I'd sort of like to be a mechanic

May 15, 2007 6:32 PM

I've always liked cars, but I'd really like to learn how to repair them and get some hands-on experience, if possible. How can I do this?

I got my very first car (ever) about two months ago, and ever since then it's really been bugging me that I have almost no idea how it works, and thus what could go wrong, and why, and so forth. Part of the reason I want to know this stuff is that it just seems bizarre to rely on something so much without having any idea of how it works, but a big motivation is that there are a lot of things that can and probably will go wrong on this car and I'd like to know how I can take the best possible care of it.

It's pretty much the car of my dreams- it's a 79 Benz (not a diesel), but I know that it wasn't the most practical choice of transportation for a semi-broke college student. To that end, I'd really like to know what kinds of things I could reasonably learn to work on myself, and what sorts of things I should surrender to my mechanic (who is trustworthy and excellent, but I'd still like to do some of it myself if possible). I never learned anything at all about cars growing up (my grandfather actually is a mechanic, but he told me girls couldn't do that kind of work and so he wouldn't teach me anything) so I recently bought an introductory automotive mechanics textbook, along with the specific repair manual for my car, and I feel like I'm gaining a decent understanding of basic stuff. However, I'm really hesitant about ever trying to perform even a simple repair myself, until I have real experience of what to expect, what it's supposed to look like, and so forth.

It seems like the obvious answer would be to enroll in some community college courses in this field, but the problem is, I work full-time when I'm not in school, and when I am in school I work on the weekends. So, is there any hope for me or will I have to wait until that misty time in the future when I might have time for something like that? If you occasionally perform repairs on your own car, where did you learn to do it?

(I looked at this question- http://ask.metafilter.com/28606/Teach-me-how-to-fish-FOR-CARS- but I don't have a friend with a garage, or who have the knowledge I'm looking for, and my ambitions are a lot humbler)

posted by Oobidaius to education (26 comments total)

Buy the Haynes repair manual at the local auto parts store and start at chapter 1 (Basic Maintenance). Then have a good look at the troubleshooting section. Joining a good auto forum dedicated to the Benz will also prove enlightening.
posted by IronLizard at 6:40 PM on May 15, 2007

I should say: Buy the manual that covers your particular year/model.
posted by IronLizard at 6:41 PM on May 15, 2007

Oh yes, Harbor Freight will be a great resource to get some of the tools (cheap!) found in the Basic Tools section of the manual.
posted by IronLizard at 6:43 PM on May 15, 2007

Buy the set of factory manuals from your local MB dealer's parts dept. I've got the factory manuals for my '66 MB 200d and they are amazing. Expect to pay about $150 for the pair and be prepared to be blown away at the detail they go into.
posted by buggzzee23 at 6:45 PM on May 15, 2007

I forgot: there are 2 factory manuals: the engine manual for the engine and the chassis manual that covers everything else.
posted by buggzzee23 at 6:46 PM on May 15, 2007

Sorry, I jumped the gun here. You already have the manuals (I hope you got the Haynes, I wouldn't recommend the Chilton's for a beginner), I see. Well, let's start with me. I learned to fix cars by breaking them constantly (no joke) and then fixing them. I had no one who could teach me very much, but being inquisitive at the parts counter and to various other people I would meet would flesh out the missing bits in the manual and teach me a few tricks here and there. Sometimes you can get very lucky and find a few retired mechanics at the parts stores who have nothing better to do than talk all day long :)
The only way to get this hands on experience (other than a course) is to dive in and follow the instructions. You'll be pleasantly surprised at how simple most operations can be and, on the other side of the coin, irritated at how complicated some basic maintenance items are. What, for example, are you thinking of taking on right now?
posted by IronLizard at 6:52 PM on May 15, 2007

Seconding IronLizard's Harbor Freight recommendation. When I did what you're doing (though I was doing so with an old Ford truck), Harbor Freight was practically my second home.

Good luck! It's great fun working on old vehicles, I've learned. I hope you enjoy it as much as I did.
posted by barnacles at 6:52 PM on May 15, 2007

Start with stuff that is easy, routine. and simple to verify that it has been done correctly. Changing the oil, fluids, spark plugs and fuses, all as needed. Follow the instructions meticulously; have a back-up plan for your plans if you mess up your car. Understand the function of everything in the engine bay that you can see. Consult your manuals every day. Browse a junkyard and check things out. Work your way up from there.
posted by jcwagner at 7:09 PM on May 15, 2007

Thanks for the answers so far- in terms of what I'm trying to do right now, thankfully there is nothing urgent. However, my front brake pads will need to be replaced in a few months, and the rear hydraulic brake booster is also going to need replacing (alas). So, I think the second one is pretty much out of the question for me, but maybe doing the first? Unless it's one of those complicated basic maintenance functions IronLizard is referring to. The car is older than I am, and it has about 280,000 miles on it, so I doubt I'll have a problem finding things that need to get fixed.
posted by Oobidaius at 7:13 PM on May 15, 2007

Just start doing things on your car. Make sure you read and understand what you are going to do before you do it and then go slowly. Find the online community for your car (there surely is one for that vintage of MBs) and read and ask questions there. Pop the hood and spend some time learning what all the different parts of the engine look like. Try to follow the path that fuel or air takes to get to your engine. Learn what all those different fluids are for. Buy yourself some basic tools (sockets, bits, and wrench, torque wrench, jack and jack stands) and then start with the easiest jobs. Could your car use a new air filter? Changing the air filter is usually very easy (perhaps even no-tools-required easy). Changing the oil is only slightly more complicated. Once you get going, you'll come to understand what you can do yourself and what to let your mechanic take care of.

I learned (what little I know) about car repairs and maintenance by doing.
posted by ssg at 7:21 PM on May 15, 2007

Replacing brake pads is not very hard at all: go for it.
posted by ssg at 7:26 PM on May 15, 2007

Bentley manuals are pricey, sometimes hard to find, and completely blow Haynes and Chilton out of the water.

Also, do some poking around online and find a good classic Mercedes enthusiast site. Look for W123 models. (The designation given by Merc to identify your series of car.) You'd be surprised at how many nifty tips and tricks you can pick up just poking around the forums, and there's usually a few helpful sorts around who will answer any particulars you're dying to know.

A decent set of socket and combination wrenches is a good place to start for the inevetable tool collection you'll want to have around.

Having someone with a good general knowledge of car repairs present the first few times is incredibly handy, as long as they're patient and willing to help you learn. Plus, it's great fun to have someone there to drop tools on your face while you're under the car. (Thanks, dad.)

My final bit of advice? Zip ties are your best friend, maybe even moreso than duct tape.

Now get out there and get grimy!
posted by The GoBotSodomizer at 7:34 PM on May 15, 2007

Thanks for the Bentley manual recommendation- mine's actually the W116 (450 SEL) so it looks like they don't have it for those. But if I ever get some of the other old models I covet, I know where to go now.
posted by Oobidaius at 7:42 PM on May 15, 2007

I'd avoid starting with brake service, just because they rate awfully high on the "capacity to kill you if you screw up the repair" scale.
posted by mendel at 7:47 PM on May 15, 2007

Seconding jcwagner's advice. To that I'd add, pick a project for the car that's not routine and that really gets you excited, and then do it. One that will give you a lot of bang for the buck, whether it's emotional (make it into a convertible!) or practical (rustproof the sh*t out of it and paint it too). Congrats, it's really rewarding to wrench your own car!
posted by cocoagirl at 8:14 PM on May 15, 2007

I'd suggest you buy at good set of wrenches, ratchets and sockets. You can Harbour Freight specialty tools but a $100-150 spent at Sears on one of their 150-200 piece mechanics sets will be money _well_ spent. Working with cheap wrenches is frustrating, can create work when they round off a fastener, can cause injury when they slip, and are generally depressing. You want to be excited about getting your tool box out. It's hugely cheaper to buy a huge set at the outset than buy your kit one socket/wrench at a time.

You also _need_ a set of jack stands if you ever get the wheels off the ground. I like having two sets for some jobs so you can get both axles off the ground.

If there is a u-pull junk yard in your area it's a good place to get experience removing things on cars you don't care about.

Absolutely join a web forum or mailing list (or two or three) focusing on your model if you can. They are an invaluable source of perfect knowledge and car guys have MAS in spades. They'll be able to tell you what is going to go wrong before it does.

On zip ties: get the black ones not the white. The black are UV stabilized.

On brakes: if you decide to do it do one side at a time. That way if you can't figure how to get it back together you can look at the other side for a reference. Also a digital camera can help out in this regard.

On 280K mile cars: Replace every vacuum hose, heater hose, rad hose and belt as you can afford it. Start with the vacuum hoses because often drivability problems are caused by cracked or hardened hoses. Next do the belts and keep the old ones on hand, they make a good spare set. Expect things to go wrong with alarming frequency (compared to a new car) so keep your tools, a flashlight and small tarp (for lying on) in the trunk. Some spare fluids wouldn't hurt either along with some duct tape, zip ties and a bit of wire. I like to keep a 1lb roll of stainless steel welding wire in my vehicles. Better than baling wire as it won't rust and therefor won't get rust on your hands.
posted by Mitheral at 8:22 PM on May 15, 2007

Ask all your friends if they know how to do this stuff. It is vastly easier to learn with someone who has done it before than from only a book. The book will say "remove part a" but then you will find part b in the way, and one of the bolts will stick, and when you put it back you will forget to lube the threads so that next time the bolt will break when you try to take it out. Yes, you can learn with a book, but trust me, you will end up with far fewer leftover bolts and nuts that you have no idea where they were supposed to go if you have an experienced person walking you through the process.
posted by caddis at 8:24 PM on May 15, 2007

rear hydraulic brake booster

I think you're referring to the Vacuum Brake Booster, no? Big pancaked cylinder right behind the master cylinder? This isn't so much complicated as it is a PITA, because you have to remove the four bolts that hold it to the firewall from inside the car. It requires flailing about with your head under the dash, at best.

The brake pads up front, OTOH, are a perfect thing for a beginner to tackle.


What you will need:

1) A very large 'C' clamp to compress the piston(s) back into the calipers
2) New pads
3) hydraulic jack (not the thing that came in your trunk, though it can work in a pinch)
4) Jack stands
5) I recommend nitrile gloves (or latex, or whatever) and throwaway clothes (this job is DIRTY)
6) A decent socket set (probably metric for this vehicle) and you may will want a breaker bar
7) 2 Cans Brake cleaner spray (3-4$ at the parts store) Your choice if you want them
8) Brake lube (you'll be given a packet with your new pads most of the time, don't get this on the brake rotor or the contact surface of the pads)
9) A spare vehicle, or a ride to get your rotors machined if necessary (be prepared to buy new ones, or you can reuse crappy, unturnable ones if you must) or some 800-600 grit sandpaper (aluminum oxide type, not the stuff you use on wood) if you're not going to do that
10) 2 three foot lengths of rope or two wire coat hangers
11) A digital camera is nice, but not absolutely necessary
12) A rubber mallet or a length of 2x4 or Big screwdriver, prybar
13) A small mirror can help you determine what kind of

Get used to you jack before using it. Don't use it on a surface with any type of grade, you want a nice flat concrete slab, preferably. Most of the jacks I've used have this 'catch point', where it'll get suddenly hard to turn the handle. It's easy to keep turning too hard and it will suddenly get past this point and drop the car HARD. You want this to be while you have one side of the car jacked up with it's wheel still on, not when you're trying to slowly put it on a hard steel jack stand. Dropping it hard on one of these will almost certainly bend something (might be just cosmetic, might not). Practice lowering slowly a couple of times to get the hang of it.

You're used to it? Great. Engage the emergency brake. This is very important.

Press the brake a few times while the car os off to relieve pressure in the brake booster (you'll hear it hiss and the pedal will harden)

Loosen the front lugnuts on both wheels, but don't move them very far, just enough to make them removable later. (If you forget this part and you're already on the stands, you can make someone get in and hold the brake while you remove them. )

If your vehicle had a jacking point in the center, front this will be best. Otherwise, jack up one side and put a stand under it, in the approved jacking location. Lower the car slowly onto the stand. Jack up the other side carefully and repeat.

At no point in this process should any part of your body be under the vehicle.

Now, it's safely(?) sitting on the stands, right?Stand back a bit. Push on the car. Shake it. Better to have it fall now, onto it's wheels, than onto you while your wrestling with and cursing at a particularly difficult bolt, right?

Remove the Lugs and both wheels.

Spray liberally with brake cleaner.

Now is the moment you decide whether or not you need to machine/replace the front rotors(discs). If they're badly grooved or the car was exhibiting shaking when applying the brakes, this is certainly a good idea.

There are usually two bolts that hold each caliper on. In my experience they are all either Torx or allen (recessed hexagon) style. You manual should tell you which, and you did get the appropriate socket/bit, right? Well, starting with one side, remove these.

Now you pull (if it's nice) bang, pry and generally go nuts on the caliper (if it's not, remember the 2x4, mallet, ect)

Do not ever let the caliper hang by the rubber hose attached to it. This is why you have the rope/coat hangers to attach it somewhere (I use the big spring, you can use whatever you like or find handy.) Tie them up to something when they're loose.

There may be metal clips and a few other little pieces attached in there (anti-rattle clips, ect). Don't worry about these too much but pay attention to where they go. You don't want noisy brakes, do you?

Now, remove the cap to the master cylinder reservoir (thing where brake fluid goes).

Use the big C clamp to compress the cylinder down into the bore as far as it will go. (Note, some fords used composite cylinders on their brakes instead of metal. These can't stand up to a clamp worth a damn and you'd need to use a thin board in between them and the clamp, YMMV, I hate fords.)

Put in the new pads and whatever associated hardware while your memory is still fresh, remembering to grease the metal parts of the pad where they contact the caliper. If they don't want to stay in place on their own, just be sure to remember how they need to be so you can hold them in place while slipping the caliper on the rotor.

Take your rotors in to the machine shop or parts store that does this (oreilly's here) for a quick machining/surfacing OR

Carefully roughen up your calipers with the fine sandpaper in a motion that is outwards from the center (don't go in a circle around the middle). This will break the glaze and allow the new pads to break in properly. Don't overdo it.

Put the rotors back on.

Slide the calipers back in place, and bolt them on tightly. The manual recommends a torque wrench. I do too. But sometimes, when I'm lazy, I just tighten the hell out of them.

Put the wheels/lugs back on snug, drop the car, tighten the lugs in a star pattern.

Test your brakes out carefully after you do this, after the first time I did it I had no confidence in my work :) That will grow with time, but I still have misgivings about things I do to my cars to this day.

If memory serves, that's about it. You can make it really quick by taking shortcuts but don't skimp on the safety. It's also a good idea to do a break in for the pads, (you can google that) even though many people seem to think its no longer necessary.
posted by IronLizard at 8:24 PM on May 15, 2007 [1 favorite]

Oh, and one thing I used to forget years ago: With the calipers, you're not facing the heads so righty tighty, lefty loosy will be reversed.

you will end up with far fewer leftover bolts and nuts that you have no idea where they were supposed to go if you have an experienced person walking you through the process.

Tape and a permanent marker are a good substitute. I find that leaving the bolt/nut taped to whatever part I'm removing, in it's proper place, saves me all kinds of headaches. For those that must be loose, I put a tab of tape on them and write exactly where they go in clear letters. Masking tape is OK for this, but I got hold of some colored rolls of paper tape that work OK. Main thing is not to let grease wipe away the marker.
posted by IronLizard at 8:31 PM on May 15, 2007

First - though you have a fairly expensive car, with expensive parts to match, IMO it is an excellent one to begin working on. The cars are complex, so with everything new take your time and become a maniac about organizing the parts that come off the car when you do something. Egg crates for things that come in bunches, paper cups with covers, stuff like that.

Clean everything to the maximum extent you can before removing anything; that way crud doesn't get into the works.

Please do not buy cheap tools. They look appealing until a socket splits and you spend $800 in the ER getting your hand stitched up. Craftsman tools are fine, I have never broken one doing anything sensible with them.

If you take your time, and when you get stuck stop and think, you will be fine. Gute Reise!
posted by jet_silver at 8:32 PM on May 15, 2007

Almost forgot: IANAM
posted by IronLizard at 8:33 PM on May 15, 2007

I applaud your interest in learning about your car--I had the same interest when I was your age. My approach was to read a good book, "The Petersen automotive troubleshooting & repair manual", until I understood how the various parts of the car work, how they break, and how to fix them. This understanding of the basics adds another dimension to the "this is exactly how to do it" information in the technical manual for your particular car.

Other than that, it really helps to have somebody to ask questions when you're puzzled. Don't make any risky assumptions or try to use force where you aren't sure what the ramifications are. Go slow. Keep a clear mind. Don't lose any parts. Have fun. And feel the glow of pride in what you accomplish.
posted by exphysicist345 at 8:36 PM on May 15, 2007

Please do not buy cheap tools.

May I recommend these?

I don't give a rats ass what anyone says about TV commercials, my mom bought me these ten years ago when they were $250 and despite my, now getting awesome, collection of tools I won't use anything else. The only thing that sees more use is my Leatherman. P.S. I have nothing to do with this company.

That said, as long as you but the Chrome Vanadium type tools at harbor freight, there's nothing to worry about. Cheap steel is something else, altogether.
posted by IronLizard at 8:39 PM on May 15, 2007

IronLizard's description of how to do your brake pads is great, and pads are usually an easy item. But ... the last vehicle I tried to put new pads on was impossible, the brakes had been overheated at some stage and the caliper mounting bolts were solidly unremovable. I've worked on cars for forty years, from changing sparkplugs (they're another nice easy job) to engine rebuilds, so it wasn't inexperience ... just want to point out that not everything turns out easy just because it should be easy.

Best to have a Plan B for whatever job you do!
posted by anadem at 9:52 PM on May 15, 2007

Ack, those would suck. I recommend replacing the whole knuckle, in those cases, with a junk yard part and new wheel bearings. The knucle and brake assembly can be removed as a unit by taking out the lower ball joint, upper ball (or two bolts attaching it to the strut) joint and tie rod end (Your Model May Vary).
posted by IronLizard at 11:37 PM on May 15, 2007

I'd really recommend reading Zen and the Art of Motorcycle Maintenance not for its metaphysical meanderings, but for its practical advice on learning about "mechanics feel" and how to avoid gumption traps, how to avoid some kinesthetic problems (the importance of working comfortably), etc. Every mechanical repair job on an old vehicle is partly a challenge of seeing what is wrong (diagnosis) [which depends to some extent on knowledge of how the mechanism is designed to work, and observation of what it is actually doing, plus some reasoning about the differences between those states], and some allowance for age, dirt, and conditions of parts which might have been removed/reassembled before. Accordingly, every repair is a risk/benefit calculation.

Changing spark plugs is pretty simple, if you know what threading a new plug into the head feels like, but it is equally easy to ruin an engine head by cross-threading a plug, and putting just a little muscle behind it. You should be able to finger tighten a plug down to the last half-turn, but in some cases, you can't quite, and this can create real quandries for a new mechanic, who hasn't developed what Robert Pirsig calls "mechanic's feel" in their fingers. That's the value of working under personal instruction, and doing excercise with taps and dies to learn how screw threads are formed, and how metal feels when it stretches a bit under torque, to pull up the tension needed to keep fasteners in place under vibration. That's the reason that apprentice mechanics in Germany spend 6 weeks working the hand file, to learn in their fingers how to file, how to finish, how to sharpen with the file, etc.

Good tools are essential in developing mechanics feel, but so is manual practice, and a practical knowledge of the grain structure and working properties of different metals. Cast iron has a differerent "feel" than aluminum, which is nothing like steel, which is altogether different than soft "pot metal" or bronze or copper, etc. Learning to identifiy different metals and materials, and how to protect precision machined surfaces while applying force to them is vital. Learning to hammer safely and efficiently, and get vital feedback through the hammer, takes doing some hammering, and ruining some metal. So that's the "risk" in risk/benefit, when doing repairs on your own primary transportation.

Learning to use the measuring tools properly, to assess parts conditions and duplicate specifications and settings is important. Good torque wrenches are important. Calipers and micrometers are necessary, as is the knowledge on how to use them. Feeler guages are cheap, but the information they give you is priceless. Cars work because of precision parts, and measuring tools help you keep precision fits.

It's also necessary to learn a little chemistry, particularly as relates to solvents and to lubricants. You need to understand how oils work, how greases differ based on their intended uses and formulations, and how penetrants and solvents work. Restoring an old car requires lots of clean up, and re-lubrication, and using the wrong products, or using the right products incorrectly can totally screw up the job, and force you to replace damaged parts.

You're likely to do a lot better if you start seeking out some gearheads in your area, to help you learn, and to advise you. Get around to some auto parts stores, get on a first name basis with one or two experienced counter men, check around for Mercedes owners clubs in your area, and see who is in to doing their own repairs. In any major town, or city, you'll quickly find a couple of people who do this as a hobby, and who would generally be delighted to help you, and get familiar with your car. They can help you put together a comprehensive maintenance and restoration plan, which will be a big help in budgeting for repairs, and in "getting ahead" of the car's maintenance needs.

A car of that age and mileage is going to have a lot of suspect rubber parts, and will be developing electrical problems, most likely. Wiring in particular has come along way in the last 25 years in terms of reliability. Good luck. I hope this car stays fun for you.
posted by paulsc at 12:42 AM on May 16, 2007