Did BMW engineers learn from previous model mistakes in designing the E46 platform?

Based on this thread today:
- BMW: A Driving Obsession on cnbc...
it would be an interesting survey (below) to see if BMW engineers actually learned anything from their well-known previous (reliability) mistakes.


Solely to broaden our mutual perspective, may I ask the E46 team how many of these notorious (older platform) E39 problems are also common to the (newer vintage) E46 model?

Note: A single canonical thread link was chosen as the descriptor for each of these extremely common issues (affecting up to 75% of all E39s):

• Behr cooling system leaking
• Plastic DISA valve breaking & destroying the engine
• Bosch ABS control module frying
• GKR/BMW/Valeo FSU dying
• Power steering cap & hose leaking
• Trunk wiring loom fraying
• Cluster pixel tape lifting
• MID pixel tape lifting
• PBT plastic Hella headlight adjusters breaking
• CCV clogging
• Ambient temperature sensor breaking
• Window regulators breaking
• Cupholders breaking
• I6 VANOS seals deteriorating
• Thrust arm bushings leaking
• Vapor barrier adhesive leaking
• Jack pads falling off
• Windshield cover molding crumbling
• Driver's seat control switch breaking
• Seat cables fall out causing seat twist
• Windshield washer tanks & pumps leaking
• Vent trim corner cracking & wood trim varnish cracking
• BMW roundel paint chipping
• etc

Based on wading thru the deluge of complaints here on the 'Fest in the past 2.5 years I've been around, at least 17 of the items you list are also a headache in the E46 universe, so the answer to your question would seem to be: Not Very Well.

Too late and too tired to itemize the coincidences, but I'll get around to it if someone doesn't beat me to the punch.

Originally Posted by bluebee

• Behr cooling system leaking
• Plastic DISA valve breaking & destroying the engine
• Bosch ABS control module frying
• GKR/BMW/Valeo FSU dying
• Power steering cap & hose leaking
• Trunk wiring loom fraying
• Cluster pixel tape lifting
• MID pixel tape lifting
• PBT plastic Hella headlight adjusters breaking
• CCV clogging
• Ambient temperature sensor breaking
• Window regulators breaking
• Cupholders breaking
• I6 VANOS seals deteriorating
• Thrust arm bushings leaking
• Vapor barrier adhesive leaking
• Jack pads falling off
• Windshield cover molding crumbling
• Driver's seat control switch breaking
• Seat cables fall out causing seat twist
• Windshield washer tanks & pumps leaking
• Vent trim corner cracking & wood trim varnish cracking
• BMW roundel paint chipping
• etc

My car has experienced the bolded ones above(plus some other, fun exciting ones). So, no.

It seems they didn't fix most of the "traditional" (like the cooling system and suspension) BMW problems until the E9x, but they introduced new problems, arguably more serious (N52 lifters, HPFP, turbo waste gate). Interestingly enough, the only problem above that I've experienced on the M3 was the roundel chipping.

In my old car (330i ZHP) I've experienced

• Cooling System Leaking (more of a catastrophic failure actually)
• DISA Valve failure (non-destructive though)
• Cupholders breaking
• Vanos seals deteriorating
• Control arm bushings failing (E46s don't have thrust arms)
• Windshield washers leaking (actually headlamp washers)

Originally Posted by TerraPhantm

It seems they didn't fix most of the "traditional" (like the cooling system and suspension) BMW problems until the E9x

Very interesting. Thanks for the details!

Originally Posted by TerraPhantm

E46s don't have thrust arms

BMW suspension terminology still throws me for a loop, even after doing extensive research shown in the BMW acronyms thread:
- BMW-specific acronyms (list and definition)

Note the four different names for the same suspension members!

Originally Posted by bluebee

Very interesting. Thanks for the details!



BMW suspension terminology still throws me for a loop, even after doing extensive research shown in the BMW acronyms thread:
- BMW-specific acronyms (list and definition)

Note the four different names for the same suspension members!

You're right, the names are confusing. The suspension is pretty different though Generally I've always heard those "squigly" pieces (#4) referred to as "thrust arms" which we don't have at all in the E46. It seems #5 in the picture below (which is referred to as the wishbone in the ETK, and most people online refer to them as lower control arms) is "equivalent" to your #11, but we don't have anything that's equivalent to your #4. The bushings I was referring to would be #6/#7 (on non-Ms, the bushing doesn't separate from the bracket)



With the E90s, BMW switched to a front suspension design much more similar to that of the E39

In fairness to BMW, I'd consider the e46 and e39 to be in basically the same design cycle, with introductions 2 years apart. I'm sure that the test mule e39s didn't develop any/many of the notorious issues until after the e46 design was sealed up and pre-production models started finding their way to the streets as test mules.

Now, should BMW have learned from the e36 issues, like the water pump? I guess they tried, with a metal impeller after a couple of model years (2000 or 2001 intro?) but still the design is flawed for the slushboxes with the clutched fan riding on the end of the shaft, rotating on bearings that just don't cut the mustard.

Originally Posted by TerraPhantm

wishbone in the ETK, and most people online refer to them as lower control arms)

Interesting. It looks like the E46 "lower control arm bushing" is likewise "filled with fluid" and, it seems to fail just like the E39 "upper control arm" bushing does:
- E46 BMW Lower Control Arm Bushing Replacement (E46)


So, maybe that's an "equivalent failure mode", which is in the spirit of what this thread is trying to identify the existence of.

Originally Posted by TerraPhantm

the names are confusing

I agree!

My best guess on the (confusing) 'naming' conventions across the three models is summarized below:

E46 I6 front suspension arms:
- Control arm (common name) = right wishbone (BMW name) = trailing control arm = lower control arm
- Thrust arm (does not appear to exist on the E46; however, it 'may' be that the E46 "left wishbone" is the equivalent? If so, might this be the naming convention for that particular suspension component?
- Thrust arm (common name) = left wishbone (BMW name) = trailing control arm = upper control arm


In contrast, these are well established (albeit equally confusing) terms:

E39 I6 front suspension arms:
- Control arm (common name) = wishbone (BMW name) = trailing control arm = lower control arm
- Thrust arm (common name) = tension strut (BMW name) = leading control arm = upper control arm

E39 V8 front suspension arms:
- Control arm (common name) = wishbone (BMW name) = leading control arm = lower control arm
- Thrust arm (common name) = traction strut (BMW name) = trailing control arm = upper control arm

Originally Posted by RSPDiver

I'd consider the e46 and e39 to be in basically the same design cycle, with introductions 2 years apart.

That may explain the (apparent) similarity in many of the common problems to both platforms.

I think BMW engineers either ignored results of durability tests or skipped them.
But I tell you what? Bean counters in BMW are laughing all the way to the bank for the profit they are making from selling all these repair parts.

My question is simple in regards to this thread's title. "Did BMW engineers learn from previous model mistakes in designing the E46 platform?"

And what if they didn't? We are talking about a car that isn't in production anymore. So what does it matter? Are you going to write a letter to BMW saying "I wish you had done better making the E46"?

Everyone knows this stuff is common failure items on a BMW. And yet we still own them because we are willing to deal with the problems for the driving experience. I see no point in this thread at all.

The part marked above with "could this be...." is actually a control arm bushing bracket. It holds the bushing which fits onto the end of the control arm/wishbone and is bolted onto the subframe.

Originally Posted by bluebee

Based on this thread today:
- BMW: A Driving Obsession on cnbc...
it would be an interesting survey (below) to see if BMW engineers actually learned anything from their well-known previous (reliability) mistakes.


Solely to broaden our mutual perspective, may I ask the E46 team how many of these notorious (older platform) E39 problems are also common to the (newer vintage) E46 model?

Note: A single canonical thread link was chosen as the descriptor for each of these extremely common issues (affecting up to 75% of all E39s):

• Behr cooling system leaking
• Plastic DISA valve breaking & destroying the engine
• Bosch ABS control module frying
• GKR/BMW/Valeo FSU dying
• Power steering cap & hose leaking
• Trunk wiring loom fraying
• Cluster pixel tape lifting
• MID pixel tape lifting
• PBT plastic Hella headlight adjusters breaking
• CCV clogging
• Ambient temperature sensor breaking
• Window regulators breaking
• Cupholders breaking
• I6 VANOS seals deteriorating
• Thrust arm bushings leaking
• Vapor barrier adhesive leaking
• Jack pads falling off
• Windshield cover molding crumbling
• Driver's seat control switch breaking
• Seat cables fall out causing seat twist
• Windshield washer tanks & pumps leaking
• Vent trim corner cracking & wood trim varnish cracking
• BMW roundel paint chipping
• etc

That's a great list. Good fodder for a poll!

Might want to add these E46/M54 specific issues to the list:

• Valve cover gasket leaking
• ZKW headlamp reflectors burning up
• Engine oil level sensor failing
• Rear suspension subframe failing
• Console hazard & lock switch module failing
• Rear trailing arm bushings breaking

Originally Posted by jcourcoul

Might want to add these E46/M54 specific issues to the list

This thread today has an excellent list of E46 specific common repair problems:
-> E46 (1999 - 2006) > Preventive maintenance tips/questions

For example:

Originally Posted by GoForthFast

Vulnerable e46 points
Pulled this out of my file and good to review from time to time.
Or for new owners who ask what to look for.

Getting EDGEucated: the "75k mile list"
The E46 3-Series (1999-2005, including M) Edition

After years of working on BMW's, we have begun to see common problems and maintenance concerns that need to be addressed on nearly every middle-aged BMW. E46 3-series cars, like all BMWs, they have certain areas that need to be inspected regularly, and prospective owners should always have a pre-purchase inspection done to verify the condition of these items.

In this list, you will find items that should have been replaced or at least inspected by 75k-100k miles. Some are model specific, and will be noted as such.

If you suspect you may have some of these issues, or just want us to take a look for your peace of mind, print out your free inspection coupon (located here), and call us at 925.479.0797 to schedule an appointment!

Areas of Concern:

Broken window regulators: Leaves you stuck with your inoperative window in the down position.
Warning signs sometimes are a noisy crunchy sound a few times before you lose control of your window.
DIY's abound on various sites, and pay particular attention to your door seal when backing out of that area if you want to avoid rain soaked floors in your car.

Lower Control Arm Bushing Failure

Common symptoms for torn or cracked lower control arm bushings are undesired front toe changes during cornering, vague and rubbery feel in the steering, and vibration experienced while braking at freeway speeds. Non-M bushings are commonly replaced with M3 bushings to increase performance with little to no change in comfort.

Tie Rod Wear

Symtoms include: steering shimmy, clunking during steering input and inability to hold proper alignment. If any of the ball joint boots is cracked (you'll see grease coming out) then expect that component to need replacement. All components should also be checked for excessive play, and replaced if out of BMW spec.

Worn or Blown Shocks and Struts
Factory BMW shocks work great for about 30k. By 60k they are completely shot. Most folks who have been driving their cars since new hardly notice the deterioration as it is gradual. Symptoms includeiving under braking and acceleration, excessive lean and suspension compression during cornering. Bouncy and uncomfortable ride. Shocks and struts may visibly leak shock oil. EDGE generally recommends replacing the factory units with quality shocks from Koni whenever possible. When replacing shocks and struts, keep in mind it is a great time to install lowering springs or freshen up other areas of the suspension. You will be amazed at the difference a good set of shocks can make in both comfort and performance!

Worn or Failed Swaybar Endlinks
Worn swaybar endlinks can compromise handling. A worn swaybar can sound like a metallic clicking noise. There is no critical danger in a failed swaybar endlink, but the handling of the car is severely compromised.

Torn Rear Trailing Arm Bushings (RTABs)
E46's are prone to the same RTAB failure as the E36. In fact, since they are heavier cars, they tend to wear faster on the E46. If the rear of the car feels strange during cornering or you have excessive rear tire wear, expect that your RTABs are shot. Typical mileage for the E46 is around 35-45k. Failure to replace could lead to torn subframe and costly repairs. EDGE recommends replacement with factory units and RTAB limiting shims. The shims prevent excessive movement and can double the life of the bushing.

Torn Rear Shock Mounts
Torn or destroyed rear shock mounts will produce a very pronounced clunk during any sort of suspension movement, and could possibly just tear right through the trunk carpeting into the passenger cabin. Sloppy and erratic handling and excessive rear suspension play are common symptoms of a RSM failure.

Torn Subframe and Subframe Bushings
Torn subframe bushings could lead to subframe failure. Common symptoms of subframe failure are erratic handling and unidentified clunks and bangs from the rear of the car. Early detection of a torn or cracked subframe bushing can prevent costly subframe repair and welding. We see subframe issues mainly appearing in tracked and autocrossed E46's, but we have swapped out cracked bushings in higher mileage E46's as well.

Torn or Cracked Transmission Mounts
Torn transmission mounts could lead to the dreaded 'money shift,' or mechanical overrev and the possible (and likely) destruction of the car's motor. Worn transmission mounts allow for an excess amount of transmission movement. Symptoms can be hard, notchy and forced shifting during cornering, excessive shifter jerk during hard acceleration and braking, and muddy shifter feel.

Ripped or Failed Guibo
A torn guibo (Flex Disc) will result in a perceivable 'drivetrain elasticity.' Acceleration will be preceded with a loud clunk as the guibo bolts bind together.

Dirty Automatic Transmission Fluid or Clogged Filter
Hesitation and/or hard shifting could be the result of dirty and old automatic transmission fluid or clogged transmission filter.

Water Pump Failure-----extremely common & tragic

Water pump failure is without a doubt the easiest way to cause extensive and expensive damage to your BMW. The main symptom will be a rapidly overheating motor. What occurs is that the bearing or impeller on the stock pump breaks, completely disabling the cooling system. If you ever see the temperature gauge on your BMW climb above the 3/4 mark,...

TURN THE CAR OFF IMMEDIATELY AND CALL A TOW TRUCK!!

We can't stress this enough. Failure to catch the overheating motor in time can result in a warped head or even more severe engine damage. We recommend changing out the water pump in these six cylinder cars every 60-80k.

Cracked Radiator Necks
BMW loves their plastic radiator tanks....Unfortunately...The plastic around the radiator necks become brittle and crack with age, often without warning (see warning above.) Radiators should be thought of as 80-100k mile wear items. Trust us, this is cheap insurance!

Fan Clutch Failure
Most fan clutches fail between 80 and 100k miles. They provide the primary cooling for your car, and are easy for us to diagnose.

Accessory Belt and Tensioner Failure
Worn tensioners and idler pullies will sound like a squealing noise from the engine bay. Belts should be inspected for cracks regularly. If a belt happens to snap, the cooling system will fail as the water pump will cease to operate. Power steering and the alternator will also fail to work. Again, pull over and shut the car off immediately should you suspect a belt failure or see the temperature gauge rise past the 3/4 mark.

Leaky valve cover gasket
Prevalent on all BMWs, a burning oil smell could indicate a leaky valve cover gasket. If the condition continues unchecked, oil can seep into the spark plug holes and damage the ignition coils, resulting in costly replacement. Replacement of this inexpensive gasket is a good idea when changing sparkplugs as the coilpacks will already be out.

Vanos seals. See www.beisansystems.com for details for explanation, symptoms and upgraded parts.

Oil Filter Housing Gasket leaks. $6 part requires removal of the housing for replacement.

DISA is pretty high up on the list of high fail rate components.

Tail light ground circuit fix (recall on this).

Sunroof - what a disaster that design is with leaks and jams and broken clips. Labor on this one is torture.

Door locks can break. If your locks unlock and windows all roll completlely down by themselves spontaneously, replace the driver's door lock mechanism.

O2 Sensor Failure
Poor mileage, poor idle and flat spots in the power curve could be caused by bad O2 sensors. Even if your car isn't throwing a check engine light, they may not be performing optimally. BMW recommends replacing the O2 sensors every 100k miles. Extended high-RPM running/racing and high-performance chips may shorten the replacement cycle.

Oil Separator
Non M cars. If you have a poor idle and periodic Check Engine lights, you may have a bad oil seperator. This valve tends to go bad and introduce a vacuum leak which produces the above symptoms and will eventually strand you somewhere. We started seeing these a year ago and we are now repairing more and more cars with this problem. Typical mileage seems to be around 80k. The good news is that the part is only around $75..the bad news is that the labor runs about 4 hours, depending on the year of the car.

Clogged and dirty pollen filter
If the flow of air out of the air conditioning and heater system is not as strong as it used to be, it strongly suggests the pollen microfilter of your car has become dirty and clogged over time. A damp and musky smell can also indicate a dirty filter. This is a service II replacement item.

IMHO, people will buy something based on its quality/price ratio, or based on a brand.
cars nowadays are experiencing deterioration in quality, and are becoming more Japanese-like built (with all due respect to Jap cars of course)
and since the ratio of deterioration is somewhat equally based in all car manufacturers, people who were BMW dedicated will still buy the BMW because they are accustomed to their quality and build, and since other models are becoming of similar quality to BMW, some may also switch to BMW, since BMW triggers a prestigious brand name.
and due to the above, they can fix let's say 10% per each model release and people will still buy them, they will tolerate BMW's nuisance because they love that BMW badge and its driving experience (personal experience)
so why make the BMW perfect and lose the maintenance income, when they can make them suffer from this and that and earn a lot more money from spare parts since people will buy them anyway?

E30 and E36 both got complains about being too small inside, E46 improved that part.