Since there is not a lot of clear information, with photos, on rebuilding the 2.5L KLZE engine, maybe I should make it. Please note that it is very important to have the Shop Manual for this. It contains a wealth of information on correct procedures, torque specs, and measurements. When looking in the MX-3 shop manual, also remember that some measurements are different for the KLZE. The information I have provided should only be used as a general guide. This should by no means be viewed as an idiots guide to rebuilding an engine. Is more suited to someone who is somewhat familiar with performing engine work. Also note that I am a Computer Engineer and not a licensed Mechanic. Take my words with a grain of salt.
So firstly, for those who don't know:
My KLZE was installed into my MX-3 but started going through oil quite quickly. I thought that maybe some seals and rings were a little dry and would soon swell up again after some good driving... nope... After a year, the engine was burning up over 1 Lt of oil for every tank of gas. Fuel efficiency was going down as well. I figured that I might as well rebuild it since I can't justify the loss in oil, fuel, and power. People tried to talk me out of it since buying another KLZE is cheaper. I did not want another since I run the risk of having the same problem with the next engine and I don't like seeing $1400 go to waste. See, the problem is, even though these engines are supposedly "low mileage" they sit on warehouse shelves for a long time. This can cause seals to dry up and crack over time. In my case it was valve stem seals and the piston rings were pretty crappy too. I needed new pistons too since the top edge of the pistons was beveled badly.
I won't get into details of the disassembly, I'll just show you the nasty part.Here is what the pistons looked like
after I cleaned them (just before the initial swap)Here is what they look like after 1 year
of driving. Note the caked on oil that was being dumped
by the broken valve stem seals. Anyone who drove behind
me on the 2006 Kelowna trip knows about this.Now here are new stock bore JDM Mazda
KLZE pistons with a slightly higher 10.1:1 compression ratio.
A stock KLZE piston has a flat top across the middle giving it a 10.0:1 compression ratio. A KLDE piston is dished out in the middle, giving a 9.2:1 compression ratio. These new pistons are opposite the KLDE pistons by having a raised center effectively giving them a 10.1:1 compression ratio. Not really a big deal. If I'm lucky it will give me +1 HP and slightly better fuel efficiency.
The Main and Rod bearings, seals, gaskets, piston rings, and thrust washers finally made it in. So now I can begin putting things back together on the block internals.
...... Bearings .................... Thrust Washers ................ Piston Rings Assembling Block Internals
To begin, we'll make sure all the oil ports and crevices are free of any old oil. I had a bit of an accident here since I was using BrakeClean degreaser to remove the old oil. When I used the air hose to blast out some of the ports, I covered the assembly with a large towel and put on safety glasses but some degreaser still splattered into my eyes from somewhere. F@#%^&*%!!!!
After bolting into the house to wash my burning eye-frickin-ball, I was back at it in no time. As well as cleaning out the internal crevices, it is good to make sure all the old silicon sealant is removed from the perimeter of the 2 halves.
Before installing the new Bearings, make sure you remove and clean the oil-jets. They can be removed with a proportionately sized flat head screw driver. Use some Degreaser on this as well, and then blow it with an airhose. The manual suggests using a small amount of Lock-tite on the threads prior to assembly.
Now, begin with the cleaned main section of the block and start installing the main bearings. Be sure you use the correct orientation on these. The Bearings with the oil groove go into the main section of the block (over the oil-jets). There is a mating notch that the bearing should fit into. Make sure it is installed nice and evenly. When installing the thrust washers, make sure the notches on them are facing outwards. It might be useful to use some suitable grease to hold the thrust washers in place since there really isn't anything to hold them in place at this point.
Add a light coating of grease to each main bearing surface. This will help lubricate the bearings during the initial startup, since any oil you place here will tend to run off during assembly. After the grease, pour a bit of oil over top of the bearings. Make sure you use only non
-synthetic oil during the assembly. I'll explain more on the reason for this later.
Now you can install the crankshaft. Make sure it is free of dirt and lint before putting it in place.
Once it is in place, make sure everything is still where it should be, including the thrust washers. Give the shaft a bit of a turn to spread the lubricant around. The white streaking in the photo below is the grease.
Now proceed to install the main bearings into the lower half of the block. Again make sure the bearing orientation is correct along with the thrust washers. I know only an idiot would screw that up, but it's better safe than sorry. Once the bearings are in place lubricate the surface of them the same way as before. Now it's time to place the two halves together. It's best to have someone help you with this to make sure it goes together properly. You don't want it knocking around when mating the halves together otherwise your thrust washers will fall out of place.
I used a special high-temp copper-silicon sealant (O2 sensor safe). Use the shop manual to see the sealing pattern that you need to follow around the perimeter. Use about a 3-4mm bead of silicon. Once this is done, don't let it sit for long. Make sure you assemble the two halves withing 5 minutes.
Once the two halves are together, begin installing the bolts. The manual explains what bolts go where and in what order, so I won't go into detail. Tighten them down in the correct order, but don't torque yet. After about 1 hour, torque them to the correct spec as stated in the manual. This helps ensure a better seal. Remember that some bolts of these require 80 to 60-Deg additional turn after torquing. (Follow the manual)
After a day or so, you can peal off any excess Silicon that has squeeze out the edges.
Now for the Pistons and Cylinders. The cylinders on my KLZE had very little wear on them. This saved me having to bore the cylinders to a larger size. Just a quick honing and the cylinders are ready to seat some new rings.
When installing the piston rings, they will need to be gapped before being placed onto the pistons. This means that they are pressed into the cylinders and then the gap in each ring is measured(excluding the oil rings). If it is not to spec, it will need to be carefully filed. Rather than me getting into details on this, I have included the instructions from Ross Racing. I have noticed a slight discrepancy between Ross Racing's info on the oil control ring orientation vs the Mazda shop manual. I chose to follow the Mazda Shop manual on that one.
For installing the connecting rods to the new pistons, it is important to have them installed in the correct orientation. Most stock pistons will have either an L or an R mark on the piston (meaning left bank or right bank). This mark also indicates the side of the piston that faces the front of the engine (the side that the belts go on). The connecting rods should have the pin holes facing the same direction. See the images for a better explanation. Note that my new pistons are simply marked with an "F" to designate the front of the engine. All this means is that it does not matter what bank my new pistons are installed into; since they are balanced for either side.
Now that the rings are installed and connecting rods attached with the new wrist pins, you should install the rod bearings onto each half of the connecting rod assembly. I used a small amount of grease to secure them in place. When installing the pistons into the cylinder, ensure that the correct piston goes into the correct bank (L or R) and that the markings are facing the front of the engine. Make sure you add some clean oil to the cylinder walls and piston rings. Also follow the ring gap alignment pattern noted in the Mazda shop manual. You will need a piston ring compressor to install the pistons. Don't even bother trying to do it without one. Connect the rod to the Crank shaft with it in BDC position. It makes it much easier to attached. Before bolting the connecting rods onto the crank-shaft, make sure you squirt some oil in between first. This is very important since there will be no other oil here at the point of initial startup. Follow the manual for torque specs. Also note that it is much easier to start with cylinder #1 and work your way back along the crankshaft.
Do not rotate the completed crankshaft assembly more than you have to. It could compromise the engine break-in process, later on.
Now all 6 new KLZE pistons are installed.
Next I will install the new oil pump. First I will pour a bit of clean oil into the oil pump ports and spin the gear, just to pre-lube things up a little. Make sure the mating surfaces are clean before applying new silicon to the pump. Torque the oil pump onto the block and proceed with installing the lower brass cover and oil pickup.
Now you can continue to install various other components around the engine block (just to keep a bit of the dust out of the internals). I will install the oil pan next with a new gasket and some silicon. This will close off the bottom end of the engine.
Now to flip the engine over and install the heads.
I did not rebuild the heads myself since I do not have the proper tools or machining equipment required for this. I took them to a local machine shop which charged me a base price of $300CDN per head with the cams & HLAs removed. They needed to replace 6 intake valves which is not bad out of a total of 24 valves. I supplied them with the new valve stem seals and they acid cleaned the heads, replaced the guides, machined the valves, seats, light port polish, etc. and put it all back together. The grand total came to around $740CDN with shop supplies and sales-tax.
Ugh... This thing better run good afterwards!
Put the new head gaskets in place and apply a small amount of oil to the O-ring on the oil control plug. Make sure that both block and head deck surfaces are clean along with the new gaskets. Follow the manual for installation and torque instructions.
Now add a small amount of clean oil to each spring retainer and smear the inner wall with your finger. Install the correct HLA into each socket and make sure they move and spin smoothly once installed.
Now proceed with installing the Cam Shafts & caps. Since the manual is quite detailed on explaining this, I won't go into details. Install the valve covers with silicon and new rubber gaskets afterwards.
Now follow the manual along to installing the timing pulleys and tensioners.
Proceed with installing the intake manifold with new intake gaskets. Follow this installing all other external items listed step by step in the manual (alternator, brackets, headers, etc).
Hoist the engine up and install the flywheel, clutch assembly, transmission, and engine mounts (and anything else I might have forgotten to mention).
You may now install the engine back into the car.
Now finalize everything by hooking everything up, including driveshafts, mounts, hoses, wires, etc.
You now may proceed to fill the engine with the required fluids (10W-30 Oil, synthetic transmission fluid, 50/50 Coolant/Water mixture, etc.) Make sure you do not use synthetic motor oil for the break-in process and first 10,000km of driving. The wear reduction properties of synthetic will cause the engine to not wear-in properly during the initial stages. So only use normal 10W-30 motor oil.
To begin, verify all fluid levels are correct. Do the following: (spark plugs removed, disty unplugged, fuel pump unplugged). It is also a good idea to pour a small amount of lubricant down the spark plug holes and onto the pistons. Things will be bone dry in there for the first few seconds, so it's best to give it a head start. Crank without starting for 10 secs to prime oiling system.
Re-Install spark plugs, connect disty, and reconnect fuel pump. Turn the ignition to "On" and leave in that position for 4 seconds before attempting to start the car. This will insure fuel is flowing trough the injector rails. Start the car. If it doesn't start, figure out what you screwed up.
Once it has started, immediately rev to 2500rpm and modulate RPM between 2500rpm and 4000rpm for a 15min period while someone else checks for leaks or problems. If a problem occurs, shut down the engine, fix the problem, and then start again. Please note that some new engine parts will give off a little smoke when they get hot (ex: chrome headers). The new internals will account for much of the smoke coming out of the exhaust. Video of the Initial Start-up Video after 15 mins running while modulating RPM between 2-4K rpm
After the 15 minute period, Shut down engine and change oil immediately (filter can stay since large particles will be safely captured by it.) Do not reuse this oil in an engine. It will likely be filled with microscopic metal particles which will not be caught by the filter. Refill with clean engine oil (again non-
Now for a road test.
Drive vehicle smoothly for the next 2000 km and make a point to regulate the RPM so that it is not always at the same point. Also make a point to avoid any heavy engine loads during this period. Periodically check fluid levels for changes and act accordingly (oil & coolant specifically).
Use your digression when driving the KLZE after the rebuild. I would not advise putting any heavy loads or rough racing conditions on the engine until at least after 5000 km. Again, what you do with your engine is up to you, but I wouldn't do it.
Change oil and filter after 3000 - 5000 km. It is not recommended to switch to synthetic oil until after 9000 - 10,000 km.
2 years later
The Engine is pulling very strong and has a noticeable power increase. No more burning oil after the rebuild and I have switched to Full Synthetic Amsoil. It is nice to have clean engine oil every time I have a look at the dip-stick. Even during oil changes, it is only slightly brown and murky. That's a nice change!
I took it to the track a little while ago and pulled a 15.0 sec 1/4 mile (400m) at our 1000m (3000ft) altitude here in Calgary, Alberta. That calculates to approx 14.1 sec 1/4 mile at sea level. (and yes that does make a difference!) It could probably be faster if I were to upgrade the clutch, shifter, suspension, and suspension bushings. (they are all quite bad). Depending on my frame of mind, I might just swap this engine over to my other MX-3 because it is much prettier and in better condition. It already has a KLZE that is running great, but definitely does not have as much power as this rebuilt one.
3 years later (2010)
I have now transfered this engine to another MX-3 as the body of the White MX-3 was crap and rusting out. (Didn't know it came from Ontario)
Anyways, here are some pics of the swap... Removing 1 KLZE and Installing the beefed up KLZE from the white car.
Paint on the new MX-3 is Seal Grey Metallic from a 2005 Porsche. This car has also had a slight weight reduction on it, so it should feel much more lively.
I had a video of testing the car out, but I took it down since it shows me speeding on the highway, and I should learn from the people who got arrested by authorities for doing the same thing.
Well, here is the vid anyways
. I'll keep it up temporarily and we'll just say this is in Germany...
Car runs great, but I think there is a sensor acting up, as I sometimes feel a little lag at certain RPMs. Might be a bad connection to the VRIS.~ More info to come ~