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Rebuilding Head

Hopefully, this will be a helpful guide for anyone that wants to rebuild their head. It should add some more indepth and detailed photos than the mazda/haynes manual. Enjoy!

For those wondering, I did this 20,000 miles ago, which is why my head is so shiney. Suddenly, I started using LOTS of oil and my #4 plug was very dirty. Suspecting a valve seal (because of the fast oil usage), I took the head off to conduct an investigation....

I'd recommend a good set of tools, some mechanical ability, and a CLEAN work environment. If it's not clean, you might end up doing this again in the near future.

This head is off an F2 out of a 1991 Mazda 626 LX. This is the same head used from 1988 to 1992 on Mazda 626 and MX6 models DX, LX and GT. Also, anyone overseas with a 12 valve 2.2L motor, this is probably your head as well.

The most commonly used tools are (for rebuilding the head):

- 3/8" drive
- 12 mm - 14 mm sockets
- 3" extension

Starting

We start with the head. First step is to take the rocker arm off. This can be done with the head in or out of the car, and gives access to the HLAs and camshaft. Make sure the #1 is pointing up on the cam gear, and lightly loosen the rocker arm retaining bolts in the order listed in the picture, then loosen them completely in the same order.

NOTE: These bolts also hold down the cam bearing caps. The cam beraring caps MUST be kept in order so they are re-installed in their orginal place with the oil seals lined up.

NOTE: Keep these bolts and spacers paired together and store them in labeled plastic baggies so they can be reinstalled in the same place.

Rocker Arms Unbolted

NOTE: Be careful of stuff sliding off. If it does, they HAVE to go back in the original order.

Rocker Arms

Again, be careful to keep the components in the original order.

HLA Unit

If you need to service the HLAs, they are on the underside of the rocker arm. They can be pulled out by hand.

Head without rocker arms

Head with the rocker arms taken off. The cam shaft is now accessible by removing the 5 bearing caps (2 ends, 3 middle pictured here).

NOTE: The 3 middle ones MUST be kept in order, and the oiling hole in the middle cap MUST be installed in that position (hole on the intake side)

Head with camshaft exposed

Here is the head with the camshaft exposed. It can now be removed (with the head in or out of the car). Now is a good time to inspect the cam for damage.

Scored Cam

By visual inspection, I can see that my cam is scored. This area is the part that sits in the pillow bearing. Compare it's surface to the cam lobes to the right and left and note the difference in smoothness. This is bad, and I'm going to have to get the cam resurfaced or replaced if the scoring is too deep. However, this is not the cause of my problem. The scoring was probably due to sand or some foreign object (which is why a CLEAN work environment is a good idea). It might not look that bad in the picture but it is (by feeling it).

To completely remove the cam, unbolt the sprocket (probably need an air ratchet or strong hands), unbolt the front bearing cap and lift out the cam. It's pretty straight forward.

Removing Valve Springs

The next step is to remove the valve components. This should only be done with the head OFF THE CAR, due to the danger of valves falling down into the combustion chamber. To start, we need to obtain a valve spring compressor. The one I have I got from autozone for about $20.

The bottom hooks grab the spring, and the middle part touches the top. As you twist the handle, the spring compresses, and in theory the retainers fall out.

The "tap" trick

After many failed attempts to remove the spring, a contact at a machine shop suggested tapping the top of the spring with a hammer before compressing. This upsets the valve spring retainers and lets them free. Low and behold, it worked!!

Compressing the spring

You should attach the valve spring compressor as far down the spring as possible. However, because the hooks are so large, the gaps in the spring get too small, so the compressor can only hook in right around the middle.

Uncompress

Take the spring off and SLOWLY uncompress the spring. THERE IS A LOT OF ENERGY STORED SO BE CAREFUL!!!! It can shoot a hole in your ceiling. Be careful not to lose any valve components

Storing

VERY IMPORTANT: The parts pictured below are from the #4 exhaust valve. The parts are in a plastic bag and CANNOT MIX with any other parts. This way, all the same parts go back in the same place. That is VERY important. Remember, there are 2 intake valves per cylinder.

You should have a valve, a spring, the top washer, two retainers, and a bottom silver washer (not pictured). Make sure you have all the parts in the bag and put away BEFORE you start on the next valve, or you'll probably get them confused.

This process is repeated again for each valve. This leaves the valve stem seals exposed.

Valve Stem Seals

After a short visual inspection, my assumptions were correct.

Obviously, you can tell the difference between a good valve stem seal (left) and a bad one (right).

I actually found this quite humorous despite all the work it took to get to it. It was in TERRIBLE shape for something with 20,000 miles on it.

Broken Seal

Here are the parts of the seal that separated from the rest of it. This rubber ring is supposed to seal around the valve stem to prevent oil from going into the combustion chamber. Obviously, it wasn't doing it's job. I have NO IDEA what caused this.

Removing the seals

These valve seals are a pain to get off. You need plyers to get them off and they CANNOT BE REUSED. They require just as much effort to pull off as they do to press on. As you can see, the top rubber part and the bottom metal part have completely separated from eachother. Hopefully this will not happen again in another 20,000 miles. Repeat this step for the other valve stem seals.

Installing valve seals

Ok, now to putting everything back together. Make sure you throughly clean everything first. Try to get all the carbon out, bring it to a machine shop and have them hot tanked, or buy some decarbonizer and scrape it off. I recommend cleaning the valves and the cylinder head. If you need to grind the valves, make sure you use valve grinding compound.

The valve seals are tricky to install.

Take the seal, make sure it's on the guide straight and then take a socket (i used a 12 mm one because it was just big enough to clear the rubber so it was pushing on the metal) and a hammer and bang it down. You can hear a difference in sound when it's all the way down. When you do, take the hammer and bang around the rim of socket just to make sure, and then look down the guide to see if you can notice a gap between the top of the guide and the bottom of the seal.

Install valve

now, take one of the baggies with the valve components in them. Might want to start with exhaust #1 or intake #1 just for reference. Make sure you put them back in the spot labeled on the bag.

To install the valve, just push the stem in the bottom of the guide and push, it should come out the top

Install shim

Next is the shim. I dunno what it's really called, it's just a thin metal peice at the bottom of the spring. It just goes there real easy.

Compress valve spring

Before you compress it, you might want to check the lenght. It should be around 2" i think. Usually if your car has like 150,000 miles the springs will have sagged a little anyways, but I didn't really care since I don't have enough $ to get new ones.

Put the spring in the compressor, with that little black top on. The part of the spring that touches the cylinder head is more condensed with the spring coils

Install retainers

Just put the spring over the top of the valve. It should be low enough for you to slide the retainers in.

The bumb on the retainer half fits into the groove on the valve. This part is kind of tricky, cuz they are small like to fall out of your fingers.

Try to get one half in there, then keep it in place by pulling the compressor up. Then put the second one in there and press it down and move the compressor down too. Once it pops in, pull the compressor up again to lock them in. Then, slowly release the compressor making sure the spring seats well.

Installed Retainer

Top view of installed retainer. The camera make it look like my thing is scratched real bad but it's not.

Done

This is what you should have just done. Now repeat it for the next 11 valves!

The rest of the assembly is kind of a no-brainer. The camshaft drops right in. When you put in the camshaft put some Assembly Lube (I used Lucas Oil Heavy Duty Stabalizer) around the cam bearings (not the lobes that touch the rocker arms, the part that goes under the bearing caps.)

Then the rocker arm assembly is next. Before bolting it down, take out the HLAs, fill them with oil. To fill an HLA with oil, take a paperclip and press on the ball on the backside of the HLA and squeeze it. Oil should squirt out. Now, with the HLA still squeezed, dunk it in some clean engine oil and let it expand. Then, fill the HLA hole in the rocker arm up and slowly press the HLA into place. Oil should squirt out of the top bulb on the rocker arm. If it doesn't, your didn't clean the passeges well enought. Torque in a 2 step sequence to 13-20 ft lbs in the following sequence. Make sure all the rocker arms and plastic things are clear of the bearing caps so it bolts down correctly.

10 6 2 3 7
09 5 1 4 8

The front housing bolts on after, 13-20 ft lbs on those bolts, and the cam sproket is 35-48 ft lbs.

I don't have any pictures cuz my hands were covered in oil and I wasn't about to touch my camera. That about concludes the head rebuild. Hope everything went well!

Great article mrfunji ...... the photos are extremely interesting !

great article gives me ideas of something to do with my head

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Thank You for the Info-It is efford much appreciated. I wonder, When building a Turbo charged engine to handle Medium to high Boost, Is it better to convert your head from HLA to solid lifters ? I take HLA is Hydraulic Lifters. Thanks Shadow