Saturday, September 27, 2014

Diesel Engine Emissions A New Frontier In Preventive Maintenance

When 2007 rolled around and the EPA increased their emission standards everybody was waiting on what the original equipment manufacturers were going to do.

The diesel engine has always evolved through the decades but the challenge in the new millennium was to reduce soot and ash discharge levels out the tail pipe.

The catalytic muffler was the first on the scene along with ultra low sulfur diesel and low ash engine oil. The muffler transformed into the DPF diesel particulate filter which traps soot and then through an oxidation process remove harmful particulates from entering the atmosphere.

The very difficult problem for the engineers and the battle to stay within EPA specifications is costing Cummins, Mercedes and Navistar a lot of money in research and development. The progression to cooled exhaust gas recirculation worked for many years along with the DPF technology.

However the EGR by itself wasn't enough to keep up with environmental demands. Navistar this year will no longer supply diesel engines in the medium duty market. The EGR pictured above is out of a MaxxForce DT diesel engine. We have several of these engines in out fleet and this component needs regular maintenance or replacement at least once a year.

At the vary least removal and cleaning of the soot and ash buildup is necessary or the shaft that opens and closes the valve sticks and eventually causes the EGR valve to stay open which creates problems with power and take off ability. Every one of our fleet buses are checked for stuck EGR valves especially the older units.

Mercedes EGR valves have the same problem and eventually the electric motor that opens and closes the valve mechanism does not have enough strength to over come the soot covered shaft and valve assembly. At the end of this year Navistar medium duty diesel engines like the MaxxForce DT and MaxxForce 7 will not be manufactured any more.

The Cummins ISB will be taking over the field with it's own technology including the SCR (selective catalytic reduction) system that uses DEF diesel exhaust fluid to reduce emissions. They also have the VGT variable geometry turbocharger to increased heat to assist in the regen process that cooks out the soot build up in the emission system.

It's a heavy duty challenge to keep up with emission demands but when the going gets tough Cummins diesel engines get going. They have really excelled over other diesel engine manufacturers and went outside the box to over come the high demands from the EPA to reduce emissions levels to zero through out the transportation industry.  

Saturday, January 25, 2014

Mechanics Hub Membership Site Tour

I not only post here but also at Mechanics Hub...an interactive site for mechanics and non mechanics to hang around and talk about machinery /equipment in all industries. I joined in 2009 and have enjoyed sharing information, videos and photos.



Mechanics Hub also has a forum, job board and industry news along with many other related links to some great information. If you click on the 'Blogs' link you will find my articles there on diesel engines, school buses and several other commercial transport related posts.

Mechanics Forum

I know from experience that finding good information online is extremely difficult. There are lots of forums and sites that want to sell auto parts etc. but not a lot of reliable information to answer mechanical questions. I see sites that offer "ask a mechanic" but that comes with a fee. The MH forum has categories for construction, highway, bus and coach, forestry and many more.

Great Information For Tech Schools

There are a lot of sites on the Internet and I haven't seen many better than MH for the simple reason that they deliver quality information. If you are looking for a Technical school in your area there is a link on the site for technical schools in Canada and the USA.

There are a lot of jobs available if you're willing to pack your bags. I would encourage anyone who wants to get into the commercial transport or heavy duty mechanic trade to have a look at the jobs board and see what's available. There you will see jobs all over the continent that pay very well. I an seeing a huge need for mechanics these days and there will be an even larger demand in the future so now is the time to get to school for your pre-apprenticeship course and start pulling wrenches!

See my Mechanics Hub Members Tour Video

Hey I appreciate your visit!

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Thursday, June 27, 2013

School Bus Garage Photos

I've been taking photos in our school bus garage since 2005 and didn't want them to go to waste so here is a short video with RANDOM pics. There's everything from instant snow chains to engine repair.




 2005...I remember it well, we still had mechanical diesel engines in the fleet. They were semi-retired as spare buses and just this year we are auctioning off our last mechanical engine equipped units (Cat 3116 models). The 3116 Cat gave us pretty good service but nothing stellar to speak of.

 I believe there were 4 engine rebuilds because of the exhaust valve dropping at a very bad moment. Usually the high heat pulling full load would cause the mishap. It was a lot of work since the block was solid without removable piston liners. The entire engine had to be removed from the chassis, stripped down and rebuilt from scratch. The rebuilt head ran about 1500 dollars Canadian, if the cylinder wall was scored then the block was sent to a machine shop which MUST know the repair steps when boring and re-sleeving these engines.

There is a special jig to be used to secure the block so it doesn't warp during the re-bore. It adds up to about 5K labor and parts. This of course is far less than buying a long block. The top end on the 3116 was the weakest part of the engine so valve adjustment is crucial. The engine operating temperature is a factor as well so they need TLC or they start to heat up over 200 degrees.

The engine fan in the pusher school buses were transversely mounted so it was hard to keep the temperature down especially in warmer months. We disabled the shutters (opened permanently) and installed an over riding dash switch to turn the engine fan on full which took some horsepower out of the engine. In the video you'll see the coolant sensor that runs the hydraulic fan solenoid.

When you unhook the sensor wire the fan runs full on. The dash switch we installed for the driver just caused a break in the circuit. It should also be mentioned that the cooling system also had to cool the transmission oil which could get up to 200 degrees. The radiator mounted sideways at the back of the bus had a hard time cooling especially when the bus was in 3rd gear with a full load climbing a hill in 80 degree weather. Thanks for viewing this post and I hope you liked the video.

Monday, May 20, 2013

The Mechanic Red Seal Journey

Mechanic Red Seal Certification
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.  

Monday, March 25, 2013

Mercedes 900 Diesel Engine Runs poorly after fuel filter change

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.

Sunday, February 24, 2013

Special Tool Saves Components When Welding

Protecting Vehicle Components While Welding

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.

Sunday, February 17, 2013

Diesel Engine Exhaust Defining Different Smoke Color

A Smoking Diesel Engine

What Do The Different Colors Of Smoke Mean?

Thank you to the us.gov EPA Dept.

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. :)


Monday, January 07, 2013

How To Find A Good Mechanic Review

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.