Replacing the head gasket, step by step. Part IV: Removing the Head Bolts.

Time to remove the head. But... we want to be able to put back the head in the exact same way later on.
Otherwise...

So we’ll need to document it well.
The chain you see in the yellow area is the timing belt. This drives the camshaft, which can be seen in the red part.
The belt is fastened to the crankshaft on the underside the engine. The cylinders are also on the crankshaft.

This is how it works (in a very simplified way...):
1. the piston goes up;
2. the crankshaft turns and the belt ensures that the red camshaft rotates too;
3. the brown valve rocker pulls open the inlet valve underneath, and a fuel-air mixture flows into the cylinder;
4. the piston goes further upward, the camshaft rotates, the valve shuts, and at (almost) the highest point, the spark plug puts the whole thing on fire;
5. this really shocks the piston ;-) and it’s forced back down by the pressure of the explosion;
6. the camshaft keeps rotating, another valve rocker opens the outlet valve and the burnt fuelmixture flows into the exhaust.

Now is this interesting to know when we want to remove the head bolts?
No, just forget about it.
Yes. Because if the timing belt shifts by just one tooth, the valves open too early or too late and the spark plugs ignite too early or too late.
Result: with one tooth, the engine will probably run joggly. But be ware if the belt shifts by more teeth, because then... nothing will happen: the engine refuses to run.

So what’s the point of this whole story? We’d better make sure the belt is placed over the exact same teeth later on.

So we need to put everything back together in the exact same way. How do we accomplish this?

Here we go.
We place the piston in the first cylinder all the way at the top.
To do this, we go to a wheel at the bottom of the engine that sits on the camshaft. This has a marker.

You can see it here.
The red area shows the crankshaft at the bottom of the engine.
You can see the wheel with the marker in yellow. We used a black marker to make it more visible.

This marker should be at the top. We already placed a big wrench (right) on the nut that’s on the crankshaft.

The wrench on the crankshaft. On the right, the blades of the fan.

The black marker should be precisely aligned with the 0. When that’s done, piston 1 is at the absolute top of the cylinder.

Own idea: to ensure that the belt is placed on the gear in the exact same position later on, we fixed the belt to the wheel with straps (those plastic/elastic straps).

Time to take the gear apart. This will stay behind, while “the head” is taken out along with the camshaft, valves and valve rockers.

The bolt goes off…

Gear is taken off. As you can see, there’s only one way to place it.

A picture of the atmosphere. Click on it to see some more ;-)

Here’s the gear with the chain pulled forward. There’s also only one way to put it back here.

So far, so good...

The gas throttle cable runs along the block, so we disconnect it.

...as well as this vacuum hose.

It’s a little tight, but you can just pull the hose off.

Another hose, this is getting a little boring. Just pull it off.

But do NOT forget to label it!

Now to detach a few connectors.

Connectors, connectors and even more connectors. Detach them all after you’ve “lettered” them.

...and another wire. Just pull it loose.

And this is what it looks like after the demolition.

                                 

Time to start what we came here for: removing the head bolts. But it must be done carefully. Loosening random bolts will probably lead to a cracked head.

We turn to Toyota for some advice on paper.

We follow Toyota’s wise advice and start on the bolt all the way in front, before the gear even.
The picture isn’t that sharp, but our goal is clear: the bolt in the yellow area.

We work our way from bolt 1 to 10. BUT: we do this in stages. So first you loosen 1 a little bit, then 2, then 3, etc., until you get to 10.

Then you loosen bolt 1 a little more, then bolt 2 a little more, etc.

We did this in three stages.

Here, bolt 1 is being loosened slightly. As you can see we use a solid wrench because the bolts are pretty tight.

And here we are at number four...

Some of the bolts came off smoothly. The thread looks like this.

But bolt numer 8 wasn’t in the mood. It came out with great difficulty. And so the thread on it looked like this...

Inquiries with Ferry and LandCruiser-forum-Ron (thanks to both!) produced the following recipe for baking such a damaged bolt. Also thanks to Mark for information on the bolts themselves!

One takes a pinch of engine oil, a bit of fuel-air mixture and some drops of coolant.

One presses that together well.

Then one puts it on fire (we hired the spark plug for that :-))
The result is the black gunk you see on the thread.

And because the head gasket is broken, this also gets to the bolt.

We’ll try to remove it with a bristle.

The screw hole is filled with this deposit. We’re going to twist a tap (which is a sort of bolt with sharp thread on the outside) with the correct external thread in it, in the hope that the gunk will come off...


---more next time---

Replacing the head gasket, step by step. Part III: Disassembling the Area Around the Head

Disassembling the head. But what exactly is "the head"?

It's the part shown in the following picture.

“The head” consists of several parts:

-         the camshaft. This operates a number of levers (the "valve rockers")
  that...

-         open and close the valves.

-         these valves are in a "cover" that sits on top of the cylinder. This cover
  is called the cylinder head.

Because this is a four cylinder engine there are four covers (cylinder heads) in a row, all in one metal housing..

Which is a little confusing, because this metal housing with the four cylinder heads is called "the head".

We're going to remove the complete head so we can get to the gasket between the "lower block" and the head. The lower block is the part that contains the cylinders and pistons.   

You still with us? :-D

Good, then we can continue with the photo manual.

This is a top view of "the head".
Click a picture to see it full screen.

The colors:

- yellow = the timing belt. We'll see that again later on;

- red = a valve rocker, which is basically a lever that opens and closes a valve.

- blue = two of the ten (actually eleven) head bolts. These are screwed straight through the head into the lower block.

- green = part of the camshaft. The cams move the rockers up and down.

A little more information, this makes it easier to understand what we're doing.

- yellow = the tube through which coolant flows from the radiator to the engine;

- blue = the fuel pump;

- green = the fuel pump's drive: a lever (to the left in the green part) that runs over a wheel which has an opening that's not in the center (for word puzzle lovers: eccentric :-))  This makes the arm move up and down, thus driving the fuel pump. Actually pretty simple, but also quite ingenious;

- red: the aforementioned timing belt.

Next step: disconnecting the three hoses from the fuel pump. All neatly labeled...

Get rid of the supply tube that connects the radiator to the engine.
Unscrew and remove the tube clamp.

Take out the two bolts that connect the fuel pump to the head.

...the fuel pump and lever can now be removed.
As you can see, no more dirt can get under the nails. That space is already full ;-)

...and this is what's left.

An interesting picture, because you can see the ultimate goal of our labor, the head gasket. This is the thin, black line you see in the red circle.
But you also see:
- the fuel hoses are connected to the intake manifold, these stay connected to the head. The fuel lines must therefore be disconnected, which you can see in the yellow "circle";;
- the law of communicating vessels still applies, which is why coolant keeps dripping from the engine. This happens in nice, separate drops that you can see in the green area.

Now it's time to disconnect the bypass hose (in yellow): when there's no need for cooling, the coolant immediately flows back to the radiator..

To remove: unscrew the hose clamp and pull the tube off while twisting simultaneously.

The green part is the intake manifold.

And then we got tired of the coolant's constant dripping. So we drain it the LandCruiser way: open the tap and let it flow. Nice and simple.

Time to take a break and have a look at the joint packing. That's a lot.

And this is our "objet du désir" (object of desire): the new head gasket.

The accompanying description provides valuable information, including the cylinder diameter (92 mm), order in which the head bolts need to be tightened, and torque. More on that later.

Click the picture for a (very large) magnified view.

Meanwhile, there's still something in our way on the right side of the engine block: the power steering pump (in yellow). We'll have to take it off.

By unscrewing this bolt you can detach the pulley (= wheel with a notch for the V-belt on the outside) and move it to the right, so the V-belt that runs over it can be removed.

Then the bolts are removed from the power steering pump, and the pump can be taken out in its entirety.

This can be seen here.

Now it's the exhaust's turn. A manifold is attached to the right side of the head. Each cylinder has its own exhaust and the exhaust manifold turns the four pipes into one. This is the exhaust...

The exhaust manifold (the red part shows the connection to the head) is a little bit hot, so a sort of shield is placed in front of it: a heat shield (yellow).

The heat shield (yellow) is disconnected. The manifold is visible in all its glory.

By twisting the nuts off the manifold, you can pull the manifold forward.

---more next time---

Replacing the head gasket, step by step. Part II: The Valve Cover.

The next step in replacing the head gasket or replacing the head: removing the valve cover.

We'll need to remove a few things first.
Starting with the distributor and the spark plug wires.

The spark plug wires are up first. We've learned from our earlier experiences with S's Porsche 924, and label the connections and cables well before we get started.
An overview picture.

A convenient distributor which is already numbered.

Even the spark plug wires have numbers.

Just to be sure, we number the spark plugs anyway. Little extra work, and saves a lot of time when reconnecting.

...and the spark plug wires can be disconnected.

The cable from the contact points to the ignition coil. Everything was thought through on this Toyota. The cables are fitted with a watertight plug and socket and are easy to disconnect.
Here's a (green) plug-socket.

Plug out of the ignition coil (right side).

Take out the dipstick.

The vacuum hoses have been labeled and are taken off the distributor.

The distributor housing can be rotated slightly to delay or speed up the ignition timing. This has been marked here.

Bolt number 1 on the distributor is loosened.

After the bolts have been loosened, the whole distributor can be pulled out.

This is what the distributor's drive shaft looks like.

To prevent dirt collection, a clean cloth is placed in the opening.

The hose for the oil supply at the valve cover is loosened and removed.

The gas throttle cable is removed from the support on the valve cover.

The four bolts on the valve cover are loosened and removed.

The rubber rings seem to be stuck quite nicely. We were able to remove them by pulling upwards while twisting.

And... the valve cover can be lifted off!

This is what the top looks like. Click the picture to view it in full screen.

---more next time---