BMW Camshaft Timing

and Vanos Unit Installation Wayne R. Dempsey

Difficulty Level: 6

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

This article is one in a series that have been released in conjunction with

Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The

book contains 272 pages of full color projects detailing everything from

performance mods to timing the camshafts. With more than 650+ full-color

glossy photos accompanying extensive step-by-step procedures, this book is

required reading in any 3 Series owner's collection. The book was released in

August 2006, and is available for ordering now. See The Official Book Website

for more details.

Need to buy parts for this project? Click here to order!

This technical article is designed to be used in conjunction with other ones in our

Technical Library. If you replace your head gasket, you will need to retime your

camshafts and re-install the Vanos unit. For the purpose of instruction here, we'll

assume that you have your cylinder head installed on the engine block, the

crankshaft is locked at Top Dead Center (TDC), and your two camshafts are

locked using the BMW camshaft locking tool. This article will guide you through

the process of retiming your camshafts, and re-installing the Vanos variable

camshaft timing unit.

This article departs from our normal format of text and words mingled together.

Since there are so many photos associated with this article, I have arranged

them in assembly order with captions for each. Read through each caption as a

step in the assembly process.

Figure 1

We start the procedure by making sure that the engine is at Top Dead Center

(TDC). At this point, the TDC pin is installed into the locking position, and is

holding the flywheel steady (see Head Gasket Replacement article for more

details). The camshafts are locked in place using the camshaft locking tool. This

will allow us to properly align and time the camshafts and the Vanos unit.

Figure 2

Shown here is the sprocket for the exhaust camshaft. Prior to mounting it on

your engine, verify that the teeth of the gear are not worn or damaged. Also

inspect the inner mounting slots to see if there is any wear from being loose at

one time.

Figure 3

Install the sprocket onto the exhaust camshaft. Make sure that the mounting

holes located on the camshaft flange are visible through the slots in the

sprocket, and also make sure that the holes are biased towards the left side of

the slots, as is shown by the red arrow. It may require some maneuvering to get

the sprocket into it's proper position. Normally, it takes multiple attempts to get

it to look exactly like the photo on the left.

Figure 4

Turn your attention now to the lower chain tensioner, which is located on the

lower part of the block, on the right side of the car. We will be removing this

tensioner and replacing it with a tensioner tool, which will keep the chain tight

while we time the cams.

Figure 5

Here is the tensioner tool, which we use in place of the spring-loaded tensioner

when timing the camshafts. It's important to use this tool, and not to rely solely

on the spring-loaded tensioner - it does not provide enough tension when the

car is sitting to accurate time the camshafts. Use the tool, and get the accurate

reading that your engine deserves.

Figure 6

Remove the tensioner by placing a socket on the end piece of the tensioner. Do

not remove the tensioner block which is attached to the housing (not

necessary). When the tensioner comes out, it is spring loaded, so be prepared

for it to pop out when you release the tension with your socket and driver.

Figure 7

Here is the tensioner assembly when you remove it. The assembly consists of a

plunger, spring, cap, and sealing ring.

Figure 8

Replace the tensioner with the proper tensioning tool. For now, simply tighten

the tool so that it is hand tight - we don't need or want the chain tension to be

super-tight right now.

Figure 9

With the left sprocket installed, install the center plastic chain guide and torque

down the long bolts that hold it in place. Don't over torque (10 Nm) - the first

time I did this, the long bolt was brittle and broke off in the cylinder head. I had

to take the assembly back apart, fish out the bolt, and then special order a new

one (3 days wait).

Figure 10

With the guide in place, reinstall the top chain tensioner. These tensioners

sometimes fail, but there really isn't a good method for testing them. I

recommend replacement if your engine has at least 80,000 miles on it or so. A

little bit of preventative maintenance can go a long way here. Tighten the bolts

down to 20 Nm.

Figure 11

This photo shows the tensioner installed and ready to go. Inspect the ramp

before you install it to see if there is any significant wear or obvious

deformations. The ramp should still be held in place using the two small hex

keys that you inserted when you removed it. Do not release the tensioner yet.

Figure 12

Place the camshaft sensor cap onto the intake camshaft. This metal cap serves

to trigger the camshaft position sensor, and lets the engine know whether the

engine is on an intake or exhaust stroke of it's 4-cycle process. The camshaft

position sensor fits into the hole on the right side of this photo (you can make

out the small green o-ring to the lower right).

Figure 13

Shown here are the studs for the thrust washer and sprocket. These studs look

very similar to the ones that mount the valve cover to the head - don't mix them

up. Compare yours carefully to the ones in the photo to make sure that you

have the right studs. It is also important to keep in mind that there are two

types of Vanos units (early/late). The early units do not have a plate spring,

whereas the later ones do. The plate spring fits over the intake camshaft thrust

washer, and requires slightly longer studs. This particular car does not have the

spring plate.

Figure 14

Install the thrust washer onto the intake camshaft. Use the special studs, and

install it in the same configuration in which it was removed. In other words, in

this photo, you can see the oil stain from the slots that surround the studs.

Install this side facing you when you reinstall this thrust washer (copy the

photo). Torque the studs to 20 Nm.

Figure 15

Now, take the two intake sprockets and chain and attach it to the assembly. See

the photo for the proper orientation of the two sprockets. The exhaust sprocket

should have it's cup facing outwards, and the intake sprocket should have its cup

facing inwards. Verify that both sprockets are correctly mounted flush to the

surfaces behind them. The intake sprocket is installed with the flat side facing

you (the Vanos unit). The collar of the intake sprocket faces and points to the

camshaft. Align the two sprockets and the chain so that the slots are centered

on both sprockets (see arrows).

Figure 16

Here's another view of the intake Vanos sprocket, correctly mounted flush

against the thrust washer behind it. Soak all of the sprockets, gears and chains

in clean motor oil before you install them - these are sliding parts that need

lubrication.

Figure 17

Now, install the thrust washer onto the intake camshaft and tighten the nuts

down. It's okay to reuse the old nuts. If you have the Vanos unit with a spring

plate, then install it first, before the thrust washer (not shown). Tighten the nuts

down to 10Nm. IMPORTANT: With the nuts tight, the inside sprocket should be

free to rotate back and forth about 20 degrees, along with the chain. When I

assembled this engine, I found that it could not. Some of the bolts and flanges

were worn, and I had to order new ones. The Vanos unit requires that this

"sandwich" of parts be able to rotate smoothly. Verify this prior to proceding.

Figure 18

Install the screws onto the exhaust camshaft. Place them onto the sprocket and

tighten them only HAND TIGHT. We will be making adjustments later on, and

these bolts only need to be in place to hold the exhaust camshaft in its proper

position.

NOTE: From this point on, these are the instructions that you will want to look

at if you are simply replacing the Vanos unit.

Figure 20

Here is what your engine should look like now. You have the new camshafts

installed, you have the chain and sprockets properly setup, and we're ready to

install the Vanos unit.

Figure 21

Shown here is the Vanos unit. It consists of a solenoid, and a hydraulic gear that

is activated when oil pressure is released into the unit by the solenoid. It's a

rather simple device. The gear on the unit is pushed out by oil pressure and as it

moves outward, it rotates the small sliding camshafts sprockets, thus advancing

the camshaft timing.

Figure 22

Test the Vanos unit by pulling out the gear plunger all the way. You should be

able to simply pull on it with your hand, and it should extend from the housing

(see arrow). If the unit still has oil in it at this time, it will make a gurgling noise

or two. Push the plunger back into the unit when you are finished.

Figure 23

The BMW service manuals recommend that you place some silicone sealant

around the left and right mounting points (alignment pins) for the front Vanos

seal. This photo shows the right side (looking at the engine from the front).

Repeat for the left side alignment pin.

Figure 24

Install a new seal onto the front of the cylinder head (indicated by the arrow).

The seal should be made of a thin metal.

Figure 25

Now comes the tricky part. Rotate the front sprocket/chain assembly all the way

clockwise to the right (towards where the air cleaner sits). With the plunger of

the Vanos unit pushed all the way back into its housing (important), place the

Vanos unit on the cylinder head.

Figure 26

The Vanos unit has inside gears that need to mesh with the ones on the sprocket

(see arrow). When you push the Vanos unit onto the cylinder head, it will not

want to easily mesh with the gears on the sprocket. Important: the

sprocket/chain assembly should still be rotated as far clockwise as possible.

Figure 27

With your fingers, rotate the spline shaft on the Vanos unit, until you can engage

one spline of the sprocket. Pushing forward on the Vanos unit, carefully rotate

the sprocket/chain assembly counter-clockwise. As you do this, the Vanos unit

should slide in towards the cylinder head. Always ensure that the FIRST suitable

tooth combination between the sprocket and the Vanos unit engages.

Figure 28

Reinstall the main mounting bolt and the engine lift ring.

Figure 29

After tightening down the Vanos housing, and clean up any squeeze-out from

the silicone that you used to help seal the unit to the cylinder head.

Figure 19

With the sprockets properly installed, now pull out the retaining pins and reapply

tension to the chain. The tensioner should spring back with some force and tight

the chain quickly. If it appears sluggish, or does not spring back, then replace

the tensioner before continuing.

Figure 32

Now, tighten down the tensioner tool to 1.3 Nm. This is such an incredibly small

amount, that you can simply use a hand-wheel ratchet to tighten the chain very

tight. You want to remove all slack in the chain prior to tightening down the

exhaust sprocket. Use of the regular spring-loaded tensioner does not place

enough tension on the chain to correctly tighten the sprocket.

Figure 30

With the tensioner tool still in place, tighten down the four nuts on the exhaust

sprocket (15 Nm). Reinstall the plugs on the outside of the Vanos cover.

Figure 34

Remove your tensioner tool, and replace it with the real tensioner. Make sure

that the slot in the end of the tensioner is correctly aligned with the ramp on the

inside of the engine. If you make this mistake, it will cause the chain to rattle

fiercely and may cause damage to your engine.

Figure 35

Remove the camshaft holding tool from the rear of the engine. Also remove the

flywheel locking tool.

Figure 36

You're finished! Your Vanos unit should be installed, the camshafts will be timed

properly, and all you have left to do is:

Connect Vanos oil line Connect Vanos electrical control line Install valve cover with new seal Reinstall

[click to enlarge]

One of the more common oil leaks on BMW engines is the

large, long valve cover gasket. In general, it's pretty easy to

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

remove and replace this gasket. This article goes over in

detail the procedure to replace the valve cover gasket. Begin

by prepping the car. The only thing that you really need to do

is to make sure that the car is cold. If you try to remove or

install spark plugs in a hot car, then you may encounter

problems with the spark plugs gumming up or damaging the

relatively delicate threads in the aluminum cylinder head.

Just make sure that the car is cold, or at the bare minimum, only slightly warm to the touch.

Let's talk about the six cylinder cars first. The first step is to

remove the top plastic covers from the engine. These serve

no mechanical purpose - they are there only for decoration

and to prevent dust and debris from getting into the recesses

of the engine. On the six cylinder cars, there are two covers,

a long thin one on the top of the car, and a wider one

towards the left. Speaking of left, for the purpose of this

particular tech article, I will refer to the left side of the

engine as being on the left as you are standing in front of the

car looking at the engine. The right side would, of course, be

opposite to that. For reference, the windshield washer bottle

would then be on the left, and the air filter would be on the right.

On the two plastic covers, there will be two small, snap-in

plugs on the top. Carefully remove these plugs (don't drop

them into the engine) with a small screwdriver, prying them

up as you grab them (Figure 1). Underneath you will find a

nut that holds the cover onto the top of the engine (Figure

2). Remove the four nuts on these two covers, and they

should both simply slide up out of the way. Figure 3 shows the engine with the center cover removed.

Underneath the left cover, you will see the six spark plug

coils that sit on top of each of the plugs (Figure 4). You need

to remove each of these carefully, in order to gain access to

the plugs. Using a screwdriver, release each connector from

each coil. There is a metal retaining ring on the rear of each

one that fastens it to the coil (Figure 5). Once you lift up on

the retaining clip, then the connector should simply slide out

of the coil. Carefully remove all of the connectors from each

coil (Figure 6), taking care not to bend the wire harness too

much. These wires are stiff, and generally don't take well to

being bent in multiple directions. Just be gentle with them.

To assist with your maneuvering of the wires, detach the

center clip that holds the wires that come from the center

channel. This clip is shown in Figure 7. Gently place the wires

off to the side and out of the way, without bending them terribly.

With the wires detached and placed slightly out of the way,

you can now remove each of the six coils. Each coil is

fastened to the valve cover using two screws. On two of the

coils, there are two small ground straps that connect the coil

to the stud on the cylinder head. Take note of these ground

straps - they must be installed properly when you are

finished, otherwise your car may encounter problems. These

two ground straps are shown marked by the greens arrow in

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 8 and Figure 9 (coil already removed in this photo).

Remove each of the two nuts that hold each coil to the valve

cover. At this point, the coil should be able to be easily pulled

right off of the engine (Figure 10). The coil has a small coil

pack on one end, and a spring-loaded spark plug connector

on the opposite end. Simply remove the coil/plug assembly

and place it off to the side. All of the coils are the same, so it

doesn't matter which cylinder bank it came off of - unless

you are specifically trying to troubleshoot a bad coil fault code that was displayed by the main computer.

With the coils removed, you can now remove the top plastic

cover on the wire harness box that straddles the intake

manifold and the valve cover (Figure 11). The lid on this box

simply snaps off. With it removed, you can then reach in so

that you can carefully pull the wire harnesses out of the way

(Figure 12). At this point, you can start removing the nuts

that hold on the valve cover. Take careful note of which ones

have ground straps attached (Figure 13), and make sure that

you record where they are located so that you can put them

back into their proper place when you're reassembling the

valve cover.

Some of the nuts may be difficult to reach, in particular the

one located all the way at the rear of the engine

compartment underneath the windshield wipers (Figure 14).

A small ratchet comes in handy here. When you have

removed all of the nuts (there should be 15 of them), take a

rubber mallet and tap the side of the valve cover to loosen it

off of its gasket (Figure 15). You should then be able to remove the valve cover.

Inspect the valve cover when it comes off. In particular, be

careful with the baffle and seal on the inside (Figure 16). This

seal does not appear to be available as a separate part (it

comes with the valve cover). The good news is that it doesn't

really do much - it just seals an air baffle to the valve cover.

Also, when you remove the valve cover, make sure that you

don't loose any of the rubber grommets (Figure 17), or flat washers that hold them in.

If you take your valve cover into your machine shop to be

sand blasted, make sure that you assemble all of the bits and

pieces back together in their proper order. Especially

important are the rubber studs that hold on the top plastic

covers (Figure 18), as well as the baffle on the inside of the

cover (Figure 16).

Prep both the surface of the cylinder head and the valve

cover for the new seal by carefully cleaning all remnants of

the old seal off of all of the mating surfaces. Be careful not to

scratch any surfaces, and also be careful not to drop bits of

pieces of the gasket into your engine.

The BMW factory manuals recommend adding some sealant

to some leak-prone sections of the cylinder head. I chose to

use Permatex High-Temp RTV, and it worked very well for

sealing these areas. Specifically, the factory recommends

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

adding sealant at the interface where the VANOS unit or front

mounting timing chain cover meet (Figure 19 and Figure 20).

They also recommend a small bit of sealant at the rear of the cover (Figure 21).

With the sealant attached, simply place the new gasket on

the cylinder head (Figure 22). Place the two inner gaskets on

the spark plugs holes in center of the head (Figure 23).

These are the gaskets that leak oil into the spark plug holes

(see the Pelican Parts Technical Article on Replacing Your

Spark Plugs). Finally, bolt down the cover, and reattach all

off the nuts on the cover, making sure that you replace the

rubber washers/bumpers under each one. Using a torque

wrench, tighten the nuts down to 89 in-lb (10 Nm). Figure 24 shows the finished product.

If you haven't replaced your spark plugs, now is a good time

to do it. See the spark plug replacement article for more

details. Reinstall the coils, reattach the wire harness, and

replace the top plastic covers.

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.

[click to enlarge]

One basic tune-

up procedure for

just about any

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

car on the road is

the replacement

of your spark

plugs and spark

plug wires

(where

applicable). On

the BMW E36 six-

cylinder engines,

BMW has

eliminated the

use of spark plug

wires by

integrating six

small spark plug

coils that sit on

top of each spark

plug. While this

configuration

may be a bit

more expensive

than the typical

single coil, single

capacitive

discharge box

configuration, it

makes the car's

ignition system

more reliable by

removing a

component that

constantly wears

out and fails

(spark plug

wires). It's a

pretty cool setup,

not commonly

found on older

cars. As

manufacturing

components has

become

increasingly

inexpensive,

ignition setups

like these have

become more

common.

I recommend

replacing your

spark plugs every

10,000 miles, or

about once a

year. In reality,

you can probably

go longer than

that, however,

you never really

quite know how

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

long the plugs

are going to last,

or you may

forget to do it if

you don't setup a

yearly schedule.

Needless to say,

replacing your

spark plugs is

one of the easiest

tasks to do on

your BMW -

provided you

have the proper

information,

which I will provide here.

Begin by

prepping the car.

The only thing

that you really

need to do is to

make sure that

the car is cold. If

you try to

remove or install

spark plugs in a

hot car, then you

may encounter

problems with

the spark plugs

gumming up or

damaging the

relatively delicate

threads in the

aluminum

cylinder head.

Just make sure

that the car is

cold, or at the

bare minimum,

only slightly

warm to the touch.

Let's talk about

the six cylinder

cars first. The

first step is to

remove the top

plastic covers

from the engine.

These serve no

mechanical

purpose - they

are there only for

decoration and to

prevent dust and

debris from

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

getting into the

recesses of the

engine. On the

six cylinder cars,

there are two

covers, a long

thin one on the

top of the car,

and a wider one

towards the left.

Speaking of left,

for the purpose

of this particular

tech article, I will

refer to the left

side of the engine

as being on the

left as you are

standing in front

of the car looking

at the engine.

The right side

would, of course,

be opposite to

that. For

reference, the

windshield

washer bottle

would then be on

the left, and the

air filter would be on the right.

On the two

plastic covers,

there will be two

small, snap-in

plugs on the top.

Carefully remove

these plugs

(don't drop them

into the engine)

with a small

screwdriver,

prying them up

as you grab them

(Figure 1).

Underneath you

will find a nut

that holds the

cover onto the

top of the engine

(Figure 2).

Remove the four

nuts on these

two covers, and

they should both

simply slide up

out of the way.

Figure 3 shows

the engine with

the center cover removed.

Underneath the

left cover, you

will see the six

spark plug coils

that sit on top of

each of the plugs

(Figure 4). You

need to remove

each of these

carefully, in order

to gain access to

the plugs. Using

a screwdriver,

release each

connector from

each coil. There

is a metal

retaining ring on

the rear of each

one that fastens

it to the coil

(Figure 5). Once

you lift up on the

retaining clip,

then the

connector should

simply slide out

of the coil.

Carefully remove

all of the

connectors from

each coil (Figure

6), taking care

not to bend the

wire harness too

much. These

wires are stiff,

and generally

don't take well to

being bent in

multiple

directions. Just

be gentle with them.

To assist with

your

maneuvering of

the wires, detach

the center clip

that holds the

wires that come

from the center

channel. This clip

is shown in

Figure 7. Gently

place the wires

off to the side

and out of the

way, without

bending them terribly.

With the wires

detached and

placed slightly

out of the way,

you can now

remove each of

the six coils.

Each coil is

fastened to the

valve cover using

two screws. On

two of the coils,

there are two

small ground

straps that

connect the coil

to the stud on

the cylinder

head. Take note

of these ground

straps - they

must be installed

properly when

you are finished,

otherwise your

car may

encounter

problems. These

two ground

straps are shown

marked by the

greens arrow in

Figure 8 and

Figure 9 (coil

already removed

in this photo).

Remove each of

the two nuts that

hold each coil to

the valve cover.

At this point, the

coil should be

able to be easily

pulled right off of

the engine

(Figure 10). The

coil has a small

coil pack on one

end, and a

spring-loaded

spark plug

connector on the

opposite end.

Simply remove

the coil/plug

assembly and

place it off to the

side. All of the

coils are the

same, so it

doesn't matter

which cylinder

bank it came off

of - unless you

are specifically

trying to

troubleshoot a

bad coil fault

code that was

displayed by the

main computer.

With the coil

removed, you

should be able to

look down the

hole and see the

spark plug hiding

in there. Figure

11 shows what

the top of a

normal looking

spark plug looks

like. However, as

you remove the

plugs, you may

discover

something

peculiar. The way

that the ignition

system is

designed on

these BMWs,

there is the

opportunity for

the spark plug

holes to

completely fill up

with oil, if you

have a leaky seal

on your valve

cover. When you

pull out the spark

plug connector /

coil combo, you

may find that it is

completely

submerged in

engine oil, as

shown in Figure

12 and Figure 13.

Looking down the

hole, you may

not even be able

to see the spark

plug because the

entire hole is

filled up with oil

(Figure 14 and

Figure 15). While

common sense

says that this is

not a good thing,

the reality is that

this is actually

quite common,

and doesn't seem

to affect the

performance of

the car one bit. If

you do find this

oil in your spark

plug holes, I

would suggest

that you go one

step further and

replace the valve

cover gasket.

This replacement

procedure is very

simple, once you

have the coils

removed, and

should only take

you about 20

minutes more,

providing you

have the actual

gasket on hand.

If you find oil in

your spark plug

holes, then you

should definitely

replace the gasket.

If you find that

you have oil in

your spark plug

holes, I suggest

that you take

some paper

towels and

attempt to soak

up as much of

the oil as

possible, before

removing the

spark plug. If you

don't get rid of

the excess oil,

then it will leak

into the cylinder

head through the

spark plug hole

when you remove

the spark plug.

This will cause

your car to run

sooty when you

first start it up,

and it may even

foul your brand

new spark plugs

that you just installed!

Spark plug

removal is easy -

you just need the

right spark plug

wrench. I have

one that I love -

it's a spark plug

socket with a

rubber insert that

catches the plug.

In addition, it has

a built-in swivel

on the

attachment end.

This is especially

useful when

trying to remove

plugs in hard-to-

reach places, as

they are always

located on

Porsche engines

(BMW engines

aren't really that

bad with respect

to spark plug access).

Using a breaker

bar, grip the plug

and turn it

counter-clockwise

until it is loose.

Then pull out

your tool and

grab the plug.

When the plug

comes out, you

may want to take

a close look at it.

The spark plug is

really the best

way to visually

‘see’ what is

going on inside

your combustion

chamber. You

need to pull out

all of the spark

plugs to replace

them, so you

might as well

take a close look

at them while

they’re out. While

today’s modern

fuels make plug-

reading much

more difficult,

you can still

glean a lot of

information from

looking at them.

A good, well-

balanced engine

will produce a

plug that is light

brown in color,

and dry. If the

engine is running

too rich, the plug

will often be

coated with a lot

of extra carbon.

Keep in mind that

the rest of your

combustion

chamber

probably looks

the same. An

engine running

too lean will have

a powdery white

coating on it, and

the outer

porcelain ring

may have a

burned

appearance.

When reading

spark plugs, pay

close attention to

the white

porcelain ring

around the plug.

This white area

will give you an

excellent

background to

inspect the color

of the plug, and

to help determine

how your

combustion

chamber looks inside.

If the plug is wet

with oil, then that

indicates that

there is

significant

leakage into the

combustion

chamber past

either the valve

guides or the

piston rings. This

is generally a bad

sign, and an

indicator that a

future

compression test

may not yield

good results.

Figure 16 shows

an unusual spark

plug with all four

of its electrode

eaten away. I

would hazard a

guess that this

plug was

improperly plated

from the factory,

and as it

progressed

through it's life,

the repeated

sparking slowly

ate away at the

electrodes until

they were gone.

A plug in this

condition would

misfire often (if

at all), and would

generate poor

performance for

this particular

cylinder.

Surprisingly

enough, none of

the rest of the

spark plugs in

this set exhibited

this type of

damage. This is

what leads me to

believe it was

defective from

the

manufacturer.

Figure 17 shows

a brand new

Bosch Platinum

spark plug. While

I don't have any

specific

preference for

any specific

manufacturer of

plug, you should

definitely make

sure to get the

proper ones for

your car. Spark

plugs have varied

over the years as

engines have

been changed

slightly due to

smog

regulations. The

important thing

to remember is

to get the proper

ones for your car

(they are scaled

by electrode type

and also by heat

range), otherwise

you may

encounter odd

ignition

problems. Spark

plugs are cheap -

I would go with a

brand name like

Bosch or NGK,

choosing to avoid

the no-name

brands. Make

sure that you

measure the

spark plug gap (if

single electrode)

with a spark plug

gap tool before

you install the

plugs.

Install your new

plugs using a

torque wrench to

measure the

amount of torque

applied to the

plug (Figure 18).

This is very

important, as it is

easy to over or

under-tighten

spark plugs.

Make sure that

the plug is firmly

seated in your

spark plug socket

as it is very easy

to insert the plug

into the head and

have it cross-

thread. This

means that the

threads of the

spark plug don't

mesh properly

with the ones in

the head, instead

choosing to "cut

their own path."

This damages the

threads on the

head, and in

extreme cases,

may destroy the

threads in the

cylinder head

entirely. Trust

me - you do not

want this to

happen. Proceed

carefully and

cautiously here.

Install each plug

into the cylinder

heads without

using any anti-

seize compound.

Torque the spark

plugs to 25 Nm

(18.4 ft-lbs).

While writing

"How to Rebuild

and Modify

Porsche 911

Engines", I

discovered that

Porsche doesn’t

recommend the

use of anti-seize

compound, as

detailed in

Porsche Technical

Bulletin 9102,

Group 2,

identifier 2870.

The bulletin

applies

retroactively to

all Porsche

models and the

theory is that the

anti-seize tends

to act as an

electrical

insulator between

the plug and the

cylinder head.

This could have

detrimental effect

on the firing of

the spark due to

the loss of a

good, consistent

ground

connection.

Keeping those

findings in mind,

I would make the

same

recommendations

for the BMW cars.

With the new

plugs installed

(Figure 19) and

properly torqued,

you can replace

the coils (don't

forget the small

ground straps

shown in Figure 8

and Figure 9) and

reattach the coil

connectors

(Figure 20 and

Figure 21). Snap

the wires back

into their center

holders (Figure

7) and replace

the top two

plastic covers.

When you're

done, your

engine should

look back to

normal (Figure 22)

Changing plugs

on the 318 4-

cylinder cars is a

bit different and

a bit easier. You

remove the spark

plug cover in a

similar manner

(Figure 23).

There should be

a handy little

blue spark plug

wire pull tool

under the cover.

Use it to remove

the plug wires

from the ends of

the spark plugs

(Figure 24). With

the wires

disconnected,

remove and

reinstall the plugs

in a similar

manner to how I

described the

procedure for the

six cylinder cars.

You will also want

to replace the

spark plug wires

every 30,000

miles or if they

look cracked and worn out.

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.