MajorCommonFluid Leaks

Mitsubishi Lancer: 4B11T Oil Cooler Adapter O-Ring Seal Leak (Evo X)

4B11T Oil Cooler Adapter O-Ring Seal Leak (Evo X) is a common fluid leaks fault on the Mitsubishi Lancer on the 2007–2016 cars, and we rate it major. Putting it right costs $280 to $700 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 39 documented faults on the Mitsubishi Lancer.

Vehicle: Mitsubishi Lancer
Only on: Evolution
Engine: 4B11-T
Years: 2007–2016
Fuel: petrol
Gearbox: manual
System: Fluid Leaks

This page covers the Mitsubishi Lancer as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Mitsubishi Lancer faults39 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Exhaust manifold yet. We would rather show none than show a picture of a different part.

What goes wrong

The 4B11T engine in the Lancer Evolution X has a documented oil cooler adapter O-ring failure that is the subject of a Mitsubishi technical service bulletin. The adapter, which connects the oil cooler to the block, uses O-ring seals that harden and crack with heat cycling. The resulting oil leak drips onto the exhaust manifold, creating a burning oil smell and fire risk if the leak is significant. Mitsubishi revised the O-ring material and issued a TSB covering the repair. Many NZ Evo X examples have not had this TSB applied.

What you would notice

Burning oil smell from engine bay, particularly after hard driving
Visible oily residue on exhaust manifold or heat shield
Oil level dropping between service intervals with no other identified leak
Smoke from engine bay at operating temperature
Oil staining on underside of engine forward of sump

How to check it

Where to look. Oil cooler adapter on driver's side of engine block, adjacent to exhaust manifold

With engine warm, inspect the oil cooler adapter where it bolts to the block on the exhaust side of the engine.
Look for oily residue or fresh seepage around the adapter flange.
Check for staining on the exhaust manifold heat shield below the adapter.
Confirm whether the Mitsubishi TSB has been applied — dealer service records will show if this was carried out.

Parts involved: Exhaust manifold.

What it costs to put right

$280 to $700 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the oil cooler adapter O-ring TSB been carried out at a Mitsubishi dealer?”
“Has there ever been a burning oil smell from the engine bay?”
“Has the oil level been dropping between services?”

Now check the Mitsubishi Lancer you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Mitsubishi Lancer buyer questions

Is 4b11t oil cooler adapter o-ring seal leak (evo x) serious on a Mitsubishi Lancer?

We rate it major and common on the Mitsubishi Lancer. The 4B11T engine in the Lancer Evolution X has a documented oil cooler adapter O-ring failure that is the subject of a Mitsubishi technical service bulletin. The adapter, which connects the oil cooler to the block, uses O-ring seals that harden and crack with heat cycling. The resulting oil leak drips onto the exhaust manifold, creating a burning oil smell and fire risk if the leak is significant. Mitsubishi revised the O-ring material and issued a TSB covering the repair. Many NZ Evo X examples have not had this TSB applied.

How much does it cost to fix on a Mitsubishi Lancer?

$280 to $700 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Mitsubishi Lancer years are affected?

Our research records this fault on the 2007–2016 Mitsubishi Lancer. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

With engine warm, inspect the oil cooler adapter where it bolts to the block on the exhaust side of the engine. Look for oily residue or fresh seepage around the adapter flange. Check for staining on the exhaust manifold heat shield below the adapter. Confirm whether the Mitsubishi TSB has been applied — dealer service records will show if this was carried out. Look here: Oil cooler adapter on driver's side of engine block, adjacent to exhaust manifold