Tutorial - Thursday 13th November 2014

Today's Tutorial was presented by David Catling and concerned the use of energy drinks.  It focussed on a Canadian TV show that was investigating the contents of the drinks (namely Caffeine and its derivatives), exposing the marketing techniques and ambitions of the manufacturers concerned, and also highlighted a couple of "as yet" unproven deaths in relation to their unguarded consumption.  This was an interesting presentation and very informative. 

Fuel Leak Back Test - Monday 10th November 2014

Leak Back Test Kit

Today was a resumption of the practice Fuel Pressure Task from last Tuesday, on the Citroen C4 1.6 HDi (CI) engine.  We commenced by re-hooking up both the Carman Diagnostics scanner and the Picoscope to double check our results from the previous session.  The issue with the vehicle is one of a slightly "uneven idle".  Using the Carman Diagnostics scanner we re-ran a search for codes which turned up an open circuit fault on Injector Cylinder 1 (which according to Autodata is the cylinder on the right hand side of the block).  This was disproved by subsequently testing each injector for continuity using a multimeter set to Ohms.  All Injectors provided a reading of 0.7 Ohms respectively (Autodata says expect 0.3 Ohms).  With the engine running we then disconnected and reconnected each injector's electrical connector in turn, and noticed that there was a noticeable "indifference" (at idle) to the disconnection of Injector No1.  We then re-ran the engine and re-tested the Amperage consumption of each injector using a Picoscope, but in each case the test returned similar performance patterns to one another, both over time and frequency.

Picoscope Pattern of Injectors

Leak Back Kit Connected

By this stage we were scratching our heads and decided to call Carl Black in to present our findings thus far.  With all our data and results proven, he suggested conducting a Leak Back Test using the equipment pictured top left.  I have never seen this test conducted before so the experience of it's guided demonstration was most beneficial. The equipment is fitted to the fuel return side of the injectors, which is not under the same extreme pressure as the delivery side, and basically collects the excess fuel delivered to each injector (which would otherwise return to the fuel tank), through tubes into small indexed pots.  Once the equipment is fitted the engine is started and the pots then collect the fuel.  If all injectors are performing equally then each pot should collect an equal amount of fuel.  This test proved that there was definitely an issue with the injector on Cylinder No1 and in fact, an uneven delivery over a couple of injectors.

Collection Pots after Test
(Cylinder 1 RHS)

With our findings duly recorded it was time to start clearing away for the end of session.  Unfortunately, after the injector's fuel return re-connection, there was a slight fuel return leakage issue on one of the injectors, which will be rectified first thing tomorrow morning.  A very interesting and enjoyable task indeed.  Thank you muchly!

The Garage - Wheels and Tyres - Friday 7th November 2014

Leak Detection ATV Tyre

Today was a day of changing wheels, balancing wheels and repairing punctures for the most part!  Upon arrival I met the new Master Technician (Jim), and also saw the newly repainted floor, which has made a big difference to the appearance of the premises.  The garage is also currently "man down" due to illness at present, and I wish him a speedy recovery and return to work and college soon.

I only managed to get a couple of photographs today due to the pace of events as they rapidly unfolded.  I was therefore unable to capture any evidence of the rear wheel bearing task I was also allocated to in between tyres and wheels, under supervision of the new Master Tech. However it was a NSR on a Rover 75 and was actually relatively straight forward, as it did not require pressing out or in, due to its' convenient "single unit" design.  Remove caliper, carrier and disc, remove hub nut, remove hub and bearing complete - new one on, torque hub nut to manufacturer's specification and re-peen.  As always the 7 hours passed in what felt like 5, and then it was off to work again - where 5 hours feels like an eternity!  Thankfully I was detailed to Shunting and spent most of the shift outside of the Zoo, rather than amidst the Chimps Tea Party itself!

Wheel Balancing

Tutorial - Thursday 6th November 2014

In Remembrance
2216672 Corporal Horace Henry Davey

Royal Engineers
Borneo
26th August 1945 Aged 36

Thank you Grandad

"WELL DONE"

Martin,

I thought it would be better and less likely to be missed if I created a new post instead of commenting on each individual post.

What a fantastic resource this is turning in to showing some great work and experiences. This blog is showing all that I visualised when the though first came to me, well done!

Fuel Pressure Test - Tuesday 4th November 2014

Fuel Pressure Tester
(Petrol)

 We were assigned 2 different engine types for this task, one being SI and the other CI.  The SI was a Volvo S40 and the CI was a Citroen C4.  The methods of testing both differ in terms of which test equipment to fit and where, as the CI fuel system operates at vastly increased pressures to that of a SI system (SI 3-4 Bar and CI approximately 1600 bar and above).  We started by gathering all of the vehicle data for both vehicles relating to expected pressures upon testing.  The test equipment for a SI fuel system is connected to the fuel rail via a Schrader valve, and then the ignition turned one position to activate the fuel pump and bring fuel to the rail under pressure.  The reading is taken from the gauge (and monitored for approximately 30 minutes to observe any leak down) and noted on the job card.  The ignition is then fully activated and the reading from the gauge also noted and compared.  The accelerator is then "blipped" to observe any pressure fluctuations under load.

Connector fitted to
Fuel Rail Schrader Valve

In order to test a CI system a suitable diagnostics scanner (such as a Decscan or Carman) with live data reading facility must be used.  This is connected via the vehicle's EOBD port and the relevant section activated accordingly.  Results were noted and compared to the manufacturer's specifications as before.

Amps Clamp fitted to
Injector Live Feed

Having completed both tests and noted down possible causes of fuel pressure loss we were then asked to undertake an analysis of the Fuel Injector performance on the CI engine.  

This was achieved by connecting a Picoscope and monitoring the Amperage being supplied to the injector and also observing the number of pulses produced in its' operation.  This is displayed in a live data graph format and can then be compared to  a known good example contained within the software package itself.  This task remains incomplete as the data we obtained from all four injectors only produced 2 pulses, whereas the example contained within the software displays 3.  Multiple bursts are introduced as a means of evening out the combustion process and reducing diesel knock.  Further investigation required and will be resumed on Monday morning.

Example of expected pattern
from a Bosch Injector

Timing Chain Task - DOHC V6 Jaguar - Monday 3rd November 2014

Jaguar DOHC V6 (Petrol)
RHS Cam Cover Removed

Today saw a welcome return to activities after a week of half term, and it was straight back into the thick of it.  I was assigned the practice Timing Chain Task, again something I had never done before.  My initial impression from the instructions and diagram was one of confusion, however once all was explained by Julian Jones step by step, all became clear and I enjoyed the task very much indeed. Therapeutic even!  Having aligned the Crank key and RHS Cams (Inlet & Exhaust) to the correct positions I was then able to disengage the tensioner, with the aid of a pin inserted to the withdrawn plunger, remove the tensioner and then the guide, slipper and timing chain.  I then repeated the procedure to the LHS ensuring correct alignment first as per the provided instructions.  All adjustments are made from the crank with chains attached.

LHS & RHS Tensioners, Guides,
Slippers and Chains Removed

With parts removed it was time to re install, which first required the loosening of the RHS Camshaft Cap Covers, in order to be able to rotate the shafts a full 180 degrees to ensure the correct timing upon re-assembly.  With both LHS cams and the crank in the correct position I then re-fitted the timing chain as per the marked links in the chain, followed by the guide, slipper and tensioner.  With the pin removed the tension was then taken back up.  I left all torques until the end.  The same process was repeated to the RHS and, after an inspection by Julian of work completed to satisfactory standard, I was then able to torque up the camshaft caps and all other bolts to the manufacturer's specified settings.

Re-torquing LHS Camshaft
Cap Covers 

Both Chains Re-instated
(less Cam Covers)

After rotating the Crankshaft 9 times it was deemed that the procedure had been completed to standard and I was then able to re-install the cam covers and be signed off as complete.  A very enjoyable task (accompanied by my "whale song" music, according to Carl Black - on my new Tablet Distraction Device)!  Happy Days!