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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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Old 04-11-2012, 09:55 AM
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Complete E46 Cooling Guide (Information w/ complete parts list)

I posted up on sister site E46Fanatics.com. This applies to the E46 BMW 3-Series and E39 BMW 5-Series models with the M5X engine.

Introduction:

This thread is for you if you just purchased your E46 3-Series and/or have more than 75,000 miles on your current cooling system on your E46 3-Series BMW.

The E46 3-Series (as well as the E36 3-Series) are known to have somewhat of a delicate cooling system which are sometimes known to fail prematurely. In the event of a failure, the results are often times catastrophic.

The inherent design of the inline-six BMW engine having a long block/head coupled with the fact that the head is made of aluminum means that the head is particularly vulnerable to heat damage (or warp). This damage to the head and headgasket can occur in seconds once your car is overheated and usually means a top-end rebuild which may cost around $2,500 to repair.

As such, it is absolutely imperative that you maintain your BMW E36/E46 3-Series cooling system.

If your temperature gauge does go into the red zone, immediately shut off the car and have it towed.

The failures:

How, why, and when do the failures typically occur?

Plastics. Your E46 contains lots of it. The typical first failure of the E46 cooling system is the expansion tank. It will typically develop a hairline crack anywhere from 60-95k miles (give or take a few). That crack will expand under heat and water will leak out. This will trip the low coolant warning on your dash. If this level becomes low enough, there will not be enough coolant for the water pump to circulate. No circulation means no flow through the engine/radiator. No flow through the radiator/engine means overheating.

Other typical failures are the pulleys and belt systems. The main belt drives the water pump, alternator, and power steering pump. This belt is guided by pulleys. These pulleys contain ball bearings and grease. After around 60k miles, this grease dries up and the pulleys are vulnerable to failure. The belts are then thrown off once this pulley fails and you now have no cooling system, no power steering, and no charging system. Your dashboard will light up like a christmas tree and your temp needle will fly into the redzone.

The water pump is another potential failure point. It can fail in at least three ways. 1) The impellar itself will break and cannot continue to push water. 2) The seal may leak and, 3) The bearings will fail causing the shaft to wobble and break.

Failure isn't that common but can still happen. You might hear nightmares of water pumps with plastic impellars, but don't pay attention to this. Replace your water pump due to age and/or mileage, not because what its made out of. The latest BMW water pump design (at least 10-15 years old) features a plastic composite impellar. BMW did once try metal impellars but quickly phased those out due to premature balancing and bearing failures. Design is more important than physical materials. You might hear stories and internet legends about the Stewart water pump (and they may be true) but really it is unnecessary and a waste of money (unless you plan to drive your car enough to justify the cost--at least 180,000-220,000 actual driving miles)

The thermostat sometimes fails around the time the expansion tank does. Maybe a little longer. They are generally designed to fail stuck open but don't risk it. Just change it.

Belts. Self-explanatory. No belts, no cooling system. Replace them every 35k miles.

Radiator is typically robust, but the endtanks are made of--you guessed it--plastic. The rubber seal between the endtanks and the main body may deteriorate as well. You'll notice staining or slight weeping. The radiator has thin passages which can become clogged with sediments as well and may cause water to flow slowly to where it needs to go. This may cause problems in traffic or while stopped.

Fan blade and clutch (for automatic transmission equipped vehicles). Another failure point. If the blade chips or deteriorates, there goes its balance and will explode in your engine bay. There goes your belts, hoses, hood and whatever else it feels like taking out. The fan clutch is typically robust, but is good practice to replace it anyway. It controls the speed of the fan. You don't want it spinning too slowly or too quickly.


The parts list with prices as of 4-6-12:


(Free plug for sponsor ECSTuning )

OK, Mr. Mango, you have convinced me to replace the entire cooling system. Where do I get the parts?

There's many places. Personally, I like BMAparts.com, RMEuropean.com, and OEMbimmerparts.com. All are cheap and lightning fast. I put together the following parts from BMAparts.com and partly, Amazon.com (for one part)
I included part numbers so you can cross-shop and get your own prices.

Cooling system

Radiator
Behr $137.30 (Manual transmission) Part# 17119071518
Behr $139.29 (Automatic transmission) Part# 17119071519

Expansion tank Part# 17117573781
Genuine BMW $63.29

Expansion tank cap Part# 17111742231
CRP $10.19

Water pump Part# 11517527910
Saleri (OEM) $54, BMAparts.com part# BMW006731 (you won't find it on their site as of 4-9-12 but you must add it to your cart using the store part#)

Radiator hose lower Part# 11531436408
CRP $24.68

Radiator hose upper Part # 17127510952
CRP $27.03

Thermostat Part# 11537509227
Wahler $44.19

Radiator fan switch Part# 13621433077
Genuine BMW $26.01

Water pump pulley Part# 11511436590
URO Aluminum $22.68
Genuine plastic $30.55

Water pump pulley bolts x4 $0.25 ea. Part# 07119904524

Belt tensioner pulley Part# 11281748131
SKF $15.93

Alternator deflector pulley Part# 11287841228
Ruville $23.25

A/C tensioner pulley
(hydraulic, SKF $15.93) Part# 11281748131
(mechanical, Dayco 89133 $21.94) Dayco 89133 - Amazon.com

Alternator/accessory belt Part# 11281706545
Continental $14.21

A/C belt
Part# 11281437450 (5-rib up to 9/2002) $8.72 or;

Part# 11287512762 (4-rib from 9/02) $7.91

Expansion tank mounting plate (optional) Part# 17111436250
RMEuropean Genuine BMW $54.53

Automatic cars: (If you drive an auto trans., add the following parts to the above list)

Expansion tank mounting plate (optional) Part# 17111436251
RMEuropean Genuine BMW $54.53

Thermostat Part# 17111437362
Genuine $84.34

Fan blade Part# 11521712058
Genuine $61.05

Fan clutch Part# 11527505302
Sachs $90.59

Grand total manual transmission cars: $500.18

Grand total automatic transmission cars: $738.15


Bleeding the system: (VERY IMPORTANT-DANGER-DO NOT SKIP!!)

This step is extremely important. No amount of brand new cooling parts in the world will work if you do not bleed. The point of bleeding is to remove air bubbles. The cooling system is most efficient when it is circulating pure fluid.

Here is the official procedure per BMW TIS: http://tis.spaghetticoder.org/s/view.pl?1/06/06/86

Here is a quick cheat sheet:

Raise front of car on ramps (Not necessary, but recommended)

CAUTION: ONLY DO THIS WHEN CAR IS COOL AND ENGINE IS OFF. At no point should the engine be turned on.

1) Remove expansion tank cap and bleed screw and set aside

2) Turn ignition to ON (dash lights on but do NOT start the car)

3) Set heat to MAXIMUM (90) and fan speed to low (this opens heater valve)

4) Begin to fill your expansion tank with ideally a 50/50 mix of Genuine BMW coolant and distilled water (do not use anything else--no reason to. The proper stuff is cheap) The system might take a while to swallow the water. Massage the hoses if you think it will help. Keep pouring. Water will begin to pour out of the bleed screw hole with air bubbles. The point is to keep filling and filling until the bubbles are gone. This may take a while--be patient.

5) Once you are satisfied that a continual stream of bubble-free water is emerging from the bleed hole and that your cooling system is adequately filled, go ahead and replace the bleed screw (do not overtighten). The expansion tank will be full to the top at this point so you'll need to siphon off any excess so that the appropriate tank level can be achieved.

Congratulations. Your E46 is now ready for another 75k miles of trouble-free driving. Never will you have to worry about being stranded with your wife, girlfriend, pets or kids in the car. Never will you have to worry about posting a thread asking why your car is overheating or why your engine is stained with coolant. Never again will you have to worry. (at least for another 75k miles) :thumbsup: The mileage is just a guide. Your results may vary.

Happy motoring
(if there's anything which I should address, edit, or add. Let me know)
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Complete BMW E46 Cooling System Guide
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  #2  
Old 04-11-2012, 11:25 AM
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Excellent post.
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Old 04-11-2012, 01:42 PM
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Thank you, Mafia. Fix that valve cover gasket yet?
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Old 04-11-2012, 01:57 PM
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Awesome Post - every time you mention something that can go wrong I would end with - "and that's bad".
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Old 04-11-2012, 02:45 PM
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Quote:
Originally Posted by synenergy52 View Post
Thank you, Mafia. Fix that valve cover gasket yet?
Yup already did my VCG. Now I'm dealing with tuning or who knows what... car is undrivable at the moment.
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BMW 2006 M5 - REALLY LOUD
Incoming - Mclaren MP4-12c
BMW 2007 335i. Single Turbo 6266. SOLD
Audi S4 2000 Stage 3 - Dat turbo spool - SOLD
BMW 2000 3-series - Supercharged Because race car SOLD
Maserati 2004 M128 GT - HREs/tint/straight piped SOLD
BMW 2006 M3 - stock - SOLD
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Old 04-12-2012, 12:28 PM
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thanks. haha
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Old 04-13-2012, 08:51 AM
1benji 1benji is offline
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But yU forgot the MOST important part and the one that fails usually,..the fan module box that tells the fan to kick on. THIS part gets lazy and dies leading to expansion tank explosion, heat and stress and all the other issues yU mentioned,..trust me I went thru it. Might as well have bought another car LOL. And the diagnostic machine doesn't even catch tht fault precisely.
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Old 12-05-2017, 09:19 PM
bimNaround bimNaround is offline
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Quote:
Originally Posted by synenergy52 View Post

...

Cooling system

Radiator
Behr $137.30 (Manual transmission) Part# 17119071518
Behr $139.29 (Automatic transmission) Part# 17119071519

Expansion tank Part# 17117573781
Genuine BMW $63.29

Expansion tank cap Part# 17111742231
CRP $10.19

Water pump Part# 11517527910
Saleri (OEM) $54, BMAparts.com part# BMW006731 (you won't find it on their site as of 4-9-12 but you must add it to your cart using the store part#)

Radiator hose lower Part# 11531436408
CRP $24.68

Radiator hose upper Part # 17127510952
CRP $27.03

Thermostat Part# 11537509227
Wahler $44.19

Radiator fan switch Part# 13621433077
Genuine BMW $26.01

Water pump pulley Part# 11511436590
URO Aluminum $22.68
Genuine plastic $30.55

Water pump pulley bolts x4 $0.25 ea. Part# 07119904524

Belt tensioner pulley Part# 11281748131
SKF $15.93

Alternator deflector pulley Part# 11287841228
Ruville $23.25

A/C tensioner pulley
(hydraulic, SKF $15.93) Part# 11281748131
(mechanical, Dayco 89133 $21.94) Dayco 89133 - Amazon.com

Alternator/accessory belt Part# 11281706545
Continental $14.21

A/C belt
Part# 11281437450 (5-rib up to 9/2002) $8.72 or;

Part# 11287512762 (4-rib from 9/02) $7.91

Expansion tank mounting plate (optional) Part# 17111436250
RMEuropean Genuine BMW $54.53

Automatic cars: (If you drive an auto trans., add the following parts to the above list)

Expansion tank mounting plate (optional) Part# 17111436251
RMEuropean Genuine BMW $54.53

Thermostat Part# 17111437362
Genuine $84.34

Fan blade Part# 11521712058
Genuine $61.05

Fan clutch Part# 11527505302
Sachs $90.59

Included in this list is the upper and lower radiator hose. The expansion tank on my 2004 E46 with a manual transmission has two hoses that connect towards the bottom of the expansion tank and route back towards the firewall. Should both of those hoses also be replaced?

Are people that are doing preventative cooling system replacements of parts like shown in this list also skipping the hoses that connect to the bottom of the expansion tank or are you replacing them at the same time as the upper and lower radiator tank hoses? It seems reasonable that you would want to replace all coolant carrying hoses at the same time.
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Old 12-05-2017, 09:34 PM
Y2K_Bimmer Y2K_Bimmer is offline
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I replaced mine at 200,000 miles and they were OK. I was doing the hard pipes so I replaced everything that hadn't been replaced. Now my expansion tank is leaking.
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Old 12-06-2017, 12:19 PM
bimNaround bimNaround is offline
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Quote:
Originally Posted by Y2K_Bimmer View Post
I replaced mine at 200,000 miles and they were OK.
And by mine, you mean you replaced both of the expansion tank hoses at 200k for the first time?

Also, how did you know they were OK? I don't want replace parts unnecessarily but I've read a lot about how various cooling components in the E46 are like ticking time bombs as they age so I don't want to overlook replacing something which causes bad damage to the engine and strands me somewhere.
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Old 12-06-2017, 12:58 PM
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Fast Bob Fast Bob is offline
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Quote:
Originally Posted by bimNaround View Post
And by mine, you mean you replaced both of the expansion tank hoses at 200k for the first time?

Also, how did you know they were OK? I don't want replace parts unnecessarily but I've read a lot about how various cooling components in the E46 are like ticking time bombs as they age so I don't want to overlook replacing something which causes bad damage to the engine and strands me somewhere.
Unless you like to play Russian Roulette, replace every component in the cooling system. Every old component is a potential "weakest link in the chain", and is guaranteed to come back and bite you in the ass if you neglect to replace it.
Overheating is BAD juju for these cars....replacing the whole system is not exactly cheap, but it`s like buying life insurance for your engine.
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Old 12-06-2017, 07:32 PM
John Davis John Davis is offline
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This thread should be a sticky.
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2004 330ci w/ sport package, 6 spd manual

Modifications: 3.46 differential, Pedalbox throttle signal amplifier, Active Autowerke performance software, Bilstein HDs, B&M short shifter, Zhp shift knob

2006 650i convertible in stratus gray
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Old 12-06-2017, 11:55 PM
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Originally Posted by John Davis View Post
This thread should be a sticky.
Agreed....Done !
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Old 12-08-2017, 10:02 PM
John Davis John Davis is offline
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Now that this thread is a sticky (thanks Bob!), I'll fill it out a bit by mentioning a cooling system kit recommended in lots of threads in this forum--the oembimmerparts master cooling kit:

https://www.oembimmerparts.com/BMW-E...astrkit-vl.htm

I'm about 5,000 miles away from renewing my entire cooling system, and this is the kit I plan to use. It seems to have everything, and high quality parts.
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2006 650i convertible in stratus gray
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