Back to FAQ list and "how to" index for mk4 a4 pumpe
difficulty level: 3/5
The factory change interval is before every 100,000 miles with an inspection at 80,000 and 90,000 miles. Also replace the rollers/tensioner/water pump because they will most likely not last another 100,000 miles and replacement requires timing belt removal. Failure of the timing belt or components will probably cause severe damage to the cylinder head and maybe the whole engine.
If you find the tips on this page helpful, please use the donation button at the top so that I can continue to keep publishing great articles. The Bentley service manual is about $80 and doesn't even mention most of the tips here. This page has color photos, more detail, and videos. I know it will save you some money even if you're just reading this to know your mechanic should be doing. Thanks in advance!
Part 1 shows how to remove the timing belt. Part 2 shows installation and final checks. Disclaimer- this article is revised and updated to include the most current information but is not a substitute for the factory service manual! See the TOS Agreement for the full legal disclaimer. Although a timing belt job can successfully be done with basic tools plus the timing belt tools and basic mechanical experience, improper installation of the timing belt can cause severe engine damage so take all precautions listed in the factory service manual. If you have never worked on a car, I suggest gaining experience with easier projects first before doing something as critical as a timing belt!
If you've never done a TDI engine, the main difference is that you must buy/rent/borrow the timing belt tools. The crankshaft lock tool is a fine fit and cannot be substituted. During timing belt tensioning, the camshaft sprocket rotates independently of the hub underneath it. This sets belt tension evenly. Unlike many engines, you can't just remove and replace the belt by marking it because there are no accurate index marks on the timing belt. You must also remove the motor mount because it's in the way.
Some more tips: If you're not familiar with the engine bay, label the fuel lines and plugs/wires that you remove with a piece of tape and marker, not pencil. It will make installation much easier, especially if you are doing other maintenance items over more than 1 day. See 1000q: tips for the mechanic for more handy tips. Please read all of the instructions thoroughly and check your parts before attempting timing belt replacement. If you have any questions regarding the tips on this page for replacing the BEW VW TDI engine timing belt, don't hesitate to ask at the forums linked here: myturbodiesel.com forums. If you are not comfortable that you can successfully do this job after reading the instructions in your factory service manual and the tips on this page, take it to an experienced VW TDI mechanic!
(click links to compare current prices and kit components, shipping, tax, etc. ) 1 timing belt kit with some G12/Pentosin coolant and a timing belt special tool set is suggested.
1 timing belt kit (recommended) - from Kermatdi, Dieselgeek, MetalManparts kit. The generic parts linked from here are often made by the same exact supplier as genuine VW and are the same exact part without the VW box. The different kits contain different components and are all sold by well known TDI vendors. Below are the individual components.
CAUTION - generic parts available on ebay or other online sellers may be of questionable origin since some similar parts are also used on other VW/Audi engines. The above linked sites are all well known and experienced TDI vendors.
CAUTION - I would not buy the or any other of this seller's copycat sites' timing belt kit. These are almost certainly low quality copycat parts! It's not worth saving a few dollars on critical engine parts when it could result in thousands of dollars of engine damage! I and many others have had bad experiences with this seller so never again.
I prefer the metal impeller water pump over the plastic impeller water pump because the plastic can sometimes fail and spin on the shaft. It's rare but it happens.
Parts list for timing belt kit
BEW engine timing belt VW# 038 109 119 p
water pump VW# 038 121 011 g
tensioner VW# 038 109 243 m
idler pulley (roller) VW# 038 109 244 j
serpentine belt VW# 06a 260 849 c
Always replace bolts/nuts
(exact part numbers may be superceded)
2x 18mm motor mount bolts VW# n 102 096 05
2x 16mm motor mount bolts VW# n 105 167 02
15mm nut VW# 038 109 454 a
13mm nut VW# n 015 083 15
Note - The service manual does not specify to replace the 4x
crankshaft pulley (harmonic balancer) bolts each time but they often get
stripped and the torque spec has a "+1/4 turn". The service
manual for the later BRM pumpe duse engine also does not say to replace the
bolts each time. What you choose to do is up to you.
(37mm long version) 4x harmonic balancer (crankshaft pulley) bolts VW# n 903 396 05
(short version, unknown length?) 4x harmonic balancer (crankshaft pulley) bolts, part number unknown
2x horizontal motor mount bolts VW# n 907 124 01
1x horizontal motor mount bolt VW# n 103 280 02
aluminum motor mount (sometimes gets stripped) VW# 038 199 207 h
bolt kit (may be in your belt kit)
Also get some G12 coolant to replace lost coolant. You only need 3 liters of coolant or 1 gallon and an equal amount of distilled water for the timing belt job and to account for spilled coolant. Do not use generic green coolant, see 1000q: coolant flush for more details.
genuine VW (1 gallon size , VW #G 012 A8F A4 ) genuine VW (1.5 liter size, VW #G 012 A8F M1),available from kermatdi 1.5L size, dieselgeek (1.5 liter size, VW #ZVW 237 G12)
WARNING: There was a recent batch of VW tools tool 10050 which had the pointer arrow in the wrong spot to the right of the peg. It should be to the left of the peg. See this post in the forum for more details.
VW special timing belt tools
I rent the tools as a courtesy service, see this page for details: myturbodiesel tool rental
|tool kit from metalnerd from dieselgeek,
T3359 camshaft lock pin (or equivalent MN3359) from metalnerd parts
T10115 is normally included with a new tensioner
T10060A serpentine belt tensioner lock (can substitute with metal pin) from metalnerd parts
5mm and 6mm allen wrenches
19mm 12 point socket
10mm triple square bit (not torx or star, it's a triple square head)
regular and deep socket 13, 15, 16, 18mm sockets/wrenches
T25 Torx bit/screwdriver
regular pliers and remote cable operated spring hose clamp pliers (pictured below, these are optional)
wheel chocks/blocks of wood, floor car jacks, jack stands
engine support and chains/shackles (shown in use near the bottom of the page)
If you wish to use a service cover, do so now. I tape an old clean towel to the fender to prevent scratches from belt buckles, jeans buttons, or watches. Also make sure you don't have loose necklaces, hair, sleeves when working on your car, consult your factory service manual for all cautions, always wear eye protection, see the TOS for the full legal disclaimer, etc..
Pull the engine cover straight off to remove it. There are some pop snaps that hold it on.
Raise the car and rest it securely on jack stands. See 1000q: jack points for some pictures of where the factory jack points are. Make sure the car is safe and secure before getting underneath it.
Remove the plastic splash shield under the car by removing a few T25 torx screws. If you wish to replace it with a metal skid plate due to low ground clearance, see 1000q: skid plate installation.
Drain the engine coolant in the radiator. There's a valve at the bottom corner of the radiator. Use a hose to divert it into a bucket. See 1000q: coolant flush and 1000q: water pump replacement for more pics and details. You don't need to do a full flush during a routine timing belt change since most of it will be drained anyways.
Remove the coolant reservoir overflow hose and coolant sensor plug. Also remove the 2x phillips screws holding the coolant reservoir down (yellow arrows in below pic). This is a good time to check for coolant migration, see 1000q: coolant migration for more details. Once it's loose, remove the hose underneath the coolant reservoir and tuck it to the side.
Remove the fuel lines at the fuel filter (white arrows in below pic) and tuck one end to the side. Also unclip them from the plastic intercooler output pipe. After removing each spring clamp, twist the hose to break the seal before pulling it off. This makes it much easier to remove the hoses and helps prevent damage to the line. If they won't come off, remove them at the engine side. Note the blue and white arrows and mark which is the feed and which is the return line. Diesel fuel melts rubber and asphalt driveways so wad a rag around the ends to prevent excessive spilling. Tightly wrap some clean rags or paper towels around the exposed fuel lines to avoid contamination.
Optional: change the fuel filter if it's due for its 20,000 mile
change. See 1000q: fuel filter change
if you need more tips.
Remove the 5mm allen bolt holding the power steering reservoir down (red arrow in the above picture). Move the power steering reservoir and line around as needed for clearance but don't disconnect the lines.
Remove the plastic intercooler output pipe (it's the hose you've been working
around). There's a shielded electrical wire stuffed in the side, move it
to the side. This will give you more clearance.
There is 1 spring clip at each end holding it down. Tape over the
open pipes so nothing falls into them. I try to
avoid using paper towels because they tend to get stuffed down the piping but
the pipes may be oily and prevent the tape from sticking.
If the retaining tabs on the rubber hose are worn off, it will cause a
massive boost leak and poor running. You can use an aftermarket
doggie collar or replace the hose. For the BEW engine the hose is VW# 1j0 145 838 t
Remove the serpentine belt (alternator/power steering/AC belt).
Place a wrench on the serpentine belt tensioner to align the hole in the
tensioner and tensioner body. Insert VW tool T10060 or equivalent to hold it in the
loosened position (you can also use a nail). You don't need to hold the
tensioner back but it makes accessing the 3x 13mm bolts holding it on easier.
Remove the serpentine belt tensioner (3x 13mm bolts) and the upper timing belt cover
to its left/aft (2 clips).
If the car is not on jackstands yet, engage the parking brake, jack up the car, rest the car securely on jack stands, chock the wheels, and make sure the car is stable, safe and securely raised before doing anything else. I use wood blocks to raise the car. Here are instructions and some more useful tips: 1000q: tips for the mechanic , 1000q: making wood blocks.
Remove the plastic splash shield under the car (bunch of T25 torx screws).
Remove the passenger side side splash shield (2 speed nuts, one is yellow
arrow). Remove the speed nuts by sticking a screwdriver in the gaps and
Here is a picture of it removed. The speed nuts (silver discs) slide
into little clips.
At the same time, remove the 10mm "nut to body" nut and clip holding the piping to the
intercooler (green arrows above). Thread it back onto the stud to avoid
losing it. Move the intercooler pipe to the side.
There's a rubber elbow at the turbo which will let you bend it. I don't
suggest removing the rubber hose because there should be room to bend it to the
side and work around it. Pictured below is an older type
hose - yours is the same except the intercooler side uses a wire clip instead of
a spring clamp.
Remove the 4 bolts on the harmonic balancer pulley (crankshaft pulley/serpentine belt pulley). If you have a rubber cover over them just pull it out. Caution:†The pulley you are removing is the crankshaft pulley/serpentine belt pulley/harmonic balancer pulley only!† Do not remove the crankshaft sprocket bolt, the large rusty bolt 19mm 12 point bolt in the above picture. It's a one use only torque to yield bolt so donít remove it or apply a very large force to it.
If there is any corrosion or resistance, I
suggest soaking the bolts in PB Blaster or another penetrating lubricant.
The bolt heads are easy to strip. Let them
soak since PB blaster needs time to soak and penetrate into the threads and
under the bolt heads. When
satisfied, counterhold the pulley by having someone put the car in gear and
stepping on the brakes. If the pulley still moves, use a 19mm 12 point
wrench on the middle bolt to counterhold even more. If the
bolts get stripped, use an EZ out stripped bolt extractor to grip the outer diameter of the bolt heads.
If the harmonic balancer is stuck after the bolts are removed, use a rubber
mallet or a piece of wood to gently knock it back and forth to wiggle it off. The 4 bolt holes are not
symmetrical. The pulley will only go on with the holes oriented in the
CAUTION: Some may be 6mm allen head and some may be 10mm triple square bolts (not torx!) I believe the allen head bolts are long but check the length of the original bolts against the length of the new bolts! Some timing belt kits include replacement allen head bolts (pictured below) which may be too long for your pulley if you have triple square bolts! The pictures above show a pulley that requires the short style bolts. It doesn't have the raised ridges. Some pulleys have 4 raised ridges to accommodate the long bolts (similar to the below picture from an earlier engine). Some came with short allen head bolts, some came with short triple square bolts, and some came with long bolts.
The OEM allen head bolts also tend to strip. The triple square bolts are less likely to strip assuming you didn't try to jamb a torx bit into them. The torque spec includes a "+1/4 turn" which suggest they are single use torque to yield bolts but the service manual for the BEW or later pumpe duse engines don't say to replace them so I don't know which is best. If you have replacements that fit I would use them.
Remove the black lower timing belt cover (5x 10mm bolts). The middle-lower cover
overlaps the lower-lower round cover. Note the tabs on the edges. (Pic
is from a similar engine, your car will look slightly different). The fuzz
on the backside is normal but wipe off any oil and dirt.
Set the engine to top dead center (TDC) by manually turning the 19mm 12 point bolt on the crankshaft clockwise to test fit the crankshaft lock and camshaft pin. If manual, the transmission should be in neutral when you turn the engine over or else the transmission will hold the engine. Since you chocked the wheels and applied the parking brake the car won't roll away. Do not apply strong force to the crankshaft bolt like an impact wrench because it's a one use only stretch bolt. It's safe to use the bolt to turn the engine over by hand because the force is low compared to the bolt's torque value and this is how the service manual says to turn the engine over. Do this after removing the serpentine belt because otherwise you'll be turning those too and using more effort. The service manual suggests doing this after removing the motor mount - I suggest doing this before removing the mount because the engine will be more stable.
While you could also turn the engine over at the camshaft sprocket using a counterhold bar, this is not recommended. Despite having more teeth engaging the timing belt, it pulls on the tensioner side of the belt instead of the water pump side of the belt. This stresses the tensioner so don't turn it over there unless you're discarding the tensioner.
The crankshaft is at TDC when the dash mark on the crankshaft sprocket is aligned with the arrow on VW tool# T10050. When inserting the tool, slide it into the teeth on the sprocket (moving towards the engine) - don't push it down (moving down towards the ground) or else the teeth won't be meshed. As a test, pull the tool up (away from the ground) and if the teeth are meshed it won't lift up. There is a peg on the backside where the tool's handle is which fits into a hole on the crank front flange. The peg is visible in the tool pics at the top of the page.
When inserting the tool, insert it while gently turning the crankshaft clockwise. There's a little play and it will be off if you insert it while turning the engine/crankshaft sprocket counter clockwise. If you miss, the service manual says to turn it 1/4 turn counterclockwise before trying again. If you didn't read the warning earlier, here it is again: VW made a few defective T10050 whose arrows were to the right of the handle's hole. The arrow should be to the left of that and in line with one of the bolt holes at the 11:30 o'clock position.
The camshaft is at TDC when VW tool# T3359 can be fully inserted into the hole in the cylinder head. The toothed
window should be near the top and not near the bottom. If the toothed window is in the lower half of the sprocket, turn the crankshaft 1 full revolution. Make sure that the pin is fully inserted in the hole! It goes through the sprocket, through the hub that the sprocket mounts onto, and into the hole on the cylinder
Here is a view with the camshaft sprocket removed, the pulley removed for
pulley should not be
removed so don't loosen the large center bolt), and a view from straight on. Use a mirror to confirm the
position of the hole. Make
sure you're not inserting the pin into the empty space way below the hole.
(If you've triple checked the hole position with a mirror and find that the pin
is a hair off and won't go in, that's OK. Once you remove the timing
belt you can use the 18mm center bolt to slightly wiggle the camshaft hub 1 or 2
degrees to insert the pin. If it's more than a hair off something is
The Bentley service manual mentions a "mark on the rear timing belt
cover" but it's blocked by the belt. There is another mark "4Z" stamped into the
rear cover which roughly lines
up with the camshaft sensor tabs. These marks are highlighted in yellow below. You
can ignore these marks because they are just there to locate the pin's hole and the toothed window is much more visible.
Raise the engine about 1/4", just enough to get the weight of the engine off the passenger side engine mount and put the passenger side engine mount to be in a neutral position. By getting the weight off the engine mount, it's less likely to strip the threads in the aluminum mount. If the mount threads get stripped, get a new mount since the engine can fall down if the 18mm bolts strip or break.
The factory method to support the engine is to use a support bracket above the car.† Refer to your
service manual for more details on the bracket. If you want to buy a
support bracket like the one pictured below, they are available at Northern
Tool or Harbor Freight.† Loop chains
through the engine lift loop or loop chains through a shackle or large+thick
bolt and secure them to the hooks hanging down from the support. Make sure
the engine is secure and steady before removing the mount! Make sure your
support/chain/bolt/shackle is rated to support the engine/transmission!
The support bracket can also raise and lower the engine. As an aid in
raising/lowering the engine I use a hydraulic jack on the oil pan with a piece
of wood as a buffer (so it doesn't crack the aluminum oil pan). This
should not be the primary method of supporting the engine because hydraulic jacks can suddenly fail.
Never put yourself in a position where you could be injured if the
jack or engine slips/falls because it may cause damage to property and/or
serious injury/death! Before removing the motor mount, make sure the
engine is secure!
Loosen all the bolts circled below about a single turn before removing
them. This will help hold the mount and engine steady. Then
completely remove them. Ignore the torque values, that's for
installation. Again, you must securely support the
engine BEFORE you remove the red or blue circled bolts or else the engine will
fall down! Also note the alignment of the mount since the 18mm bolts have a
little bit of adjustment range. This is explained more in part 2 -
It should look something like this after removal. The engine support is
holding the engine up since you removed the mount.
Then remove the other motor mount on the engine (3x 16mm bolts). These are tricky to get at because the wheel well is blocking access to all 3 bolts at the same time. Raise and lower the engine for access. Here is the same mount pictured on an earlier engine. Don't bother trying to remove the mount until the timing belt rollers are removed because there isn't enough clearance yet. For now, just work around it. If you can get it out later, good, otherwise just work around it.
The upper right bolt is longer (about
120mm long) than the other 2 bolts (about 94mm long). If the shorter 16mm
bolt holes or the engine mount tab on the engine block are broken you can use
the mount repair kit
from dieselgeek to fix it. Although the service manual doesn't suggest
replacing these bolts, some mechanics do it because they are holding the engine
up and repeated use could cause failure. New bolts will stress the
mounting tab less but it normally breaks from under/over torquing the bolt.
Below is a similar engine for illustration (mount is the same).
Release tension on the timing belt tensioner by loosening its 15mm nut. Insert a 6mm allen wrench or spanner wrench VW# 3387 (fits in the 2 pegs) into the center part and turn it counter clockwise. If the tensioner is being reused, the service manual says to insert the triangle lock pin, VW tool# T10115. The tensioner will stay in the released position even if you don't use the VW triangle pin. You should never reuse an old tensioner during routine timing belt changes since it will almost certainly fail before the next scheduled service. Since tensioners are so cheap, I suggest replacing it with a new one every time the timing belt is removed unless it was just changed.
Remove the idler pulley (13mm nut). It will not last until the next scheduled service so always replace it. Don't tighten the new nut yet. If you can slip off the belt do it now.
If the belt is too tight, remove the 3x 13mm camshaft sprocket bolts but don't loosen or turn the center 18mm bolt. If you move the 18mm center bolt it will move the camshaft and you don't want that. Removing the camshaft sprocket will not move the camshaft. You have to remove the pin VW tool T3359 to remove the sprocket but don't worry, the camshaft won't move and the pin will go back in with no problem later.
Remove the water pump. It should be replaced before every 100,000 miles as part of the timing belt replacement. See 1000q: engine water pump replacement for more details.
Here is a view of a similar engine (BHW) for illustration. The timing belt routing is.....
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