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A d v a n c e d   A u t o   M a i n t e n a n c e


Maintenance lessons learned...

Hereís a comprehensive collection of auto maintenance lessons learned the hard way to enable you to avoid common pitfalls and save yourself a lot of trouble, time and money:

Only use six-point sockets to protect fastenersÖ

If you work on your vehicle yourself, it is a really good idea to only use six-point sockets wherever possible when unfastening bolts or nuts, rather than twelve-point sockets which can tend to slip and round the heads of the bolts or nuts (i.e. damage the heads by knocking the edges off), which makes them more difficult to unfasten the next time around.

A six-point socket has six corners inside the open face of the socket and can be placed on the same-sized bolt or nut in six different rotational positions.

A twelve-point socket has twelve corners inside the open face of the socket and can be placed on the same-sized bolt or nut in twelve different rotational positions.

A set of 3/8 inch drive and 1/2 inch drive six-point sockets of adequate quality should be available inexpensively from your local automotive parts shop or tool outlet.

Replace all damaged fasteners...

Replace bolts or nuts on the vehicle with rounded heads or other damage as you come across them.  Bolts or nuts with rounded heads are difficult and problematic to unfasten, requiring a lot of time and causing a lot of irritation for you or your mechanic.  Itís really best to never put a bolt or nut with a rounded head back in its same position but rather to replace it with a new, genuine bolt or nut if available.

If a bolt or nut is not available as a genuine part, some companies specialise in providing a range of bolts or nuts to match.  Itís simply a matter of taking the damaged bolt or nut to the company so that they can match it.  After obtaining a replacement, itís best to keep the original damaged bolt or nut in a labelled snap-lock bag so that other matching bolts or nuts can be purchased in the future if required.

Donít over-tighten fastenersÖ

One of the biggest obstacles facing people who are new to auto maintenance or working on cars is that they tend to over-tighten fasteners like bolts and nuts.  This is understandable since they have a correct perception that itís important to ensure that the fasteners donít come loose and threaten the safety of the vehicle (e.g. wheel nuts which hold the wheels on!).

However, fasteners generally donít have to be tightened as much as many think.  By obtaining a torque wrench and learning to observe the torques specified in the ownerís manual and other manuals (such as a workshop manual for the vehicle), you can develop a better understanding of how tight fasteners really need to be.

A torque wrench is a socket wrench that allows you to select the torque you want to apply when you tighten a fastener such as a bolt or nut.  Torque is mostly measured in foot pounds or Newton metres.  The higher the torque, the tighter the fastener will be tightened.  You select the torque you want to apply on the torque wrench and proceed to tighten the fastener.  When you hear the torque wrench produce an audible Ďclickí, then you know that the fastener has been tightened to the torque you specified and you can stop tightening it.

Personally, I always use a torque wrench on a fastener like a bolt or nut when there is a torque specified in the workshop manual for that fastener.  It eliminates guesswork.  Where no torque is specified for a particular bolt, thereís generally information available in the workshop manual to specify the torque that should be used on bolts of different diameters.  (Itís worthwhile obtaining a pair of inexpensive, plastic vernier callipers from your local automotive parts shop or from your local hardware store in order to accurately measure the diameters of different bolts.)

Donít snap bolts with rubber washers under themÖ

It is important, however, to be aware when tightening bolts or nuts that have a rubber washer or bush underneath the head of the bolt or the nut, that even if a torque is specified and a torque wrench is used, the torque wrench will often fail to Ďclickí at the right torque due to the rubber washer or bush compressing as the bolt or nut is tightened.  The result is usually a snapped bolt or stud due to over-tightening.  (It makes a really loud noise when it snaps, like a bomb going off!)  Having had this happen to me a couple of times, Iíve learnt my lesson.  Although itís quite exciting to snap a bolt, itís really just an inconvenience and is best avoided.

How to remove a snapped boltÖ

A snapped bolt can be removed from the place that itís screwed into using a screw extractor.  You drill a hole into the face of the snapped bolt which matches the size of the screw extractor that youíre using.  You then screw the screw extractor into the bolt in an anti-clockwise direction because the thread on the screw extractor is a reverse thread.  After the screw extractor is tightly inserted into the bolt, you keep turning anti-clockwise so that the actual bolt itself begins to unscrew and until the bolt is removed completely.

Avoid using a knife to remove hosesÖ

When removing a stubborn rubber hose from the vehicle such as a coolant hose, heater hose or vacuum hose which doesnít come off easily, itís best to only use a knife as a last resort to cut through the rubber because of the high risk of scoring the sealing surface of the metal or plastic stub over which the hose fits.  This kind of damage to the sealing surface, however minor it might appear to be, can result in the replacement hose leaking because the damaged surface now has a tiny channel cut into it caused by the scoring which can allow that leak to occur.  This is especially relevant to hoses in the cooling system because theyíre under great pressure during engine operation as the coolant heats up.

A better method of removing a stubborn hose is to heat the rubber hose with a hair dryer or heat gun while avoiding heating the stub onto which the hose is fitted.  This should cause the rubber hose to expand so that itís easier to remove.

If you still need to use a knife to cut through the rubber, itís important to exercise a high degree of caution to avoid cutting through to the stub and scoring the sealing surface of the metal or plastic stub over which the hose fits.  One way of minimising the risk of scoring this sealing surface is to use a knife with a retractable blade and only allow the blade to protrude a small distance that is less than the thickness of the hose that youíre cutting.

Use a little grease when installing hosesÖ

When youíre installing any rubber hose onto the vehicle such as a coolant hose, heater hose or vacuum hose, itís a good idea to smear a light coat of light-weight grease (such as Vaseline) onto the metal or plastic stub over which the hose fits.  In the case of vacuum hoses, only an extremely light coat of light-weight grease should be used to prevent the grease from contaminating the vacuum system.  This light coat of light-weight grease will go a long way to making sure that the hose is easy to remove the next time around.

The grease minimises the likelihood of chemical bonding occurring between the rubber hose and the metal or plastic stub, which often makes rubber hoses very difficult to remove.  Even though itís unlikely that youíll need to remove the hose again for quite a while, when you do eventually come to remove it again, youíll be grateful to yourself for the easy manner in which the hose slides off after only a little force is applied.

Only drain oil when itís hotÖ

Before draining and replacing fluids such as engine oil, automatic or manual transmission fluid or differential fluid, itís good practice to drive the vehicle until the fluid to be drained and replaced is hot.  This maximises the percentage of contaminants removed from the engine, automatic or manual transmission or differential that the fluid is being drained from.

Only drain coolant when itís coldÖ

In contrast, the coolant should strictly only be drained from the cooling system (which includes the engine) when itís cold and the engine is cold, so as to prevent burning oneself and to prevent possible damage to engine components in the form of warping or cracking.

If the coolant is drained when itís hot and the engine is therefore hot, colder air moves in to replace the drained coolant.  This colder air can cause some parts of the metal components in the engine to cool more quickly than other parts of the same components.  These different rates of cooling can actually result in the metal components cracking or warping.

Certainly the forbidden practice of flushing a hot engine with cold water from a garden hose after draining hot coolant from it would escalate this kind of damage and destroy the engine.  An engine empty of coolant should strictly only be flushed with cold water when that engine is cold.

Wash off spilled coolant or brake fluid with waterÖ

If any coolant or brake fluid is spilled on the paintwork of the vehicle, wash it off immediately with water to prevent it from damaging the paintwork.  Do not wipe it off.  Coolant and brake fluid both eat into the paintwork, making it soft so that wiping the fluid off could smudge and damage the paintwork.

In addition to having a garden hose close to where your vehicle is parked at home, itís quite handy to also have a plastic watering can next to the garden tap, which can be quickly used to wash away small spills such as coolant or brake fluid on paintwork.

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