Mechanics tips and other useful stuff for working on your car


This article has some neat auto mechanic tips that I've come across and other basic mechanical knowledge that you may have been wondering about.  

At the bottom are tips on keeping organized in your garage.  It will make every job faster and less frustrating.  Do you have any good tips?  Post them in the forums.

SAFETY FIRST! - The following or any other information on this site is not a substitute for following common safety practices, professional supervision of a certified mechanic, proper instruction, and common sense!  If at any time you have any doubt of your safety of your persons or property or anyone else, do not continue working on your car and consult a professional.  Never expose open flames or other sources of ignition to any flammable objects around the car or when working with any kinds of flammable objects around the car.  Always make sure there is adequate ventilation and that hazardous vapors or flammable liquids are fully evacuated before you work on your car!  Wear appropriate gloves when working on your car because your hands may be exposed hazardous chemicals.  By continuing, you agree to the TOS Agreement legal disclaimer.

Tips for the mechanic

Always read the Material Data Safety Sheet when working with any chemicals! - These are not on the spray can or packaging for fun!  Before working with any chemicals, do an internet search on their safety!

Did you know that when exposed to MIG/TIG welding, many brake or carb cleaners will readily release phosgene gas so poisonous that a tiny release of invisible vapor is enough for a fatal dose? There are still cases of people dying from this despite widespread knowledge of the dangers. R12 freon released near a running car (being burned) can also produce phosgene gas. Smoking cigarettes around certain chemicals will also produce poison gas - trace gases go into the lit end of the cigarette and come out as poison gas that you just inhaled. Welding galvanized metal releases toxic zinc vapor. Know something about the chemicals that you are working on or at least ask someone who does!

Secure the car as much as possible when underneath it - When you are under your car, your life depends on the car being as secure as possible.  Place the jack stands in an appropriate and safe location and on a solid, flat, even, safe surface as specified in your factory service manual.  Do not let minors work unsupervised on the car.  If you have any doubt that the car is not secure there is no doubt - secure it more. Always check to make sure the car is secure and safe before getting under the car far enough to be injured.  Never get under the car unless it is fully secured and stable, never get under the car if it's on a hydraulic jack.  

After raising the car and resting it on jack stands, I use the hydraulic floor jacks to add additional securing points as a backup only.  It's bad for the jack to hold up the car for a long time, so just have it as a backup in case the jack stand fails.  Jack stands can fail and they do tip over!  Wheel chocks (wedges of wood or other material) around the wheels can help prevent the car from rolling forwards or backwards.  For pictures of jack points on an mk4 jetta, see 1000q: jack points on mk4 Jetta.  For pictures of jack points on a B5.5 Passat, see 1000q: jack points on VW Passat.  For the mk5 Jetta or mk6 Golf, see 1000q: jack points on mk5 Jetta.

In my opinion, using only 2 jackstands is not safe enough for me because if 1 jackstand fails, slips, is knocked over, or the asphalt underneath sinks and cracks on a hot day from the weight, the car could fall down and you could be seriously injured or killed, or result in damage to persons and/or property.   I always use a backup to the jack stands supporting the car and bearing its weight.  This can be a second pair of jack stands.  I may also use wheel ramps to support the front of the car and use jack stands as the backup.  Always make sure the jack stands or wheel ramps are rated for the weight that they need to support.  Also apply the parking brake and put the car in gear as appropriate.  You can put wood planks under the jackstands to spread out the weight, especially on a hot day when the jack stands could sink into the asphalt.  Never get under the car if the weight of the car is on the hydraulic floor jack only.  These could blow a seal and collapse, get tipped over or slip, or have the jacking point slip, etc.!  If you've ever seen a hydraulic floor jack fail, you know how quickly you can die from a failure!  Never get under the car or put yourself in a position to be injured while the car is on a hydraulic floor jack or rely on the "widowmaker" scissor jack in the trunk.  They are for emergency roadside wheel removal and should not be used for regular maintenance or to support the car while you are under it!  Many people have died because they went under the car for just a second and were crushed when the car came down.  Shake the car a little to test how secure it is before you get under and never get under unless it's secure!

Again, always check that the jack stands are placed in the factory recommended jack spots and are placed on a solid, level surface.  Double check their position once the car's weight is rested on them.  If you fail to place them in the proper spot or become complacent in checking them it could result in an accident like shown below.  That one time you say "it's good enough" could be when the accident occurs, like shown below (not mine).  Luckily no one was injured in this case but that crushed oil pan could be your chest and that oil could be your splattered brains.  Hopefully discipline and fear will prevent complacency.

NEVER use cinder blocks as a substitute for proper car jack stands or to support a car.  You cannot see rot, cracks, or defects well.  They are stronger when stacked in one orientation and weak in the other - do you know which direction is the strong one? If you don't and have used cinder blocks to support the car you have risked your life and didn't even known it.  Even if you did use cinder blocks to supporting a heavy weight, you should place a layer of plywood between the weight and the block to spread the load out.  Not using something to spread the load out can cause cinder blocks to suddenly crumble.

I think the best value hydraulic floor jack right now is the costco 3 ton "arcan" aluminum jack.  Not every store may carry it.  It's about 58 lbs vs. 100 lbs for a comparable steel jack, has a lower padded bar to avoid scratching your car, is about $145 after everything, and has a range of 3.7-19.3" so it will fit under most lowered cars but lift high too.  It is not a racing "quick drop" jack so lowering it is safe and controlled, avoid racing jacks in general.  It also has a quick lift feature.  Craftsman jacks tend to leak and stop lifting after a while due to dirt clogging an internal valve.  They can be cleaned and rebuilt but I avoid craftsman jacks now due to their current design.

You could also make your own blocks like the ones pictured below.  Use large coarse decking screws to secure 2x4 treated wood pieces under a solid layer of wood.  Position the end pieces to hold the tire.  Do not use 2x4 that are not securely screwed together or soft wood otherwise it could crack or shift resulting in serious injury or death.  Below are examples of home made blocks.  The last picture also shows ramps that can be purchased at any auto store.  Here are more suggestions on how to make wood blocks in 1000q: making wood blocks.

Here is a good picture of an assortment of jacks, ramps, and jack blocks.  As you can see, blocks raise the car about twice as high as rhino ramps, enough to clear a transmission or subframe from the bottom.  

For wheel chocks, you can use wedges of wood.  I use this rain gutter guide.  It's shaped perfectly for a wheel and heavy enough so that it won't move.

How to free seized and rusted bolts nuts

First, use a hexagon 6 point socket instead of a 12 point socket - 6 sided/6 point sockets on 6 sided nuts/bolts will help prevent stripping vs. using a 12 point socket.  12 point sockets are better for nuts/bolts where you do not have a good range of motion to loosen the fastener.  Don't substitute a torx bit for allen wrench sockets either.  Some VW/Audi bolts are "triple square" bits.  These are specialty VW/Audi bits and are not torx.  Tap them in with a hammer since they tend to not be fully seated and strip, especially on the axle bolts where dirt can clog the bolt head.

Get PB Blaster or a similar penetrating lubricant - these are similar to wd-40 because they are lubricants, but they can also penetrate seized bolts by seeping into the threads of a fastener and eating rust.  Although PB Blaster is about as slippery as WD-40, PB Blaster eats rust and penetrates much better - WD-40 is a lubricant only.  If you are having trouble breaking loose a bolt, spray penetrating lubricant around the edges and let soak for a minute.  It will creep into the threads and help you loosen seized bolts.  Tap with a hammer and then apply again.  You will find that the brakes or suspension will always benefit from pre-soaking since these are exposed to water and road salts.

PB blaster also works on removing seals.  Rear main seals or any other pressed in seal can be hard to remove, especially when you don't have the right size drift to press it out.  It's better to spray the seal with PB Blaster and let soak then to scratch the sealing flange and have a leak.

Other brands of penetrating lubricant or a homemade mix - Machinist's workshop magazine did a test of loosening rusty pins with penetrating oil in April 2007.  The results are below.  Each pin was electrolytically rusted into a hole.  If you search the internet, you'll see references to this rusty bolt test- the test was actually done with pins stuck in holes, not bolts.  The difference is that a pin has a lot less surface area to penetrate than bolt threads.  In addition, the table shows Power steering fluid-Acetone instead of ATF-Acetone because PS fluid was used.  Although an ATF mixture works, the author of the test actually used PS fluid (they are similar).  Most websites also spread these errors, the table below is correct.  The author answered questions about this article and corrected the typo here: homemachinest bulletin board.  

Because of these differences, I find that PB Blaster works better than the other brands of penetrating oil and eats rust.  I haven't tried ATF-Acetone but I hear it works great and is cheap too.  These oils penetrate better if you let them sit and tap them with a hammer.  I would also keep Acetone off rubber or plastics.  Most, if not all of these are flammable. Here is a thread in the forum where other people report on their experiences with penetrating oils.

Penetrating oil Average load (lbs)
None 516
WD-40 238
PB Blaster 214
Liquid Wrench 127
Kano Kroil 106
Power steering fluid-Acetone 53

Also try using a propane torch to loosen seized fasteners - But never use near any flammable objects or vapors.  Heating seized nuts or bolts can loosen them just enough to remove them.  For more heat, try MAPP gas.  For the most heat, use an oxyacetylene welding torch.  Be careful when using oxyacetylene because it can cut through steel when used as a cutting torch.  Never use near the presence of any flammable liquids, objects, or vapors.  Beware of vapors from nearby sources.  Also be careful of any fuel lines, flammable liquids or flammable vapors when using an open flame.  Always maintain adequate ventilation when using a torch and make sure that any flammable vapors or liquids are fully evacuated before using any flame or spark such as torches or pilot lights.

Always open the fill plug before you open the drain plug - If you can't open the fill hole refill the fluid after draining it, just take it to someone who can open the fill hole or else the car will be stuck.  They may have to weld a bar to the plug or use an impact wrench on the plugs if it is too rusted/seized/stripped.

Use a breaker bar - if you find yourself struggling with rusted or high-torque bolts/nuts, use an extension or breaker bar.  A breaker bar is normally a 1/2" square drive that attaches directly to the socket.  I use an extension instead, pictured below.  Yep, just a thick pipe.  Just make sure that the socket isn't twisting on the bolt, otherwise it will strip it.

I use it only with a 1/2" drive because otherwise it will probably break the ratchet.  Craftsman has a lifetime warranty on their ratchets and I don't abuse it too often.  If it's really bad I get out an impact wrench but to use these you need an air supply, impact wrench, and impact wrench rated sockets.  Be careful when using any extension because when it comes loose, you may scrape your hands badly or damage whatever is behind the breaker bar.  I suggest wearing gloves so that your hands are not cut up.  

Using your legs instead of your arms - if you can't fit an extension, are under the car and have no clearance, etc., try using your legs to push the wrench.  Your legs are a much longer lever and much stronger than your arms.  Using your leg will be faster, easier, and leave you less tired.  This especially applies to wheel lug nuts.  When (not if) the bolt suddenly breaks free and your leg slips, your shoe will help protect your foot and using your leg will help you control the force.  Otherwise, your arms and hands will be over stressed, slip, and get cut.

Position your arm/head to be prepared when the bolt breaks - often you can't use your legs to torque a wrench and have to use your arms.  When applying force, position your body so that it is braced for when the bolt breaks or the head gets stripped, so that your arm/head/hands will not suddenly jerk free and injure yourself.  Even if you do follow this piece of advice, you will still occasionally slip and get cut, only less so, and it helps.

How to torque your fasteners properly (aka using a torque wrench) -  The tendency is to overtorque small bolts and to undertorque large bolts, so be aware of this when tightening fasteners.  VW loves to use allen, torx, and 12 point (not torx, also called triple square) head sockets so make sure you have these tools ahead of time.  Almost all torque specs are dry - without oil, grease, threadlocker, or anti-seize.  See 1000q: torque wrench FAQ for more tips and a detailed look at how a torque wrench works, brand recommendations, etc.

Avoid parallax with proper viewing angles - Look at a spot close to your face and close one eye and then the other.  See how the spot appears to move?  This is a type of viewing error called parallax and a similar type of error can cause stripped bolts, improper timing and other problems.  Always try to view bolts, timing points, timing belt index marks, etc., at a perpendicular angle.  If you can't see it or visualize it, use a mirror to view it straight on.  Threads, marks, or pulleys, etc., are not always 90o to the surface.  For example, the glow plugs on VW 4 cylinder diesel engines do not thread 90o to the head - they are threaded at different angles.  If you can't see the bolt, try to visualize it at the correct angle to get the threads engaged properly and try turning it counterclockwise for 1 full turn before tightening it - this can help you "feel" the threads.

When setting the timing belt index marks on the injection pump or using a timing gun on a gasoline engine to check the timing, always view the marks at an angle that will cross its axis to avoid misreading the index marks. Another example is tightening the timing belt tensioner on a TDI.  Some cars have a mark on the tensioner that must be lined up with a mark on the engine block.  Because the tensioner isn't easily viewable from above, I recommend using a mirror to view the tensioner marks and to double check that it is set properly, otherwise it could result in timing belt failure.

A picture showing the correct vs. incorrect viewing angle when examining the green mark.

I was using my clothes washing machine when I noticed another example.  When I'm standing up the knob is viewed at an angle and it looks like the dash is pointing to to medium when it's really pointing at heavy.  To the right is another angle showing that it really is pointing at heavy.

Another example: during a timing belt job on the ALH TDI engine, the injection pump lock pin could fit into more than 1 spot!  If it's to the left or right of the correct hole the engine probably won't start.  When viewed inline with the axis of the pump pulley, the pin is lined up with the center of the square mark on the pump.  Not confirming these marks in line can cause you to misplace the pin!  The timing belt articles on this site show multiple pictures of this pin location to help positively identify the correct pin location.

Use gloves - use vinyl/nitrile gloves or mechanix gloves.  Gloves help keep your garage clean, your car clean, and your tools clean.  Good gloves are the blue or purple vinyl gloves that you can find at any auto store.  Avoid painter's rubber gloves because they fall apart at the slightest scratch.  "Black Lightening" brand vinyl gloves are very tough.  In the winter time, I put a cotton glove under the glove and it also keeps you warm and clean.  Mechanix gloves work well but they will absorb grease and oil so I try to save them for heavier work and when I know my knuckles will get scraped.  You can find them on sale at clearance discounters for about $10-12 or ebay vs. the auto parts store at $20.

Always use a torque wrench on lug nuts/bolts, also try wrapping the sockets in masking tape to avoid scratching wheels - They sell plastic coated sockets for lug nuts to avoid scratches but you can wrap them in masking tape to avoid wheel scratches.  Excess torque from impact wrenches can damage lug nuts lug nuts and even crack the wheel so always use a torque stick with an impact wrench.  Always use a torque wrench, torque stick, or other way of measuring torque on the lug nuts.  I always remove and install the lug nuts with a breaker bar by hand and torque them by hand.  Excess torque will not only damage the wheel and lug nuts, but may also cause wheel vibration.  

I always use anti-seize on lug nuts because it would be impossible to remove a wheel in an emergency situation due to seized lugs.  Caution - almost all torque values in your VW service manual are dry values, without lube or anti-seize - reduce the torque according to the anti-seize data sheet.  As noted above, do your research before playing with torque values or coatings.

Get a good creeper - I used to use a lousy wood creeper that got caught on every pebble.  I had to struggle to move around and this wears you out after a few hours of work.  Get a good creeper that glides smoothly and has 6 wheels.  The 4 wheel models can get stuck on small dips and put more pressure on less wheels.

How to keep track of wires, bolts, etc.! - If your project involves many parts over many days, label everything with a piece of tape/paper, tag, etc..  Time is money, and some don't think this saves time.  It really does save time during reassembly.   Never use pencil to make labels since the lead can get wiped off.  

After removal of an item, I thread the bolts back so that it's impossible for them to get lost.  The ones that cannot be put back are taped onto a large piece of cardboard and labeled with notes written directly on the cardboard.  If you remove a hose or electrical plug, label both sides so you can easily identify both sides. You can also use ziplock bags with permanent marker labels.

I've also seen a particle board peg-hole board instead of cardboard.  These are those brown boards with rows of holes that you stick metal hangers onto. The advantage of this is no wasted plastic bags.  You can also write on the board and thread the screws into the particle board.  The disadvantage is that bolts could fall out and many larger bolts won't fit into the holes.

Do a boost leak to detect any air intake leaks - (for turbo and supercharged vehicles) This causes you to lose power and run poorly because of lost metered air.  Lost air also makes the turbo work harder and put out hotter air than it should.  See 1000q: boost and vacuum leak detection for more details.

Keep the battery terminals clean - This is something that every car owner should know.  Over time, the battery terminals will corrode.  Clean them with battery post cleaners, pictured below.  When pulling the terminals off just wiggle them off, don't pull them hard!  A little baking soda and water is optional.  If you don't drive the car often, a trickle charger will help the battery hold a charge.  You can also put on some battery post sealant afterwards to help prevent future corrosion.

A TDI also may have trouble starting if the battery is low.  If the battery is weak or there is too much corrosion, the fuel pump won't inject fuel, the cranking speed will be too low, or the immobilizer may get confused.

A battery post cleaner - each end has bristles.  It's about life size.  Before and after cleaning. 

Don't let it get to this point!

To dispel some myths, storing the battery on a piece of wood won't effect the charge one way or another.  Also, a regular car battery is not a deep cycle battery, so try to minimize the drain while the engine isn't on and charging the battery.  Listening to the radio, leaving the headlights on while you walk away, etc., will drain the battery if the engine is off and reduce it's lifespan slightly.  If you let the battery drain a few times in "deep cycles", it's lifespan will be greatly reduced or completely fail.

Battery safety notes - don't let the positive side (+) touch the negative side or let a wrench, wedding ring, dangling necklace, or anything else that conducts electricity contact the positive side and a ground such as the body of the car or engine.  This will cause an arc and you could be seriously injured or killed.  Remove the negative (-) side first and reconnect it last for maximum safety.  Also always wear eye protection and observe all prudent safety practices when you are near a battery when starting, charging, working on the battery, or jump starting the car.  Batteries are most likely to explode at that time due to the load and a spark.  If they overheat or get low on water, it will create hydrogen gas which can explode and throw acid all over the engine bay and all over you.  If this happens, immediately disconnect and remove the battery and wash the acid off with baking soda and water.  If it gets on a person, seek immediate medical attention.  

How to avoid extension cord tangles - Are your extension cords tangled in a ball or twisted in loops?  The reason is because you are twisting them when you coil them.  Sailors and electrical gaffers deal with long lines all the time and proper coils = less time/money/frustration.  Do not buy extension cord keepers because they coil the cord too tightly.

When you coil them, do not twist them.  Just fold the line over itself.  You'll notice that it wants to fall in a certain way.  You can also try looping the coil once overhand, once underhand.  Tie it with a string tied to the end of the extension cord.  Do not just tightly loop the end of the cord to tie it - this damages the cord and leads to tangles.  If you have more than one cord or a very long cord, you can coil it inside of a large round bucket - the ones with a warning and an outline of a baby falling in work great!  This way you can also carry the bucket around with all the cords inside easily.


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