[AMA] I'm a Mechanic. Ask Me Anything

AMAs seem to be the cool thing to do lately, so thought I'd give it a try. Have been a mechanic for 15 odd years, worked on everything from Hyundai to Porsche. Recently moved to marine in the last year or so. Will try to answer when I can.

Edit - Wow this was much more popular than anticipated, thanks for the great response everyone, hopefully it's helped a few people out.

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  • +7 votes

    Have you (or anyone you know at your workplace) ever told someone naïve that something needs replacement when in fact, it didn't?

    • +11 votes

      and don't lie!

      • +30 votes

        I can honestly say I never have. My previous boss did twice when he made an assumption on what a problem was before looking at it, this one was one the reasons I left. I find you keep way more customers by being honest.

  •  

    Do mechanics rip people off?
    Is that feeling of wanting to find a 'trusted' mechanic really warranted?

    • +25 votes

      Some sure do. The most expensive "almost rip off" I found was a customer that bought in their 118tsi golf with a misfire. A well known "euro specialist" had told them it needed an engine, and quoted them $10k or so. I replaced the dead coil pack and it ran perfectly, compression was fine.

      • +1 vote

        And how do you find these trusted mechanics? My engine light is on and a sound coming from front left wheel so I know it needs work but don't want to be taken for a ride.

        • +4 votes

          We generally got customers from word of mouth. Our Google reviews were 100% 5 star buy you can't really trust that. Recommendations from friends family is the best way really. What model is your car?

          • +2 votes

            @brendanm: 99 liberty,
            recently felt a vibration in the brakes and feel it first time applying brakes slowly every morning. A metal on metal sound is heard when turning left at low speed… the sound of money vacating my wallet

            • +15 votes

              @David Warners Mo: Engine light is likely the knock sensor if it still drives ok, common and cheap to replace. Noise is likely a wheel bearing, definately get it checked as it's not only a safety issue, bit the longer you leave it the more bits get damaged, and the more expensive it is.

    •  

      same question, is exchanging working with broken/old parts from customer cars common practice? or is it just paranoia from customers?
      Thanks for the AMA!

  •  

    does porsche really costs that much to own ?

    • +3 votes

      Not really, for anything relatively new tyres and brakes will be the biggest expense, as they chew through them as a general rule. Places like Pelican parts have parts at good prices as well. Some will have certain issues, like the one issue.

    •  

      Porsches are generally very solid. The sweet spot is 987.2/997.2. Perfect blend of analog and digital, and actually not as complicated as one might think. Expect to pay 300-450 for a basic service at a Porsche Specialist. There is also a tonne guides online and for minor maintenance. Porsche engines generally have timing chains, with nearly no reported failures. As per all cars since the mid 2000s, you will get the odd nitpick airbag light or electrical gremlin and you will pay an arm or a leg to get it fixed.

  • +1 vote

    How's your apprentice's stock of left-handed screwdrivers? Long weights? Blinker fluid?


    What's the worst car to work on? (Guessing something like a 300zx?) What's the car/brand that causes you the most issues? What's the brand that causes you the least issues?

    • +10 votes

      Haha funnily enough I haven't had an apprentice for a long time, they become more trouble than they were worth, and most either had crap attitudes or no common sense.

      Anything french. They just do things in spectacularly stupid ways. 300zxs are horrible for many reasons. The cars with the most issues were captivas and cruzes. I have lost track of how many Cruze head gaskets, oil coolers etc I've done. Same with abs modules, a/C compressors etc on captivas.

      • +1 vote

        What brand/s would you recommend?

        • +14 votes

          Haha that's a loaded question, and completely depends on what people are looking for in a car. A-b car, Camry, corolla, small Hyundai's or Kia's. You will have very few issues with these, as you would know ;)

          •  

            @brendanm:

            Haha that's a loaded question

            Nooo…. never! ;)

          •  

            @brendanm: I agree with Camry and Corolla being a-b best cars. Ive owned a few over a period of 11 years and I got truly excited when I needed to change the tyres or a battery. Once I had a burnt stop light on the Corolla and the dealership replaced it for $3 during regular service. They could have made the Camry discs more solid though.

          • +5 votes

            @brendanm: You know that suggesting Corolla or Camry get @Spack just a little bit moist?

            What's the worst car to work on?
            Anything french.

            OMG, you are a mechanic… :D

            • +1 vote

              @pegaxs: Moist - the most ewwww word in the English language

            •  

              @pegaxs: Having owned and serviced a number of French cars I agree the older ones (say anything over 10 years) would leave you wondering why they designed some of the stuff the way they did, as if they had a different interpretation of what a logical layout should be compared to everyone else.

              New ones are becoming boring though… they're getting more and more… conventional and dare I say… German-like, especially PSA cars. And Renaults are becoming more and more like Nissans.

              • +1 vote

                @huit: I think that is one good thing that will come of the Renault/Nissan situation, is that Nissan will rub off on the French and improve their cars.

                •  

                  @pegaxs: My last car was a Megane RS250 which ran faultlessly for the 4 years I owned it (and I did thrash it every opportunity I got but kept it serviced), I know the AC unit is a Japanese Denso, it's probably full of other Japanese bits.

      • +4 votes

        OMG,why you weren’t in the selection panel when govt choosing who gets build our next generation submarines? Out of German Japanese French they got the worst one….

      •  

        I've had two 300ZXs and well… I replaced the timing belt on the last one over a day, said "(profanity) this is way too difficult", and then sold it :( Miss the old Nissan

      •  

        In considering a 2012 alfa romeo giulietta at the moment. What's your view on their reliability these days? (I know they used to be terrible)

      • +1 vote

        Huh (French) a mate has a business that services these vehicles, been there 30 odd years and all work word of mouth. One mechanic is always swearing . Bloody French this and bloody French that and it's no wonder they went to war etc lol..I've seen some rediculous stuff regarding the vehicles and cost of parts. I've always been a Holden man and always had oil on my driveway and one-day I decided to fix it. It was easy really I bought a Toyota Hilux. Nothing in over 10 years until recently, My daughter moved back home and now it's everywhere she drives a bloody SS Holden Ute… I'm hoping the oil will disappear again shortly….

        Cheers

    •  

      My favourite one is a bag of compressed air.

    •  

      I still miss my 300ZX

  •  

    How do you measure fluids used when a customer brings in their own parts for servicing?

    When you order in parts, let's say a customer needed spark plugs, do you buy off a wholesaler or purchase it at a local Supercheap etc. and factor in a margin on it?

    • +2 votes

      If they bring in their own oil, whatever not used is simply returned to them.

      Buttons, global, hsy, and various others. We only every charged RRP, as we got parts at trade price, so profit is already built in. No point charging more.

  • +1 vote

    Is it true that Camry are indestructible and should be the 2WD of choice when WWIII comes round?

    • +12 votes

      They are very reliable. The old s series engines were damn near unbreakable no matter what you did to them. Any of the timing chain Toyota motors need regular oil changes, they hate missed services. Apart from that they are excellent reliability wise.

  •  

    Are you worried about the rise of electric cars? / Can you transition to services these types?

    • +5 votes

      Not really. There are still plenty of things to replace on electric cars mechanically, plus I have my auto elec quals as well ;) However, I'm now doing marine, which is a very long way off being all electric.

      •  

        Can you elaborate on why boats are a long way off?

        • +2 votes

          I'll hazard a guess and say "electricity + water" :P

        • +3 votes

          The amount of batteries would be insane. Boats work under a lot more load than a car cruising on the highway, need a lot of constant horsepower. Would kill the batteries in a very short time. They do have electric boats, there are a couple of them as marina patrol boats at a marina up the river from me.

          Have a look at fuel consumption on boat at cruise, and the speed it does, and then compare it to a car. My little 18 footer uses about 1l per km at cruise, a lot more at full noise. Bigger boats use a lot more.

    •  

      I'd be more worried about the dimise of Ford and Holden in this country if I was a mechanic / tow truck driver / spare parts supplier.

  •  

    What did you move to marine ?

    • +26 votes

      I was basically running the shop I was at while my boss was perpetually on holidays, but he "couldn't afford to pay me more". Was planning to leave that job anyway, and this came up. More money, less hours, close to home, something different. The insane penny pinching of a lot of people was driving me crazy as well. Also means I can get parts cheap for my boat :P

      •  

        Excellent reasons to switch - good luck at the new job!

        Have you found boat owners not as 'penny pinching' as car owners?

        • +18 votes

          Thanks very much. They are generally not shy of spending money. I should clarify when I say "penny pinching" I meant people who won't replace brakes or tyres, when they have kids in the car for example, drives me mad.

      • +1 vote

        That's why I moved out of it.

        My boss (tyre retailer) told me I could lease the space after 6 months if I set up a suspension / brake workshop next to his wheel alignment machine. A buddy and I set it up, did quotes, made bookings and built up the business. We were covering our wages and overheads after 2 weeks and making profit after 6 weeks. We asked to lease the area after 3 months and he laughed and said we were making too much money for him. We both quit within 2 months and his next mech was a junkie. The hoist was sitting idle after 12 months.

        Some bosses are so dumb. I did hydraulics for a while and then went to aircraft.

  • +1 vote

    What cars do you own?

    • +5 votes

      I have an r51 pathfinder which I have grown to hate, and will soon be replaced by a touareg. Other car is a TDI passat.

      •  

        As a fellow R51 owner and out of curiosity, what makes you hate that car? This is the only car I ever owned that I actually don't really like but I just can't put my finger on the reason…

        • +1 vote

          I answered someone else below, basically it's underpowered and the auto trans and torque converter combination is horrible. It's ok in a manual.

      • +1 vote

        ive got a TSI 1.8L Passat. Found it v reliable so far! (6yrs old). Anything i should watch out for in the future?
        Oh, and whats the best way to upgrade the radio firmware? Doesnt play music off paired phones which are new (android), but works with older phones.

        •  

          Do oil changes. People try to skip them and they sludge up a lot. Had a couple with timing chains gone.

          Not sure about the firmware, vwvortex or similar may be of assistance. It's quite possible that your Bluetooth gateway isnt compatible with the phone, and may need upgrading

        •  

          I have a Skoda Octavia with the same engine.

          main issues:
          Waterpump
          Inlet manifold clogged with oily gunk.

          great engine otherwise

  • +2 votes

    Out of Audi, Merc and BMW - what is the best car to buy 2nd hand (Year 2015) from purely a maintenance perspective? You can assume all have perfect service history to date

    •  

      Depends where you are getting it serviced, whether petrol or diesel, and what model.

      •  

        All serviced from their respective delearships, petrol models.

        Merc - c200 / c250

        Audi A3

        BMW 3 series

        •  

          All much of a muchness really, Audi should have had more services as the Merc and BMW service intervals are longer from memory.

        • +1 vote

          An Audi a3 isn't in the same class as the above. You'd be looking at an A4 for comparison.

  • +1 vote

    Is VW as bad as people say in terms of reliability?

    •  

      Some are terrible, 7 speed dsg, and the 118tsi engine. I've seen the diesels with 6 speed dsg get very high, reliable KMs. I actually own a vw haha.

      •  

        isnt DSG/ZF one of the best trannys but as you said some of the former types being known to have major issues?

        •  

          Borgwarner make the vw dsg from memory. It's simply the different styles of dsg used. Dry clutch dsgs use a "normal" style clutch, cooled by air and with no fluid, causes high wear, shudder etc. The others use a "wet clutch" like a motorbike, cooled and lubed by oil. The wet clutch is a far superior design.

          •  

            @brendanm: I always thought why not every clutch be a oil bath type clutch but have read recently something like the economies of scale make OEMs choose every single part for its ease of service and reliability along with its efficiency and price point.

            I just found this on quora lol:

            I think the main reason is just a lack of necessity. Motorcycles have multi-plate clutches that are designed to be compact and fit into a tight little space. The clutch on a manual transmission car just doesn’t have that constraint, and a simple single-plate dry clutch works just fine. People are terrible at changing their transmission fluid in their cars, and clutch material would circulate around in their transmissions
            for 50,000 miles at a time or more. Oil bath clutches in motorcycles get fresh oil every time you service the bike.
            Dry clutches are more efficient with less power loss overall, because they aren’t using energy to move oil around.
            One less thing to leak and fail catastrophically when it runs dry.
            That’s just how it’s always been done. Even the Model T Ford has dry band “clutches”.
            The overall surface area needed to make a wet clutch work properly in a car would be much larger than a dry clutch, because car engines are an order of magnitude more powerful than motorcycle engines. (Automatic transmissions get away with smaller wet clutches because they have a torque converter, and there isn’t a whole lot of controlled slippage happening at take off, like you do with a manual clutch.

            • +2 votes

              @abuch47: That's quite incorrect. Auto transmissions simply have enough surface area, and enough clamping force to be able to transmit the power. You can direct drive an auto transmission and it will still not slip, torque converter has nothing to do with it

              •  

                @brendanm: There is a lot of this kind of utter BS on the internet about cars. Does that impact your job at all?

                •  

                  @stumo: It sure did, people would argue about work that was to be done, or what they thought should be done, based on what some random wrote on Facebook or a forum. Sometimes you'd spend half your time trying to re-explain things to customers rather than working on the cars.

  • +1 vote

    Got a few questions if you are willing to indulge…TIA

    I posted about a Honda Oil change issue recently.

    TL;DR My Honda is telling me to change my oil a lot sooner than 10,000kms, in fact it starts at 6,000km off the bat.

    1) If I asked the dealership at the next service, would they be able and/or willing to take a sample of my oil and test it somehow? I want to verify the oil management system is accurate. Or do I have to engage an independent tester?

    2) Are you familiar with oil management systems in general or heard of them not being accurate?

    • +1 vote

      1) I've never worked in a dealership so I'm unsure sorry. There are companies that will give you an oil sample kit that you can do yourself. We use CAT for oil samples, not sure if they will deal with the general public.

      2) Afaik, with the Honda's, they base oil life purely on how it has been driven. Short drives to the shops being harder on it, long highway drives being easier. BMW have an actual oil quality sensor, though I'm not sure exactly how it works or how accurate it is.

      •  

        Oil quality sensor is employed since 1997, AFAIK, these are a $6 opto sensor bolted into bottom of the sump. It measures the contaminants in the oil by passing light through it. There is always an oil level sensor too, it drives a separate orange/red light in the cluster. Plus the usual pressure switch up in the oil pump housing which warns of catastrophic loss.

  •  

    Are direct inject engines more likely to have carbon deposits when compared to port inject engines?

    If so, are additional fuel injection services worthwhile? (I say additional because they are not specified in the service manual). Or is there any other evidence-based preventative treatment?

    Asking for a 2018 Honda CR-V 1.6L turbo.

    • +2 votes

      Yes, by design the fuel is injected directly into the combustion chamber,and doesn't have a chance to "wash" the inlet tract and the backs of the valves.

      By fuel services, do you mean the snake oil in a can? If so, these will do nothing, as they still don't touch the backs of the valves. Something like Subaru upper cylinder cleaner can help, or at high KMs, physically cleaning the valves.

      Direct injection has been relatively common since 2000 or so, without too many issues, and you likely won't have the car long enough to need to worry about it.

      •  

        Oh thanks for the reply. As for fuel injector service, I meant whatever the dealership recommends, i’m not entirely sure what they do or if it’s worth the expense. Is there something that I should ask them before deciding to proceed or not?

        • +3 votes

          You can ask what it is they will do, but anything they try to sell you that just tips into the fuel tank will do nothing but lighten your wallet.

          •  

            @brendanm: Ok thanks! I suspect that’s what they’ll do for preventative work, I heard a person at work agreeing to have their fuel lines flushed with some additive… I figure the fuel lines will continually be flushed by virtue of the engine using fuel, but i’m Unsure if my logic is correct.

            As for my car, yeah, I can’t see them cracking out the walnut shells.

  •  

    How much a prices typically inflated by to rip people off

    • +2 votes

      As I stated in an earlier reply, we always charged retail price, as we pay trade price. So basically people would pay the same price for the part as if they has purchased it from the store themselves. I obviously can't speak for other places, but that's how it's been at anywhere in worked.

  • +2 votes

    Is there a way to tell if the car battery is on its way out by using a multi meter? (Resting voltage is 12.75 but haven’t taken any other measurements)

    • +21 votes

      Crank the engine with the multimeter still on the battery. Shouldn't drop much under 10 volts, if under 9 it's basically done.

  •  

    What's the reliability on the 2017+ BMW X3s?

    • +3 votes

      No idea sorry, I doubt people will know until they are a bit older. Going off past BMW experience, they will be ok under warranty, and go downhill from there, as they are normally sold after the lease runs out, then the second owner doesn't keep up the maintenance.

  •  

    I drive little, under 3000 km a year. Is it OK to change oil just once a year?

    • +7 votes

      Yes it sure is. Yearly or 10k km as a general rule, whichever comes first.

      • -1 vote

        So if a car is basically sitting in the garage 99% of its life (<3000km), still change oil yearly? Feels like throwing money away.

        •  

          Yes, things break down over time. Brake fluid, coolant, tyres perish, rubbers perish. A service is much more than changing the oil.

        •  

          If the car is sitting in the garage 100% of its life then there are ways to store it long term, but wont be able to just walk out one day and go for a drive.

    •  

      HI Brendamn,
      thanks for your time doing AMA

      "I drive little, under 3000 km a year. Is it OK to change oil just once a year?"

      even on small runs like around 7-10km ?
      I own a AD 2016 Hyundai Elantra ,anything to watch out for ?
      thank you

      • +1 vote

        Short runs aren't ideal, do you do any highway stuff? The main problem with short runs has historically been that the oil doesn't get hit enough to evaporate out any rubbish such as fuel that has ended up in it for cold starts, bit this is much less of a problem nowadays with the precision from direct injection. The interval on your Elantra should be 15k or yearly anyway I think?

        The Elantra is a good car, I'm sure you'll be happy with it 👍

        •  

          I thought the issue with short runs was also that a lot of the engine wear happens at start up, when its cold, and as it has high load during acceleration, which doesnt happen as often of you are doing longer runs.

          Have an 04 Elantra with iver 220k kms and it has given very little trouble, general maintenance only. Biggest expenses were timing kit and new radiator. I would assume the new ones are better?

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