Any good head gasket requires that it get properly torqued. I am going to outline some of the tips that go with making a head gasket work properly and last as long as possible.
I believe it goes with out saying that cleanliness is an absolute must. When you read my article on head gaskets you will note that I emphasize having clean mating surfaces so that the gasket takes a hold of the metal. Using acetone and alcohol will ensure that it has that edge the gasket material can get a hold on to.
You will need before you move on:
- a good square of glass about 8 inches,
- 800 grit wet-dry sand paper,
- some light oil
- small wire brush
- can of spray carburetor cleaner
Find a good stable flat surface to place the glass onto, put a section of wet-dry sand paper down with the grit side up on the glass. Put a teaspoon of oil onto the paper. Find the acorn nuts that hold the head on. Place the flat side down on the paper and using circular strokes, polish the end of the nut until it appears flat. This re-establishes a new flat surface for proper torque. Next do the same thing with the washers on both sides. This will ensure a level torque to the washers, and seal the head from leaks around the stud. Any grit under the washer will cause a water leak. Last, take the carb cleaner and the small brush to clean the threads on the nuts to remove any residual grit or grime.
Install the washers with the curved side up. The thin washers go on top of the engine lifting bracket. Next is to oil the studs with enough oil to coat the threads. I hand install the nuts until they make contact with the washers. Set the torque wrench to 25 lbs and following the factory torque sequence of cross torquing and working your way out from the center, set the value. Turn your torque wrench to 40 lbs and repeat the process. My last setting is to the factory value for your particular engine, rechecking twice to make sure they are all the correct value. Last step is to clean up any residual oil left behind.
I can’t imagine having to do a head gasket or work on an Alfa, or any other car for that matter with out a good “quality” torque wrench. There are several types that I will discuss the good and bad of each one. I have my preferences as you probably do too, so just understand this is my opinion and not to cast stones at any ones preference. The several types are: slipper, click type, beam, electronic, programmable electronic and mechatronic/angle.
Slipper torque wrench – this wrench will slip when the proper torque is reached and will not go any further.
Deflecting beam torque wrench- This is usually what a novice will get because of cost and how often it will be used. This is just a simple pointer indicator on a dial to give you a close approximate to the desired value. I have seen better ones with a gauge that you can adjust so that it comes to zero before you use it. How wide the gap is between the increments would be better for a more accurate result, compared to a gauge that is narrower between the marks.
The click type is the most popular as it releases tension when the device reaches the dialed in torque value and you hear or feel the “click”. There is also the ratcheting head so it can be used like a ratchet without having to remove the tool for going forwards as well as backwards. Usually the torque is dialed in by twisting the base of the wrench to the ft/lbs that are desired in half/lb increments. Then the tool is applied and torque is introduced. As the bolt or nut reaches the value, the torque wrench lets go with a click and no more torque should be applied.
These come in various torque ranges from in/lbs up to 250 or more ft/lbs.There is now the electronic version that has an electronic indicator number face and an audible tone when the torque is reached. The strain on the transducer measures the torque.
The programmable torque wrench works the same way but with a preset limit.
In addition to this is the “angle” torque wrench. When the torque is set, then an angle gauge is installed and the torque wrench is swung to a set factory limit in degrees. The Alfa cylinder head on a V6 is torqued to 80 lbs and then angle torqued. This device usually sits between the bolt or nut and the torque wrench.
Lastly is the mechatronic torque wrench which is a “click” type, with a transmitter to a remote box that reads output on a numerical face.
Always remove the torque from the wrench before storing and in a box that protects it. This is a precision tool that if properly it will last a very long time with repeatable accurate results. If you buy a high quality torque wrench like Snap-on you can send it back to the factory for re-calibration.
I personally have a Snap on beam torque wrench with a rotating dial so I can reset my zero point and a movable indicator for setting the limit. When the dial indicator for torque moves it reaches the movable limit indicator letting me know I am there. It is simple and accurate. The end of the torque wrench is open for inserting a longer arm so less pushing force is applied over the longer distance.