4AFE Cylinder Head Removal

BACKGROUND:      

   
      In this article I will describe the procedure for a head gasket replacement I did to a friend's 94 Toyota Corolla DX. He contacted me about oil appearing in the coolant when he inspected his deposit and radiator level; I refer to this as "oil to coolant mix." This is an indication of head gasket failure.
It can also occur the reverse --"coolant to oil mix-- where the coolant mixes in the engine's oil. Obviously, both situations are bad for the engine, but the most detrimental is having the coolant mixing in the oil because the lost of necessary lubrication in the movable parts such as the crankshaft/connecting rod relationships, camshafts, and pistons leading to bearing failure, knocks, deformations, and even breakage of parts. The other situation can manifest by engine overheating and no heating air because obstruction of coolant passages.

      In the case of this Corolla, it did not present any symptoms of overheating, loss of power, loss of compression, nor the presence of coolant in the oil; in other words, the vehicle was operating very good with the exception of the oil/coolant mix. This is something hard to believe but it happened to this car and let us know that old Toyotas are very good cars. Newer ones are good too but they are not worth repairing, in my opinion, because of the complexity of having every internal bolt to stretch specification--if they are out spec, you will need to buy every single bolt and that becomes expensive.

REMOVAL PROCEDURE:

First I will list some basic tools for doing this job:

• Socket wrench and 8mm to 17mm sockets (both regular and long sockets preferable)
• Nose pliers, adjustable pliers, and regular pliers
• 8mm to 17mm wrenches
• Oil receiver pan
• Socket extension bars (different lengths will be great)
• Universal Joint (good to have it)
• Adjustable Wrench
• Flat screwdrivers
• Breaker Bar
• Phillips Screwdrivers
• Pulley Extractor (sometimes necessary)
• Floor jack
• 1 piece of 4x4 or 2x4 (wood) cut to 1 foot in length
• Pick up tool (good to have it...good for you knees and back)

Engine Bay Overview:

         
Inspection:

    While inspecting the oil fill cap and the PCV valve, I found sludge (milky substance); however the engine oil was appearing as it should. This led me to the conclusion that the sludge in the oil cap and PCV was just condensation.

OIL CAP

PCV

CLEAN OIL

Moving to the actual removal:

• Disconnect battery
• Drain coolant
• Drain oil
• Remove fuel pump fuse and start the engine--wait until stalls and then remove the fuel line attached to the fuel rail by a 17mm banjo bolt.
• Remove fuel injector connectors
• Remove the valve cover by unplugging the spark plug wires and set them aside and remove the four 10mm nuts marked in black, two 10mm bolts marked in black holding the wiring harness cover marked in green, and the PCV valve and ventilation hose marked in yellow.

Valve cover showing no signs of coolant invasion which support the
formation of sludge in the oil cap and PCV valve by condensation

• Remove the air cleaner box and the airduct; you need to release 4 clips for the box and loose the 10mm or Phillips clamp holding the air duct to the throttle body.

• Remove throttle body (you don't need to remove it if you have access to the clamp holding on of the coolant hoses attaching to the throttle; I had  to remove it just to gain access)

The coolant temperature sensor and the throttle body bracket did not allow me
to remove the hose clamp that you can see between them and
I was not able to use nose pliers either under the throttle due to the
coolant hoses.

• Remove the heater water hoses and distributor connectors while you are there.

• Remove all vacuum hoses and mark their location for easy installation. There is a vacuum line hose which you need to remove the wiring harness below the intake manifold.

• Remove the fuel line attached to the intake manifold

• Remove intake manifold bracket, there are two 12mm bolts along the manifold and one 12mm lower holding it to the engine block

• Remove the returning fuel hose from the fuel pressure regulator and the brake booster hose. There is also the nut that you should removed holding the fuel lines to the intake manifold.

• Remove the power steering pump bracket and belt--bolts are 14mm

• Remove the wiring harness from the intake manifold; there are two 10mm bolts holding it (1 marked). Remove the seven 12mm bolts and 12mm nuts holding the manifold and remove the manifold afterwards. Always pull gently and with precaution for not tearing any remaining vacuum hoses or wires that might be still attached.

• Remove the water inlet to the head

• Remove the alternator and the belt. Removing the alternator will allow you to gain access to one exhaust manifold bolt. Remove the water pump belt.
  

• Remove the exhaust manifold from the head (no need to remove it all) and both lower and upper water hoses. The exhaust manifold is attached to the engine block by a bracket, you will need remove it from whichever end.

Manifold Bracket

• Remove the crankshaft pulley. You will need the breaker bar and a 17mm socket. You put it in place and making sure that the breaker bar is hitting against the floor going clockwise. Then crank the engine and that should be enough force to loose the bolt. If you have and impact wrench, utilize that instead.
• Usually, you will be able to remove the pulley without the need of extractor in this engines. I had to use one because rust developed in the pulley which made it bind to the shaft.

• Remove the timing belt covers, there are three. You will need to remove the idler pulley in order to remove the middle one.

• Before removing the timing belt, it is necessary to take the piston #1 (the one next to the big gear) to top dead center so we don't lose our timing and is easier to install later on. There is a notch in the first camshaft cap and a hole in the main gear

Making sure that the four camshaft lobes for piston #1 are not engaging; this
tells us that we are in the compression stroke (TDC) for that piston.

• Next, you will need to obtain a 6mm thread diameter bolt with 1mm thread pitch and 16mm long which will be used to lock the intake camshaft's gears . The bolts of the front cap are 6mm X 1mm and just enough long to use in this case. So remove the cap and utilize one of those bolts to hold the gears in place--you will need to rotate the engine slightly counterclockwise to be able to install the bolt in the gear.   

Always check that the bolt will go in smoothly; if you are unsure of using the cap bolt;
go to a convenient store and buy the bolt described above.

• Loose the timing belt tensioner so you can remove the belt from the main gear. You don't need the remove the engine mount bracket if you are not going to replace the timing belt. If the timing belt has considerable miles in use, it would be good idea to replace it. (The timing belt life rounds between 60,000 to 100,000 miles).

• Now we remove the camshafts making sure that we are TDC for piston #1 and the service bolt is installed in the intake camshaft. It is good advise to get some egg cartons for putting the caps in a orderly fashion. These caps are usually labeled but is good practice to do the egg carton and leave the bolts placed in their respective cap so when it's time to reinstall the bolts are replaced in their respective threaded holes. Also, it is to note that the camshaft caps are themselves the bearings as well as the head mounting places; therefore, special care must be taken in order to not scratch their surfaces, hence, damaging the cap. Also, the camshafts are loose from the center to the sides so we can avoid bending the shaft. 

Loose the caps following this order: loose the bolts marked in red first; loose the bolts
marked in green second; finally loose the ones marked in yellow. Then
finish removing the caps and place them in order in an egg carton. Do not clean the oil
since helps to protect their the journal mating surfaces. Remove the distributor
so the head can be easily removed

Make a mark to the bolt and distributor housing so
you will now where to rotate the distributor when installing
it and not lose the actual timing.

• If you are thinking that you may take more than 2 to 3 days for re-installation I suggest to coat them in new oil and wrap the whole camshaft and gear in plastic wrap and place it in a dry place; this will prevent rust formation in the journals, lobes, and gears. In my case, I always do it regardless of the time a take in repairing.

• Finally, it's time to loose the head bolts and just as the camshafts, you start from the center and moving to the sides so head warpage is avoided. After loosing, you remove the bolts. 

• Do a last inspection for still hooked wires or hoses. Remove the head

Do not be rushed to dry the coolant. Leave it in-place since it has additives
that prevent rust and is important in this engine since the block is cast iron.
This will prevent rust formation in the cylinders.

• This is it in removing the head; I'll be posting other articles in regard to repairing the head and a few notes in reinstalling it and cranking the car after all assembly is done.

Leave your comment or questions!