This is my first Instructable... Please comment below if it needs further editing. Videos can be seen by opening the video URL in your media viewer.
Here's my experience with replacing a new head gasket on my '91 Civic. But first, some background:
This is a great car! It ain't pretty but it gets almost 40mpg on a good day. About a year ago, it failed to pass several emissions tests. My mechanic told me that the pistons needed new rings. Because the engine would be in pieces, and because of the expense and effort invested already, I agreed to have the water pump, timing belt, and head gasket replaced. Afterwards, the car passed emissions with flying colors and ran very well until recently.
Several weeks ago, the engine began to overheat erratically. After googling the problem, I personally replaced, in ascending order of expense, the radiator cap, the thermostat, and eventually, the radiator, which was very old. Because the problem was intermittent, it seemed that each part replacement solved the problem. I hoped it wasn't the water pump because I knew that would be a huge pain to replace.
In the end, some white smoke and serious engine vibrations told me that it was not the water pump but some cylinder/coolant related problem. I was afraid that it was a cracked cylinder which would have meant replacing the engine block, which didn't seem worth the expense on a 16 year old car with 174,000 miles on it. So, I went into the engine bay prepared for the worst. What follows is my experience and illustrates why your trusted mechanic can't always be trusted....
Step 1: You are probably NOT a mechanic....
To get started you might want the Haynes repair manual, and a couple of impact-wrench quality sockets; I broke a Craftsman socket trying to remove the header pipe from the exhaust manifold. Having a digital camera might also be useful for recording your progress as well as problems you might encounter. You MUST have the following:
About 16hrs total total time: In addition to putting the valve assembly back on the head, putting the timing belt back on MAY require that you remove belts, pulleys, and an engine mounts, just as if you would replace the water pump. In fact, if it's old, plan on replacing that water pump. Also plan on changing the oil a couple of times as well as flushing the radiator. Sorry, but it's a big job, which is why a $30 part requires about $1,000 worth of labor. Don't bother taking shortcuts; I tried to lever the timing belt back on to the valve pulley to avoid the proper way and ended up ripping it. Plan on spending the time to do it correctly....Sorry! But you might as well learn from my boneheaded efforts.
Several Jackstands: You will need these to elevate the car and get deep underneath.
A torque wrench up to 70ft-lbs.: Don't even THINK of tightening the crankcase bolts without one!
A breaker bar: Some of your exhaust system bolts were likely tightened by Lucifer himself. A breaker bar will help release his grip.
3/8" and 1/4" drive socket sets: Also with various extenders, adapters, and universal joints.
Band-Aids: If you don't know why, you'll see soon enough.
Call the local parts supply places for expertise. The counter help might include gals/guys who are going to mechanic school or have rebuilt engines just like this one. Their help may be invaluable.