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Pelican Technical Article:

BMW E30 3 Series Timing Belt Change
Jared Fenton
Wayne R. Dempsey

Difficulty Level: 4
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

     In this tech article I will cover the most important piece of maintenance you can ever perform on your E30 6 cylinder, changing the timing belt. The timing belt on these cars is probably the only weak link in these otherwise nearly bulletproof engines. For some reason BMW decided to use a rubber belt instead of a chain. (In fact BMW themselves recognized the problems with the belt and changed over to a chain in the later E36 models) Iím suspecting that the reason for the belt is to keep noise down under the hood.

     The timing belt is used to rotate the camshaft in relation to the position of the crankshaft. With out this belt, the cam would not turn. Over time the belts begin to stretch and wear, eventually causing them to snap.

     BMW recommends you change the timing belt every 60,000 miles. This isnít really a recommendation; itís more like a requirement! These timing belts have an almost supernatural ability to break at 60,001 miles. Well not THAT actual mileage, but for some reason they always seem to break just after 60K. Breaking a timing belt is bad. Let me again stress, it is VERY bad. If it does happen to break, you will bend or break nearly all the valves in the cylinder head, and maybe even put holes right through your pistons. So itís important to get this belt replaced every 60,000 miles.

     In this article, I will go over the steps involved with changing the belt out yourself and perhaps learning something about your car at the same time. That said, letís begin. The first step is to disconnect the battery, as we will be working around fuel injection and electrical components. Next, jack the front of the car up using a frame rail of other structural piece of the car and firmly support it on jack stands. A handy reference for doing this is Wayneís article on jacking.

     Now, crawl under the front of the car and locate the radiator drain plug. We will need to remove the radiator in order to remove the timing belt. Use a drain tray to catch the coolant draining out of the engine. Once all the coolant is drained, remove the hose clamps for the lower and upper radiator hoses and pull the hoses off. Loosen the hose clamp for the coolant overflow hose at the top of the radiator and pull the hose off. You may need to stick a screwdriver in between the hose and the flange in order to free them up. Now, remove the two screws that hold the retainer plate up top and pull it off. Now remove the electrical plug for the fan switch on the driverís side at the top of the radiator. Now pull the radiator out of the car and set it aside.

     Now make a drawing of the locations for the various hoses for the radiator then, loosen all the hose clamps and remove all the hoses. These vary from model to model, so itís important to get a good idea of how they go on. This will help you when you go to re-install them. Next, we have to remove the fan and fan clutch. You will need an open-end 32mm wrench to get this off. There is also a special BMW tool that is used to lock the fan. Keep in mind that this nut is reverse threaded. Once you have the fan off, remove the three 10mm bolts that hold the distributor cap to the engine. Remove the cap and set it out of the way. Now remove the three bolts that hold the rotor on and set it aside.

     We will now need to remove the alternator, power steering and air conditioning compressor belts. Locate the bolt tensioners on each belt, loosen them and pivot the bracket sin order to remove them. Now remove the upper alternator bracket by removing the nut, which holds it to the timing cover. These locations vary from model to model so look through your manual or drop me an email with your exact year, make and model, and I can help you out.

     Now use a socket wrench on the center crankshaft bolt, and rotate the engine to top dead center on the No. 1 cylinder. Do this by looking on the vibration damper for an ďO/TĒ marking. When this mark lines up with the notch scribed into the lower camshaft drive belt cover.  Once lined up, remove the reference sensor for the fuel injection and timing. This will simply pull out of its clip.

     Now remove the lower camshaft drive belt cover mounting bolt together with the cover. You will now see the timing belt fully exposed. We will now need to lock the crankshaft in place. An easy way to do this is have an assistant apply the brakes and put the car in gear. Another method is to hold the center bolt in place with a socket wrench and hold the crankshaft. This will lock the engine in place and allow you to loosen and then remove the six bolts that hold the lower drive belt pulley and the vibration damper to the front of the crankshaft. You may need to use a small screwdriver to pry the pulley and damper off.

     We now must relieve tension on the timing belt to remove it. This is done by loosening the center bolt that holds the camshaft tensioner the engine and the lower mounting bolt. Now use a long screwdriver to rotate the belt tensioner counter clockwise.  Rotate it as far as it will go and then re-tighten the tensioner bolt. This will relieve the tension on the bolt and give you enough slack to take the belt off.

     Now very carefully remove the belt, making sure not to turn the crankshaft pulley or the camshaft pulley. Both of them are at top dead center and must remain there until we re-install the new belt. If you move the pulleys, the timing for the camshaft will be off.  Look at the front of the camshaft pulley. You will see a small arrow that lines up with a scribed notch on the cylinder head. Make sure these are lined up. This notch and arrow is there to notify you of top dead center.

     Now remove the tensioner bolt and very carefully rotate the tensioner clockwise, keeping in mind to slowly take the tension off the spring above. Once all tension has been relieved, remove the tensioner and the pin and spring above.  We will be replacing these parts. You always want to replace the tensioner and spring. Itís just cheap insurance in case the old ones fail. 

     Now, take the new spring and tensioner and carefully install them onto the engine. This may take some time because of the spring tension, but it will go on with a little force. Use a long screwdriver again to rotate it counter-clockwise as far as it will go and then tighten the mounting bolt.

     Before you install the new belt, check the positions of both pulleys again. Loosely attach the vibration damper and the lower timing belt cover onto the crankshaft ad make sure that the ďO/TĒ marks line up.  Up top, check the arrow and notch as described before. Now take off the damper and cover and begin to install the new belt from the bottom crankshaft pulley in a counter-clockwise direction, slipping the belt over the intermediate shaft and the camshaft sprockets and the camshaft tensioner pulley. DO NOT use any tools to do this. You may accidentally turn either of the pulleys. Once the belt is firmly in place, loosen the tensioner bolt again. This will put tension on the belt and hold it firmly in place.

     Put the socket wrench back on the center crankshaft bolt, and rotate the engine clockwise through two complete revolutions. Now re-check the timing marks on both the crankshaft and the head. If either are incorrect, pull the belt off again, and re-align the pulleys. If the marks are correct, continue by torquing the tensioner mounting bolts to 16 ft./lbs.

     Now, re-install the lower timing cover and the vibration damper and drive pulley. Lock the crankshaft again, and re-install the 6 bolts. Torque them to 16 ft./lbs. Reinstall the reference sensor it itís mounting clip on the lower timing cover. Now re-install the upper timing cover.

     Now re-install the mounting bracket for the alternator and re-attach the drive belts for the alternator, power steering and A/C. Once again, there are different mounting and pivot points for each car, so email me and I will more than willing to help you on your particular model.

     Re-attach the fan and clutch using the lock that secures the shaft and tighten the locking nut. Keep in mind that this nut is reverse threaded.

     Now re-install the distributor rotor and bolt in place as well as the distributor cap. Now re-install all the cooling hoses for the car and tighten the hose clamps that hold them in place. This is different for each year, so make sure that you know what goes where. Now re-install the radiator in the lower mounts and attach the upper and lower hoses as well as the overflow hose. Tighten all the connections that hold them in place. Now re-install the upper radiator mount and tighten the two screws that hold it in place. Re-connect the leads for the fan switch as well.

     Now fill the radiator with a mix of coolant and water, this ratio depends on the climate you live in. Just check your ownerís manual for the exact ratios. Now re-connect the battery and start the car. Once running, we will need to bleed the system. Do this by locating the bleeder screw on the top of the thermostat housing and leave it open until you see only a straight stream of coolant escaping (no air bubbles) Top up the coolant reservoir as needed.

     Well, there you have it - it's really not too difficult at all.  If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

Comments and Suggestions:
Centaur48 Comments: Correction: It's the timing marks on the camshaft that do not align while the crankshaft marks are in alignment. -Centaur48
May 18, 2009
  Followup from the Pelican Staff: This tech article should help you: - Nick at Pelican Parts
Centaur48 Comments: Two problems. I'm replacing the timing belt on a 1987 325iC. Everything has gone well up to putting the new belt on. It's easy to rotate the crank with a 22mm deep socket and breaker bar to get the TDC lines to line up. However, the TDC marks on the crankshaft do not match. How do I rotate the camshaft sprocket? Can it be done rotating the the crankshaft? Problem #2. I can't seem to get the diamond shaped part behind the crankshaft sprocket to remove in order to replace the seals. I've used PB Blaster. It rotates but does not slip off. Suggestions? -Centaur48

Correction: It's the timing marks on the camshaft that do not align while the crankshaft marks are in alignment. -Centaur48
May 18, 2009
  Followup from the Pelican Staff: There's another article on our site that's a bit clearer: - Wayne at Pelican Parts  

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