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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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