6-cyl double vanos problem assessment

[cn]

http://www.bimmerhaus.com/tech/vanos.html

If one "lump" in front of camshaft: SINGLE Vanos (early 1998 or so).....fewer problems

If two "lumps" in front of camshaft: DOUBLE Vanos (? later 1998 and 1999+).....more problems...Hope there is a fix for Double Vanos fellows

cn
1998 528i single vanos

[jszeto]

[loach1]

I'm no BMW enthusiast, let alone an E39 follower, but I can say with confidence that any engine with a double VANOS with the same part number as in the M52TU will have this problem. I don't follow BMW development closely but I believe there has been a substantial change to the VANOS recently. It would be nice to think that they solved the seal problem, and even nicer if they incorporated the changes into the remanufactured VANOS units that our dealers sell. But, in reality they probably won't put any engineering effort into what is essentially a 'service part' unless they are mandated to do so.

[Ginger]

I'm with BMW of North America, LLC. I've passed this message on to a BMW NA Customer Relations Representative who will be in touch with you soon.

[frankieNJ]

Please don't assist just a select person or persons. BMW should take care of their customers that spent between 42-54 thousand dollars on these 6 cyclinder 5-series vehicles. The I6 used to be BMWs bullet-proof engine. Please keep us informed and tell us what we have to do or who we have to speak to regarding this issue.

frankieNJ

[chivas]

don't "get back to him"... GET BACK TO US, the community not the individual.

[Nmufti]

I have the cold engine symptoms in my 2000 528. Interested to see what BMW comes back with

[Philip Bradley]

I have these symptoms on my 99 528i, and would appreciate an acceptance of responsibility by BMW and no assertion of warranty expiration.

Philip Bradley

[Koister]

[DC52240]

So has anyone got a response on if these seals can be purchased seperatly? i have the idle problemin my 1999 528ia. Annoying! Is this something that a shade tree mechanic could do?

[jtt777]

great job with the research! nicely documented.

one question though... When the engine warms up the problemd goes away. Doesn't that suggest that the oil is no longer leaking past the seals. THis is probably because the warm oil now has expanded the seals solving the leak issues I guess.

if it isn't leaking anymore, how can performance be affected after the warm-up? i know you mentioned you felt a difference but is there any data to back that up? if the vanos wasn't positioning the cam shaft correctly, shouldnt we see an error for the crankshaft position sensor?

regards,
jeff

[rajaieq]

Hi Jeff,

Thanks for the nice comments on our work.
Your questions are fair. I’ll try to address them.

The toughest question to answer is the one regarding performance increase. You’re correct by saying we don’t have definitive data on this. Here are my personal observations after replacing the vanos pistons (seals).
I had stronger torque and power at lower rpms. Torque was stronger at midrange and increased further to higher rpms before flattening. There was an overall increase in power, and it increased further into higher rpms. The most absolute (not relative) discernable characteristic for me was the engine smoothness into the upper rpm range. There is seemingly little engine strain increase from the 4k to 6k rpm range. It’s easy to red-line the car without noticing. Smooth as silk! Really the whole rpm range is so smooth. I’ve never driven a car with such smooth engine behavior. This smoothness was introduced simultaneously with extra power and torque. It’s impressive!
It might very well be that these improvements are more noticeable on a manual transmission. Loach has an auto tranny and was first to repair his vanos. He indicated to me having performance improvements, and was questioning his assessment. When I performed my repair, I found the results clear. My driving behavior also changed. I was hot-dogging the car around the neighborhood. I just couldn’t stop myself from driving like a maniac. The car just wanted to go.
I recall that a couple of owners from the past had noted performance enhancements. They had questioned it as well. At the time I really didn’t understand what a vanos was. Even when I repaired my vanos I didn’t really understand why I got these changes. Now that I’ve spent some time trying to understand the vanos, it’s clear to me the performance improvements were directly related to vanos function. These performance behaviors are exactly what a double vanos provides.
To definitively assess this, I suspect we’d need to test a failing vanos car on a dyno, repair the vanos, and retest on the dyno. I don’t know much about dyno testing, but from what I’ve seen on the forum it seems this would be a definitive test. It would be great if someone could take on this effort.
The other aspect that needs to be tested is EGR (emissions control). This is what we would need to get the government’s attention, if we decided to choose that path. I really wish someone would take on this effort.

Your other points might be easier to address.
You say the problem goes away when the engine warms up. This is an overly simplistic assessment of the situations. The M52TU cold engine symptoms are caused by the DME software. At these cold temperatures a special software mode is executed to bring the cats to operating temperature quickly. The vanos techniques used are different than in other operating modes. For instance, if the car is driven when having the stall encounters, the problems go away. But if the car comes to idle again the problems revert. So, how is it the vanos started working all of a sudden and then reverted? It’s not an issue of the vanos not working and then working. It’s an issue of software algorithm. During the cat warm-up mode, the software reacts badly to the vanos malfunction. In other modes the software behaves well to vanos malfunction. I suspect the vanos failure was found during M52TU testing and the software was modified to behave well to the failure. I suspect the cold engine cat warm-up problems were overlooked in testing. These software problems were addressed in the M54. This is why the M54 and M56 don’t exhibit the vanos cold engine symptoms like the M52TU.

You say that “if the vanos wasn't positioning the cam shaft correctly, shouldn’t we see an error for the crankshaft position sensor?”
You’re quite right. The CPS provides feedback to the DME as to the positioning of the camshaft. This is the feedback the DME needs to control the vanos for proper camshaft positioning. One would hope that the DME would set a code if the vanos was not functioning well. We know for a fact that the DME is aware of the vanos malfunction. The DME being aware of this is what causes it to create the M52TU cold engine stalling episodes. But even with that extreme outcome, the DME still doesn’t set a code!!
Given that, it's presumptuous to expect that the DME would set a code at other times when it’s handling the vanos failure well.
Even more egregious than not setting a code when the vanos is failing is not setting a code when the EGR is failing. EGR physical implementation is almost completely a responsibility of the vanos. If the vanos is failing, the EGR is surely not functioning. EGR is a major emissions control function. OBDII is mostly about indicating emissions control failures. So how is it that a code is not set as an outcome of EGR failure? The answer is the same as for all vanos failure circumstances; the DME is hiding the failure.
The DME not reporting EGR failure should be a serious EPA violation.

I suspect it’s simply hopeful thinking to expect that the piston seals expand and seal well when the engine warms up. Maybe someone with a better understanding of Teflon and Buna expansion characteristics can try and address this point. The inner seals have flattened, shrunk, and hardened. The new pistons (new seals) fit tightly into the vanos cylinders while the used failing pistons (seals) fit more loosely.
There’s a current effort to try and assess the seals more definitively and maybe more definitive data will be available as an outcome.

As much as I’ve tried to refute your points, they are nevertheless fair points to consider and discuss. I’m sure others have your thoughts, and I hope I’ve taken a logical approach at addressing them.
Loach and I have had the advantage of inspecting the inner seals and driving our cars after the vonos repair. These are first hand qualitative assessments that can’t be gained fully by reading our reports. I hope these assessments can be quantified into numerical data as you suggest and as discussed here.

Thanks for your input and questions.
Rajaie
528i 5sp 06/00

[chivas]

and what did Raj/Loc send back? what is BMWNA doing about this?

[dc52241]

So has anyone found new seals? Does BMW allow for these to be purchased?

[rajaieq]

Rajaie
528i 5sp 06/00

[chenowski]

i have a question for those more knowledgeable about this double vanos issue.

i noticed some time ago that my engine idle fluctuates wildly on cool mornings on warmup, but then disappears later once the engine reaches operating temp. does this occur by a similar mechanism as that in the 528i? perhaps the idle control kicks in before the engine can stall. i wonder if i should be concerned.


thanks.

[rmedure]

Cheers!
Robert


'99 540i sport, 6 spd
3.15 differential
Stop Tech front big brake kit, SS lines
Eibach front/rear sway bars
Dinan strut tower brace
Hamman HM2 18" wheels w/Potenza SO3 tires
Rogue Engineering short shifter
Zionsville Autosport aluminum radiator
Resonator delete
ACS exhaust
ACS front & rear body kits
ACS 3 piece trunk spoiler
ACS pedal set and e-brake handle
CDV delete
EVO Sport under-drive pulley kit
M5 Grills
Hella Xenon AE, auto leveling, clear corners
Clear rear tail lights
Clear sidemarkers
Pre-wired V1 radar
Traction control default "OFF"
Homelink (lighted)
Icelink w/ID tag display
35% titanium tint

I am a BMW Car Club of America member, are you? http://www.bmwcca.org/

[thematrixz]

Hopefully BMW sees the amount of failures and addresses this issue.
-----------------------------------------------------------


1999 540ITA Sports, Dinan CAI & software. M5 rear swaybar. Debadged for your pleasure.
Phatbox now installed + in-dash CD
M-Technik Aerodynamic

1999 528IT, Phatbox, CAI.

[TiSlvrBMW]

I know my car has the same issue regarding the shotty run character while the car is in the warm-up stage. Mine keeps almost wanting to stall until the RPM's kick back up to recover from the near stall. This occurs repeatedly until normal operating temperature. However, on colder days, when the car hasn't been used in a while, the car is also very loud, in conjunction with the car almost wanting to stall.

Any ideas what's making this sound? Does anyone know what I'm talking about?

Will

[David G]

I've taken my 99 528i to the shop for this reason twice. They replaced some hoses and checked for engine codes with no luck. I have cleaned the ICV and the throttle body, with no improvement. At least now I know the source of the problem.