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 pressure.
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.
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 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.
Mitsubishi 4G63 Honing with Torque Plate
See what a difference a torque plate makes on a Mitsubishi 4G63 block out of an Evo IX makes as John Edwards @ Costa Mesa R&D Automotiove Machine walks you through the steps. (949) 631-6376 Don't forget to 'Click' and SUBSCRIBE.
How to polish a crank ( crankshaft )
Engine-Guru.com Presents a video on how to polish your crank shaft. Any questions call 616-430-3114 ask for KYLE. We are located out of Grand Rapids ,Michigan.
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.
Mitsubish 4G63 Block Resurfacing
Here's another block that was brought into Costa Mesa R&D Autmotive Machine that was cleaned with an abrasive rotary pad. John Edwards explains how the repair is completed. (949) 631-6376 Don't forget tp 'Click' and SUBSCRIBE.
Cylinder Head 106 - Casting & Porting Tech
No really guys, what can I type here? I just went on for 18 minutes without shutting up. I apologize for deviating from my normal format, but we're almost there...
...when I port a head, there will be no voiceover, and it will be a 200-series video.
Reading a Standard Micrometer.mp4
This video continues the series on using precision measuring tools that are used by the mechanic. The detailed video uses closeup video to show hoe standard micrometers are used.