BMG garage services

Auto Repair & Servicing Articles


_How to – Car servicing the simple way

_ Introduction:

People tend to be fearful of that which they don’t understand and the way cars have developed with their overabundance of electronics it’s not surprising people have turned away from getting their hands dirty. But it doesn’t have to be all that complicated because mechanically cars have changed very little over the years. What car engines essentially need; fresh oil for lubrication, plenty of water to keep it cool, a clean supply of air for to mix with the fuel in the combustion chamber and a set of spark plugs to ignite the fuel air mix. A lot of the electronic gadgetry on the cars now was introduced purely to lower emissions and increase safety. But we won’t be worrying about any of that stuff for now. Emissions are lowered by ECU (Electronic Control Unit - car engines main computer) programming fine tuned to reduce amount of petrol used in each stroke. By regulating the hydrocarbon gases / vapour released from the petrol tank using active charcoal filters. And by filtering the exhaust through the catalytic convertor which neutralises the harmful waste (Carbon Monoxide and Hyrdocarbons) in the smoke.

How to know when to service your engine? Well an engine service interval is based on many different variables, most obvious being the mileage and the number of months since the last service. But climate conditions like temperature and humidity also have an effect on the oil's condition, as well as whether the car is being driven for short or long journeys. From servicing experience and Irelands mild climate we find on average a car should be serviced every 8000 miles or 1 year – See note 1 below. This can be achieved through changing the oil and oil filter, topping up the coolant (water + antifreeze), replacing the air filter and checking or changing the spark plugs. All these parts can be bought at your local Motor Factors – See list at bottom. There are many other vehicle checks that can be done and these are all listed after the engine service.

Tools required:

Oil basin (at least 5L), suitable sump bung spanner, philips & flathead screwdriver, spark plug socket with extension bar and a pull bar, car jack, jack support 

Safety Notice:

This is simply a guide to maintaining your vehicle please be careful when working around or under a car. Don’t run a car in a closed room as the trapped gases can kill. Oil is a toxin don’t pour it down the drain please dispose of waste products responsibly. If jacking up a car always have a second support in place in case the jack moves or breaks. I don’t take any responsibility for the safety of your person, if you are unsure about what you are doing please ask for advice.

Steps 1 - 5


Service Kit
Service Kit
_ Step 1 : Preparation

Buy your engine oil, oil filter, air filter and spark plugs at your local motor factors – See note 2 below.  Check to see that you have the right tools and filters appropriate to the car you wish to service. There is nothing worse than half a service done and no car to go get the tool or filter you need to finish it.


_ Step 2 : Oil & filter

Place the basin underneath the car below the sump (where the engine oil is stored) using a suitable spanner (size 15, 17, 19 or 21) release the bung (bolt that plugs the sump). Let the oil drain into the basin over 10 minutes and then screw the bung back into the sump. Now refill your engine oil with about 3L of the new oil and using the dipstick repeatedly measuring, wiping and filling another 250ml until you get the level just right (where the oil is at the second notch up on the dipstick).

Steel spin on filter
Plastic housing for paper filter
_ How you change the oil filter will depend on whether its the steel or paper type. The steel type shown on the left is a good deal simpler and can be unscrewed by hand. Rub some oil around the seal of the new filter and screw it hand tight back into place . The paper filter housing shown on the right will be held in a plastic housing with a large plastic nut on the head (possibly a size 27). Using a suitable socket (27, 30, 32) unscrew the top plastic cap of the housing and pull out and replace the filter. There will be a new oil ring with the filter, this goes around the base of the threads on the plastic cap.

Now check the oil level is ok, the bung is secured in place and the oil filter is back in position you can start the car and let it idle, allowing the new oil to circulate and fill the new filter while you check for leaks. Stop the car and give it 10 minutes for the oil to drain down into the sump and recheck the oil level. Add some extra oil as needed. Careful don’t overfill as too much oil is as damaging as too little.


Car service - air filter
Car service - Air filter
_Step 3 : Air filter and Spark plugs

Changing the air filter is pretty easy, they are usually held in a plastic housing unit which can be opened with a few Philips screws or finger clips.

_ Replacing the spark plugs is also straight forward. There is one per cylinder (4 cylinders in the average car engine) and to access the spark plug you’ll have to first remove the spark plug leads as shown on the left. Or more commonly used since 2002 a coil pack as shown on the right which was held in by two bolts. Although its not always needed its common practice to replace plugs at every service. They are relatively inexpensive and can save the coil from taking the strain off an inefficient plug, which would reduce the coils life expectancy causing a more costly repair. There are plugs available now produced with plantinum tips and should be good up to about 60,000 or 80,000 miles. These are known as long-life plugs and this characteristic is reflected in their high price.
Car Service - Rover Spark Leads
Car Service - Corsa Coil Pack
_ Step 4:  Reset service light

Now that the engine service is completed we can go ahead and reset the service interval light. Not all cars are equipped with a service reminder light so don't worry if you cant find yours. Normally its displayed as words (INSP-Inspection, Oil, Service) or a symbol of a spanner. Below we can see the word INSP is displayed when we turn the ignition on. Follow the instructions below to reset this timer.


Car Service - Dash display
_ Each make and model has a different technique to resetting the service and oil lights but they all loosely follow the same idea. Locate the button on your dash that resets the trip mileage and with the ignition off press the reset button . In the above image this is the button on the lower right. Hold this button down as you turn on the ignition, now after a few seconds the service light, icon or symbol might start to flash or a countdown may appear. Continue to hold the reset button for about 10 secs and hopefully the next service interval will appear, if not wait for about 15 secs and turn off and on the key again. Now if the service symbol or word doesn't appear you are done, simple as that. If the service light is still up you may need to throw me a text or google it. Some cars can be a bit awkward with service lights or may even need to have the diagnostic computer connected to reset the light although this is less common.

_Step 5: Check Fluids & Lights

Rover engine
Car Service - Engine Fluids
_ There are a number of checks you can do following your engine service. Most importantly is the coolant level, this is the water reservoir tank. The term coolant is used to describe water mixed with antifreeze, so if only a few 100mls are needed either will do.

Check that the brake fluid reservoir is almost full. Check the power steering fluid using the cap as it has a little dipstick connected to it. And lastly of the fluids the window wash bottle should be filled (water + cleaning agent).

Check all the lights easily by first putting on the hazards and the parking lights and walking around the car. Switching off the hazards and parking lights you can check the brake lights, reverse lights and fogs one at a time if you reverse up to a wall or window and look at the how the reflection changes. If that doesn’t do it get a second person to help.

Check your wiper blades condition by gently pulling back the wiper arm and checking to see if any part of the rubber strip is ripping, if so its worth changing them. Wiper blades that cause streaks maybe just need a clean with a degreasing agent and use an alcohol based cleaner in your washer bottle to reduce bluring on the windscreen. If you find the sprayer jets (nozzles) aren't very efficent they're probably blocked up with dirt. Disconnecting the washer feed pipe from the underneath of the bonnet and using a pressurised line you can blow air pressure back through the nozzles. This generally sorts them out until the next service.

I’ll list more checks here that are done in a garage service but I won’t go into much detail yet;

a.       Brake pad wear on the front and rear discs,

b.      Tyre Condition, Pressure and Thread Depth

c.      Auxiliary belt (fan belt) condition

d.      Suspension system checks

e.      Electronic instruments

f.       Diagnostics

g.      Wheel bearings and steering rods


1.       The use of a fully synthetic oil eg 5w-30 can increase the service interval to 15000 or 2 years depending on engine design. A lot of newer cars > 2008 are using fully synthetic oil and is becoming a standard. Although it is better for the engine and helps lower emissions (contains less sulphurs etc), this oil is a lot more expensive :(

2.      All the parts you’ll need can be bought at your local motor factors, Engine oil (10w40 Semi-Synthetic) x 4.5L, Oil filter, air filter and set of spark plugs. Ring your motor factors with the car model, engine size & year and they’ll tell you the parts you need. Cheap engine oil that is commonly seen on offer could be 15w40 Mineral and is not recommended for about 90% of road cars nowadays, so its worthwhile reading up on what type it is.


You'll find them everywhere, and they can usually always supply any of the parts you'll need when servicing a car. The guys we use and would vouch for are Lexlip Autoparts (016247450) and Matt Reillys (Lucan village 016240011). Since we're based in Lucan these are our local suppliers, if your dealing with either of these guys mention us (it may work in your favour).

Thats all I got time for now folks. Hope you'll find this article was of some use.

Ian Boyle



01 6280741


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They may not be used except by written permission from Ian Boyle.

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Top Tips - Fuel Economy

Tyre pressures should always be kept between 30 and 35 psi, this is found to be the most suitable setting for 99% cars in helping reduce fuel usage. Keeping tyres at this pressure reduces the rolling friction caused by the wheels on the road and so reducing the amount of effort required by the engine to move the car. Also keeping your pressures right will keep the tyres from wearing out faster than they should, since an under pressurised tyre heats up more causing it to wear out more.

You should visit your local petrol station and use their tyre gauge to check your tyres its quite easy once you try it. Otherwise drop into ourselves and we ll pressurise your tyres for you.

Hope this was helpful,

BMG Car Advice

Ian Boyle

_NCT Statistics Review

This review is based on the NCT results published on the NCT website at:
It was from here that I collected and compiled the information into digestible graphs to view for those who are interested. The graph below shows the number of cars tested per year and it can be seen that the numbers have been rising considerably up to a total of nearly one million cars being tested in 2011.

car NCT count

The bar chart shown below is calculated from the same list and lays out the probability of a car at a certain year passing the NCT test. The lower section of the bars shows the percent chance of a car of that age passing the first time. For simplicity the 1st time pass percentage has been rounded to the nearest 10 but in all cases the discrepancy was below 2 percent.

Probability of car passing NCT test

And finally the pie chart below lays out the most common reasons a car may fail the test. It should be kept in mind though that "front suspension" covers many more components then the other common failures.

Most common NCT fail issues

I had hoped to elaborate more on the details of the findings and how they might affect a person going for the test or how a garage prepares a car for the test. But I find time is at a constraint for the moment so will leave you with the charts until a later date until I can more fully layout the advantages of focusing ones attention to the right areas. I hope that this will be found to be of some use.

BMG Car Advice

Ian Boyle


BMW 320 diesel with noisy rattle at cold start

Its becoming more and more common on the N47 BMW engine, the dreaded BMW chain rattle. This is usually caused by the very light timing chain stretching and flexing about hitting the guide and/or the oil nozzle bolt.

It is first noticed on cold starts, due to the fact that it takes more time for the chain tensioner to become hydraulically pressurised by the oil as it extends out far enough to take the slack of the chain.  The tensioner pushes the guide against the chain in order to keep it taut and reduce the chains flexing, reducing the noise generated by the chain. But as the chain stretches, the tensioner has to extend out further and further until when it reaches its maximum piston length, where the chain will then stay slack. At this point it is very likely the chain will soon break causing expensive damage to the engine.

It can be seen in the 2nd and 3rd image how the chain tensioner is fully extended and how the chain is practically rubbing against the oiling nozzle that lies about 4 inches to the left of the tensioner.

Images 4 and 5 show the new timing chain fit to the engine, it can be seen how the now slightly shorter chain is taut with the tensioner almost fully retracted.

For more information please call 01 6280741

Hope this was helpful,


Ian Boyle