My introduction to the turbocharger was my father’s 80’s SAAB turbo, back then a turbocharged car was exciting, a little unpredictable, and fragile. Most modern cars use turbochargers to aid fuel economy, while they are less exciting than the old SAAB they are a lot more reliable. I’ve been a mechanic for over twenty years and I’ve replaced a ton of turbos.
Replacing a turbocharger can be challenging. Modern car engine bays are compact and many turbo units are fitted in confined spaces where tool use is difficult. Some vehicle manufacturers recommend engine removal to replace a turbocharger.
In this post, you’ll learn which engine configurations are easier to replace a turbocharger and what the general process looks like. You’ll also learn some very important turbo-fitting tips.
Turbos Location Affects Replacement Difficulty
Where your turbo is fitted on your engine will make a big difference to how difficult it is to replace. Modern cars are very compact under the hood. In an effort to make vehicles more fuel-efficient, cars are lighter and engine bay space is reduced. That’s bad news for the humble mechanic, if you’re troubleshooting a turbo charger or replacing it, it means you’ll need patience and tenacity and a few long reach tools, especially if your vehicle has a large engine.
I worked for Chevrolet for a number of years and while the smaller compact cars were great to work on, some of the larger engine mid-size models were challenging.
Many require engine removal to make repairs, as there simply isn’t enough space to manipulate hand tools. To be fair engine removal is relatively simple, most modern cars use a subframe set up, meaning the engine is bolted to a subframe and the subframe is then mated to the vehicle body.
Engines are configured in one of two ways, transverse or longitudinal. Transverse is the standard layout for front-wheel-drive cars (FWD). It simply means the engine is mated to the transmission and is mounted to a subframe and fitted sideways between the front wheels, usually.
Some manufacturers use a transverse setup, but the engine and transmission are located in the rear of the car, making it a rear-wheel-drive (RWD) transverse setup.
The transmission in this type of configuration may also be called the transaxle (transmission + axle) as it also houses the differential. This type of configuration is by far the more common type of engine layout as most smaller cars today are front-wheel drive (also used in AWD cars).
In transverse type engine setups, the turbo is either fitted out front of the engine (between the radiator and engine) or to the rear of the engine (between engine and firewall). Generally, when they are fitted out front, they are a little easier to work on, I say generally because no matter where your turbo is fitted, space will be tight.
The second type of engine layout could be described as the more traditional rear-wheel drive (RWD) layout, and it’s known as longitudinal engine layout. It’s where the engine is fitted to the front of the vehicle lengthways with the transmission to the rear.
Some Audi models use a longitudinal engine layout but are actually front-wheel drive (Germans like to be different!)
The transverse layout is common in trucks but is becoming much less common in cars. Rear-wheel drive (RWD) is more complex, expensive, and is a disadvantage in terms of cabin space. However, higher-end luxury brands still use the RWD configuration, it’s more comfortable and offers a superior driving experience.
In the longitudinal setup, the turbocharger is generally easier to work on, we won’t call space generous but in a longitudinal, the turbo is at least on view.
Tools That Make Turbo Replacement Easier
Attempting this in the driveway is possible for most models. A vehicle hoist would obviously make life a lot easier, without it you can expect to spend a ton of time on your back.
Here’s a list of tools that make life easier, note I haven’t listed all the regular wrenches and screwdrivers, etc.
- Hose clamp remover
- Axle stands
- Swivel sockets
- Extra long extensions
- Ratcheting wrenches
- LED lamp
- Oil line clamps
Check out my favorite tools on the Mechanics tools page.
How To Replace A Turbocharger
The best place to start is at the computer, buy a manual, read it, and know the process before turning a wrench. Modern cars are as said compact, and you’ll likely need to remove several components in order to remove the turbo. Removing components that don’t need to be removed is frustrating.
The usual seals include exhaust gaskets, turbo oil line banjo bolt copper washers, and coolant gaskets. Make a list of gaskets and seals that need to be replaced and have them ahead of time.
You’ll need fresh coolant for top-up or go ahead and replace it if older than three years old. You’ll need to change the oil and filter, clean the air box and fit a new air filter. A fresh air filter is especially important to the health of a turbo.
Have a clear idea of what needs to be removed and in what order. Have a container for small fasteners, but keep fasteners with their relevant components, and set components aside in the order of removal. This process helps speed up reassembly.
A can of WD40 will be useful, spray heat shield fasteners and let sit.
To replace a typical turbo you’ll first need to remove:
- Remove all air intake ducting
- Remove turbo heat shields – With the covers off you’ll get a better view of exhaust clamp, oil and coolant lines.
- Remove boost sensor wiring
- Mark and remove actuator vacuum lines/wiring plug
- Remove and clamp off coolant lines (not all turbos are water cooled)
- Remove oil lines and clamp off
- Remove turbo assembly stabilizer supports
- Remove exhaust to turbo fasteners
At this point the turbo is free of the engine, removal often resembles a bit of a puzzle, twisting and turning until eventually it’s set free. It’s not uncommon for the headers/manifold to come off with the turbo. You may as said earlier need to remove other components to make way for the turbo assembly.
Tips for fitting the new turbo:
- Clean all exhaust mating surfaces
- Keep blanking caps on new turbo until turbo in place
- Replace exhaust gaskets
- Torque exhaust to spec – overtightening can lead to broken header/manifold bolts as heat expands the metal later
- Fill turbo oil port with fresh oil before attaching oil line
- Fit new oil feed line and gaskets
- Check oil drain line and replace if damaged
- Fit new coolant line gaskets if applicable
- Fit all heat shields, they are important
- Check intake ducting and intercooler for debris
- Check vacuum hoses and wiring connectors damage
- Spin turbo shaft by hand before fitting intake ducting
- Replace oil and filter
- Clean air box thoroughly and replace air filter
If your turbo is water-cooled, you’ll need to top up the coolant and bleed the air from the system. When starting the car for the first time, avoid revving the engine until oil pressure builds and oil reaches the turbocharger.
Loose or damaged boost hoses are a common cause of poor turbo performance, so too are damaged actuator vacuum hoses. Finally, check their condition and that they’re fastened securely.
Check for oil or coolant leaks around the turbo before calling it good, nice work you!
Check out all my favorite tools on the Mechanics tools page.