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Fluid level checks BMW 3-Series 1998 - 2006 Petrol 318i - 1.8

OnDemand step-by-step maintenance & repair BETA

BMW 3-Series 1998 - 2006  | 318i - 1.8 Fluid level checks

  • time 5 to 30 minutes
  • difficulty 1

Underbonnet check points

4-cylinder engine (2.0 litre shown) A Engine oil level dipstick B Engine oil filler cap C Coolant expansion tank D Brake and clutch fluid reservoir E Screen washer fluid reservoir
6-cylinder engine (2.5 litre shown) A Engine oil level dipstick B Engine oil filler cap C Coolant expansion tank D Brake and clutch fluid reservoir E Screen washer fluid reservoir

Engine oil level

1 • Make sure that the car is on level ground.
2 • Check the oil level before the car is driven, or at least 5 minutes after the engine has been switched off.
HINT: If the oil is checked immediately after driving the vehicle, some of the oil will remain in the upper engine components, resulting in an inaccurate reading on the dipstick.

The correct oil

3 Modern engines place great demands on their oil. It is very important that the correct oil for your car is used.
Engine oil grade:
  M43TU, M52TU and M54 engines BMW long-life oil* SAE 0W-40 or SAE 5W-30 (fully synthetic) to ACEA A3/B3, API SJ/CD, ECII
  N42 engines BMW long-life oil* SAE 0W-30 (fully synthetic) to ACEA A3, API SJ/CD, ECII
  N46 engines BMW long-life oil* SAE 5W-30 (fully synthetic) to ACEA A3, API SJ/CD, ECII
* Refer to your BMW dealer for brand name and type recommendations

Car care

4 • If you have to add oil frequently, you should check whether you have any oil leaks. Place some clean paper under the car overnight, and check for stains in the morning. If there are no leaks, then the engine may be burning oil.
5 • Always maintain the level between the upper and lower dipstick marks (see photo 3). If the level is too low, severe engine damage may occur. Oil seal failure may result if the engine is overfilled by adding too much oil.
The dipstick top is often brightly coloured for easy identification (see Underbonnet check points for exact location). Withdraw the dipstick.
Using a clean rag or paper towel remove all oil from the dipstick. Insert the clean dipstick into the tube as far as it will go, then withdraw it again.
Note the oil level on the end of the dipstick, which should be between the upper maximum mark (1) and lower minimum mark (2). Approximately 1.0 litre of oil will raise the level from the lower mark to the upper mark.
Oil is added through the filler cap. Unscrew the cap and top‑up the level; a funnel may help to reduce spillage. Add the oil slowly, checking the level on the dipstick often. Don’t overfill (see Car care). If you need to renew the oil and filter, click below
- Close + Open

Engine oil and filter change

1 Frequent oil and filter changes are the most important preventative maintenance work which can be undertaken by the DIY owner. As engine oil ages, it becomes diluted and contaminated, which leads to premature engine wear.
2 Before starting this procedure, gather together all the necessary tools and materials. Also make sure you have plenty of clean rags and newspapers handy, to mop-up any spills. Ideally, the engine oil should be warm, as it will drain better, and more built-up sludge will be removed with it. Take care, however, not to touch the exhaust or any other hot parts of the engine when working under the car. To avoid any possibility of scalding, and to protect yourself from possible skin irritants and other harmful contaminants in used engine oils, it is advisable to wear gloves. Access to the underside of the car will be improved if it can be raised on a lift, driven onto ramps, or jacked up and supported on axle stands. Whichever method is chosen, make sure the car remains level, or if it is at an angle, so that the drain plug is at the lowest point. Where necessary remove the splash guard from under the engine. On vehicles equipped with front reinforcement plate between the front suspension lower control arms, access to the sump plug is via a removable flap in the plate (see illustration) .
Access to the sump plug is via a flap in the reinforcement plate
3 Working in the engine compartment, locate the oil filter housing on the left-hand side of the engine, in front of the inlet manifold.
4 Place a wad of rag around the bottom of the housing to absorb any spilt oil.
5 Using a special oil filter removal tool or socket, unscrew and remove the cover, and lift the filter cartridge out. It is possible to unscrew the cover using a strap wench (see illustrations) . The oil will drain from the housing back into the sump as the cover is removed.
Screw-fit oil filter cover
Use an oil filter removal tool . . .
. . . or a strap wrench
6 Recover the O-rings from the cover.
7 Using a clean rag, wipe the mating faces of the housing and cover.
8 Fit new O-rings to the cover (see illustration) .
Fit new O-rings (arrowed) to the screw-on cover
9 Lower the new filter cartridge into the housing.
10 Smear a little clean engine oil on the O-rings, refit the cover and tighten it to 25 Nm (18 lbf ft) if using the special filter removal tool, or securely if using a strap wrench.
11 Working under the car, slacken the sump drain plug about half a turn (see illustration 10.2) . Position the draining container under the drain plug, then remove the plug completely. If possible, try to keep the plug pressed into the sump while unscrewing it by hand the last couple of turns.
12 Recover the drain plug sealing ring.
13 Allow some time for the old oil to drain, noting that it may be necessary to reposition the container as the oil flow slows to a trickle.
14 After all the oil has drained, wipe off the drain plug with a clean rag. Check the sealing washer condition, and renew it if necessary. Clean the area around the drain plug opening, then refit and tighten the plug to the specified torque (see illustration) .
Check the condition of the sump drain plug washer
Engine oil sump drain plug: Nm Ibf ft
  M12 plug 25 18
  M18 plug 30 22
  M22 plug 60 44
15 Remove the old oil and all tools from under the car, then lower the car to the ground (if applicable).
16 Remove the dipstick then unscrew the oil filler cap from the cylinder head cover. Fill the engine, using the correct grade and type of oil. An oil can spout or funnel may help to reduce spillage. Pour in half the specified quantity of oil first, then wait a few minutes for the oil to fall to the sump. Continue adding oil a small quantity at a time until the level is up to the lower mark on the dipstick. Finally, bring the level up to the upper mark on the dipstick. Insert the dipstick, and refit the filler cap.
Engine oil quantity: Litres
  1796 cc (engine codes N42 B18 and N46 B18) 4.25
  1895 cc (engine code N43TU B19) 4.0
  1995 cc (engine codes N42 B20 and N46 B20) 4.25 litres
  6-cylinder engines 6.5 litres
Engine oil grade:
  M43TU, M52TU and M54 engines BMW long-life oil* SAE 0W-40 or SAE 5W-30 (fully synthetic) to ACEA A3/B3, API SJ/CD, ECII
  N42 engines BMW long-life oil* SAE 0W-30 (fully synthetic) to ACEA A3, API SJ/CD, ECII
  N46 engines BMW long-life oil* SAE 5W-30 (fully synthetic) to ACEA A3, API SJ/CD, ECII
* Refer to your BMW dealer for brand name and type recommendations
17 Start the engine and run it for a few minutes; check for leaks around the oil filter seal and the sump drain plug. Note that there may be a delay of a few seconds before the oil pressure warning light goes out when the engine is first started, as the oil circulates through the engine oil galleries and the new oil filter, before the pressure builds-up.
18 Switch off the engine, and wait a few minutes for the oil to settle in the sump once more. With the new oil circulated and the filter completely full, recheck the level on the dipstick, and add more oil as necessary.
19 Dispose of the used filter and engine oil safely.

Coolant level

Warning: Do not attempt to remove the expansion tank pressure cap when the engine is hot, as there is a very great risk of scalding. Do not leave open containers of coolant about, as it is poisonous.

Car care

6 • With a sealed-type cooling system, adding coolant should not be necessary on a regular basis. If frequent topping-up is required, it is likely there is a leak. Check the radiator, all hoses and joint faces for signs of staining or wetness, and rectify as necessary.
7 • It is important that antifreeze is used in the cooling system all year round, not just during the winter months. Don’t top-up with water alone, as the anti-freeze will become diluted.
The coolant expansion tank incorporates a float device which indicates the level of coolant. When the upper end ofthe float protrudes no more than 20 mm above the filler neck, the level is correct. See the information adjacent to the fillercap.
If topping up is necessary, wait until the engine is cold. Slowly unscrew the expansion tank cap, to release any pressure present in the cooling system, and remove it.
Add a mixture of water and antifreeze to the expansion tank until the top of the coolant level indicator float protrudes no more than 20 mm above the filler neck. Refit the cap and tighten it securely.
Anti-freeze type Long-life ethylene glycol based antifreeze*
* Refer to your BMW dealer for brand name and type recommendations
Should you need to replace the coolant, click below
- Close + Open

Coolant replacement

Warning: Wait until the engine is cold before starting this procedure. Do not allow antifreeze to come in contact with your skin, or with the painted surfaces of the car. Rinse off spills immediately with plenty of water. Never leave antifreeze lying around in an open container, or in a puddle in the driveway or on the garage floor. Children and pets are attracted by its sweet smell, but antifreeze can be fatal if ingested.

Cooling system draining

1 With the engine completely cold, cover the expansion tank cap with a wad of rag, and slowly turn the cap anti-clockwise to relieve the pressure in the cooling system (a hissing sound may be heard). Wait until any pressure in the system is released, then continue to turn the cap until it can be removed.
2 Unscrew the bleed screw from the top of the hose junction above the expansion tank. Some models are equipped with a bleed screw adjacent to the oil filter cap (see illustrations) .
Unscrew the bleed screw (arrowed)
On some models, a second bleed screw is located adjacent to the oil filter cover (arrowed)
3 Undo the retaining bolts/clips and remove the undershield from beneath the engine (see illustration) .
Engine undershield bolts (arrowed)
4 Position a suitable container beneath the drain plugs on the base of the radiator and the expansion tank. Unscrew the drain plugs and allow the coolant to drain into the container (see illustrations) .
Open the expansion tank drain plug (arrowed) . . .
. . . and the radiator drain plug
5 To fully drain the system, also unscrew the coolant drain plug from the right-hand side of the cylinder block and allow the remainder of the coolant to drain into the container. On N42 and N46 4-cylinder engines, a second block drain plug is fitted to the left-hand side of the cylinder block (see illustrations) .
The cylinder block drain plug is located on the right-hand side (arrowed)
On N42 and N46 4-cylinder engines, a second engine block drain plug is located on the left-hand side (arrowed – engine removed for clarity)
6 If the coolant has been drained for a reason other than renewal, then provided it is clean and less than two years old, it can be re-used, though this is not recommended.
7 Once all the coolant has drained, refit the bleed screw to the hose junction. Fit a new sealing washer to the block drain plug and tighten it to 25 Nm (18 Ibf ft).

Cooling system flushing

8 If coolant renewal has been neglected, or if the antifreeze mixture has become diluted, then in time, the cooling system may gradually lose efficiency, as the coolant passages become restricted due to rust, scale deposits, and other sediment. The cooling system efficiency can be restored by flushing the system clean.
9 The radiator should be flushed independently of the engine, to avoid unnecessary contamination.

Radiator flushing

10 To flush the radiator, disconnect the top and bottom hoses and any other relevant hoses from the radiator.
11 Insert a garden hose into the radiator top inlet. Direct a flow of clean water through the radiator, and continue flushing until clean water emerges from the radiator bottom outlet.
12 If after a reasonable period, the water still does not run clear, the radiator can be flushed with a good proprietary cooling system cleaning agent. It is important that their manufacturer’s instructions are followed carefully. If the contamination is particularly bad, insert the hose in the radiator bottom outlet, and reverse-flush the radiator.

Engine flushing

13 To flush the engine, remove the thermostat, then temporarily refit the thermostat cover.
14 With the top and bottom hoses disconnected from the radiator, insert a garden hose into the radiator top hose. Direct a clean flow of water through the engine, and continue flushing until clean water emerges from the radiator bottom hose.
15 On completion of flushing, refit the thermostat and reconnect the hoses.

Cooling system filling

16 Before attempting to fill the cooling system, make sure that all hoses and clips are in good condition, and that the clips are tight and the radiator and cylinder block drain plugs are securely tightened. Note that an antifreeze mixture must be used all year round, to prevent corrosion of the engine components (see following sub-Section).
17 Slacken the bleed screw(s) (see illustration 14.2a and 14.2b) .
18 Turn on the ignition, and set the heater control to maximum temperature, with the fan speed set to ‘low’. This opens the heating valves.
19 Remove the expansion tank filler cap. Fill the system by slowly pouring the coolant into the expansion tank to prevent airlocks from forming.
Coolant quantity: Litres
  1796 cc (engine codes N42 B18 and N46 B18) 7.0
  1895 cc (engine code M43TU B19) 6.0
  1995 cc (engine codes N42 B20 and N46 B20) 8.4
6-cylinder engines (engine codes M52TU and M54) 8.4
Anti-freeze type Long-life ethylene glycol based antifreeze*
* Refer to your BMW dealer for brand name and type recommendations
20 If the coolant is being renewed, begin by pouring in a couple of litres of water, followed by the correct quantity of antifreeze, then top-up with more water.
21 As soon as coolant free from air bubbles emerges from the radiator bleed screw(s), tighten the screw(s) securely.
22 Once the level in the expansion tank starts to rise, squeeze the radiator top and bottom hoses to help expel any trapped air in the system. Once all the air is expelled, top-up the coolant level to the MAX mark and refit the expansion tank cap.
23 Start the engine and run it until it reaches normal operating temperature, then stop the engine and allow it to cool.
24 Check for leaks, particularly around disturbed components. Check the coolant level in the expansion tank, and top-up if necessary. Note that the system must be cold before an accurate level is indicated in the expansion tank. If the expansion tank cap is removed while the engine is still warm, cover the cap with a thick cloth, and unscrew the cap slowly to gradually relieve the system pressure (a hissing sound will normally be heard). Wait until any pressure remaining in the system is released, then continue to turn the cap until it can be removed.

Antifreeze mixture

25 The antifreeze should always be renewed at the specified intervals. This is necessary not only to maintain the antifreeze properties, but also to prevent corrosion which would otherwise occur as the corrosion inhibitors become progressively less effective.
26 Always use an ethylene-glycol based antifreeze which is suitable for use in mixed-metal cooling systems.
27 Before adding antifreeze, the cooling system should be completely drained, preferably flushed, and all hoses checked for condition and security.
28 After filling with antifreeze, a label should be attached to the expansion tank, stating the type and concentration of antifreeze used, and the date installed. Any subsequent topping-up should be made with the same type and concentration of antifreeze.
29 Do not use engine antifreeze in the windscreen/tailgate washer system, as it will damage the vehicle paintwork. A screenwash additive should be added to the washer system in the quantities stated on the bottle.

Brake and clutch fluid level

Warning: Brake fluid can harm your eyes and damage painted surfaces, so use extreme caution when handling and pouring it.
Warning: Do not use fluid that has been standing open for some time, as it absorbs moisture from the air, which can cause a dangerous loss of braking effectiveness.

Safety first!

8 • If the reservoir requires repeated topping-up this is an indication of a fluid leak somewhere in the system, which should be investigated immediately.
9 • If a leak is suspected, the car should not be driven until the braking system has been checked. Never take any risks where brakes are concerned
The MAX and MIN marks are indicated on the side of the reservoir. The fluid level must be kept between the marks at all times.
If topping-up is necessary, first wipe clean the area around the filler cap to prevent dirt entering the hydraulic system.
Unscrew the reservoir cap and carefully lift it out of position, taking care not to damage the level switch float.
Carefully add fluid taking care not to spill it onto the surrounding components. Use only DOT 4 fluid;mixing different types can cause damage to the system. After topping-up to the correct level, securely refit the cap and wipe off any spilt fluid.

Power steering fluid level

10 • Park the vehicle on level ground.
11 • Set the steering wheel straight-ahead.
12 • The engine should be turned off.

Safety first!

13 • The need for frequent topping-up indicates a leak, which should be investigated immediately.
The reservoir is located near the front of the engine compartment. Prise up the plastic rivets, and remove the air inlet hood from the front of the engine compartment (where applicable). Wipe clean the area around the reservoir filler neck and unscrew the filler cap/dipstick from the reservoir.
The fluid level should be between MIN 2 and MAX.
When topping-up, use Dexron III fluid and do not overfill the reservoir. When the level is correct, securely refit the cap and switch off the engine.

Screen washer fluid level*

14 * On models with a headlight washer system, the screenwash is also used to clean the headlights
15 • Screenwash additives not only keep the windscreen clean during bad weather, they also prevent the washer system freezing in cold weather – which is when you are likely to need it most. Don’t top-up using plain water, as the screenwash will become diluted, and will freeze in cold weather.
Warning: On no account use engine coolant antifreeze in the screen washer system – this may damage the paintwork.
The screen washer fluid reservoir is located in the front right-hand corner of the engine compartment. The level is visible through the reservoir body, if topping-up is necessary, open up the cap.
When topping-up, add a screenwash additive in the quantities recommended by the manufacturer. It could also be time to replace the wiper blades. For details, click here
- Close + Open

Wiper blade replacement

Check the condition of the wiper blades; if they are cracked or show any signs of deterioration, or if the glass swept area is smeared, renew them. Wiper blades should be renewed annually.
To remove a wiper blade, pull the arm fully away from the screen until it locks. Swivel the blade through 90°, press the locking tab with your fingers and slide the blade out of the arm’s hooked end.
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