How To Service Your Car

I am no mechanic.  A mechanic is someone you pay to service your car.  Rather, I'm a home mechanic.  Sometimes being a home mechanic can lead to damage, pain and injury (see here for some real life stories) but sometimes it can lead to cost saving and a sense of satisfaction.  This is how to service your car if you are a home mechanic.

My 1998 BMW E36 323i SE Touring jacked up

I have just serviced my 1998 BMW E36 323i SE Touring in 90 minutes.  It's a 2.5 litre, 6-cylinder petrol car and relies on regular replacement of the oil, spark plugs and filters to operate efficiently.

I ordered a service kit from www.onlineautomotive.co.uk.  They only needed my car's registration number and put the kit together themselves.  It arrived in the post and consisted of an air filter, oil filter, new seal for the oil filter, a new sump plug seal and 5 litres of 5/30W oil.

I waited for a sunny day - working in the rain is miserable, plus you don't want to get water in the oil - and set to work.

The first step is to make a cup of tea.  Once that is done you need to understand where everything is in the engine bay.  There is usually an engine cover, you need to remove that.  On top of the engine block will be things called coils which sit on the spark plugs, although on old cars there may just be leads leading to the spark plugs and a cap on top of each plug.

The spark plugs sit in a hole a few inches deep.  You need to find the air filter and where the oil filter goes.  Sometimes it's on top of the engine, as it is in my BMW, and sometimes it is underneath.  Sometimes it is a metal cylinder which screws onto the engine blocks and sometimes, like mine, it is a cartridge that sits in a special housing.  The latter is less messy.

It is also worthwhile investing in some latex gloves.  Servicing is a messy business.

Step one is to replace the air filter.  Look for a plastic box somewhere in the engine with clips holding a lid down. You can see mine below.  If you can't find it look for an air intake pipe and work backwards to find the air box.  It was easy in mine just just to pull up the air filter cover and replace the filter.

Air filter replacement

Job done.  Now it's time to change the spark plugs.  In my BMW the plugs are under the engine cover so I took that off.  It was a two piece cover held in place with four bolts and was easy to remove.

Under the cover you will see the coils, in the case of this BMW there are six.  I've shown you the first three.

The BMW's coils

The coils need to be removed to get to the spark plugs.  In this case I pulled up that silver metal brace, unclipped the electrical connection and unscrewed the bolts holding the coil in place.  I took photos so I knew exactly where everything should go afterwards, particularly the earthing wires.

This is what you see.  A spark plug down a hole.  Now you need to put together a spark plug wrench to get the old ones out and the new ones in.

Spark plug in cylinder head

This is mine.  I cobbled it together from two Halfords socket sets.  The wrench on the end is 15mm and has a piece of rubber inside it to hold on to the plug.

Spark plug wrench made from socket set

You unscrew each spark plug and remove it.  Then you take a new spark plug, put it in the wrench and gently lower it into the hole.  In my case I tightened it back up using a nip - i.e. based on experience I knew how tight the plug should be.  If you're new to this then you might want to use a torque wrench.

The worst thing you can do is either get the spark plug in the hole at such an angle that you thread it, or that you over-tighten the plug.  Both can be disastrous and can crack the cylinder head so make sure you get it right.

With all the spark plugs back in place I reattached the coils and the job was done.  I turned the engine over to make sure everything looked and sounded good.  It was.

The next job is the oil.  Do the filter first so you don't mix any old oil with the new stuff you're about to put in.  The BMW has a cartridge filter.  I found the top of the filter housing, used a 36mm socket and undid it.  It requires a lot of effort to undo.

This is really messy so make sure you're careful and wear your gloves.  I took the old filter off the cap's spindle and put the new one on.  That black circle in the plastic bag is a new seal for the filter cap.  Remove the old one and replace it.  Then screw the filter cap, with new filter in place, back into its housing.  Make sure it's nice and tight, and use a torque wrench if you're not sure.

New and old oil filters with 36mm socket to undo the cartridge

Then we come to the oil itself.  It goes into the engine via a cap on the top of the engine and comes out at the bottom via something called a sump plug.

Undo the oil cap at the top, jack the car up and find the sump plug, which should be right at the bottom of the engine block.  Get an oil pan that can take at least 10 litres and position it under the sump plug.  This part is seriously messy.

Undo the sump plug, mine needed a 15mm socket.  It might take a huge amount of effort.  In the past I've put a bar over my ratchet handle for extra leverage.  I've also come across sump plugs that have been seized solid and have managed to round the bolt so it couldn't come off at all.

Happily the BMW's came off with one hard tug of the ratchet.  Now, make sure your oil pan is in place and unscrew the plug by hand.  Don't drop it in the oil!  The oil will start to pour out.  You may want to reposition your oil pan.

Put the sump plug somewhere safe and go and make a brew whilst the oil pours out.

Oil draining out of the sump

Once all the oil is out put a new washer on the sump plug, my service kit had one in it, then clean the hole where it goes with a rag and screw the plug back in place.  Tighten it with a hard nip, or use a torque wrench.

Put the car back down on the ground and fill the engine with oil via the cap on top of the engine.  Look up how much oil your engine takes.  Mine needed about 6 litres but the service kit only had 5 litres - luckily I had a spare bottle of 5/30W to top it up.

Filling the engine with new oil

Once you think there is enough check the dipstick.  Once the oil is at the correct level on the dipstick start the engine and leave it for 5 minutes whilst you make another brew.

After 5 minutes check turn the engine off and check the oil level on the dipstick.  If it's in the middle you've finished, if not top it up and check it again.

Once done put the oil cap back on and put the engine cover in place.  The old oil needs to be recycled.  Pour it into a container like the one in the picture below.

Old engine oil ready for recycling

You've just serviced your car.  Shut the bonnet, take it for a spin to the tip and drop off your old oil, and think about how much money you've saved.

By Matt Hubbard