Chain Tensioners, Spring Diaphragm & Vanos timing guide article…. video coming soon
Is your engine starting to sound more like a tractor than a performance BMW? In this article we’ll zone in on a few parts that can help quiet and prevent catastrophic engine damage . I’ve included the Vanos Spring Diaphragm procedure which was an update Bmw made to help solve their Vanos chattering noise. We will also look into a few common internal engine parts that can fail and cause performance issues or worse. The parts I’m referring to are the chain tensioners. Keeping up with the primary & secondary chain tensioners are important as these parts are responsible for keeping tension on your timing chains, think of it as preventive maintenance.
Chain tensioners: There are two of them, one for the primary chain which is replaceable from the outside of the engine and one for the upper camshaft chain which is located inside the engine under the valve cover. A tensioner is a hydraulic piston that pushes against the chain rail which keeps your chain under tension, if this part fails all hell can break loose. Chain tensioners can fail for multiple reasons, here are a couple of them…..(1) The tensioners are fed pressurized oil through a small orifice which can become plugged or restricted by contaminates like varnish build.. (2) Normal wear and tear, which can weaken the internal spring and decrease the tensioners apply pressure causing chain slack. At worst, if you have a really bad chain tensioner and it’s not corrected, chain slack can lead to chain breakage or chain to sprocket tooth jumping & possibly chipped sprocket teeth “very bad”.
Don’t confuse this noise with the dreaded Vanos Chatter which I have found to be caused by worn sprocket disks.
The chains themselves are very rob-bus with the exception that the engine oil was kept up with. A worn timing chain tensioner will usually produce a rough sound, like a chain scratching & slapping against plastic; It sounds like it’s eating itself up inside your engine. There are other things that can cause front engine noises, like the serpentine belt tensioners, the serpentine belt pulleys, or one of the most common noises is the plastic water pump pulley falling apart. It’s a good idea to check these moving parts as well.
Only certain parts can be changed from the top of the motor. Unfortunately the primary chain and guides cannot be replaced unless you remove the cylinder head & timing case cover. Although there is a procedure that allows you to replace the primary chain without pulling the cylinder head & timing case. Its called “rolling the chain in.” It requires a special removable master link chain and special chain crimping tool. They also make a chain with a clip on master link that does not require crimping although I don’t recommend it, but I just wanted to throw that idea out there.
To sum it up, we will tackle the primary timing chain tensioner, secondary upper chain tensioner, upper timing chain guide, upper timing chain & Vanos Spring Diaphragm.
Be sure to check out my “How to remove Vanos article” if you haven’t yet. This Vanos removal article will get you prepared to perform the procedures in this article.
- 1. New replacement secondary timing chain tensioner BMW# 11-31-1-738-700
- 2. New replacement upper timing chain guide rail BMW# 11-31-1-722-651
- 3. New replacement upper timing chain BMW# 11-31-1-432-176
- 4. New replacement primary chain tensioner: Verify which one you have – The fork style tensioner before 09/1994 has a bolt screwed into the back of the cylinder body, which is visible from the U.S. front passenger side of the cylinder head. The rounded tensioner 09/1994 and up has a smooth back to the cylinder body with out the center bolt.
- Up to 09/1994 Cylinder #11 in the diagram below Bmw# 11-31-1-738-861
- Piston#10 in diagram BMW# 11-31-1-722-667
- Spring #12 in diagram BMW# 11-41-1-706-809
- Sealing ring #13 in diagram BMW# 07-11-9-936-418
- Screw Plug With Gasket Ring #14 in diagram BMW# 11-31-1-722-674
- 09/1994 and up Cylinder #9 in diagram below Bmw# 11-31-1-703-746
- Piston #12 in diagram BMW# 11-31-1-703-747 –
- Spring #11 in diagram BMW# 11-41-1-706-809
- Sealing ring #10 in diagram BMW# 07-11-9-936-418
- Picture of 09/1994 and up tensioner
- 5. Optional but highly recommended… Blue Locktite medium strength which will be used on the nuts, studs & bolts that secure the intake & exhaust camshaft sprockets.
- 6. Vanos gasket BMW# 11-36-1-740-840
On 3/95 BMW added an additional part to the Vanos on their engines known as the Vanos Spring Diaphragm. Basically its job is to dampen the rotational play of the intake camshaft sprocket which also helps quiet vanos chattering. This seems to be a popular upgrade for the M50 motors found in 92-95 3 series & E34 5 series. Here is a parts list of what you’ll need.
Spring Diaphragm parts required for update:
- 3 intake sprocket studs #6 in diagram below BMW# 11- 36- 1- 403- 824
- 3 hex nuts black oxide #12 in diagram BMW# 07 -11 -9- 900 -910
- 1 vanos spring diaphragm #10 in diagram BMW# 11 -36- 1- 403 -550
- 1 2 mm stop disk #9 in diagram BMW# 11- 36- 1 -403- 822
- 1 4 mm stop disk #11 in diagram BMW# 11 -36 -1 -403- 823
Additional Optional Parts:
- 1 New replacement inner stop disk #8 in the diagram above BMW# 11-36-1-735-908
- 4 New exhaust cam torx bolts #4 in the diagram BMW# 11-31-735-164
- Vanos Spanner wrench from your tool kit
- Camshaft timing blocks which should be installed already
- E Type sockets: E8 & E10 torx sockets
- Torque wrenches: An inch pound torque wrench that reads from at-least 25 inch lbs to 250 inch lbs and a foot pound torque wrench that can read from at-least 20 ft. lbs to 150 or 250 ft. lbs range. If you ever plan on replacing your front wheel bearings then go with the wrench that can handle up to 250 ft. lbs. You probably can get away with just an inch pound torque wrench in this article if you have a good feel for tightening bolts in the 24 to 37 ft. lbs range. Otherwise you should pick one up.
- Special tool BMW# 90-88-6-113-390 this dummy chain tensioner tool simulates the function of the primary chain tensioner, it’s used before you tighten the torx E10 exhaust sprocket bolts.
- Continued: You can make your own dummy tensioner for under 10 cents by using your existing primary tensioner: Read more… “dummy tensioner tool”
At this point your Vanos should be removed, your engine at top dead center and your flywheel and camshafts locked.
Step: 1 What we want to do first is remove both camshaft sprockets so we can access the upper tensioner and chain guide. Grab a rag and tuck it under the Exhaust cam sprocket to block any hardware that might fall into the engine.
Step: 2 Grab an E10 torx socket and remove the 4 exhaust camshaft sprocket bolts along with the round retainer disk that the bolts were securing. Double check to make sure your E10 socket snaps & locks onto your extension.
Step: 3 Next, grab a 10mm Socket and remove the 3 nuts securing the intake camshaft thrust disk and then remove the thrust disk. Set them aside, The nuts and disk will not be reused for the Spring Diaphragm setup.
Step: 4 Next, mark both sprockets to chain relationship, this will help in case the chain skips a sprocket tooth while being removed. Also, the marks will be used to help transfer the new upper camshaft timing chain if you have one. This will be done by counting the number of links from one mark to the other and transferring the information over to the new chain. Try not to move the sprockets while you’re marking them.
Step: 5 Now the sprockets can come off together with the chain. Grab both sprockets and gently rock them back and forth as you pull them off. Keep outward tension to prevent the sprockets from falling in on each other and losing their clocking position. Set the sprockets aside for now.
Step: 6 Next, we’re going to remove the 3 studs along with the backing disk and camshaft position sensor trigger wheel which is located on the intake cam. Using a felt pen make some sort of mark on the backing disk so you can identify it as the backing disk. The reason for the marking is because the disk & sprocket have worn a pattern in together and it’s best to keep them that way. If you have a new disk than no marking is necessary. Grab a 10mm socket and remove the 3 studs and backing disk along with the camshaft sensor trigger wheel. Set the disk & camshaft sensor trigger wheel aside for the re-install. The studs will not be re-used.
Step: 7 Next, remove the secondary timing chain tensioner that keeps tension on the camshaft sprockets. There are 4 bolts total, one long bolt in the front and 3 bolts on top in a triangular pattern. Tuck some rags into any area that you feel a bolt could drop into, especially the spark plug holes. Grab a 10mm socket and withdraw the 4 bolts from the tensioner, then remove the tensioner.
Step: 8 Now that the secondary chain tensioner is removed, the upper chain guide can be removed. Tuck some rags into any space that you feel a bolt could fall into. Grab an E8 torx socket and remove the 2 bolts that secure the upper timing chain guide to the cylinder head. The guide is located below the front of the cams. For future reference there are a total of 3 timing chain guides in your engine, 2 behind your timing case cover and the one we are replacing now. They all become hard & brittle overtime, you should never pry on them with any type of object.
Step: 9 Ok, the upper timing chain guide is removed so now we can swap in the new one. You want a clean surface for your new guide to sit on, use a rag to clean off the mounting pads where your bolts would go. I know, I keep repeating this but be sure to block any holes that hardware could fall down into. Next, drop your new guide in and bolt it on. Torque the bolts to 89 inch lbs.
Step: 10 Upper timing chain tensioner… Take a rag and clean the mating surfaces that your new tensioner will sit on. Plug up any holes that you feel a bolt could drop into like the spark plug hole. After you have your mounting surfaces cleaned to your liking you can install your new upper chain tensioner. First snug all 4 bolts evenly and then torque them down to 89 inch lbs. Your new tensioner should have come with its own pin to compress the tenisoner piston, leave it in for now.
Vanos Spring Kit preparation. follow these steps in order….Step (1) Install your camshaft sensor trigger wheel.
Step (2).. Sprocket backing disk.. Place your new or original backing disk that you removed earlier over the trigger wheel, make sure you have the correct disk unless you are installing a new one.
Step (3).. Secure the backing disk with the 3 new longer studs from your Vanos Spring Kit, apply some blue Locktite which is optional to the larger diameter end of the threads. Using a 10mm socket thread the studs into the intake cam. Torque the studs 15 to 16 ft lbs. Go slow here you don’t want to over torque the studs.
Step: 15 Now lets head back over to the intake sprocket to install the Vanos Spring Kit in these steps. (1) lightly lubricate the Vanos Spring Kit disks and spring diaphragm with some oil.
Step (2)…install the thin 2mm disk over the intake camshaft sprocket studs.
Step (3) Install the spring diaphragm over the 2mm disk, you want the center of the spring diaphragm to bow out toward you.
Step (4) Install the 4mm thick disk over the spring diaphragm.
Step (5) Grab some blue Locktite which is optional but highly recommended for this particular setup. Apply the Locktite to the 3 stud threads and spin your 3 new nuts on. BMW calls for the nuts to be torque to 89 inch lbs. What’s nice about using Locktite with low torque values, is that it will prevent the nuts from vibrating off. After you torque the nuts, grab your Vanos spanner wrench and rotate the sprockets back and forth, you should feel a medium drag, it does take some effort but it shouldn’t feel locked, if no oil was put on the diaphragm plates then it may be very hard to turn.
Step: 16 At this point we have both sprockets and hardware installed. Now would be a good time to remove the primary chain tensioner and swap in the BMW tensioner tool or a homemade dummy tensioner to keep timing in check. First, place a rag under the tensioner to catch any oil that might spill. Using a 32mm socket remove the primary tensioner which is located on the front U.S. passenger side of the cylinder head just above the A/C compressor.
Once you have your dummy tenisoner, thread it into the cylinder head. BMW states that when using their tensioner tool, the inner bolt be torque to 1.3 Nm …. this is a very low torque, about 1 ft lb. If you are using a homemade dummy tensioner you can do the same. Thread the tensioner in finger tight until it stops on its own, from that point nudge it about 15 to 20 degrees further. There should be no slack in the primary chain….. Here’s the article for the homemade tensioner again “dummy tensioner tool”
Here is a behind the scenes look at the guide your tensioner tool will be pushing on. Note: this is a 09/1994 and up guide
Step: 17 Now that there’s adequate tension on the chain we can move on to the Vanos install. If you have a new Vanos gasket, now would be the time to replace it. After you have the gasket on, it’s recommended to apply RTV silicone to both outer cylinder head dowels that the Vanos locks onto so oil will not seep out.
Step: 18 Prep the Vanos for installation…. Compress the Vanos gear until it bottoms out all the way. Double check this because it has to be compressed as far down as it will go.
Step: 19 At this point we should have the dummy tensioner and a new Vanos gasket installed. Now we can re-install the Vanos. Take your Vanos spanner wrench and rotate the sprockets full clockwise until you feel it stop. After that double check your camshaft blocks and make sure they are resting flush against the head. Next apply some oil or lube to your Vanos gear and slide it onto the cylinder head. Spin the Vanos gear back and forth with your finger while pushing the Vanos gear into the camshaft. Keep spinning and pushing until you feel the gear mesh & lock into the sprocket teeth.
Now rotate your Vanos spanner wrench counterclockwise while pushing and guiding the Vanos in, keep your eye on the Vanos gear as you want the sprocket to pull the Vanos gear in right away without a delay. If you the Vanos gear does not catch onto the sprocket right away then pull the Vanos away and try a different tooth position on the Vanos gear. Your Vanos should end up flush against the cylinder head with only a gasket thickness gap between the head and Vanos. If your Vanos binds up at any point try to verify if it’s the cylinder head dowels or the Vanos gear that’s hanging you up. You can give the Vanos some love taps to see if it was just the dowels. If it doesn’t go in with the love taps then remove the Vanos and make sure you sprockets are rotated full clockwise and then try again.
(1) rotate the sprockets full clockwise with your spanner wrench until it stops.
(2) Slide your Vanos on, spin the Vanos gear back and forth until you feel it mesh with the sprocket & lock.
(3) Next, rotate the Vanos spanner wrench counterclockwise while guiding the Vanos onto the cylinder head. After the Vanos is fully seated, remove the spanner wrench.
(4) Check to make sure that there is only a gasket thickness gap between the Vanos and cylinder head.
Step: 20 Ok, the Vanos is on at this point. Now it can be secured to the head. Grab your 6 Vanos nuts and install them, tighten the nuts to 89 inch lbs. Also at this point you can re-install the engine lifting bracket and tighten both bolts to 16 ft lbs
Then wipe off any excess RTV silicone that squeezed out from the outer edges of the Vanos.
Step: 21 Now that the Vanos is secured to the head, the secondary chain tensioner pin can be removed. After you pull the pin, give a gentle upward pull on the tensioner piston to make sure the chain has no slack in it. Then go ahead and tighten up the 4 E10 exhaust sprocket bolts. Make sure your E10 socket locks onto your extension, you don’t want it to fall into your engine. Tighten all 4 bolts starting with 44 inch lbs working in a crisscross pattern then torque the bolts 16 lbs in a crisscross pattern.
(1) Pull pin from secondary tensioner
(2) Next, torque the exhaust cam E10 torxs bolts in a criss-cross pattern to 44 inch lbs and then a final 16 ft lbs
Step: 22 Next, remove the dummy chain tensioner and replace it with your real tensioner …. Lubricate your new primary chain tensioner by removing the inner piston, then put it back together. After that install the tensioner using a 32mm socket…torque to 30 ft. lbs. If you are installing an earlier style tensioner with a notched end, you want the notch to be vertical straight up and down. The diagram in the parts section above shows the correct orientation
Step: 23 The camshaft timing blocks and flywheel lock pin can be removed.
If you want to double-check your hard work and make sure everything is timed properly you can follow this procedure……. “facing the engine” rotate the engine clockwise 2 full revolutions to check camshaft timing. First, remove the camshaft blocks and flywheel lock pin. Then grab a breaker bar and 22mm socket to rotate the crankshaft with. I usually place a white mark on the harmonic damper pulley and watch for it to come around 2 times. After you make your 2 revolutions, line up your damper and timing case marks for top dead center. Next install your flywheel lock pin and then your camshaft timing blocks. If everything is good your camshaft timing blocks should sit flush against the head like before.
If your blocks did not sit properly which I highly doubt will happen, you will than have to start over by first finding top dead center and installing your flywheel lock pin; (2) loosening the exhaust sprocket bolts —- (3) re-installing the dummy chain tensioner —- (4) removing the vanos —- (5) adjusting the cams so the timing blocks sit flush against the head. Then you can start at Step 19 and give it another try.
Step: 24 Once you’re good checking the timing of the cams, the last hardware that buttons up your Vanos are the access plugs. Thread your plugs in and torque them down to 37 ft. lbs. Although BMW calls for 37 ft. lbs I go with a lower torque of 30 ft. lbs. “Its only a plug”
Well that’s pretty much it. Now it’s just a matter of putting everything back together in the reverse order. You can start in the “How to remove Vanos” article and work your way backwards. I have included torque specs below and Major don’t forget stuff.
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Upper timing chain guide rail two E8 torx bolts 89 inch lbs
Upper timing chain tensioner bolts 89 inch lbs
Intake camshaft studs 16 ft. lbs or 192 inch lbs….use blue strength locktite
Intake Vanos spring plate nuts 89 inch lbs. Use blue strength locktite
Exhaust sprocket torx E10 M7 10.9 grade bolts first 44 inch lbs then 16 ft. lbs to 17 ft. lbs max
Primary timing chain tensioner 32mm socket 30 ft. lbs
Vanos nuts 89 inch lbs
Vanos access plugs 37 ft. lbs can be hand tightened
Vanos oil line banjo fitting 24 ft. lbs
Engine lifting bracket 16 ft. lbs
Engine cooling fan to water pump, BMW calls for 30 ft. lbs without special holding tool and 22 ft. lbs with special holding tool. I just spin the fan nut on and tighten it with my tools until it feels tight. The way that BMW designed the fan nut with the reverse thread actually keeps a tightening force on the nut.
Spark plugs 14mm diameter 18 ft. to 22ft. lbs I usually coat the threads with anti-seize compound to prevent the plugs from freezing in place… very light coat preferred… Porsche stop using anti-seize as they claim it insulates the spark plug form receiving proper ground. I can mainly see this being a problem with turbo or supercharged engines as the voltage requirements increase under boost……spark blow-out is a common problem on force induction motors.
3 valve cover studs that were removed for the camshaft timing blocks 89 inch lbs
Valve cover nuts 89 inch lbs or can be hand tighten
Coil nuts hand tighten
Air filter box thermostat bolt hand tighten
Cruise control to air filter box nuts hand tighten
Beauty cover nuts and bolts hand tighten
Major don’t forget stuff:
Intake camshaft oil baffle splash shield
Flywheel wheel Lock pin removal