4M40T head cracked? Repair the head or replace the engine in your Triton or Pajero
Repair, rebuild or replace?
When the overheating was caught early, compression is good, the oil is clean, and the rest of the vehicle is worth keeping.
What a 4M40T replacement costs
Mitsubishi 4M40T long bare engine: long bare Was AUD 6,500, now AUD 5,250
Read the full guide and supporting detail
Price as listed on our store on 15 October 2026.
Why do 4M40T heads crack?
The 4M40T is the 2.8 litre turbo diesel in the 1990s and early 2000s Pajero and the Triton. Owners most often report the head cracking after the engine has run hot. That evidence comes from owner forums rather than Mitsubishi documents, so treat it as a strong pattern, not a confirmed design fault.
Overheating is the usual cause of head and gasket failure on any engine: low coolant from a leak, a stuck thermostat, a failed fan, or blocked coolant passages.
Don't confuse it with the timing chain problem on later Pajeros. That was the 3.2 litre 4M41.
How do you know the head is cracked?
Signs owners describe: coolant loss, overheating, and bubbles in the overflow bottle. A crack inside a port may not show on a pressure test, so ask for a combustion gas (block) test as well, and bear in mind a negative block test is not the final word either.
What should the mechanic check before you decide?
Ask for these, in writing:
- Compression on every cylinder. Even readings mean a healthy bottom end.
- The oil. Milky oil means coolant has got in, which can damage bearings.
- How hot it got, and for how long. A short spike is different from driving on with the gauge pegged.
- What caused it. Radiator, fan, hoses, water pump, thermostat, or a fuel or turbo problem running it hot.
When does a head repair make sense?
When the overheating was caught early, compression is good, the oil is clean, and the rest of the vehicle is worth keeping.
When is a new engine the better buy?
When any of these is true:
- compression is low or uneven;
- there is coolant in the oil, or the bearings are damaged;
- the engine was driven on while overheating;
- the head repair, gasket set, machining and labour come close to a fitted new long motor.
What about rebuilding your own engine?
If the block and crank are serviceable, we can strip, inspect and quote a fixed price to rebuild it. If it isn't serviceable, there is a teardown fee for the labour.
What has to be fixed either way?
The cause of the overheating. A new head or a new engine will crack the same way if the cooling system is still faulty. Damage from overheating is not covered by the engine warranty. See fitting a new engine.
Ask us about your 4M40T
Use the enquiry form with the Pajero or Triton's year, series, rego and VIN, and the test results. Or call 02 9737 0105. See the 4M40T engine page.
