Oil- and oil-fil­ter change

Popular Mechanics (South Africa) - - In The Garage -

Take a 5 km drive to warm up your en­gine (warm oil drains out bet­ter than cold oil). Don’t go too far, as you don’t want it so hot that you risk burn­ing your­self. Park your ve­hi­cle on a level spot and put the ig­ni­tion keys some­where far away, and safe. ( You re­ally don’t want to ab­sent­mind­edly start your en­gine un­til you have fin­ished the job!)

Place sev­eral sheets of news­pa­per un­der the en­gine to pro­tect the floor, then po­si­tion your oil drain con­tainer un­der the en­gine and be­low the sump plug. (If these are com­pletely for­eign terms to you, maybe stop now and make an ap­point­ment at your near­est trust­wor­thy ser­vice cen­tre).

On many late-model ve­hi­cles, there is a large cover be­neath the en­gine to im­prove the aero­dy­nam­ics. This will have to be re­moved be­fore you can ac­cess the sump plug. Be sure to save all the small bolts or screws to re-fit the cover af­ter­wards.

Loosen the sump plug ( but do not re­move it just yet), po­si­tion your con­tainer to catch the im­mi­nent flow of warm en­gine oil, then turn the sump plug out un­til you can grab it just be­fore it falls into the tray – this will be fol­lowed by a cas­cade of warm en­gine oil. Keep your hands clear! If the plug falls into the tray, you can re­trieve it later.

Wait five min­utes while all the oil drains out of your en­gine. If you are a purist, you will now pro­ceed to jack up var­i­ous wheels to do main­te­nance work on the brakes and wheels ( but we’ll dis­cuss that an­other time). The chang­ing an­gles of the car en­sure that you drain ev­ery last dreg of the old, grimy oil. Now re­move the oil fil­ter. This is ei­ther a cylin­dri­cal spin-off car­tridge roughly 100 mm in di­am­e­ter and be­tween 100 mm and 150 mm long, which is screwed on to a hous­ing against the en­gine block, or it may be a hous­ing with a screw-on cover with the ac­tual fil­ter el­e­ment in­side. (Some en­gine de­sign­ers, it ap­pears, take great d de­light in mak­ing the oil f fil­ter as in­ac­ces­si­ble as po pos­si­ble, mean­ing you need rub­ber wrists and su­per­hu­man strength to get to it.) Clean off all dirt where the fil­ter or cover me meets the hous­ing, then unsc un­screw the fil­ter by turn­ing it anti- c clock­wise away from the mount­ing poi point. With the spin- off car­tridge type, you may find that it’s so tight you can’t turn it. There are spe­cialised span­ners avail­able from auto-spares sup­pli­ers which make this a bit eas­ier. Some are okay, and some, well, some are junk; un­for­tu­nately, you don’t gen­er­ally get

to make this dis­tinc­tion un­til you use them. I just use a ham­mer, and I punch a large screw­driver right through the old fil­ter, then pull on the screw­driver to loosen it (you’ll def­i­nitely re­quire news­pa­per on the floor in this in­stance, , as this is the messy method).

Dis­card the old car­tridge fil­ter or, in the case of those with a cover, re­move the fil­ter el­e­ment and dis­card (safely and sen­si­bly, as men­tioned in the ‘ Oil

Dis­posal’ side­bar). Smear clean oil on to the rub­ber seal on the new car­tridge fil­ter and screw it into place, as tight as you can make it by hand. (Purists fill the fil­ter with new oil first, thus re­duc­ing the time the en­gine will be op­er­at­ing with­out lu­bri­ca­tion). For the other type, in­sert the fil­ter into the hous­ing and then care­fully re­place the cover. Pour in some clean oil if you wish.

Re­place and tighten the sump plug. Don’t for­get this point. Re­ally.

Fill the en­gine with the cor­rect quan­tity and grade of new oil – check your ser­vice man­ual for these specs. You do this by pour­ing in the re­quired vol­ume through the filler cap lo­cated on top of the en­gine tap­pet cover. (‘ Tap­pet cover?’ you say… Okay, off to your ser­vice cen­tre.)

Re­place the filler cap once you’ve poured in the re­quired amount of oil.

Now, if you can re­mem­ber where you put your keys, start the en­gine and run it for about two min­utes. Switch off and check at the sump plug and oil fil­ter for leaks. Tighten if nec­es­sary. Wait an­other two min­utes, then check the oil level us­ing the dip­stick. Top up to no higher than the up­per mark on the dip­stick, and al­ways wait for the ad­di­tional oil to set­tle down to the sump be­fore you re- check the dip­stick.

Never, ever over­fill, as this can cause en­gine dam­age.

Air-fil­ter change

The air fil­ter sits in­side a big black hous­ing to one- or other side of the en­gine. Some­times it’s even right on top of the en­gine. As most en­gines these days use a pleated-pa­per air fil­ter, this is what I will talk about.

The hous­ing will have a cover or lid l of some sort, held on by means of tog­gle clamps. Clean all loose dirt from the hous­ing, then loosen the clamps. c De­pend­ing on the lay­out, you may also have to loosen the cir­cu­lar clips around the f lexible rub­ber duct con­nect­ing the fil­ter hous­ing h to the in­take man­i­fold.

Watch out for any lit­tle pipes con­nected c to the hous­ing or in­let man­i­fold. If you have to re­move any, take care­ful note of which ones o go where.

Take off the cover and re­move the dirty fil­ter. Don’t let any dirt fall into the ‘clean’ area of the hous­ing, or into the in­take man­i­fold. Wipe (or vac­uum) any dirt from the hous­ing. Fit the new fil­ter, then close up and se­cure the cover and all clips, hoses and fas­ten­ers. Job done.

Fuel-fil­ter change (petrol) Safety first, al­ways! Petrol is highly flammable, so do not smoke or use any naked flames while you carry out this task. Switch off the en­gine and re­move your keys from the ig­ni­tion.

Look for the hous­ing or com­po­nent that looks like the new fuel fil­ter you bought for your model of car. On many ve­hi­cles, this might be un­der­neath, some­where around the re­gion of the rear axle.

Quite sim­ply, clean off all ex­ter­nal dirt, undo any hose- clamps or cover screws and re­place the fil­ter. If do­ing in-line fil­ters, en­sure that you get the flow di­rec­tion right, usu­ally in­di­cated by an ar­row on the hous­ing.

Re­place all clamps or screws, and then start your car and check for any fuel leaks.

Fuel-fil­ter change (diesel) Switch off the en­gine and re­move your keys from the ig­ni­tion.

Be­cause the in­jec­tor pump op­er­ates at very small clear­ances and the fuel’s more vis­cous, diesel fil­ters are big­ger and more so­phis­ti­cated than their petrol coun­ter­parts. You may even have two of them in se­ries – one to re­move mois­ture and one for dirt.

Thor­oughly clean off the hous­ings be­fore you be­gin. Some­times the fil­ter bowls screw off just like the spin- off car­tridge- type oil fil­ter men­tioned ear­lier, whereas some­times they are se­cured by a cen­tre bolt, or sit un­der a cover. Just an­a­lyse the task and work at it log­i­cally. If you are at all un­sure, get pro­fes­sional ad­vice or as­sis­tance. Fit the new fil­ter or fil­ters. Im­por­tantly, you now have to bleed the air out of the fil­ters, oth­er­wise the in­jec­tor pump will suf­fer cav­i­ta­tion and not de­liver fuel to the in­jec­tors. The user man­ual may in­di­cate where to find the bleed screw. If not, look for a prominent screw with a drain port ad­ja­cent to it some­where on the fil­ter hous­ing. It may even have a con­ve­nient short length of hose at­tached to it. Run the hose into an empty jam tin, if there is space, or con­nect an ex­ten­sion to it and down to a tin on the floor.

Loosen the bleed screw one full turn. Switch on the ig­ni­tion, but do not start the en­gine. Some­where near the fuel tank, you will hear the fuel de­liv­ery pump run­ning. Wait at the bleed screw un­til fuel flows cleanly from the hose, then close the bleed screw. Re­move the jam tin and dis­pose of the fuel safely.

On later-model en­gines, you merely have to de­press a but­ton on the top of the fil­ter hous­ing with the ig­ni­tion on to purge any air back to the fuel tank.

Now start the en­gine. If it does not start af­ter a cou­ple of tries, re­peat the bleed­ing ex­er­cise.

Check for any fuel leaks.

Chang­ing the spark plugs The most im­por­tant thing here is to not mix up where all the spark-plug leads go, es­pe­cially on a six- or eighttcylin­der en­gine. Iden­tify them by y tag­ging each with a piece of mask­ing ing tape, then pull the rub­ber caps off the spark plugs. Be care­ful not to pull on the lead as it can break out of the end- cap p quite eas­ily, mean­ing you’ll l need to buy a re­place­ment. t.

If your en­gine is dirty and there is grime around the bases of the spark plugs, use a small paint­brush tbrush to clean this away as best you can. A house­hold vac­uum cleaner with a small noz­zle at­tach­ment works very well for this too.

Now, us­ing a stan­dard plug span­ner, re­move all the spark plugs and place them on your work­bench, ori­ented as they are in the en­gine, and ex­am­ine them. They should all be a brown­ish colour and oil-free.

If they are black and sooty, your en­gine is run­ning too rich and you are wast­ing fuel. If they are all a very light grey, your en­gine may be run­ning too lean. (These ob­ser­va­tions are es­pe­cially ap­pli­ca­ble to the older car­bu­ret­toraspi­rated en­gines.) If they are black and oily, ei­ther your pis­ton rings or your valve-stem seals are worn. These will re­quire spe­cial­ist at­ten­tion and are be­yond the scope of this ar­ti­cle.

If only one or two are black and oily, then it’s likely that there is a bro­ken pis­ton ring on that cylin­der, and be­cause you kept them in or­der, you now know which cylin­der it is.

Now that we’ve dis­pensed with this en­gine- di­ag­no­sis op­por­tu­nity, set the elec­trode gap on all your new spark plugs to the mea­sure­ment spec­i­fied in your user man­ual. The new gap is usu­ally just a lit­tle too big and you need to gen­tly tap the elec­trode to close it un­til your feeler gauge just drags through the gap. If you overdo it and need to open the gap again, use your long-nose pliers and bend the elec­trode open from its root. Never use a feeler gauge as a lever for this task, as you will stress the enamel sur­round­ing the cen­tral elec­trode, caus­ing it to crack.

Fit the new spark plugs and tighten only moder­ately. Be very care­ful not to cross-thread them – this is a very ex­pen­sive mis­take to make, as it may re­sult in you hav­ing to have the whole cylin­der head re­moved.

Re­place the spark-plug leads in the right or­der, and you’re ready to roll.

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