M20B2x Timing Belt Wite-up.
timing belt write-up E30
for M20 engines in E21, 28, 30 and 34 chassis BMW cars.
things you will need:
**10mm deep socket (10mm shallow if 89+ MY)
**8mm deep or shallow socket
**13mm deep socket
**32mm slim wrench
**17mm deep socket
**13mm deep socket
**22mm boxed wrench or socket for rotating the engine to TDC.
**a new timing belt
**2 gallons of coolant
**a coolant catch receptacle
**19mm wrench or socket
Things you should get:
**32mm bicycle bottom bracket wrench. perfect for this application and cheap at virtually any bike shop.
**new coolant, you can re use old coolant if you want to save $$
**a helper for a few of the tasks helps.
Things you should consider changing:
**tensioned. they are cheap, usually come with a good quality (Gates or Contitech) timing belt and can cause disastrous things if failed.
**front cam seals.
**water pump. if its noisy, leaking, more than 2 timing belt changes old or you dont know how old.
**new belts. carefully inspect them, and replace if worn. a lot of people just replace all of them at this time just in case.
shall we begin?
Step 1: open hood!
Step 2: (optional but recommended) remove the 4x 10mm bolts, clip and dowel pin that secure the hood and hinge mechanism to the car and set the hood aside. (on E28 and E34 cars, skip this step)
Step 3: put your coolant catch receptacle under your car and un-do the drain plug on the radiator. it helps if you take the cap off of your overflow bottle.
Step 4: un-do all the hose clamps and remove all the hoses to the radiator (and the crossover pipe if you plan to replace the water pump.
Step 5: remove the Airbox/AFM. 1 hose clamp on the boot, 2x10mm nuts and either 1 or 2 connectors. 1 on 'i' and 'SETA' cars and 2 on 'eta' cars.
once done with that, remove the radiator by removing two 10mm bolts. late model cars, they are on top, early model cars, they are on the side. don't forget to also unplug the coolant temp sensor(s).ON AUTOMATIC CARS** remove 2x 22mm transmission cooler lines on the left side of the radiator. this will cause a bit of ATF to leak out so have a catch can ready.
Step 6: un-do the 3x 8mm bolts holding the distributor cap on to the upper timing cover and set it gently aside.
Step 7: take your 32mm slim wrench and place it on the fan clutch nut, at the same time, take your large standard screw driver and wedge it between two of the four 10mm water pump bolts to prevent it from moving while you un-do the fan clutch. one thing to remember before you do this THE FAN CLUTCH IS REVERSE THREADED, so lefty-tighty, righty-loosey.
Step 8: remove the 3 small hex bolts holding the rotor to the camshaft and remove the plastic dust cover once the rotor is off.
Step 9: take off all the belts. on the alternator, there is a 13mm set nut on the back of the top bolt, losen that a tiny bit, then take a 19mm socket or wrench and move the notched tooth towards the engine. the power steering pump is the same deal except the set nut is on the front.
Step 10: remove the upper timing cover which consists of 1 10mm bolt on the passenger side, a 13mm bolt on the drivers side and a 13mm nut on the bottom which also holds the upper alternator bracket. after removing those, the timing cover slides forward about a half an inch, then up.
Step 11: Remove the lower front pulley. there are 6x 13mm bolts in it, how I took them out is, I got a standard 3/8" ratchet, a 13mm deep socket and a 22mm boxed wrench to keep the engine still while I loosened them. they are on there pretty tight but patience is key as they do like to sheer off if you put awkward stress on them. once those are out, pull the front pulley off of the timing gear.
Step 12: rotate the engine to TDC. for some reason I forgot to take pictures of this, but I will fix that soon.
on the cam gear, the OT mark is on the head towards the drivers side of the car and on the bottom (crank) there are two markers. one set is on the toothed trigger wheel, matched up to the lower timing cover and the other is visible with the trigger wheel and timing cover off. a v-shaped indentation and a lifted ridge on the crank.
Step 13: remove the timing gear and lower timing cover. use a rubber mattet and screw drivers to gently pry the toothed trigger wheel off of the front of the crank shaft. once its off, it will only go back on 1 way, so dont worry about orientation as long as you didnt rotate the engine away from TDC (Step 12). once the trigger wheel is off, remove 1x 10mm bolt that holds the lower timing cover on to the engine and remove that cover. your engine should now look like this:
step 14: remove the old belt. start with the 13mm bolt on the tensioner, losen it, but dont remove it. if your tensioner can't be pushed by hand, losen the 17mm lower bolt. once those are losened, start removing the belt from the top cog first and work your way around until it pops off. once the belt is off, remove the two bolts holding the tensioner completely and set them aside with the tensioner itself. your timing belt-less engine should look like this now:
this is what you should have taken off. belt, tensioner and spring dowel.
Step 14: install your new tensioner (or if you didnt buy a new one, re install your old one, follow same steps). place the tensioner and the bottom tensioner bolt back onto the engine, just thread in the bottom bolt, dont tighten it yet. once you have done that, grab the spring dowel and the upper 13mm bolt and insert the spring dowel between the notch on the water pump and the tensioner at the same time compressing that spring enough for you to hand thread the upper 13mm bolt back into place. once you have done that, grab your standard screwdriver and a 13mm socket, compress the tensioner spring as much as you can towards the water pump, then tighten the 13mm bolt. it should now stay in the fully compressed position.
Step 15: install your new belt. start at the bottom, feeding it on to the crank first, then slip it around the oil pump and tensioner, then little by little, feed your belt back onto the cam gear. this may take 10-15 minutes to get correctly. if you dont get it the first time, be persistant.
once your belt is back on, verify that your bottom TDC and upper TDC marks are still in the correct position. if they are, great! if not, take off the belt, rotate the crank accordingly and try again.
Step 16: tensioning the belt: to tension the belt, losen the top 13mm bolt on the tensioner. it should pop out and tighten the belt. once it has done that, tighten (not hard) the top 13mm and the bottom 17mm (a bit harder, but not hard) bolt. re-install the lower timing cover and the associated 10mm bolt and the trigger wheel.
Step 17: re-install the upper timing cover, alternator bracket and the associated 13mm nut, 13mm bolt and 10mm long bolt as well as the lower crank pulley and its 6 13mm bolts.
step 17.5: rotate the engine clockwise two full CAM rotations, or four full crank rotations and re-check timing before step 18.
Step 18: re-install your belts, distributor cap and crossover hose.
Step 19: re-install the radiator, AFM, fill with coolant and re-attach your ATF lines if you have an automatic car.
step 20: start the car and make sure you did it right.
Step 21: put your hood back on, go for a victory drive because you just saved a lot of money.
I'll add more pictures later (specific ones that will help).
Last edited by 2.5-12; 07-28-2010 at 08:09 AM.
00' BMW 323iT -- 01' Toyota MR-S -- 08' 244cc scoot-puff
84' BMW 325e/5 24V in progress -- 92' BMW 850i/6 -- 97' BMW M3/2/5