The Top Four Mitsubishi 4G63 Motor Issues. Mitsubishi’s 4G63 engine, a 2.0L normally aspirated inline-4, was introduced in 1980. The 4G63T, a turbocharged version of the original 4G63, which was released in 1988 in the Mitsubishi Galant VR4, is more common today.
The 4G63T is best known for powering the Lancer Evo’s first nine versions. It also powered the DSM Eclipse, Eagle Talon, and Plymouth Laser, all of which are still highly modified vehicles today.
Although 4G63 engines are still manufactured around the world, they were phased out of manufacturing in the United States around 2008. The engine underwent multiple revisions throughout its life. The most notable additions were a dual overhead cam variant, a switch from 6-bolt to 7-bolt heads in May 1992, and MIVEC variable valve timing for the Evo 9. In the Evo X, the 4G63 was ultimately replaced by the 4B11T.
The cast iron engine, aluminum heads, and forged crankshaft and connecting rods of the 4G63T. While the engine is extremely reliable when stock, a number of 4G63 issues emerge when power is applied to it.
4G63 & 4G63T Motor Issues
When modded, the following are some of the most prevalent 4G63 & 4G63T engine issues:
- Bearings and the balance shaft cord
- Failure of the head gasket and raising of the heads
The bulk of these issues will be unique to the 4G63T engine. While the 4G63 has some of the same issues, the majority of these issues arise on modified engines rather than stock engines. While they are still relevant, they are not as prevalent because the 4G63 engine is not as extensively modified as the turbocharged versions.
1) Breakdown of the 4G63 Balance Shaft Bearing and Belt
The balance shaft on the 4G63 is powered by a belt. The system employs two shafts with weights on them that spin in opposing directions at twice the engine’s speed. Without going into technical details, the rotating balance shafts create a force that counteracts and reduces engine vibration.
Bearings are used in balance shafts to aid rotation and avoid friction. The balance shaft bearings on the 4G63 frequently fail, resulting in incorrect rotation and increased vibration. When bearings fail, they frequently pull out the balance shaft belt with them.
The 4G63 balance shaft timing belt is driven by the crankshaft and regulates the shaft rotation. The standard belt is quite weak, so many owners have upgraded to stronger kevlar belts. However, the belt’s power isn’t the issue. The issue is that the excessive vibration caused by faulty bearings causes the belts to snap. Kevlar belts will also break if the bearings fail, and because they are tighter and stronger, they will collapse with even more force.
When the balance shaft belt breaks, it also snaps the timing belt. This disrupts engine timing and causes valves to clash with pistons. In the worst-case scenario, the valves collide and fracture the pistons, scoring the cylinders and sending metal shavings into the oil pan, as well as cracking the crankshaft. In this case, a completely new motor is required. In the best-case scenario, the valves simply bend without causing any other harm, and only the valves need to be replaced.
Symptoms of Balance Shaft Bearing and Belt Failing
- Engine disturbance has increased.
- Ticking noise emanating from the engine’s rear.
- Idling in a rough manner
- Poor total performance
Unfortunately, when the balance shaft timing belt fails, it generally happens very quickly, and all you can do is hope for the best. Even with excellent bearings, the belt can snap from normal wear and tear, so it’s a good idea to check it for wear on a regular basis.
If the balance shaft bearings are failing, you will most likely notice increased vibration and noises emanating from the engine. Frequent oil changes are one of the best methods to avoid bearing failure. Bad oil causes incorrect bearing lubrication, which causes them to wear and fail.
4G63 Balance Axle Removal
Because the bearings fail frequently and cause the belts to snap, removing the balance shaft is a typical form of preventative maintenance. With the balance shaft removed, the balance shaft timing belt can also be removed, preventing it from fracturing and ripping out the timing belt.
However, because deleting the balance shaft takes a significant amount of labor, most people recommend doing so only if you are rebuilding or building your engine. While greater vibration is bad for efficiency, the last thing you want is a bad belt destroying your brand new built motor with thousands of dollars in mods.
2) Breakdown of the 4G63 Lifter
The camshaft pushes lifters upward, which then press against the rocker arms, controlling the opening and shutting of the intake and exhaust valves. Naturally, the 4G63 engines got subpar oiling. The oil pressure in the head is insufficient, resulting in inadequate lubrication of the lifters.
When lifters are not properly lubricated, they can begin to stick and cause the valve springs to fall. Lifter tick is the most prevalent issue on the 4G63. Lifter tick, for the most part, is just an annoying noise caused by inadequate oiling of the lifters. While lifter tick can eventually lead to lifter failure, it is often just annoying and can be driven around on for a while without causing any real problems.
The use of 3G lifters is a popular “fix” for the 4G63. However, because the problem is linked to oiling, it is only a matter of time before the 3G lifters begin to tick as well. Porting the oil galleys in the head to improve oil pressure and flow to the lifters is the only tried and true answer here. Porting the oil galleys, on the other hand, is a tad aggressive unless your engine is already open and being rebuilt. Most owners will simply drive around with the irritating lifter tick until the lifters need to be changed or the engine is rebuilt.
Lifter Insect Signs and Symptoms
- The engine makes a ticking murmur.
- Idling in a rough manner
- Misfires in the cylinders
Again, on the 4G63, lifter failure isn’t as prevalent as the vexing lifter tick. Lifted tick, on the other hand, is caused by poor lubrication, and poor lubrication can eventually contribute to lifter failure.
3) 4G63 Crankwalk Issues
The 4G63 engine was available in both 6-bolt and 7-bolt configurations. This is the amount of bolts connecting the flywheel to the crankshaft. The 7-bolt engines’ main bearings have narrower journals, making them weaker than the 6-bolt variants and less suitable for performance builds.
Crankwalk issues with 4G63 motors are more common on 7-bolt engines. It happens when the thrust bearings on the crank wear down which enables the crankshaft to move, or “walk”. When this occurs, the crank wobbles as it rotates, throwing the internals off. Furthermore, the crank can move so far that it crushes the crank angle sensor, causing the engine to shut down and have trouble starting.
Crankwalking Signs and Symptoms
- Shifting is difficult.
- Left hand sticky clutch shifts
- Unreliable clutch activation
- When the clutch is depressed, the Speed decreases.
- Ticking noise coming from the timing belt region
While crankwalk is more prevalent on 7-bolt engines, it can also occur on 6-bolt engines. Crankwalk is expected to affect about 5% of the 7-bolt motor. It’s also worth noting that crankwalk is more prevalent in high horsepower engines that use upgraded clutches with high pedal pressures.
4) 4G63 Raising Heads and Gasket Issues
Head lift and related head gasket failure are the most common issues with modded 4G63T engines. The problem is that the head fasteners are extremely short, barely reaching half an inch below the deck. As a result, the head is not completely bonded to the block.
One of two factors causes head lift. First, the head fasteners can stretch, causing lifting. The second, and more accurate, cause is that the pressure applied to the cylinder head pockets forces the head to lift and the washers to sink into the cylinder head.
In any case, a rising head will result in head gasket failure. Again, this issue is most common in modified engines with high levels of boost and torque. The answer is to use ARP head studs and oversized washers. Oversized washers or shoulder dowels will require the head to be machined, so owners usually just use ARP screws for now.
Signs of a Raised Head
- The cylinder is leaking oil.
- The tailpipe emits white smoke.
- Cylinder compression loss
- Coolant depletion and the presence of a milky whitish substance in the reservoir
- Poor efficiency, misfires, and so on.
4G63T Battery Capacity
Everything is available on the internet. That the motor can only produce 400whp/400wtq before blowing the block. There are also claims that 550whp is feasible on the stock block, and that the stock block can handle 1000whp with minor improvements. It is widely accepted that if you want to exceed 400whp, you should start with a 6-bolt engine rather than a 7-bolt.
These are fine until around 500whp with forged rods and pistons. The head bolts are extremely weak, causing heads to elevate by 325-350whp. The head and gasket are fine with ARP studs until around 500whp, when the head needs to be further secured. The crankshaft is quite strong and rarely wears out, though cracked cranks are fairly prevalent on later model evos.
Finally, there is the wall. The 6-bolt block is very strong and capable of managing 700+whp, but some improvements are required. The block is sturdy, and the sleeves are well-made, but the mains and cast iron belt are lacking. However, when it comes to the block, correct tuning is essential. Torque, not horsepower, is the primary killer of the bottom end of the block. When modded, properly tuning your engine can go a long way in terms of block (and internal) dependability. The 6-bolt can handle around 600awhp without modifications, but anything above 500 is regarded to be pushing the limits. The 7-bolt is expected to produce 500-550whp.
Durability of the Mitsubishi 4G63
The 4G63, when completely stock, is a very powerful motor capable of exceeding 250,000 miles. The main engine components themselves are unlikely to ever fail due to forged internals and a strong block. Lifter issues and bearing shaft failure are still possible on standard engines, but crankwalk and lifting heads are almost exclusively found on modified 4G63 engines.
However, due to their appeal as a tuner engine, stock reliability is less important on the 4G63T. Without any major reliability mods, the 4G63 is deemed reliable up to around 450whp. However, once you begin to exceed these figures, you will need to consider upgrading different internal components as well as strengthening the block.
6-bolt engines are thought to be more dependable and powerful than later 7-bolt engines. Of course, as power rises, so does reliability. Cracked crankshafts, crankwalk, lifted heads, broken rods, low end block problems, and other issues become prevalent once your 4G63 exceeds 500whp.
Overall, these engines are very strong and have the potential to produce insane 1000whp+ levels when completely built. They are incredibly reliable when completely stock and fully built. When tuned, they will require some upgrades and changes in the interim. The 4G63 is still popular today due to its power limits and increased strength, particularly when compared to its 4B11T successor, which has block problems when torque approaches 400wtq.
How have you found the dependability of modded 4G63 engines?