell it, or scrap it

Fixing is often the right call on a car that's otherwise solid. Kelley Blue Book notes that a rebuilt or remanufactured engine is often more affordable than buying a new vehicle.

If the repair doesn't add up, you don't have to fix the car to sell it. Major mechanical work right before you sell rarely pays for itself, since a dealer can usually do that work for less than you'd pay retail. And before you take a scrap price, make sure the car is actually done.

Why a dealer with a service shop may pay more than scrap

Scrap yards and junk-removal services usually price a car by its weight and the metal in it. A dealer with its own service department may see a car that can go back on the road. FC Motors has a service shop right here on Candia Road, so our technicians can work out what your car needs and what it would take to fix, and we factor that into the offer. For a car with a fixable engine or transmission problem, that can mean an offer above scrap value. It won't always, and if your car really is done, we'll tell you that straight.

See how we buy junk and non-running cars. If your car still runs and drives well, start with our We Buy Cars page instead.

Can you sell or trade in a car that doesn't run?

Yes. A car with a dead engine or a failed transmission can still be sold or traded in. The offer is based on what it would take to put the car back on the road, plus the condition of everything else. Selling one privately is harder, since most private buyers want something they can drive home.

At FC Motors, we buy non-running and high-mileage cars, trucks, and SUVs, including ones with engine or transmission trouble, and there's no obligation to buy a car from us. If you're also shopping for your next car, tell us and we'll walk you through how a trade would work.

What you need to sell a non-running car in New Hampshire

• The title, for model year 2000 and newer. If there's a loan, the lender's lien has to be released before ownership can transfer. When you sell to FC Motors, we pay your lender directly.
• Your registration and a bill of sale, for most 1999 and older vehicles. Most older vehicles are title-exempt in New Hampshire (heavy trucks are the exception), so your registration, current or expired, plus a bill of sale transfers ownership.
• A valid photo ID for everyone named on the title or registration.
• Every key and fob you have, plus your lender's name and a recent payoff quote if you still owe on the car.

Your plates stay with you, so take them off before you hand over the car. For the full rundown, read our guide to selling a car in New Hampshire.

Getting a car that won't drive to the buyer

If the car can't be driven safely, don't push it. Driving on a knocking engine or a slipping transmission can turn a fixable problem into a much bigger one.

Call FC Motors at 603-965-2870 first and ask for Matt. Tell us where the car is and what's wrong with it, and we'll talk through the options for getting it to our lot. It's also worth checking whether your insurance or a roadside assistance plan covers a tow.

How it works at FC Motors

1. Tell us about the car. Use the quick form on our Cash for Junk Cars page or call Matt. The year, make, model, mileage, and what's wrong is plenty to start.
2. Our service shop takes a look. Offers come after an on-site look by our service department, so the number reflects your actual car.
3. Get a no-obligation offer. You don't have to buy a car from us to sell us yours.
4. Get paid. We pay by cash, certified check, or bank funds, and if there's a loan, we pay your lender directly. Most sellers are done and paid the same day once we agree on a price and confirm the title or payoff.

Stop by 1086 Candia Rd in Manchester (Mon-Fri 9-5, Sat 10-4), call Matt at 603-965-2870, or email sales@fcmotorsllc.com.

Frequently asked questions