BMW E30 - Engine Maintenance
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Engine Maintenance

Spark Plug Renewal
Parts: 6 x Spark plugs, torque wrench, extension bar, 21mm spark plug socket, spark plug adjuster.
Difficulty Rating: easy!
I change my plugs at every second oil change (6,000 miles). I use Bosch W8LCR plugs - these are the plugs originally specified by BMW for the 320i and I have found from various people that these seem to be the best available.
Changing the plugs is not a difficult job by any means and requires few tools. When doing this job, make sure that the area around the plug is clean. I find that the best way of cleaning here is to take the car to a petrol station and use the air pump (tyre pump). Use a long piece of wire to carefully loosen debris and the pump to blow it away.
Remove the HT leads from each of the plugs (when the car is turned off, of course!). Remove the lead by pulling on its connector - don't pull on the wire or it will just come apart from the connector. If your HT leads are not in an 'organiser' then label each one as you remove it so you will know where it goes. Check each lead for damage. Using a spark plug socket (21mm) carefully remove each plug by turning anti-clockwise.
Ensure that the electrode gap of the new plugs is correct (0.8mm) - if not adjust it (you can pick up adjusters quite cheap in any motor factors). Assuming the electrode gap is correct you are now ready to insert the new plug. It can be quite easy to cross-thread these so use a short piece of rubber or plastic tubing to make the first few turns. The idea here is that the rubber will give in before it cross-threads. Tighten the plugs to the correct torque (30-33Nm) and reconnect the HT lead (in its correct place!). Done!

Oil Change (including filter)
Parts: Oil & filter, wrench (size depends on your sump nut), sump nut washer(plastic), oil filter remover, oil pan & container.
Difficulty Rating: easy
I change my oil every 3,000 miles using Semi-Synthetic 10W40.
Ensure the engine is at normal operating temperature (drive around for 10 minutes). This will ensure that the oil is moving more freely and carry many of the deposits. Park the car on a level surface. Place some old newspaper on the ground under the engine to collect any oil spillages.
Raise the car if necessary to get access to the oil sump. Using the wrench, open the nut. It will presumably be tight. When the nut is loosened place the oil pan under the sump bearing in mind that the oil will shoot out up to 10cm from the opening. Remove the nut and allow the oil to drain. If you raised your car to get access then lower it again. Remember though that the oil pan may need to be moved to catch all the oil. I usually leave it draining for about 30 minutes to remove as much of the old oil as possible.
While you are waiting on the oil to drain, remove the filter. The filter is located below the exhaust manifold - on the right hand side of the engine. Using the filter removal tool (these vary from the chain type, the ratchet type or the plain screwdriver) carefully turn the filter anti-clockwise. There will be hot oil still in and around the filter so be careful. Don't take the filter off yet - try and catch as much of the oil as is possible in the oil pan. When ready take the old filter off.
Pour some clean oil into the new filter slowly. Ensure that the rubber seal on the end is coated in clean oil. Carefully screw the new filter onto its mounting. Tighten it hand tight only.
When all the oil has drained from the sump, carefully insert the nut back into the sump making sure that the new washer is on. Tighten it securely. Pour the new oil into the engine. The M20 engine takes a total of 4.3 litres. However, as there may still be some oil in the engine, only pour about 3 litres in and then use the dipstick as a guide.
Remember that oil is a contaminant and must be disposed of carefully! There is bound to be a garage near you that will accept waste oil.

Air Filter Renewal
Parts: FIlter element & wrench/socket
Difficulty Rating: easy!
Remove the electrical connector from the air flowmeter by pressing on the wire and pulling the connector out. Undo the clamp on the air intake duct. Loosen the two 10mm bolts holding the air filter cover to the chassis and lift the air filter box out of the engine bay. Release the retaining clips around the filter box cover, lift the coover off and remove the old filter element. Wipe clean the inside of the housing and insert the new filter element correctly.
Refit the cover and secure the clips. Tighten the bolts and clamp.

Valve Adjustment
Parts: 10mm spanner, feeler gauges, piece of wire (old coathanger), new gasket and sealer.
Difficulty Rating: straightforward
Before you complete this job I would recommend that you check which kind of headbolt is currently being used on the car. Do this by removing the oil filler cap and using a torch look into the engine at the head bolts (largest bolts within view). If they are torx bolts you are ok but if they are hexagonal look at the name on the top. If it says Kamax or Verbus then you are ok but if they are manufactured by Ribe get a new set of bolts! (See the section below).

I would recommend that this job be done first thing in the morning after leaving the car parked overnight (the car is stone cold!). Remove the bracket from the top of the valve cover that supports the inlet plenum (4 x 10mm). Undo the six nuts holding on the valve cover and remove the cover. Carefully remove the old gasket without scratching the mating surfaces.
Running along the center of the head is the camshaft which contains 12 cam lobes. Look at each of the 12 valve assembleys. There is a rocker arm situated between each cam lobe and the top of the valve stem. Using the feeler gauges (0.25mm if engine is cold - 0.3mm if engine is hot) on the assembleys where the lobe is not pushing on the rocker (facing down) ensure that there is a slight drag between the rocker and the top of the valve stem. Check all of the inlet and exhaust valves that are not being affected by the cam lobes. Adjust any that are not at the correct gap by loosening its bolt and turning the eccentric with the piece of wire. Retighten to the correct torque (10 +/- 1Nm) the valve clearance again. When you have addusted one mark this on a piece of paper so you will remember where you are.

By now it should have been possible to adjust about two thirds of the valves (some inlet and some exhaust) - the others being lifted by the camshaft. The valves you adjust first will depend where the rotation of the engine is currently. To be able to adjust the others you will need to turn the engine. This can be done in one of three ways - by turning the crankshaft with a 17mm spanner clockwise (as you look at the front of the car), by starting the car briefly at the ignition, or by shorting sockets 11 & 14 on the diagnostic connector (make sure you know which are the correct sockets before doing this).

But before you start tidying up, check that the oil spray tube is tight at both ends. This is the long thin tube running above the camshaft. Furthermore if the head bolts need replacing you should do this now (see this section).

When you are satisfied with everything then start tidying up! Firstly, make sure that the mating surfaces of the head and the cover are clean. Place some of the sealer along the surface of the head. Then carefully place the new gasket on and add some more sealer. Then put the valve cover back on carefully. Tighten the nuts (working from the center out) and then refit the bracket supporting the intake plenum.

Timing Belt Renewal
Parts: ... ... ...
Difficulty Rating: difficult
Due to be published soon

Head Bolt Replacememt
Parts: New Head Bolts, Gasket & Sealer, - not too sure of the socket sizes
Difficulty Rating: difficult enough
The six cylinder engines (and I think the 4s also) can end up with broken head bolts. These are the bolts holding the head onto the main engine block. First of all, check to see if the bolts on your engine are of the susceptible type:- look through the oil fill opening and read the brand name that's embossed on the head of the bolt (they are the largest bolt within view and could be either hex or torx bolts). If it says VERBUS or KAMAX then you're ok cause these two brands are not the ones that break. The RIBE brand is the only one with the problem and should be replaced immediately

Under normal usage, they should not break. The only problem that I have heard with them is that if someone replaces the head gasket and tries to re-use them, then that can lead to breakage and inproper sealing. Whenever you take off your head, you should replace your head bolts either way, because they stretch.

Plenty have broken, some take the head out when they go. Ask yourself, I have Ribe bolts, do I feel lucky today? (Ask yourself every time you start the car)

...when a head bolts breaks, and the broken part gets caught between a cam lobe and the head casting say good-bye to your head. Maybe even worse, the bolt head can stop the cam from rotating for a split second, then the timing belt breaks or strips off teeth. You have to figure... If BMW made 500,000 E30's with the defective head bolts, and only 500 have broken and punctured the head, thats not too bad at all. I asked my local BMW mechanic how many broken head bolts he has seen, and he said he's never seen one ever. The reason they break is because of a slight manufacturing defect where bubbles and contaminants work their way into the bolt structure *From what I have read about it*. Its not a matter of luck. You either have a bad one or you have a good one. If your car has 100K on it and it is still good, then there is no need to replace it unless you are taking off the head. I have heard from people who have covered over 200,000 miles and it haven't had the head bolt break yet. So don't worry - you have a higher chance of popping your timing belt than you have of the bolts popping off.

You will need to have removed all the ancillaries (wires etc.) and drained the coolant (presumably you will also be changing the oil, filters & plugs at this time). This job is best left until the engine is cold so leave the car sit overnight. See the section above on valve adjustment on how to remove the valve cover. Remove the Intake Manifold and either the Exhaust Manifold or the Exhaust Downpipe 9depending on the model). The timing belt will also need to be removed for this job.
Assuming everything is ready, and the head is uncovered - (do not disturb the rocker arm assembly!!!) then you are ready to remove the bolts...

Loosen the bolts in the opposite order to the diagram below (i.e. starting at the highest number and working inwards to no. 1) by a quarter turn (90°) each time. Once all the bolts have been loosened it is possible to remove the head. This may be stuck to the main block so your best bet for removing this is to insert a sturty wooden stick into an Intake port. Do not use metal to prise the head off the block as damage may occur.
Clean off the old gasket, ensuring no dirt is present - the mating surfaces must be spotless. If there is oil on the mating surfaces it can cause leaks. Clean out the head bolt holes to ensure there is no oil or dirt or whatever in there. use a tap to sort this out (and I mean tap as in tap and die tools and not a tap as in faucet!!!). Use the die to clean the threads of the bolts while they are secured in a vice.

Once you are 100% sure that everything is clean, place the new gasket into its correct location and the right way up - it should say "UP" or something similar in German. Place the head back on the block. You may need to use guides here to help align the head and block correctly - the old bolts maybe used here. Just cut the head off two bolts and insert them into each end of the block. Cut a notch into the top where the bolt head used to be so when the head is placed over these, they can be removed. Insert the new bolts. I assume you will use new bolts here as they cost a lot less than a new engine!
Tighten the bolts as per the pictures below - starting at no. 1 and working outwards.Tighten to the torque as listed in the table below.
  M10 (4 cyl) M20 (6 cyl with hex bolts) M20 (6 cyl with torx bolts) M30 (6 cyl till 1987) M30 (6 cyl after 1987) M40 (4 cyl)
Step 1 Tighten to 60Nm Tighten to 40Nm Tighten to 30Nm Tighten to 60Nm Tighten to 60Nm Tighten to 30Nm
Step 2 wait 15 minutes then angle tighten an additional 33° wait 15 minutes then tighten an additional 60Nm angle tighten an additional 90° wait 15 minutes then angle tighten an additional 33° wait 20 minutes then angle tighten an additional 80Nm angle tighten an additional 90°
Step 3 with engine @ normal operating temp angle tighten an additional 25° with engine @ normal operating temp angle tighten an additional 25° angle tighten an additional 90° with engine @ normal operating temp angle tighten an additional 33° with engine @ normal operating temp angle tighten an additional 35° angle tighten an additional 90°

Headbolt Tightening Sequence For M10 M20 & M40 Engines
M20 Headbolt Tightening Sequence M10 Headbolt Tightening Sequence M40 Headbolt Tightening Sequence


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