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.

More Videos...

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.

Shortblock Tech Measuring Crankshaft End Play
Crankshaft endplay is critical to ensure proper positioning of the crankshaft. Its a pretty easy measurement to take as you assemble or disassemble the your motor. To elaborate on the clutch pressures and the forces they exert, here is a written version for your viewing pleasure. We did disable the clutch start switch to greatly decrease the load on startup and im sure this aided in minimal thrust wear. The reason this is important is because, there is little or no oil to protect the thrust bearing at startup. Another contributing factor is the increased pressure that is applied by aftermarket clutches. According to Road Race Engineering, a stock clutch replacement measured 380 lbs at install height and 420 lbs when engaged. An ACT 2600 measures 530 lbs installed and 710 when engaged. Their is no measurement for the ACT 2900 but from the above specs, the install pressure of the 2600 (530 lbs) exceeds the engaged pressure of the used stock clutch (420lbs) by 110 lbs. If you compare the engaged pressures of both clutches, the ACT applies 290 lbs more pressure when engaged. Do you see why the clutch start switch could cause and issue? All the more reason to unhook it and preserve those clearances. Happy Boosting

Measuring Crankshaft Bearing Clearance - DIY
A quick demonstration how to measure a crank journal with a micrometer and measure a bearing with a bore gauge to determine clearance.

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.