4g63's are famous for hosing crankshaft thrust bearings. This video illustrates the process of how to check the thrust bearing clearance whether the motor's in the car or not. Of course in my case the motor's on a stand for this video. Lucky for me!
In cases where the engine is still in the car, the same procedures can be used so long as the indicator is attached to the engine block. The plunger can be set up touching either the inside of the crank pulley or by removing the clutch cover plate and contacting the flywheel.
What the thrust bearing does, is prevent the crankshaft from having lateral movement in the main bearings. If a crankshaft develops excessive movement here, clutch engagement and hydraulic problems will begin showing up, followed shortly thereafter by catastrophic failure of main bearings, rod bearings, connecting rod failures, oil pressure problems, or even broken blocks, crankshafts and rods in extreme cases. It's important that every 4g63 turbo engine is within spec on this measurement.
When the crankshaft aggressively wears through the thrust bearing developing lateral play, this is called "crankwalk". On some block castings, replacing the bearings will NOT fix the problem. An engine block that is prone to crankwalking can not be fixed. The only option in these cases is to replace the shortblock and rotating assembly with new or used parts that are stronger than the one you've unfortunately encountered. For the 2g guys, the best option for repairing this problem is to remove the 7-bolt turbo shortblock your car came with and replace it with a 6-bolt from a 89-92.5 production date turbo DSM. Non-turbo blocks CAN be used; however, the block will not have oil squirters that aim towards the back of the pistons. That stream of oil aides lubrication to the wrist pins, cylinder bores, and somewhat cools the pistons. All good things on a turbo setup. Aside from that difference, there are no other differences between the non-turbo and turbo blocks. The pistons and thus the compression ratios are different, but that's it. Oil squirters can be machined into the main galleries of a non-turbo block, but it's more trouble than it's worth unless you can't find a turbo block.
There are tons of differing theories about what causes crankwalk. Nearly all of them are plausible and logical arguments. I will not get into those debates in this video in order to focus on procedures for testing and replacement. Please feel free to google "crankwalk 4g63" and read the volumes of information available already. The arguments and gathered data are older than the Eclipse itself and in abundant supply on the internets. Magnus, RRE, VFAQ, and many other parts vendors have lengthy write-ups on their own research and development. The bottom line is that the 6-bolt shortblocks are LESS likely to suffer from this.
Next time you see someone with a video that looks like it was shot with a potato asking "does this sound like crankwalk", you can send them this video. There's a reason for every noise, rather than focus on the sound, focus on eliminating the real problem. KNOW if it's out of spec.
Blueprint 103 - Connecting Rods
Connecting rods are the crux of the engine. They're responsible for
carrying the force of the explosions that occur in the combustion chamber
and using it to turn the crankshaft. Oil clearance specifications of the
"big end" and "small end" are crucial to maintaining consistent oil
In this video we take 3 measurements:
Rod Journal (also called Crank Pin) Diameters
"Big End" Bore diameter
Using the Journal diameters and the "Big End" Bores, you can calculate your
oil clearances of each bearing. The process is illustrated here. Anyone
rebuilding an engine who doesn't know its history should check all of these
clearances whether or not they're re-using the rods. If the crank,
bearings or connecting rods are going to be replaced, it's imperative that
you measure the new parts as well to ensure they're in spec.
Turbo Elantra Bearing Failure Diagnosis
I had time to look at this thing up close. Go through the oil system, and
check out all the bearings. Looks like another good study for my oil
system series because it's the opposite problem that my GSX experienced.
High oil pressure can be remedied a number of ways, but left unchecked can
actually take a toll on your bearings. The way your engine bearings work,
the parts they suspend are supported only by an oil film layer, and flow
needs to be right in order for it to work as an actual bearing. If the oil
supply is insufficient, then it loses the ability to suspend the part
causing it to crash into the bearing surface. If oil flow is too great,
friction is increased, the flow becomes turbulent, and the oil film doesn't
form properly. High oil pressure can float and spin rod bearings, and
that's worst-case scenario.
I had several un-favorable conditions going on inside this engine and that
makes it a little bit difficult to link what my engine experienced to any
one singular thing. I think it's easier to look at it like some sort of
From sub-standard parts for how the engine components would be used, to oil
pressure, to part fatigue, to part history to abuse... this thing's got a
little bit of everything working against it and that's why it's such a
hilarious car. It was given to me with one condition. "See what this
thing will do, and see how long it goes before it breaks." My take on it
is, the parts are still less than ideal, and they've still got life left in
them. It's worth fixing. These parts are worthless as a race motor, and
normally I'd have junked 'em, but it's the Hyundai.
Blueprint 107 - piston-to-cylinder wall clearance
This video covers how easy it is to calculate piston-to-cylinder wall
clearance. It's too easy. This is important because too loose of a gap
and the rings won't seal properly. Too tight and the pistons will scuff
the cylinder walls, ruining the bores.
We've touched on thermal expansion several times now, and the reason it
keeps coming up is because turbo engines
achieve much higher cylinder pressures, and therefore generate more heat
than a normally aspirated combustion chamber experiences. This affects the
growth of the metal parts when they're at operating temperatures, so turbo pistons need more cylinder wall
clearance to account for this.
I will cover the ring grooves, compression and oil rings in a 200-series
video while assembling this engine with new pistons. For now, these will
just be saved for a rainy day. After all, I have a stock bore stock 4g63
engine in the Colt.
Blueprint 104 - The Crankshaft
It's important to know what you've got even before dealing with the
machinist. If you want to inspect a crankshaft, this is how you do it. I
detail the process of removing the crank and what to measure. All
specifications in this video are illustrated with a 6-bolt 4g63 turbo block, but are all actually the same for
7-bolt engines with the exception of the rod widths.
Blueprint 105 - Main Bearing Oil Clearances
In this episode we measure the bores for the crankshaft and calculate the
oil clearances based off of information gathered in the previous video. If
you subtract the diameter of the crankshaft from the bore diameter, you end
up with your oil clearances.
If this were an assembly with new parts, I would have also paid close
attention to bearing measurements 45° off-centerline just to make sure the
bearings aren't pinched. I would also have double-checked the clearances
using Plastigage. But what I'm doing here is just getting baselines prior
If you're doing a dry assembly like this, DO NOT ROTATE THE CRANKSHAFT.
Without oil, there is nothing preventing it from being damaged.
Blueprint 106 - Cylinder Bore Inspection
We're close to the end of the 100-level series. In this video I show you
how to measure the cylinder bores using 2 different tools. I compare the
results and illustrate what to look for to determine whether or not your
engine is in-spec.
The block I'm using is a 6-bolt turbo
4g63 from early '92. It has 150,000 miles and this video also serves as a
testimony for the durability of Mitsubishi's cast-iron solid-decked Sirius
I engines. This engine will be cut for a new set of pistons, so these
measurements are needed to determine what size pistons I need to get.
.030" is as far overbored as you should ever take a 4g63. Boring larger
than that will take too much off the side clearances between the cylinder
walls and result in compromised strength from hot spots. The only time
you'll ever need to cut a bigger hole is when an imperfection prevents you
from using the pistons you have, or if you're changing to a larger piston.
If you cut the block to its service limit, you have no room to fix an
imperfection should one develop... so it's best to cut as little as you can
get away with. Boring a cylinder .020" over does not significantly
increase its displacement.
6-bolt 4g63 Crankshaft Chamfer & Oil Clearances
These are some things you need to think about during your build. Some
engines don't have any chamfer on oiled journals whatsoever. All equipment
like that can benefit from at least a light chamfer like the one that's on
a stock Mitsubishi crank shown in this video.
When you Chamfer an oil passage, you create a low-pressure zone where the
edges of the oil passage lift away from the bearing as it passes over it.
The principles of fluid dynamics dictate that if there wasn't an available
substance to displace that low pressure zone (in this scenario, there is an
oil supply), cavitation might occur. If we were talking about
aerodynamics, the effect would be lift.
An extremely-advanced or leading chamfer is actually capable of sucking oil
off of a flat bearing, whereas a trailing chamfer vacuums oil out of a
gallery and does a better job of spreading it around.
The modification that was performed here is intended to increase oil flow
to the mains and the rods. It's mentioned in the video that I'm setting up
my rod oil clearances on the looser side of spec. This will decrease block
oil pressure because more oil will be able to leak past the fillets of the
crankshaft and back to the pan.
But there's another modification being performed. A balance shaft
elimination. There will be lots of debate about this in the coming videos
as that transpires, but one of the side-affects of doing a BSE is increased
oil pressure. With several internal oil holes plugged off inside the
block, I will have a spike in oil pressure. I had my chamfers cut straight
in order to offer the largest practical surface area to apply oil to the
mains and rods. My intention is to relieve some of this oil flow that
doesn't have anywhere else to go. With the added flow, the straight
chamfer is actually beneficial to the mains, allowing them to intake more
oil as well as to spread more of it on the flats below the grooved upper
The animations illustrate this completely. They were created by
yours-truly. I know the oil hole on the mains is on the wrong side. It
was too much work to fix, but they get the point across. Don't laugh at
them any harder than I did.
6&7-Bolt 4g63 Front Case & Oil Pump Rebuild
Here we disassemble, clean, inspect and rebuild both popular 4g63 front
cases. This is not difficult, you just need to know what to look for.
Something else that happens in this video is the analysis of one of the
factors that caused my 7-bolt engine to fail. It wasn't the only cause,
and we'll talk about that later, but left to its own devices and without
the other contributing factors, it would have been the only cause.
Calculate Your Compression Ratio
This is everything you need to do to calculate your compression ratio. No
foolin'. Every equation and process demonstrated. Find all your
variables. Know your exact compression ratio in every cylinder. This is
how you do it.
Just because your service manual says your car is 7.8:1 or 8.5:1
compression doesn't mean that it is. Whenever there are casting
irregularities, variations in piston height, parts that have been machined,
non-OE parts, or changes to your head gasket selection, your compression
ratio WILL change. It's highly probable that you're only CLOSE to spec if
you've never touched your engine at all since it was "born", and that it
doesn't MATCH spec. Even if it did, how would you know? This.
V1 Swept Volume
V2 Deck Volume
V3 Piston-to-deck clearance
V4 Piston dish cc's
V5 Head combustion chamber cc's
The ratio math:
V1+V2+V3+V4+V5 = volume of combustion chamber at BDC
V2+V3+V4+V5 = volume of combustion chamber at TDC
The ratio is...
(V1+V2+V3+V4+V5) ÷ (V2+V3+V4+V5) : (V2+V3+V4+V5) ÷ (V2+V3+V4+V5)
BDC ÷ TDC : TDC ÷ TDC
First you fill in the variables, then you calculate volumes, then you add
the volumes, then you reduce the ratio (fraction). It's that easy.
Here are your magic numbers:
0.7854 = Pi quartered to the ten thousandth
16.387 = number of cc's in a cubic inch.
If you divide any number in cc's by 16.387 it gives you inches. If you
multiply any number in cubic inches by 16.387 it gives you cc's.
Quartering pi lets you use the calculation:
BORE x BORE x STROKE x .7854 = volume of a cylinder
π x (BORE ÷ 2) x (BORE ÷ 2) x STROKE = volume of a cylinder
Either way is right. You get the same result if you calculate pi to the
ten thousandth. While I apologize for all the math, no I don't. I'm
really not sorry. You actually clicked here for it whether you realize it
or not. This is ALL the math, the tests, and the whole process to
calculate your cylinder volumes and compression individually even if you
don't know any of your variables yet. All of my numbers are present for
those who want to calculate out the last 3 cylinders out of curiosity just
to see how it affects cylinder volumes and compression ratios from one
cylinder to the next. Why would I do that for you? Why would I deprive
you of that practice?
Just assume that all 4 of my combustion chambers are 41.75 ml if you do
Clicking like share and subscribe helps a channel grow. It also motivates
me. Don't sweat the camera. It's enough to know that so many of you care
about what I'm doing here. From the bottom of my atmospheric dump, I thank
you all! This gift horse's teeth are all over the place, but he sometimes
poops gold nuggets.
PS: Use ATF for your piston dish volume tests, not alcohol. Of course
it's better just to use the spec sheet included with your pistons... but
not everyone gets that luxury. Water is just fine for head combustion
chamber tests. Dry and re-oil all parts that water touches.
Blueprint 101 - Using Micrometers, Calipers, & Bore Gauges
If you're going to rebuild an engine, this video is required material.
None of your measurements mean anything if they're not accurate. I
illustrate the calibration and use of 3 major tools needed for taking
measurements, and a brief demonstration of how they work. These are by no
means the ONLY ways to use or calibrate these tools. This is simply the
method I will employ to measure parts in later videos so this instruction
doesn't distract from their intended messages. Even if you're familiar
with these tools, you may find something useful here, or even be able to
correct me and my rusty skills.
Blueprint 108 - inspect the deck
There's a reason why there are no subtitled specifications in this video
for the block. It's because they don't exist in either service manual, 1g
or 2g. You're not supposed to remove material from a block on the deck
surface because it has ill effects on parts of the combustion chamber
geometry, and alters your compression ratio. It can be done intentionally
in some cases for a desired side-affect, but if you have to deck a 4g63
head, it would be advised to use a thicker head gasket. The Mitsubishi
Multi-Layered-Steel or MLS gasket is slightly thicker than the OEM
composite gasket. Also, HKS, Power Enterprise, Cometic, and other
performance brands all make MLS gaskets that are .065 and thicker.
THERE IS ONE ERROR IN THE VIDEO. I said a block with .002" warpage is
junk. I was completely and totally wrong. While I don't wish to spread
misinformation, I don't think it's a big enough error to warrant re-editing
this video. I just wasn't paying attention. .002" warpage on a cylinder
head is the service limit before it needs machining. I meant to say
.02"... or two HUNDREDTHS (not thousandths) of an inch.
...and here's my justification...
A warped block to me is junk either way even if its minimal because your
MLS gasket will never seal unless both the head and the block are perfectly
flat. Trust your machine shop to get the values for how much is taken off,
and buy the correct thickness gasket for your machine work.
A factory head gasket (composite) is .051"
The MLS Mitsubishi gasket is available in the stock .051 and a .062"
Cometic makes gaskets up to .072"
There are some brands that go as high as .127", but I'd have thrown both
the block and head away long before then.
Hyundai Elantra 4g63 Shortblock Assembly
HOLD ON TIGHT! HERE WE GO!
We begin the blueprint and assembly on my 1992 Hyundai Elantra's
bastardized 4g63. The parts used in this are from a mash of different
brands and models outside of the typical 2.0L 4g63, but the specs and
standards I am following for its assembly are for the 2.0L DOHC.
If you want to follow along in your service manual to verify what I've done
here in this video, the processes we cover here detail pages 11C-95 through
11C-105 of the 1g Overhaul manual. I would prefer you not rip them from
the binding and throw them away, relying only on this video for
instruction... but rather use this video as a motivational guide, and as a
demonstration of the techniques involved in those sections.
You gotta do the cooking by the book.
I never had any intention of making instructional videos on this particular
car, but after it blew up I slowly realized it's actually a better case
study for how a 4g63 ticks than anything else in my driveway. There are
several reasons for this. One being that it's a mix of parts that
shouldn't be bolted together, and the other is that many of you watching my
videos aren't trying to build a 600hp engine out of aftermarket parts.
You're trying to put back together what used to be your daily driver. This
car covers those bases. Don't think for a second I won't go through this
same trouble and level of detail for the GSX. I will. When I do, having
this information in this video will give you a better understanding on how
and why I do things the way I do when I get there.
This was the shortest I could condense this video. I've never uploaded a
video this long, and I hope I never have to do it again. It took a month
to create on cutting-edge equipment, 16 hours to export, and 9 hours for
YouTube to process. My script for the voiceover is 6 times longer than the
whole script for the movie Pootie Tang. 6 times. Longer. Than a
4g63 Balance Shaft Elimination - bearing modification
This is the first part of a two part series about balance shaft elimination
on 4g series engines. This video details the bearings, the other video
will cover the front case modifications. I've already got a low-def video
of the front case mods, and I plan to re-shoot that one in HD when I'm in
the assembly phase. It's linked in the video.
The balance shafts are designed to cancel out harmonic vibrations caused by
combustion and the spinning rotating assembly. They may offer a greater
degree of comfort to the driver and passengers, but with that comfort comes
Often, when a 4g63 timing belt gives up, it's because the balance shaft
belt breaks or comes loose and takes the timing belt out with it. When
that happens, it can total your pistons, valves, damage the crankshaft,
wrist pins, timing belt tensioner and crank angle sensor. Basically, it
can total your motor. The balance shafts also have a combined weigh over
10 lbs and both are driven off the timing belt making them additional and
heavy rotating mass. If you've got a lightweight flywheel but still have
balance shafts, you have your priorities mixed up.
So here's what you do with the bearings. It's easy. You can do this at
home. You CAN do it with the motor in the car, BUT DON'T. You must enjoy
punishment to do this like that.
The end result will slightly increase your oil pressure, but usually not
enough to cause concern unless you have a full-circumference bearing turbo, ball bearing turbo--with your oil feed coming off the oil
filter housing. The head feed would be better in that case because it's
regulated at 15 PSI.
Why so SIRIUS? Kia 4g64?
This video assumes you're aware that various iterations of the 4g series
Mitsubishi engines are designated as Sirius I & II.
For detailed information about which engines qualify as which, visit:
There's also this at EvolutionM:
Good luck finding info about this using Hyundai and Kia in searches.
Wikipedia doesn't have any info about it grouped with the Sonatas either.
There is no question what this is, well illustrated in this video.
I apologize for the length of this video, but a lot of ground is covered in
a short time. Hopefully there's some information in here you may someday
use. I'm just trying to expose it because there doesn't seem to be any
real information floating around in the forums about this yet.
The car is a first-generation 1999-2005 Kia Optima sedan. It has the EVO
equivalent of a 4g64 2.4L. Before using any of these parts, do your
research, cross-reference your parts and know what you're getting into.
Using parts from this rotating assembly in a 2g Eclipse will require
aftermarket rods and/or custom pistons. This is information for those who
wish to frankenstein their builds, or save a buck... whichever.... either
one of those requires skill.