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.
7-Bolt Shortblock Failure - Full Diagnosis
If you are your own mechanic, there is no more important character trait
worthy of development than the ability to own your mistakes. That's where
the line is drawn between good mechanics and bad mechanics. It's not the
failures but how they deal with them that measures their ability.
In short, it's not easy to admit you did something wrong or were negligent.
But if you don't own it and talk about it, it doesn't get fixed, and
nothing positive can come from it. It was my quest to overcome my clutch
issue that lead to the creation of a video. That video is the textbook
perfect guide for how to correctly install a DSM transmission.
Crankwalk as described is caused by a casting defect. This was not a
defect. This was preventable. A lot of people would find something like
this and not tell anyone out of embarrassment. I'm not ashamed. It's my
fault. I got good use out of this engine and it was tough enough to make
it 48K miles since the last rebuild despite my abuse. I'm here to tell you
if you bought a used car that's had its clutch replaced, or if you ever pay
someone else to do it... make sure it has this bolt. It's stashed away
between the starter and the transfer case, so it's hard to see. Make sure
all of your bell housing bolts are torqued properly because fastener
problems can destroy your shortblock, clutch and transmission. If your car
fails because of a mis-aligned transmission, you have no reason to blame
It wasn't until I bought my next AWD car that I discovered there was a
smaller bolt on the other side of the block. I destroyed 3 transmissions
in the GSX first. With the damage already done to my crankshaft, I then
lost a shortblock. It's an ounce of prevention that's worth metric tons on
your bank account.
Grade 10 M8x60 bell housing bolt = MD706012. It gets 22-25'lbs of torque.
Owning my mistake permits me to learn from it through con$equence$, and
never repeat it. What good would it have done anyone else for me to learn
this lesson and not share it? That's why I'm providing this video to all
of you. Sharing it can perhaps help someone else avoid this costly
mistake. This is the final chapter for my 7-bolt, and this book is going
back on the shelf.
Here are some valuable resources if you're trying to read bearing damage:
And of course, now that I've covered the complete oil system, transmission
and driveshaft series of videos, you now have all the tools necessary to
ensure your 4g63 lasts a very long time. Whether the casting defect
exists?... or it's all caused by a bolt, or the harmonics, or whatever...
Sure, crankwalk exists and it's horrible. But with the small amount of
movement required for your crankshaft before it contacts the block isn't
far enough to make your clutch drop to the floor when you turn. You'd be
hearing woodpeckers and jackhammers on the crank long before that clutch
pedal would fall to the floor. Some people are going to hate on me for
saying that. That's fine. I believe all of the people who experienced the
clutch pedal issues had fastener problems on their bell housing.
DSMs get a bad reputation for this but we can change that. Crankwalk is
never the cause of your engine failure. Crankwalk is always a symptom of
the real problem. It's your disease that makes you deny it's your fault.
You've got the 'itis. DSM-itis.
Whenever you dig deeper, you'll discover what applied all of those thrust
loads to your crankshaft to begin with, and it's not going to be a casting
defect that moves your crank .101". Mine only went .014", but all of the
same parts failed.
PLEASE tell me in the comments if you find this bolt is missing from your
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 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.