Smoke test for boost and vacuum leaks
A split hose or leaking intercooler can rob a turbo engine of power and trigger limp mode, yet it's often impossible to spot by eye. Our mobile smoke test fills the intake system with visible smoke so the leak shows itself, for £120 + VAT.
- £120 + VAT
- Finds boost, intake and vacuum leaks
- Carried out at your home or workplace
- Petrol and diesel cars and vans
Boost leak symptoms
A boost leak means air the turbo has worked to compress escapes before it reaches the engine. These are the signs that usually bring people to us.
- Loss of power, mainly under load or uphill
- A whistle, hiss or whoosh as the turbo spools up
- Limp mode, often with P0299 underboost stored
- Black smoke on a diesel, because there's too little air for the fuel
- Fuel consumption creeping up
- A lumpy or hunting idle, common with vacuum leaks on petrol engines
How a smoke test works
We seal off the intake and pump in a harmless vapour at low pressure. The smoke follows the same path as the boost air, through the hoses, intercooler and intake, and wherever there's a gap it escapes.
That pinpoints the exact hose, joint, clamp or seal that's leaking. You see it for yourself, which makes it easy to get the right part fixed first time.
Leaks a smoke test commonly finds
Split boost hoses
Rubber and silicone hoses perish and split with age, often at the bends where they flex most.
Intercooler leaks
Cracked plastic end tanks and stone damage to the intercooler let boost escape at the front of the car.
Loose or failed clamps
A clamp that has slipped can let a hose blow off entirely under boost.
Intake gaskets and seals
Perished gaskets around the intake let unmetered air in and upset the fuelling.
Vacuum lines
Small vacuum pipes for the brake servo, turbo actuator and EGR crack with age and heat.
Breather hoses
A split crankcase breather hose upsets the idle and can bring on lean running fault codes.
What a boost leak repair costs
Once the leak is found, the repair is often cheap, as a hose or clamp costs far less than the turbo or sensors some owners replace first. An intercooler or intake part costs more, depending on the vehicle.
We'll show you where the leak is and explain the repair before you decide what to do next.
Booking a mobile smoke test
Get in touch
Book online or call with the registration, the symptoms and any fault codes you already have.
We set up where it's parked
The technician connects the smoke machine to the intake at your home or workplace.
The leak shows itself
Smoke escapes from the split, crack or loose joint, and we trace exactly where.
You see the results
We show you where the smoke came out and what needs replacing to stop the leak.
Boost leaks on diesel vans
Diesel vans that tow or carry heavy loads put their boost system under constant pressure, and hoses and intercooler joints take the strain. A small leak that's barely noticeable when empty can turn into limp mode on a loaded motorway climb.
Fleet operators can book smoke tests at the yard or depot, so vans are checked between jobs.
What our customers say
Is this the same as the MOT smoke test?
No. The MOT emissions test measures smoke coming out of the exhaust. Our smoke test pushes smoke into the intake to find leaks, and it has nothing to do with the MOT.
How much does a smoke test cost?
A mobile smoke test is £120 + VAT, carried out at your home or workplace.
Can a boost leak damage my turbo?
A large leak makes the turbo spin harder to reach the boost the ECU asks for, which adds wear over time. Finding it early costs a lot less than a turbo.
What causes boost leaks on a diesel?
Heat, age and oil mist from the turbo soften hoses until they split, and clamps loosen with vibration. Intercoolers also crack or get damaged by stones at the front of the vehicle.
Do you smoke test petrol cars as well as diesels?
Yes. Petrol engines are more prone to vacuum leaks, which cause lean running and a rough idle, and the test finds those too.
Should I book a diagnostic or a smoke test?
If you have an underboost code or the symptoms above, start with a smoke test. If you're not sure what's wrong, a mobile diagnostic check (£100 + VAT) narrows it down first. You can also look up your code in our fault code library.
Find your boost leak
Book a smoke test for £120 + VAT and we'll trace the leak where your car or van is parked. It's the quickest way to see what's costing you power.
Send your fault codes to sales@sgrautomotive.co.uk
Eccles, Manchester M30 0SF