Blueprint 102 - Measuring 4g63 Crankshaft Endplay

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.

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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 Gap 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 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 to machining. 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 101 - Using Micrometers, Calipers, & Bore Gauges
THESE MICROMETERS ARE PROPS. They're cheap, easy-to-read, and they were defective straight out of the box. They couldn't be calibrated. The graduated sleeve was seized up and rusted to the bodies of each one. They're also not accurate enough to measure taper or runout on a bearing journal which is necessary if you're rebuilding an engine. If you're going to rebuild an engine and you're not already familiar with these kinds of tools, 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. When I can afford a $1200 set of Micrometers, I'll re-make this video.





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.




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