Heads

First, you will want to remove the camshaft sprockets. Using the end yoke holder, or the make shift 2x4 and bolt thingy,  hold the sprockets in place and use a breaker bar to loosen the bolts (these things are tightened to 60 ft pounds so it will take some strength).

Second, you will remove the rocker assembly, there will be 10 bolts holding these on, you may want to leave the outer 4 bolts in the holes of the assembly because this thing will fly apart when you take it off . After removing the rocker assemblies you can remove the camshaft from the front bank ( head closest to the front of the car), the rear bank head has the connection point for the distributor so you will have to remove the four bolts holding it on. Remove the camshafts, clean them, oil them, wrap them in a towel, and place them in a plastic bag ( grocery bags work perfectly).

Next, you will need to take out the valves. I rented a valve spring compressor from Advance Auto for $60      ( It is the purchase price so you can either take it back and get your money back or you can keep it) Those screw and plier type compressor do not work to well. Place one end on the spring and the other on the flat side of the valve (be careful not to scratch the gasket surfaces), then squeeze the handle. If the spring doesn't compress that just means the keepers are froze so take a socket and a hammer and tap on the valve spring retainer until it pops loose. Use a set of needle nose pliers or a magnet to remove the keepers ( Do not lose the keepers they are small and expensive to replace, if you do 3sx.com may have them). Keep the spring, retainer, valve spring seat, valve, and keepers together in a sandwich bag and label them with the appropriate cylinder number and type (example-3 intake)  If you are replacing all or some of these parts then what ever parts you are keeping you will need to keep them organized. Then clean the heads thoroughly, you can use a good degreaser and a wash cloth, scrub brush, or a green scrubby pad. ( You can use a SOS pad or a wire brush but to not use them on the gasket surfaces or in the combustion chambers).

At this point you should have bare heads. If you wish to have a machine shop do all the work on the heads then you may do so at this point, if not I will guide you through this part.

The valve guides and and valve seats have to be pressed in so if you are going to change these you will need to have the head machined. The machine shop will press the old ones out re-cut the surfaces to a bigger size then have over-sized seats and guides pressed back in. This process only takes them a few hours but they can charge upwards of  $1000 for a set of 6G72 heads because they are less common.

At this point if you want to continue on your own then lets get to it.


I did a port and polish on my heads, if you do not know what that is I will tell ya. When the blocks and heads are originally cast they are cast in a sand mold and the sand leaves little dimples inside the intake and exhaust ports. A porting jobs refers to removing the burrs and dimples from the ports that are left behind from these sand castings with sandpaper or sanding rolls and a drill. Sand paper offers a smoother surface because you can start with 80 grit and work your way down to 220 grit, however, you will do a lot of sanding and your hands will get tired. Sanding rolls come in two different types, the tapered roll and the straight roll. Straight rolls will help you do the floor, roof, and sides of the port (fortunately for us the port is round so there is no floor, sides, roof, or floor) and the tapered rolls will help you get into the tighter spots. One thing I like about the SOHC heads is the ports have a pretty straight design there isn't much for bended areas and there isn't any major obstructions. The rolls come with a threaded mandrel to put in a drill. Thread the roll onto the mandrel and in a circular motion start sanding the rough spots off of the ports. All we are trying to accomplish is a smooth surface so do not remove a lot of material unless you are very experienced and you know what you are doing. If you have a Dremel tool you can use that to get into the even smaller areas. The rolls come in 80 grit and 120 grit so once you are done you can use 220 grit sand paper and get an even smoother surface. Once you are satisfied with the smoothness you can polish it if you wish, a polishing compound can be used but you will need to make sure all remnants of the compound is removed, there are also polishing stones you can use, personally I do not see the point in doing all the work to make it pretty because you wont see it and within a month your ports will be dirty again, as long as it is smooth your air will flow better and the carbon wont have rough areas to stick to. However, if you are building a racer then you will benefit more from the full polish but I would let a professional do this because they will actually straighten out your port so you get optimal air flow, there is a science to perfect airflow and this is beyond the capabilities of an amateur do-it-yourself 'er. The porting job I did is a mild one and I will still get extra cfm's for it and a few more horses but it isn't the full polish.

I used this grinding stone to remove all of the old carbon build-up from the intake and exhaust ports.

This is what it looks like when all the carbon is removed

First, I sanded the port with 80 grit sandpaper

If you decide to do port matching then you will need to do some research on this process because without practice it is a difficult procedure to not mess up and if you do it wrong then you will mess up your head, so if you do not have experience then do not attempt it. However, we will be doing a minor version of this with out intake manifold and intake plenum ( there is no sense to do a port job without doing it to the intake manifold and plenum. Besides the gasket for the intake already matches up with the ports pretty good so we wont need to do port matching we will just do a polish on the manifold and plenum.

The next step I will go over is Valve Lapping. Valve Lapping is the process of making the valve and valve seat have a nice even seal. Whether you are re-using the old valves of using new ones it is a good idea to do this process, especially if they are new. We will start by taking our valve lapping tool ( which is nothing more than a wooden dowel with suction cups on both ends) and our lapping compound ( $5 at Advance Auto) and set them near your work area. Take a valve and place some lapping compound around the edge and put some clean oil around the valve stem. Turn your head upside down (elevated by 2 rolls of duct tape or whatever you have laying around) and carefully push the valve into the appropriate valve guide. Push the suction cup firmly onto the valve and with a twisting motion twist it back and forth until it sounds like it isn't grinding anymore and lift the valve up and tap it on the valve seat 3 times then repeat the process, each valve can take up to 5 minutes each so be patient. If you mess up here you will have to disassemble the head when your compression check doesn't give you the proper results. You should see a nice even line all the way around the valve and seat that was ground out by the lapping process the line doesn't have to be very wide, only a few millimeters.

Now it is time to do the valve stem seals, you can remove them by gripping them with pliers then twist and pull. Push the new ones on by hand until you can't anymore and the use a socket and a hammer to tap it on all the way.

Now it is time to reassemble the valves (remember to put them back on in their original places, unless they are all new)  If you want to check for leaks now would be a good time. If you have the old spark plugs you can put those back in and then fill all six combustion chambers with oil and let it set for a few minutes, use a flash light to look into the intake and exhaust ports and see if there is any oil seeping in to the ports, you can even wrap a clean, dry paper towel around your finger and wipe around inside to see if there is anything wet on the towel, if there is then you have to continue the process on the leaking valve. If there are no leaks then you are done. If it leaks oil than it will leak air, but if there is no leak then that means no air leaks, and the reason you use oil is because motor oil is designed to seep into every nook and cranny.

If you had any lifter tick then you will need to replace all of the lifters because it is almost impossible to tell  which one it is, but no worry they are only a few dollars a piece from partsdinosaur.com. These will come unbled so you will have to bleed them. The manual talks about a "Hydraulic Lifter Leak Down Tester" but I was unable to find one online or in any auto parts, auto supply, or tool store so if you can find one I am sure they are expensive. I talked to someone online that said you do not need one if you are replacing them with new ones. The tool is only needed to test old ones to make sure they are still good. You will need a bleeder needle but a paper clip should do sufficiently. You will also need some clean diesel fuel. Pour the diesel fuel into a metal or glass bowl (Styrofoam bowls will disintegrate)  and hold the lifter with the plunger upright, press the plunger all the way down and insert the paper clip into the hole to press the ball valve down so that it will bleed the air out. You will need to place them in something so that the diesel fuel doesn't run out and the lifter fills back up with air, an old ice tray will work. There are special little clips that you can use to hold the lifters inside the rocker arms during reassembly but I was unable to find them so I used little pieces of duct tape.

Put some reassembly lube on the camshaft bearing and caps, put the new camshaft oil seals on the camshafts, then put the camshafts back on the head ( you do not have to worry about putting them on backwards because there is only one way to put them back on).

If you didn't listen to my suggestion with the rocker assembly and it flew apart the manual will show you how to put it back together. Reassemble the rocker shafts and bolt them back on to the heads, but before you tighten them all the way down leave them loose enough to remove the duct tape. Then tighten them down to the specified torque.


If you are still unclear about the procedures you can watch the videos on Youtube.com for more clarification, just search for "Valve Lapping", "Port and Polish", and "Port Matching".

Engine Block

Make sure the engine block is clean and free of all the old gasket material, old bearings, and old freeze plugs (to remove freeze plugs you can put a flat head screwdriver at the bottom and tap on it with a hammer enough to get it moving then once the top is pointing towards you grab it with pliers and pull it out...Do not punch it all the way into the block or it will block your coolant and it will over heat.)

The engine block can be machined at a local machine shop, they will also inspect the block to make sure it is rebuildable, but this process can be expensive. If you have the money to spend on a machine shop then stop reading and give them a call, if not I will tell you what to look for.

First, you will want to visually inspect the block and make sure there are no cracks, chips, nicks, or any deep scoring (if there is than the block has to be machined or replaced) (If you stopped running the engine before any serious damage occurred than you should be fine.)  Second, you will need a straight edge and a feeler gauge, place the straight edge across the middle of your deck (the flat gasket surface at the top of your cylinder bores), if there is any gap between the straight edge and the deck then you will need to measure it with the feeler gauge, if it exceeds .0039 inches than it will need to be corrected. You can get all the car manuals for this car from 3sx.com ( the downloads are free but you will need Adobe Reader...go to 3sx.com, click "tech" and they will be there).   Once everything is good and all the measurements are okay turn the engine upside down and look into the engine block and inspect for the same things. Look at the oil holes on the crankshaft support, make sure they are not plugged (if the old bearings are still in place, remove them). After the engine has been looked over and all is good then we will prepare for the cylinder honing.

Cylinder honing is necessary to remove all of the glazing on the inside of the cylinder bores, plus it will give you new rings a nice smooth surface for maximum compression. Put a thin layer of oil on the inside of the cylinders. Attach the hone to a good cordless or corded high speed drill. Place the hone inside the cylinders then squeeze the trigger. Make sure you keep a constant up and down motion, do not set in one place or you will be removing material unevenly. As I was doing this I counted to 25 seconds then I moved on to the next one. Be careful not to go up or down to far or the stones will fly out and cause damage to the block, gasket surface, or the stones themselves. Once you are done visually inspect and make sure there is no more carbon build-up or any other deep scoring. Remember that the honing process is to remove minute layers of carbon, if you take off too much of the cylinder surface than you will have to take it to a machine shop to be re-bored. Then clean the inside of the cylinders with some degreaser and that is it for that.

To put in new freeze plugs all you do is lightly put the freeze plugs in the hole enough so that they do not fall out and take a socket that is close in size and hammer them in. (Be careful to not put them in unevenly or they may leak and do nut punch them in too far or they may fall down inside the water jackets)

As for the block it is done for now...oh before I forget put some oil or reassembly lube on the inside of the cylinders so they do not rust or you will have to re-hone them) These blocks are cast-iron and they love to rust so you will want to store it in a bag to keep moisture away from them until you are ready to reassemble.

Disassembling the Engine

With the engine on the stand remove the alternator, power steering pump, intake plenum, intake manifold, exhaust manifolds, and all 3 plastic timing covers. Use plastic baggies and labels to keep all of your bolts separated so you do not have to dig through a bolt bucket. If you are going to re-use the timing belt make sure you mark it in the direction that it spins so that it is put back on in the right direction. Remove the timing belt, tensioner, and spring. ( I purchased a new spring from 3sx.com for $7, a new tensioner from Advance Auto for $25, I think). Remove the water pump, oil pan, valve covers, and oil pump.Using an end yoke holder, remove the crank pulley. If you have problems removing the oil pan, with the engine bottom pointing down, carefully put a flat head screw driver in between the oil pan and the block and pry up. (the reason I say pry up is because you do not want to dig the point of the screwdriver into the gasket surface of the block)
You will need an 8mm hex bit to remove the head bolts (if you are re-using the old head bolts be sure to keep them organized so that they go back in their original positions) . When I was removing the head bolts I discovered one that was stripped so I went out and bought a set of Craftsman bolt extractors from Sears.com (best $20 ever). The head bolts are hex bolts and do not have a hex head so removal can be a nightmare when they are stripped. If you run into this problem you can either weld another bolt onto the head and twist it out or you can place one of the extractors over the head tap it on with a hammer and twist it out with a breaker bar.

After removing the heads make sure you mark which head goes on the what side of the engine. Place the heads on a towel or on something soft so that you do not scar the gasket surface. Turn the engine upside down and remove the 8 bolts that hold on the girdle.  Unbolt all of the connecting rods and remove the end caps ( if you have problems removing them you can place a towel over the end cap and use a set of vise grips to wiggle them loose.) You should remove these one at a time ( pull one cap off, push the piston out with a thin piece of wood, and put it back together and label it with the piston number). Remove the rear main seal assembly, then remove the crankshaft.  Place all sensitive parts on towels to keep from getting scratched (i.e., crankshaft, rods, heads, etc.)   If you have a parts cleaner then you can soak these parts to clean them, if not, you can use Purple Power to soak them in.If you use any cleaner to clean any engine parts be sure to rinse and properly dry the parts. I used Gunk Engine Bright gel because it is thick enough to stay on the parts and it does a good job to remove the grease(caution Engine Bright Gel has to be rinsed with water so make sure all steel parts are completely dry or they will rust, then coat the parts in a thin layer of clean engine oil or reassembly lube)

Removing the Engine

First you want to disconnect all the wires and tie them somewhere to the side of the engine compartment.
Disconnect the fuel lines.  (be sure to let the pressure out of the fuel lines by loosening your fuel cap)
Disconnect the shifting cables from the transmission.
Drain the engine oil, antifreeze, and transmission.
Disconnect and remove the brake master cylinder.
Disconnect and remove the power steering reservoir.
Disconnect the throttle cable.
Disconnect the exhaust.  ( use the WD-40 or liquid wrench on the bolts before removal)
You may want to disconnect the transmission from the engine because I initially did not do this and removing the whole assembly was a pain in the ass.
Disconnect all of the radiator and heater core hoses.
Remove the hood.
Strap the hoist chain to the engine  and tighten slightly
Disconnect the A/C compressor from the engine and tie off to the side near the radiator.
 Disconnect all 3 motor mounts   (the one on the front is a pain in the ass to remove so you will need a fat bar and a hammer to try to wedge the bolt out, unless you want to remove all of the cruise control components)
Using the hoist pull the engine out.

Attach the engine to the stand using 4 M-12 bolts that are about 3 and a half inches in length. (you can get these from Lowe's or Home Depot)

Introduction

Before you begin this you will want to figure out how much of a rebuild you are wanting to do. A general rebuild is bearings ( main. rod, and thrust ), pistons, rings, seals, gaskets, and freeze plugs. The rebuild kit I bought contained pistons, rings, bearings, all the gaskets, all the seals, front and rear main seals, and freeze plugs. If you are wanting to replace more than just those parts go check out partsdinosaur.com  the prices are very fair and the parts are from the original parts suppliers for Mitsubishi when these cars were originally built. If you are looking for performance parts you can go to 3sx.com, dsmgraveyard.com, and parts.com. These sites have a lot of selection but the prices can be a little higher. Advance Auto and Autozone have most of what you will need to do a rebuild and most of their prices are cheaper then most internet sites.  Next you will want to make sure you have all the tools you will need for a project like this, here is the list.

1/2 inch Breaker Bar, 1/2 inch Torque Wrench, 1/2 inch drive ratchet, ball joint separator, tie rod separator,a good set of 1/2 inch drive deep well sockets (8mm-19mm), a good set of metric wrenches  (8mm-19mm),
a 3 ton hydraulic press  ( Harbor Freight Tools $79.99), an engine stand        ( the 750lbs one from Harbor Freight will be sufficient $39.99), an engine hoist       ( local equipment rental stores usually have them, average price $40/day), 6" socket extension, valve spring compressor, piston ring compressor, valve lapping tool, lapping compound, magnet, storage bags    (sandwich bags work), labels, sharpie,  rubber mallet, hammer, wd-40 or Liquid Wrench, possibly a nut splitter, a good set of bolt extractors   (just in case you have any rounded off bolts), vise grips, piston ring wrench, paper clips, an end yoke holder (if you can't find one or do not wanna pay $60 for one you can take a 2x4 and put 2 bolts in the end about 2 1/2 inches apart), cylinder hone, high speed drill, feeler gauge, flat head and Phillips head screwdrivers.

This should be it for the tools you will need. You will need a service manual you can download them for free from 3sx.com (click on tech, they will be in there)....pick the one that says "Mitsubishi Engines Various" or you can do what I did and download them all.