MajorCommonCooling

Mitsubishi Lancer: 4G63T Water Pump Impeller Erosion and Bearing Failure (Evo VII–IX)

4G63T Water Pump Impeller Erosion and Bearing Failure (Evo VII–IX) is a common cooling fault on the Mitsubishi Lancer on the 2001–2007 cars, and we rate it major. Putting it right costs $400 to $950 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: 4G63-T
Years: 2001–2007
Fuel: petrol
Gearbox: manual
System: Cooling

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 Water pump yet. We would rather show none than show a picture of a different part.

What goes wrong

The OEM water pump on the 4G63T uses a plastic impeller that is susceptible to electrochemical erosion (cavitation pitting) when the coolant is not maintained with the correct inhibitor mix. Corroded impellers lose pumping efficiency, causing the engine to run progressively hotter under load. The pump bearing also fails at high mileage, sometimes causing the impeller to make contact with the pump housing. Many NZ imports have been run on plain water or incorrect coolant concentrations, accelerating this failure. Overheating from a failed water pump on a 4G63T can cause head gasket failure.

What you would notice

Engine temperature creeping above midpoint under sustained load
Coolant system losing pressure or needing top-up
Rumbling or grinding from front of engine varying with RPM
Coolant weep from water pump housing
Overheating under track or hard driving conditions

How to check it

Where to look. Front of engine block, driven off timing belt on passenger's side

Check coolant colour and inhibitor concentration — should be correct OEM Super Long Life Coolant mix, not plain water or wrong type. Squeeze coolant hoses to feel for loss of pressure or aeration. With engine warm, check temperature gauge behaviour under load. Inspect pump pulley for bearing play. Consider replacing proactively if service history is unknown — aluminium impeller aftermarket upgrades are available.

Parts involved: Water pump.

What it costs to put right

$400 to $950 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

“When was the coolant last changed and to what specification?”
“Has the temperature gauge ever risen above normal, particularly under hard driving?”
“Has the water pump ever been replaced?”

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 4g63t water pump impeller erosion and bearing failure (evo vii–ix) serious on a Mitsubishi Lancer?

We rate it major and common on the Mitsubishi Lancer. The OEM water pump on the 4G63T uses a plastic impeller that is susceptible to electrochemical erosion (cavitation pitting) when the coolant is not maintained with the correct inhibitor mix. Corroded impellers lose pumping efficiency, causing the engine to run progressively hotter under load. The pump bearing also fails at high mileage, sometimes causing the impeller to make contact with the pump housing. Many NZ imports have been run on plain water or incorrect coolant concentrations, accelerating this failure. Overheating from a failed water pump on a 4G63T can cause head gasket failure.

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

$400 to $950 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 2001–2007 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.