The coveted Mechanic Red Seal is the culmination of a four year apprenticeship and on-the-job experience. I never forgot about the people I worked with who took the time to explain how systems worked and the best tools to use.
The stepping stones to achieving your Mechanic Red Seal will vary depending on fate and possibly luck in some cases. Above all don't stop trying and show your true colors to perspective employers. Stay in contact and don't allow them to forget your face.
Attitude is everything. Every year our shop accepts a commercial transport pre-apprentice for a one month practicum. Every one of these guys are energetic, respectful and humble. The college instructor hand picks these 20 something future mechanics and it's very easy to work with them sharing over 100 years of combined experience in our shop.
There is a difference when working in a fleet shop compared to a customer shop. However there's no rushing around making quick decisions for the sake of saving time and money for a customer. A fleet shop has spare units to hand out and when it comes to our school bus fleet we can not cut corners for the sake of time. Transporting children means special attention on safety.
There are so many mechanical fields available. When I apprenticed the commercial transport and heavy duty trades was combined. We covered trucks and earth moving equipment so the curriculum was very broad. Now those two areas are separate trades and specialized. Just having a journeyman ticket doesn't mean you qualify for everything available. There's mining, construction, trucking, automotive, logging and so on. Pick one and go for it with the most enthusiasm you can muster.
The Mercedes MBE 900 Diesel Engine. What I have experienced since we acquired these engines in 2005 is they are built well and stand up to the rigorous start and stop routines involved in a school bus fleet. The pre 2007 engines are not emission controlled like they are today and have given us very little grief. However I would like to share a tip on a troublesome problem we had with a 2005 freightliner conventional school bus.
The Video I made above explains how to properly bleed these engines. Strangely enough we were told to crank over the engine continuously after a fuel filter service until the engine fuel pressure built up. At first we were scratching our heads thinking we're living in the new millenium and this diesel engine has no priming pump and only one starter...that was destined for failure eventually from the constant load it would have to endure turning the engine over and over just to prime the fuel filters.
We tried to innovate and pressurize the fuel tank and crack a line at the secondary fuel filter to help the system prime up faster. Unfortunately some of our new buses had fuel guage sender problems and there were buses running out of fuel out on the road. There was no choice but to load the hell out of the starter to get it going again.
By the way if you loosen the fuel line from the unit pump to the head the line must be replaced. Recommended by the dealer / engineers. We were forced to crack the lines only once and re-tightened them after start up and did not have any leaks. So I imagine the odd time the fuel line will not seal properly after it has been disturbed?
Engine Runs Poorly After Changing Fuel Filters
We recently experienced a problem with one of our MBE 900 diesel engines after a fuel filter change. It ran poorly and was not picking up fuel. It eventually kicked in and ran fine for a few days. However it died on it's bus run and had to be towed. It ran like it was starving for fuel like air in the system. The engine would idle fine but crap out under a load.
One thing noticeable was when priming the fuel system with the pump kit the pump just kept filling the lines and filter without the typical solid feeling at the pump handle indicating the system was primed and ready to go. Eventually the Mercedes diagnostics instructed us to check the return fuel volume from the head and the unit pumps.
There should only be 1.7 Liters of fuel returning to the tank every minute at an idle. We had double that...so it ended up being the overflow valve (similar to a check valve) which is in the return fuel plumbing to maintain around 60 psi. It was not doing this and caused a loss of back pressure in the return system which caused the hard starting, rough running condition. Now our shop will recognize the problem after these symptoms pop up again.
This tool (Ultra Pro from Napa) is what we use in our shop and has worked successfully for us for several years (click on photo to enlarge). I was asked what kind of coverage is available if it fails and a component burns out because of it from a high energy surge from welding.
Not sure about that question; I contacted the selling dealer and they have not come up with any answers. The other option is to disconnect the battery ground when welding. The only inconvenience from this is you have to reset your digital components like clocks and timers. Modern School Buses have several modules within the multiplex system and using either one of these precautions is mandatory to save an expensive component from failing.
I have not replaced any modules in our buses yet; the main problem being corrosion to wiring and connections. The connector plugs still get moisture inside in some cases and the use of dielectric grease helps a lot to keep moisture away from the terminals. Oxygen, moisture and electrical current can team up nicely and corrode connections quickly and cause trouble.
A lot of times I have found with corrosion on module connectors there are cross electrical signals that occur and some circuits get energized with constant battery power. We had an instance where 3 different circuits were operating on their own even with the ignition shut off.
With the wiring diagram we were able to determine where the circuits started from and it led us to a corroded connector at one of the control modules. As a preventive maintenance step we have applied dielectric grease to all of the module connectors.
The color of the smoke coming out of a diesel engine that's not running properly or showing signs of poor mileage can tell you a lot and is the first step when you start your troubleshooting process. Smoke colors to take note of are black, white and blue.
Since there are so many different diesel engine manufacturers and configurations the plan of attack depends on the engine model especially when dealing with the fuel system.
When there is an imbalance between air and fuel meaning too much fuel or not enough air induction Black Smoke will occur. Checks you can perform:
* Check the air filter for a restriction.
* Check for faulty injectors or injector pump.
* Check Turbocharger boost reading or inspect for any failures (turbine / compressor wheel)
* Check the cylinder head valve adjustment.
White Smoke means there is inefficient combustion within the engine cylinders.
* The engine timing or injection pump timing could be out of spec. or there is an internal failure
* Air in the fuel causing starvation to the injection system.
* Low engine compression
* A Possibility of water in the fuel
NOTE:
* If you get coolant loss and white smoke that will indicate a possibility of a faulty EGR or "hopefully not" a cracked block. There are several others mishaps that could happen these are just a couple examples. Case in point: We have an engine with a cracked block that was using excessive amounts of coolant and blowing white smoke out the exhaust. This is where an oil sample really comes into play. A high level of sodium indicates coolant in the engine oil.
Blue Smoke The term "burning blue" is well known and that's caused by excessive engine oil getting into the combustion chamber.
* Worn compression rings or oil rings
* Worn cylinder bore causing blow by and excess oil to enter the cylinder
* Engine crankcase over full
* Oil entering the fuel system
Of course this is very general and is meant to get you thinking when the smoke develops more than usual. cold starts in the winter season will produce white smoke which is normal. This will clear up once the engine reaches operating temperature. The diesel engine is your friend as long as you jump on small problems before they get bigger. :)
I recently read an article from my regional auto association BCAA(British Columbia Auto Association) and they covered the topic on how to find a good mechanic. After reading it I had to agree with all the tips they had pointed out. I'll go through them here and you can comment at the bottom of this post if you have any thing to add.
Let's face it finding a good mechanic is a challenge and honesty would be on the top of my list. Here are 6 tips from BCAA.
1.) Get feedback, ask around. It doesn't hurt and doesn't take a lot of time. Friends, relatives, and co-workers are a good source of recommendations. See which shops and technicians they’ve had good experiences with. Word of mouth is extremely valuable and talking to someone who has had a positive experience at a repair shop or have a regular shop they frequent because of a great relationship is one of the best ways to find a good mechanic/shop.
2.) Check credentials and reputation. Ask the shop if the technicians working on your vehicle hold a certificate of Trades Qualification or equivalent credentials. Also, research the shop’s record and rating with the Better Business Bureau. Having Mechanics with their Provincial tickets (Canada) is essential. You don't want unqualified people getting their first hand experience on your vehicle especially if you're paying a shop rate!
3.) Ask questions. This is a trust issue. If a shop mechanic takes the time to fill you in on details that's a very good sign they aren't hiding anything. Don’t hesitate to tell the service advisor that you’re not sure what something means, or ask them to explain it further. Also ask the service advisor to physically show you the problem on your vehicle. This will give you a better understanding of the issue. Any mechanical repair shop that does not want to show you the old parts off your vehicle is scamming you.
4.) This is a huge point...Get estimates in writing. Verbal estimates can be disputed or forgotten. Always get a written estimate prior to approving work on your vehicle and insist on a call if repair costs exceed the estimate. Most estimates allow up to a 10 per cent overrun. Request a call if costs exceed this allowance. This makes sense and most shops will advise you if there is a cost over run.
5.) Cover yourself down the road and make the repair shop accountable if they replace or repair anything. Ask for replaced parts. When dropping your vehicle off for service, tell the shop you want to see any replaced parts. In some cases, you are entitled to keep these parts, unless the facility must return them under a warranty or exchange program. Replaced parts and a well-documented repair order can be useful if there is a problem later. "get it on paper" there is no way any shop or mechanic can BS their way out of a dispute if you have the their black ink on your white paper invoice.
6.)CYA "cover your a--" Get a detailed copy of the repair order. Make sure it specifies the costs of labour and each part. Ask for the facility’s warranty in writing if it’s not printed on the bill. BCAA approved facilities offer a 12-month/20,000 km warranty on new parts and labour. More reason to join an automobile club. I used mine to fish keys out of my car and that alone paid for the one year membership fee.
Here's a handy video with more detailed tips on locating a reputable repair shop and trustworthy mechanic.
Check this link to a site called Rank My Mechanic where you can search ratings from other people on mechanics from all over. I haven't used it but it looks like it would work well if it applied to your area.
This is the best video I have ever watched on how diesel fuel injectors work. It covers hole and pintle type injectors that are actuated hydraulically by the high pressure fuel injection system.
There are so many different injection systems in the industry it would take a lot of posting to cover them all.
The basics is all you really need to know to get the right idea on how diesel fuel injection systems function. Most Mechanics don't specialize in the fuel injection field primarily since it takes a ton of very expensive testing and calibration equipment to repair injectors and pumps.
The main principle noted in this video is the injector is seated by a spring. When injection occurs the high pressure fuel is routed to the body gallery of the injector next in the firing order and overcomes spring pressure lifting the seated needle allowing high pressure fuel into the combustion chamber.
When the injection cycle ends the spring in the injector reseats the injector.
The mechanic must troubleshoot modern diesel engines with software compared to years ago when you could crack a fuel line one at a time to find an engine miss on a mechanical fuel injection system.
With today's electronic diesel engines a laptop armed with software is the only way to find a problem.
Watch the video and you'll get a much better idea through animation how diesel fuel injectors work.
Our latest Cummins ISC diesel engine repair involves a broken valve spring that caused the push tube to bend and the valve lifter to break apart. It damaged the camshaft lobe so everything from the head down to the camshaft has to be removed for replacement and repair.
The head and camshaft have been removed. The head requires repair so we sent it out to the local machine shop. We are replacing all the valve springs and valves to play it safe.
Here is the damaged valve lifter beside it's mate. The sharp edges scored the camshaft beyond repair. Surprisingly the cam was under $300.00 which is cheap when you price out other various diesel engine parts.
This is the bad camshaft lobe caused by the failed valve lifter. The only way to replace the lifters is to remove the camshaft. The lifters are installed into the bottom side of the engine block so they have to be held in place with doweling from above. If you have any experience with the Cummins ISC diesel engine please feel free to contribute. I'll post more on this job in a future post. Please comment if you have something to add.
The days a Mechanic can get out his screwdriver and tweek a diesel engine are gone. Yes it's 2012 and times have changed. 2007 was a year I won't forget. Emissions on diesel engines were fully operational and ready to provide us with cleaner air. I totally agree with this mandate but new technology has created a lot of headaches for us old school Mechanics who just want to fix the problem and never have to fix the same problem again.
If an engine farts the wrong way an engine code pops up. The parameters are strung as tight as a piano string so a minimal buildup of soot or carbon within the exhaust system and you're in for a challenge. However if you have the laptop, software and experience it gets easier. That's the good news....the unfortunate part is you'll need deep pockets to keep your engine fine tuned and code free.
We just had our first run with one of our 2007 Mercedes MBE diesel engines that just ran out of warranty. All this new terminology I'm going to tell you about is focused around the muffler. The code was "DPF out of range high". This means the temperature or pressure at the sensors were not in their acceptable ranges. They are located right at the DPF "diesel particulate filter" (muffler) and tell the computer that there is a blockage starting to accumulate in the dpf cartridge/filter.
The on-board computer monitors this system and carries out automatic regenerations as it sees fit. A regen heats up the exhaust system to high temperatures and cooks the particulates out of the exhaust system without contaminating the environment. This works great and will give you trouble free driving for quite a while, however over time the regeneration process needs to be forced using your laptop software with the Mercedes MBE 900 diesels.
This is easy to do and can be done every second oil change or when required according to how hard the engine is worked. The longer it runs at operating temperature the better, because of the constant heat there will be less build up of particulates.
So getting back to our problem we checked the software for the last time the cartridge was serviced and it had been done once. It was not replaced but cleaned out 2 years earlier. By the way when you service the cartridge you must enter the details into the engine software records. So we replaced the cartridge which can easily be done on the bus by removing 2 clamps. It comes with gaskets as well.
Once the codes were deleted and the bus was road tested it came back clean and we were elated that everything worked out OK. So now we know what to do with that particular code, check the wiring, make sure you're getting a 0-5 Volt signal to the sensors and service or replace the DPF the cartridge. Recommended cleaning or replacement is 150,000 km. for this particular Mercedes diesel engine. If you've had some experience with this please leave a comment :)
