The 4 Most Common Mitsubishi 4G63 Engine Problems

The 4G63T is most well known for powering the first nine generations of the Lancer Evo. Additionally, it powered the DSM Eclipse, Eagle Talon, and Plymouth Laser, all of which are popular for high performance builds. The 4G63, and T versions, are extremely reliable when left completely stock. But people tend to modify them which can lead to a number of problems including balance shaft bearing and belt failure, lifter issues, crankwalk, and head gasket failure.

We’re going to discuss each of these problems in depth and talk about overall engine power limits, to make you aware of what power levels will cause you to start running into these 4G63 problems.

Mitsubishi 4G63 Engine Problems

• Balance shaft belt & bearings
• Lifters
• Crankwalk
• Head gasket failure & lifting heads
• Power Limits

The majority of these problems are going to be specific to the 4G63T engine. While the 4G63 does experience some of the same problems the majority of these problems occur on modified engines and not stock engines. So while they are still relevant they are simply not as common given the non-turbo engine doesn’t tend to be as heavily modified as the turbocharged versions.

If you would rather consume this content via a video, check out our Mitsubishi 4G63 Common Problems video below:

1) Balance Shaft Bearing & Belt Failure

The 4G63 uses a belt-driven balance shaft. The system uses two shafts with weights on it which spin in opposite directions at twice the speed of the engine. Without getting into the technical details, the force produced by the rotating balance shafts counteracts and reduces engine vibration.

Balance shafts use bearings to help with rotation and prevent friction. The balance shaft bearings on the 4G63 do fail commonly which results in improper rotation and added vibration. When the bearings fail they commonly take out the balance shaft belt with them.

The 4G63 balance shaft timing belt is driven off of the crankshaft and controls the rotation of the shafts. The stock belt is pretty weak leaving a lot of owners upgrading to stronger kevlar belts. However, the strength of the belt isn’t the problem. The problem is the excess vibration created from bad bearings causes the belts to snap. Kevlar belts will snap too from bad bearings, and since they are tighter and stronger they will snap with even more force.

When the balance shaft belt snaps it takes out the timing belt with it. This throws engine timing off and causes the valves to collide with the pistons. In a worst case scenario the valves collide and crack the pistons, which then score the cylinders, send metal shavings into the oil pan and crack the crankshaft. In this scenario a brand new engine is needed. Best case scenario the valves just bend but cause no other damage and only the valves need to be replaced.

Balance Shaft Bearing & Belt Failure Symptoms

• Increased engine vibration
• Ticking noise coming from rear of engine
• Rough idling
• Poor overall running

Balance Shaft Delete

Since the bearings fail frequently and leave the belts prone to snapping, deleting the balance shaft is a common form of preventative maintenance. With the balance shaft deleted the balance shaft timing belt can be deleted as well which will prevent it from breaking and taking out the timing belt too.

2) Lifter Failure

The 4G63 engines naturally received somewhat poor oiling. The oil pressure in the head runs low which causes the lifters to be starved of oil. This causes the dreaded lifter tick which can over time develop into lifer failure.

A common “fix” for the 4G63 is to run 3G lifters. However, since the issue is oiling related it is only a matter of time before the 3G lifters begin to tick as well. The only tried and true solution here is to port the oil galleys in the head to improve oil pressure and flow to the lifters. However, porting the oil galleys is a bit aggressive unless your engine is already opened up and being rebuilt. For the most part owners will just drive around with the annoying lifter tick until the lifters need to be replaced or the engine is being rebuilt.

Lifter Tick Symptoms

• Ticking noise from engine
• Rough idling
• Cylinder misfires

3) Crankwalk Problems

The 4G63 engine came in both a 6-bolt and 7-bolt versions. This represents the number of bolts that connect the flywheel to the crankshaft. The main bearings on the 7-bolt engines have narrower journals which makes them weaker than the 6-bolt versions and less desirable for performance builds.

4G63 crankwalk problems only tend to occur on the 7-bolt engines. It happens when the thrust bearings on the crank wear down which allows the crankshaft to move, or “walk”. When this happens the crank wobbles around as it spins which throws the internals off. Additionally, the crank can move enough that it crushes the crank angle sensor which causes the engine to shut off and have difficulty starting.

Crankwalk Symptoms

• Difficulty shifting
• Sticky clutch on left hand turns
• Inconsistent clutch engagement
• RPM drops while clutch is pressed down
• Ticking noise from timing belt area

While crankwalk is more common on the 7-bolt engines it can also happen on the 6-bolts as well. It is suspected that about 5% of the 7-bolt engine will develop crankwalk. It is also worth mentioning that developing crankwalk is more common in high horsepower engines that are running upgraded clutches with with high pedal pressures.

4) Lifting Heads & Gasket Problems

Predominately affecting modded 4G63T engines is head lift and associated head gasket failure. The issue is the head bolts are very short, not even reaching half an inch down from the deck. Therefore, the head itself isn’t very tightly sealed to the block.

Head lift is caused by one of two things. First, the head bolts can stretch which leads to lifting. Secondly, the pressure put on the cylinder head pockets causes the head to lift and the washers to sink into the cylinder head.

The solution here is to run ARP head studs and oversized washers by ARP. Oversized washers or shoulder dowels will require the head to be machined, so it is common for owners to just run the ARP studs for the time being.

Lifted Head Symptoms

• Oil leaks from the head
• White smoke out the exhaust
• Loss of cylinder compression
• Coolant loss and milky white substance in reservoir
• Poor performance, misfires, etc.

5) 4G63T Power Limits

If you want to surpass the 400whp mark you should start with a 6-bolt engine instead of a 7-bolt. With forged rods and pistons, the 6-bolt 4G63T engines are good until around the 500whp mark. The head bolts are very weak and will cause heads to lift around 325-350whp. With ARP studs the head and gasket are good until around the 500whp mark until the head needs to be further secured. The crankshaft is quite strong and usually doesn’t get maxed out, although cracked cranks is pretty common on the later model evo’s.

Lastly, the block. The 6-bolt block is very strong and is capable of handling 700+whp, however, this will require some improvements. The block is strong and the sleeves are good, but the mains and cast iron girdle are weak points. With respect to the block however, proper tuning is the key. Torque tends to be the killer of the lower end of the block, and not necessarily horsepower. Properly tuning your engine can go a long way in block (and internal) reliability when modded. Without modifications the 6-bolt can handle around 600awhp, but anything above 500 is considered to be pushing the limits. The 7-bolt is good for about 500-550whp.

Overall Mitsubishi 4G63 Reliability

Completely stock, the 4G63 is a really strong engine and is capable of making it past the 250,000 mile mark. With forged internals and a strong block, the major engine components themselves are unlikely to ever show you any problems. Lifter problems and bearing shaft failure can still occur on stock engines, but crankwalk and lifting heads are almost exclusive to modified 4G63 engines.

When modded, the 4G63 is considered to be reliable up to around the 450whp mark. 6-bolt engines are a bit more reliable and power capable than the later 7-bolt engines. Cracked cranks, crankwalk, lifted heads, broken rods, low end block problems, etc. all become common problems once you take your 4G63 beyond the 500whp mark.

Overall, these engines are very stout and can produce crazy 1000whp+ levels when fully built. When completely stock and when fully built they are extremely reliable. In between they will require some upgrades and improvements when tuned. The 4G63 remains popular today due to it’s power limits and increased strength, especially compared to its 4B11T successor which tends to have block problems once torque gets close to 400wtq.