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Read this procedure completely before you buy parts or attempt the procedure. This procedure covers FWD and AWD 1G DSM's. Not having performed the procedure on a 2G car, there will most likely be a few different steps but the basic install should be the same. Reasonably good skills are required and access to good tools are required for this. If you are not sure you can do this after reading over the procedure, get someone to do it for you. .......Proceed at your own risk.
NOTE that this is not a "kit", you have to order the parts individually from your dealer. The oilpump stub shaft and rubber coated plug are from a Mirage 1.6L engine, so just give them the part numbers, and if they say they don't fit your car, tell them to order them anyways. The 4 parts cost about $41 LIST price, so if you use one of the Mitsu dealers that gives a Club DSM discount, you can get them even cheaper. Note that you don't have to buy new bearings if you knock the old ones out carefully enough and reuse them.
You can buy a kit from various DSM vendors and Mitsu dealers - it uses a hard metal plug and cam bearings instead of stock bearings. It works fine, but the stub shaft doesn't have an oiling groove in it like the Mirage stub shaft. It is better (and an easier install) to use the factory parts if you can get them (they are often out of stock).
Another mod some people have been doing (being more paranoid than even me) for very high revving engines is a modified rear balance shaft. They basically chuck the rear shaft in a lathe and cut the balance weight off of the shaft. The advantage to doing this is that the oilpump shaft is fully supported in the oilpump case and farther back in the block. Personally, I don't think this is necessary for the average DSMer, but if you plan on winding your engine above 8000rpm, it might be something to consider.
So why do it?
Simply put, reliability. The balance shafts are only there for your butt, not the engine. They are there to cancel out vibrations at idle and around 3-4K that would be annoying to the average driver that just owns a car for transportation, and wants the drive to be as smooth as possible. For the enthusiast, though, the slightly increased vibration from removing the shafts can easily be tolerated (right after doing this mod, you may think the vibration is much worse, but the vast majority of people barely notice it after a couple of days). The balance shaft system adds more complexity to the engine. Most importantly, if the front balance shaft belt breaks, it can tangle itself in the timing belt, leading to a trashed engine. Too many dealerships replace the timing belt and leave the old balance shaft belt in place if it looks OK. If you have a shop of any type replace your timing belt, MAKE THEM REPLACE THE BALANCE SHAFT BELT ALSO, no matter how new it is!. I know someone who had a balance shaft belt fail after roughly 30K miles, he got lucky and caught it before it tore up the timing belt and trashed his engine.
There is no reliability decrease from removing the shafts as long as the job is done properly. Reliability should actually increase, and the engine should rev slightly easier, as there is less reciprocating weight for the crank to accelerate/decelerate (roughly 5-7 lbs for both shafts). The only real drawback is that the engine will vibrate a bit more at idle and about 3-4K rpm (some people have reported it vibrating harder at 6K and up, but I haven't seen that on my 3 cars). You do NOT have to have your entire shortblock balanced to do this job. It will smooth out the engine a bit, but it isn't absolutely necessary. I balanced the engine on one of my cars, not the other 2, and they don't vibrate that much more than the balanced engine. However, if you are doing a complete rebuild on your engine, balancing it wouldn't hurt. 4G63s are usually very well balanced from the factory, so very little needs to be done to have them fully balanced.
Removing the balance shafts also makes future timing belt replacements a lot easier - I can replace a timing belt and all pulleys, etc, on my car in less than an hour (of course, I have removed the power steering and AC, that cuts down on the time a lot).
Parts Required:
Print a copy of the timing belt VFAQ as this procedure requires removal and re-installation of the timing belt.
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Raise front of car on jack stands. Remove driver's front wheel and inner splash shield. Follow timing belt procedure and remove all parts necessary to remove the timing belt BUT before removing the timing belt, crack the front balance shaft sprocket bolt loose (the belts help hold the sprocket still while breaking it loose). If you plan on installing a new oilpump seal, crack the oilpump sprocket nut loose now. The balance shaft sprocket is the small one circled in red, the oilpump sprocket is the large one. |
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Oil Pan Removal... |
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Kit installation... |
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Unbolt the oil filter block assembly from the engine. NOTE which bolts go where, there are 3 different lengths. If you lose track if which bolt goes where, don't panic. Just put the bolts into the holes of the oil filter block, and move them around until they all stick out an equal amount past the back of the oil filter block - when you have all 4 bolts in the right holes, they will all protrude almost exactly the same amount from the back. The bolt holes are circled. |
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Unbolt the oilpump cover from the engine (make sure to get all of the bolts!). Pry the cover loose from the engine block. The screwdriver shows a good spot to pry on to break the cover loose from the engine block. |
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Here is another good spot to pry on to break the cover loose from the engine block. |
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Once the cover is loose, loosely bolt the balance shaft sprocket back onto the front balance shaft, and pry out on it to pull it loose from its' bearings. Then remove the sprocket. Then prepare to pull the cover and shafts. |
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The engine must be dropped down to get the front balance shaft to clear the frame when you pull it from the engine. Place a floor jack under the front crossmember that runs along the front of the car. If possible, strap the jack to the crossmember with wire or duct tape, as the crossmember will shift and rotate once it is dropped from the frame. Remove the nuts at each end of the crossmember and lower it a little to pull the oilpump cover and rear balance shaft off of the engine (The rear balance shaft will come out with the cover). Lower the engine further until you can pull the front balance shaft out of the engine and clear the frame. |
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Here is the oilpump cover out of the car. The red circled areas are the front crankshaft and oil pump seals you should replace on a high mileage engine. When replacing the seals, it is a good idea to put a thin layer of RTV in the oilpump cover seal mounting flanges, then install the seals, then wipe off any excess RTV. I have had a couple of crankshaft seals leak around the edges after carefully installing a new one when not using RTV. The pink circled area is the bolt hole for the balance shaft tensioner pulley. When reinstalling the cover, make sure to either get a new shorter bolt, or install the old pulley and bolt. Put some RTV on the bolt threads before tightening it down. If you do not seal this hole, you will have a massive oil leak. |
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Clean the oilpump cover well, then pull the front balance shaft seal shown here. Just slip a flatblade screwdriver under the inside edge and pry it out. |
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Here is the cover with the front balance shaft seal removed. |
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Kit version - Mix up some JB Weld, and press/pound the freezeplug included with the kit into the balance shaft seal seat. The raised rim around the seat may crack when pressing the plug in, if it does, just add more JB Weld to the crack (it shouldn't crack to the point it causes a leak or anything, it's just annoying). You can also file the edge of the plug down a tiny bit to avoid cracking the lip, but use the JBWeld. |
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Factory version - Press the rubber-coated balance shaft plug in place of the old seal. I highly recommend you use RTV when installing this plug. It presses in much easier than the solid steel plug. It also wouldn't hurt to run a small bead of JBWeld around the top of the lip on the oil case and plug to make sure it stays in place. |
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Here is a rear view of the oilpump cover, with rear balance shaft still installed, for reference. |
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Unbolt the oilpump rear cover from the front cover. The small gear goes on the short shaft included in the kit, the large gear stays in the front cover. |
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A view of the rear balance shaft and rear oilpump cover, with the balance shaft bolt loosened. You will most likely have to grab the balance shaft with vicegrips to hold it while cracking the bolt loose. |
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A view of the rear balance shaft an rear oilpump cover, with the pump gear off. Note that the end of the balance shaft looks a lot like the short shaft included in the kit. |
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Bolt the short shaft included in the kit to the oilpump gear you just removed. NOTE the direction in which the gear goes on the shaft! The bolt fits inside the step in the gear. Apply high strength Loctite(red) to the bolt threads, install the bolt, and torque to 29 ft-lb. |
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This is why the step in the gear is on the bolt side - it fits around the seal/plug shown here (next to the large oilpump gear). |
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Here is the short shaft and small gear inserted back in the rear oilpump cover, from the back side. |
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Here is the short shaft and small gear inserted back in the front oilpump cover, from the back side. Pack the gears and space in the rear cover with grease (this will prime the oilpump at startup - You can also use Vaseline, white grease, or moly lube. You basically want something thick enough to stay put until you turn the engine over for the first time to prime the pump.). Oil up the short shaft with a touch of clean motor oil and slide the rear oilpump cover onto the front cover. Clean the thread holes and pump cover bolts with brake clean, apply some medium strength Loctite (blue) to the bolt threads and torque them to 12 ft-lbs. |
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Here is a view of the engine. The rear balance shaft bearing is shown circled here. This bearing can be left alone. The front shaft bearings, however, need to be removed and replaced with the blockoff bearings included in the kit. These blockoff bearings are necessary because the stock bearings have oiling holes for the balance shaft, and if you don't block them off, you will lose oil pressure. |
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Here is a view of the engine from the inside, showing the oilpump cover reinstalled, with the new short oilpump shaft sticking out of the rear oilpump cover. |
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Here is a view of the engine block, showing the front balance shaft bearing. |
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Here is a view of the engine block, showing the rear balance shaft bearing as seen through the front bearing (with the engine in the car, you won't get this view, you'll see it from the bottom of the block next to the crank). The oiling hole in the front stock bearing is circled. |
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Here is a closeup of the front balance shaft bearing. The water pump would be in the upper right of the pic if it were installed. Note the screw in plug on the left (circled) - that is to allow the factory to drill the oilfeed hole from the bearing journal into the oil galley. |
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Here is a diagram of the seals and gaskets you need to replace. To tell a 6bolt block from a 7bolt block, go here. |
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Here is a diagram of the bolt lengths for the oilpump cover. |
NOT SHOWN: Note that you don't have to replace the front shaft bearings with these blockoff bearings. It is recommended that you do so if you are working on an engine that is out of the car, but if it is in the car, many people have had no problems with just removing the balance shaft belt and letting the front shaft "block" the holes in the front bearings. If you leave the front shaft in place, it shouldn't hurt anything. Just make sure that you leave the sprocket and spacer on the front shaft so that it is locked into place and doesn't move back and forth in the bearings. The only real advantages of using the blockoff bearings are:
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Now you must remove the front balance shaft bearings from the engine block. Get a socket that is the same size as the front bearing and tap out the bearing. Or just place a flatblade screwdriver against the edge of the bearing and tap on it, then move the screwdriver over a bit and tap again, continuing until you knock the bearing out of its' bore and it falls out the bottom of the engine. If you use a screwdriver, be very careful, you don't want to slip and tear up the aluminum oilpump cover. |
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If you belong to a Regional club that has taken the time to make custom bearing removal/install tools, use them - they make the job MUCH easier. They are basically just 32mm axle sockets turned down to the right diameters to fit inside or against each bearing. |
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Grab the front balance shaft, reverse it so that you are putting it into the engine block front bearing surface first, and shove it through the front bearing hole, placing the front bearing surface up against the rear bearing. Pound on the end of the balance shaft to knock the rear bearing out. Either reuse the old bearing, or a new one - if you reuse the old one or are using a new factory bearing, rotate the bearing so the hole does not line up with the oiling hole in the block, and use the balance shaft to tap the bearing back into the block. Note the rear bearing is smaller in diameter and taller than the front bearing. |
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Now place the front bearing in the front hole, and carefully tap it into place so that it is flush with the block - again, if you are reusing the old bearing, or are using a factory bearing, make sure the hole in the bearing does not line up with the hole in the block before tapping it in. |
Reminder: There is no need to remove the rear balance shaft's bearing, as it has no oil hole in it (the bearing is fed by the shaft itself, which is hollow and feeds from the oilpump). |
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Clean the old gasket off the front of the block and clean it off with brake clean. Apply a very small amount of the Ultra Gray silicone to a few spots of the gasket outline on the block and on the oilpump cover - put the RTV on spots that do not have passages nearby. The RTV is only used to hold the gasket in place, making it easier to install, not to seal it. Stick the new cover gasket to the block and install the cover. Torque the oilpump case bolts to 14-16 ft-lbs. Jack the engine back up and reinstall the cross member nuts. Use a new gasket on the oil filter block housing to the oilpump cover housing and torque the bolts to 11-16 ft-lbs for the oil filter bracket. |
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Scrape the oil pan and oil pan gasket surface on the block to remove the old RTV. Clean liberally with brake clean. Reattach the oil pick up tube. (Do not RTV the pick up tube connection....don't want any loose RTV getting into the oil pump and passages). Apply a 1/8-1/4" bead of Ultra Gray RTV to the pan going around both sides of the bolt holes. Install the oil pan and bolt it up. Install turbo drain tube and new gasket. Do not use RTV on the drain tube. Reattach the axle to the block (AWD), reinstall transfer case (AWD), down pipe and cross member. |
SEAL THE BALANCE BELT TENSIONER PULLEY HOLE: The balance belt tensioner pulley mounting hole WILL leak oil if you don't seal it. Either get a shorter bolt and don't use the tensioner pulley, or reinstall the tensioner pulley and original bolt. No matter which way you do it, make sure so put RTV on the threads of the bolt to seal it, or you'll have a nasty oil leak and have to tear it all apart again.
Now reinstall the timing belt according to the timing belt VFAQ, put new oil and filter in, start the car and check for leaks.
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Here's a pic of the timing belt installed on the engine, after the balance shaft kit is installed. Note in this pic that the factory rubber-coated plug is used for the front balance shaft hole in the oilpump cover. |
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