Head gasket replacement in the UK typically costs £900–£2,500 depending on engine. On older cars worth less than £2,500, it's usually not worth fixing. K-series Rover engines, BMW N47 diesels and PSA 1.6 HDi engines are notorious for head gasket failure and often uneconomic to repair.
Head gasket failure is the diagnosis nobody wants. Here's how to decide whether to fix or scrap.
What it costs
Inline 4-cylinder (most cars): £900–£1,800 fitted at an independent. V6/V8 or DOHC: £1,500–£2,500+. If the head is also cracked, add £400–£800 for skim and pressure test, or £700+ for a replacement head.
What's included
Head off, gasket replaced, head pressure-tested and skimmed (small distortion), new head bolts (always — they're torque-to-yield), coolant flush, oil + filter, possibly cambelt if disturbed.
When to scrap instead
If the car is worth less than £2,500, the maths usually doesn't work. Unless it's a low-mileage example or sentimental, sell as spares-or-repair on eBay (£300–£700 typical for a runner with HG fail) and buy something else.
How to confirm before paying
Block test (£20–£40) detects exhaust gases in coolant. Compression test confirms cylinder seal. Mayonnaise under the oil cap or white smoke from exhaust = strong indicators but not conclusive on their own.
Beyond the gasket, what other parts often need replacing with a blown head gasket and how does that affect the overall cost? — A blown head gasket rarely comes alone. You're almost certainly looking at new head bolts, engine oil, coolant, and an oil filter. Often, the cylinder head itself will need skimming or even replacing if warped, and sometimes the thermostat and water pump are replaced as preventative measures whilst everything's apart. These extra parts can easily add £150-£500 to the bill, pushing the total towards the higher end of the £800-£2000 bracket, depending on your car.
Can I drive my car with a blown head gasket to a garage, or will I cause more damage? — Honestly, it's a huge risk. Driving with a blown head gasket can quickly lead to catastrophic engine damage. Coolant mixing with oil destroys lubrication, and overheating can warp the cylinder head beyond repair, or even seize the engine entirely. If you suspect a blown gasket, the safest and often most cost-effective option in the long run is to arrange recovery. The cost of a tow is usually far less than a new engine.
Will a blown head gasket cause my car to fail its MOT, and what should I check for before taking it in? — Absolutely, yes. A blown head gasket will almost certainly cause an MOT failure. Common failure points include excessive exhaust smoke (blue or white), oil leaks, coolant leaks, and engine warning lights. Before your MOT, check your oil for a 'milky' consistency, look for oil in your coolant reservoir, and observe your exhaust for unusual smoke. These are tell-tale signs of a failing head gasket and will need addressing before your car stands any chance of passing.
Will K-Seal or BlueDevil actually fix a blown head gasket? — Sometimes — for very small leaks. Most workshop mechanics see them as a temporary patch to limp a car to scrap. Don't bet long-term reliability on it.
Why is the head gasket so expensive to replace? — It's 6–12 hours of skilled labour to strip the top of the engine, plus the head almost always needs machining.