BMW M3 Forum
BMW M3 Forum BMW M3 Gallery BMW M3 Reviews BMW M3 Social Groups BMW M3 Chat M3Forum Sponsors >>
Loading


Mobile M3forum
Go Back   BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X) > BMW M3 Discussions > E46 M3 (2001-2006)
Tire Rack Buy Winter Tires Now!
Not a member? Register Now!
Register Gallery All Albums Garage Search Today's Posts Mark Forums Read Calendar FAQ

E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


Reply
 
Thread Tools Display Modes
Old Mon, May-20-2019, 12:55:34 AM   #1
SMG cog light
Registered User
 
Join Date: Apr 2019
Posts: 200
In the garage:
Reputation: 0 SMG cog light is on a distinguished road

United States




Default SMG Pump Maintenance/Troubleshooting: Complete Guide

Pressure decay is your enemy. Whether from a failed accumulator or internal seal leaks, this will make your motor prime more often, resulting in overheated hydraulic fluid. resulting in neutral drops. (Motor priming more often than normal due to leaks or accumulator will also result in a premature wear on motor commutator and excessive wear on relay contacts.)

UPDATE: So I was doing some live data test on another e46 M3 car and noticed that the pressure loss difference from cold fluid 80F and hot fluid 160 F and has some significant finds.

Cold fluid - The hydraulic pressure was able to hold pressure longer before the motor came on and build up pressure again.
Hot fluid - The hydraulic fluid pressure decay was 2x faster when the fluid was hot and made the motor come on more often to build up pressure
After careful analysis between 4 different e46 M3's with original pumps, burkharts kits, complete recondition and rebuilt pumps, these were my findings...

Original pump - took up to 20 seconds to build up pressure and had 4 minutes or less pressure decay or 2-3 shifts before the motor came on
fluid temps were 200+ degrees F
threw cog light on often even in cooler weather

Burkhart kit - (new motor, new temp sensor, pentosin chf11s, new accumulator, pump relocated to drug bin) took 8-10 secs. to build up pressure and had 2-4 minutes. pressure decay or 4 shifts
fluid temps were up to 160 degrees F
occasionally threw on the cog light during hotter days

Reconditioned/Rebuilt Pump - ALL New viton seals, new accumulator, new motor, new temp sensor, new hydraulic pressure sensor, thicker burkhart fluid. took 4-7 secs. to build max pressure and pressure decayed 15-20 mins or after 6 shifts
fluid temp averaged 90-140 highest degree F
never had a cog light come on even with a/c and after heavy driving with stop and go traffic

Conclusion: ALL SMG pumps will suffer from internal leaks that the owner is not aware of. And although a new accumulator or relay, or motor might make your car run better or get rid of the neutral drops/cog light error, this is not fixing the real problem or culprit.
Most of the leaks or early pressure decay that I found were from the 4 solenoids seals. In cold fluid; the fluid is thicker and will hold pressure a little better. But once the fluid gets hotter, the pressure decay is more rapid. This is due to the fluid becoming thinner (combined with more pressure) and now able to leak between the valve seals.
For this reason, the burkhart fluid, which is thicker, works better in high temperature settings because less pressure was loss or leaked between the solenoid seals due to the thicker viscosity. The burkhart fluid was able to hold pressure longer even on pumps with a bad seal.




Why does the temperature of the fluid get so hot or gets hotter and hotter? In the beginning it was suspected that the location of the pump and heat was to blame. If that was the case then how come some M3's present this problem and others don't? And some M3's dont have the problem at all with the pump in the original location. How much ambient heat will heat up the hydraulic fluid is up for debate. But one thing is clear. The fluid gets hot because every time the pump comes on it creates pressure. The pressure is what is heating up the fluid. In a new M3 or reconditioned pump; if the motor only comes on every 6 shift or 10-15 mins of natural pressure decay, it would make sense that the fluid will maintain a cooler temperature. In a SMG pump where you have internal leaks, the pump will take longer to reach max pressure, wearing your motor out quicker. It is like trying to blow up a balloon that has a pinhole leak. (This and also a aging motor is why your motor takes longer to prime to max bar) And since your motor is coming on more often, that means the already hot fluid is now getting hotter because the system is pressurizing the fluid once again. Basically the more your motor comes on, the more it heats up the fluid. This correlates with my other research and finding that on a cold fluid the max cut off pressure is 68-70 bars. On a hotter fluid, the cut off pressure was closer to 78-80 bars. The hotter the fluid, the higher the cut off pressure. The temperature is set to put the car in limp mode to protect the transmission from "overheating" when it reads hydraulic fluid in excess of 150 F. (In a normal running SMG M3 with good pumps, the average highest temp I recorded was around 120-140F) If I had a brand new pump from the dealer to do a data comparison, this would be even better).

This would only make sense as to why some people were able to completely fix their problem with a brand new smg HCU transplant and others still had issues after replacing vital components like accumulator and motor. If seals and O-rings on other parts of the car requires replacement often, then it would only make sense that the internal seals of the HCU also would need replacing due to normal wear and tear. And since this is a pressurized system, the seals would be abused even further due to heat and pressure.
For those of you that did the burkhart kits upgrades/repair or SMG pump relocation, be warned. Unless you did a live test while driving and monitoring your pressure decay on the SMG system. You will ultimately succumb to the dreaded cog light once the commutator on the motor wears down due to internal leaks at high fluid temperatures. Monitor your hydraulic fluid, even though your car runs fine from a resistor mod or pump relocation, if your hydraulic pressure decays rapidly (especially during high temperatures) you most likely have an internal leak somewhere.

SMGII SCHEDULED MAINTENANCE CHECK LIST

It is not as difficult as you think once you start to under stand how it works and after many years of experience and also research with the problems and issues, it gets narrowed down to one thing. The hydraulic fluid temperature. This is extremely important as this is what tells the computer to throw your car into neutral. If you can keep that in check and below the safety limp mode threshold then you are fine. The other thing is, the smg hydraulic control unit (smg pump) requires maintenance like any other part of a car. The same way u do a tune up; the smg system also needs a tune up. Here is a quick breakdown of the tune up for SMG pump.

1. Replace hydraulic temp sensor every year or every time you change your oil? it only cost 16$ easily obtained because its the same bosch part# 21532229715 as the coolant temp sensor. Remember the hydraulic fluid is the main thing you need to focus on, so having a good sensor is key.

2. Check for internal leaks. I would replace the smg pump seal ( $79 for 2x same looking special shaped) seals . Once every 50,000 to 100,000 mi. as internal leaks are not as common as other smg symptoms. Also replace the O rings on the 4 solenoids. If these are worn they also contribute to internal leaks. 3 o rings per solenoids. I upgraded mines to viton and I purchased a box of assorted viton O rings at harbor freight for 10$ Don't pay 40$ for solenoids viton rings kit online.

Buy from harbor freight or amazon. Amazon viton o rings have many kit sizes.

3. Flush your hydraulic fluid like you would flush any fluid on your car. maybe every 30,000 - 50,000 mi. I recommend the burkhart fluid. It has a thicker viscosity, so therefore will be able to create max pressure 25% faster than standard pentosin chf11s. Also thicker fluid remains less thin at higher temperatures.
https://burkhart-engineering.com/epa...Products/54134

4. Check your accumulator pressure often. Do this every month or every 3 months. it only take 2 minutes with a foxwell nt510 scan tool. Keeping a close eye on accumulator is the difference between a premature motor failure because of overworking. If your accumulator test is 29 bars or under, replace accumulator right away.
New accumulator $700 bimmerworld -$826 tuner motorsport/ecs tunning

5. Replace salmon relay. $16 Part # 12631742690 Do this every 6 months to a year or every oil change. Bad relays, sticking relays, bad contacts or failing relays all causes smg issues. it is best to replace them often or keep a spare.

6. Replace electric motor. This is the main component of the smg in my opinion. Since dead motor means no pressure. Motors can last up to 100k+ mi. If they die before that; that is because your accumulator or internal leak caused it to run more often than it should and results in worn commutator. You can remove the outside metal cover and vacuum the carbon dust every year or every other year and inspect the commutator and brushes.
New motor $300-$500 (might be cheaper to get it rebuilt)
https://www.smgsociety.com/product/h...-motor-smg-ii/

7. Hydraulic pressure sensor. (see smg wki for more details) A failed pressure sensor will contribute to erratic pump operation so test this every 2 years or replace it since it is only $89.
https://www.smgsociety.com/product/p...e46-m3-smg-ii/

If you follow these preventative maintenance or of do these tunes ups when you do your normal tune ups, your smg will run the way it should.

Hydraulic Pump
The Hydraulic Pump, installed in the Hydraulic unit, generates the pressure required to operate the clutch and perform gear changes.
The pump is a piston pump driven by an electric motor, actuated by the SMG control unit via a relay so that oil pressure is always between 45 and 80 bar. Power consumption of the electric motor is 20 amps. When the fluid pressure in the hydraulic unit drops below 45 bar, the SMG II control unit activates the relay and supplies the electric motor with B+. At a hydraulic pressure of 80 bar, the SMG II control unit deactivates the relay. To ensure there is sufficient pressure when the engine is started, the hydraulic pump is activated below an accumulator pressure of 45 bar when the door is opened or the vehicle is unlocked with the key or the remote. In the event of a hydraulic system failure the gearbox warning lamp is turned on in the IKE and if hydraulic pressure fails to build, no further gearshifts are allowed. This allows the reserve pressure in the accumulator to be used to place the gearbox in the Neutral position when the vehicle comes to a stop.

Pressure Accumulator and Non-Return Valve
The Pressure Accumulator in the hydraulic unit ensures that pressure generated by the pump is stored in the system for a certain amount of time. The accumulator is divided into two chambers by a piston, with nitrogen at 39 bar filling one chamber and fluid delivered by the hydraulic pump filling the other chamber. The volume of the accumulator is 150ccm.
The Non-Return Valve at the pump outlet prevents the hydraulic oil pressure from dropping when the pump is not running.


If your motor is priming at 3-4 shifts or if your pressure is dropping rapidly and not holding after the motor primes, then it is very possible you have an internal leak. Here are some internal leaks that is possible on our SMG HCU which I have found on the past 3 HCU that I reconditioned.

Internal Leaks
1. SMG PUMP main seal (x2)
2. Four solenoids valves O rings (3x4=12)
3. Pressure accumulator Internal piston seals
4. SMG pump O rings (x1)
5. non-return valve/pressure relief valve
6. Clutch slave cylinder
7. Gearbox actuator
8. pump brass double O ring metal gasket

External leaks
9. Metal hydraulic lines (x4)
10. SMG reservoir line (at reservoir)
11. SMG reservoir line (at red tab HCU body)
12. gearbox actuator
13. smg clutch slave cylinder
14. Hydraulic fluid Temperature sensor
15. Hydraulic pressure sensor
16. Solenoid main O ring (x4)
17. HCU black reservoir seal(x1)

As you can see, there are plenty of places for internal leaks and I have found internal leaks at many of the locations stated above when reconditioning HCU's.

The pressure accumulator should eventually naturally lose pressure (this is why when u let the car sit for a bit, it primes when you press unlock) but not faster than a rate of 15-20 minutes in between priming. If your pump is priming more than once ever 15-20 minutes without shifting, you may have an internal leak. Hot fluid loses pressure faster due to lower viscosity.


credit harber07


related links:
SMG error code Burkhart https://burkhart-engineering.com/SMG-Wiki/en

http://www.m3forum.net/m3forum/showthread.php?t=607082

https://forums.m3cutters.co.uk/threa...ardown.163209/

Here is the complete break down for the SMGII system:
http://www.leo.nutz.de/docs/bmw/smg_training_manual.pdf

More SMG Info
http://www.m3forum.net/m3forum/showp...9&postcount=25

This post will be updated when more tests and research is performed.

Just wanted to leave some experience and knowledge behind should I one day sell the e46 M3 SMG.

Last edited by SMG cog light; Fri, Jun-14-2019 at 05:55:52 PM.
Jump to top SMG cog light is online now   Reply With Quote
Sponsored Links
Register now and remove these ads
Old Mon, May-20-2019, 01:33:55 AM   #2
WOLFN8TR
/// MONEY \\\
 
WOLFN8TR's Avatar
 
Join Date: Dec 2014
Posts: 2,381
In the garage:
Reputation: 0 WOLFN8TR is on a distinguished road
Location: Las Vegas

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

NICE...

Last edited by WOLFN8TR; Thu, May-23-2019 at 12:43:42 AM.
Jump to top WOLFN8TR is online now   Reply With Quote
Old Mon, May-20-2019, 02:45:43 AM   #3
oceansize
Kwisatz Haderach
 
oceansize's Avatar
 
Join Date: Jan 2018
Posts: 572
In the garage:
Reputation: 0 oceansize is on a distinguished road
Location: TN

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

For too long the components surrounding SMG have been seen as a mystical black box. Great to see some straight forward information from you and a few others on this board. Appreciated. I'm sure others feel the same.
__________________
2003 M3 Convertible SMG w/Hardtop | GC Coilovers and Camber Plates | ESS VT1-475 Gen 3 Supercharger | Stoptech Brakes
Apex ARC-8 19" Hypersilver | CSL SMG (and 255) Tune | RE Diablo Exhaust w/ SS Tips | RE Rasp Pipe
Redish Reinforcement Plates | Polyurethane Rear Subframe Bushings | Polyurethane Differential Bushings | Beisan Oil Pump Disk
Storm Motorwerks SMG Paddles | Two Tone Black/Grey Interior | Alcantara E-brake Boot
Very Recent Maintenance: FCABs | FCAs | RTABs | Motor Mounts | PS Hoses | Inner/Outer Tie Rods | End Links | Vanos Solenoid |
Driveshaft R&R | Flex Disc | Fan Clutch | Trans Fluid | Diff fluid
Jump to top oceansize is offline   Reply With Quote
Old Mon, May-20-2019, 03:02:53 AM   #4
SeanE46
Registered User
 
SeanE46's Avatar
 
Join Date: Nov 2015
Posts: 1,284
In the garage:
Reputation: 0 SeanE46 is on a distinguished road
Location: Los Angeles

Armenia




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

Good thread for us SMG noobs!
__________________
2001 M3 6MT TiAg Coupe SOLD
2002 M3 6MT TiAg Coupe SOLD
2004 M3 SMG Silver Grey CURRENT
Jump to top SeanE46 is offline   Reply With Quote
Old Mon, May-20-2019, 03:11:35 AM   #5
Distinct70
Registered User
 
Distinct70's Avatar
 
Join Date: Dec 2013
Posts: 448
Reputation: 0 Distinct70 is on a distinguished road

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

This is great. I think I’ve got leaking from one of the solenoids. Nice information.
Jump to top Distinct70 is offline   Reply With Quote
Old Mon, May-20-2019, 03:21:57 AM   #6
SMG cog light
Registered User
 
Join Date: Apr 2019
Posts: 200
In the garage:
Reputation: 0 SMG cog light is on a distinguished road

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

Quote:
Originally Posted by Distinct70 View Post
This is great. I think I’ve got leaking from one of the solenoids. Nice information.
Just monitor the pressure decay. The leaks happens mostly in higher fluid temperatures. If the fluid is below 140 F then it will hold longer between the solenoid valve seals.

For example in a car with bad seals, low temperature fluid 80-90 F the rate of hydraulic pressure decay was 1 bar every 30-60 secs.

In the same car with old seals with fluid at 140 F the pressure decayed more rapidly making the motor prime almost every 3-4 minutes.

On the other cars with good internal seals, with the same fluid temperatures the temperatures remained relatively low, in turn making the motor come on less once it reached max pressure.

Overheat fluid and most problems occur around 80c/176 F sometimes sooner.

Normal operating fluid temps should be around 30 c -60 c/ 84 F - 140 F
Jump to top SMG cog light is online now   Reply With Quote
Old Mon, May-20-2019, 03:39:06 AM   #7
Distinct70
Registered User
 
Distinct70's Avatar
 
Join Date: Dec 2013
Posts: 448
Reputation: 0 Distinct70 is on a distinguished road

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

You can see fluid resting on the “top” of the assembly (formerly “side” when it was in the original location. I have cleaned this up before and it comes back. Does this mean one of the seal rings on the solenoid is failing at high temperatures?

This can’t be coming from the motor right?



Jump to top Distinct70 is offline   Reply With Quote
Old Mon, May-20-2019, 05:37:25 AM   #8
SMG cog light
Registered User
 
Join Date: Apr 2019
Posts: 200
In the garage:
Reputation: 0 SMG cog light is on a distinguished road

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

Quote:
Originally Posted by Distinct70 View Post
You can see fluid resting on the “top” of the assembly (formerly “side” when it was in the original location. I have cleaned this up before and it comes back. Does this mean one of the seal rings on the solenoid is failing at high temperatures?

This can’t be coming from the motor right?
Technically it can leak from the motor coupling shaft and then out onto the body, but very unlikely since the pump is mated together really good with bolts and special seals.

These are considered external leaks. External leaks are any leaks that you can physically see with your eye. Like on the HCU body or fluid on your garage floor.

Internal leaks are leaks that you cannot see or know about unless you run a live data test. Internal leaks can only be found with pressure lost data monitoring. Internal leaks will leak in between seals inside of the pump body from one compartment to the other (more often during high temperature fluid) but still the fluid is encapsulated/maintained inside of the black reservoir body (opposite end of the motor).

You have an external leak. if you cleaned it up and it came back, then something is leaking the fluid out somehow/somewhere. depending if you did a pump relocation or not, it is also very possible that acceleration/braking can make overfilled reservoir fluid leak out and onto the pump body if the reservoir was mounted above the pump body.

Refer to this thread where I stated "possible hydraulic external leaks" and try to rule it out based on my list".

Last edited by SMG cog light; Mon, May-20-2019 at 05:51:56 AM.
Jump to top SMG cog light is online now   Reply With Quote
Old Mon, May-20-2019, 11:31:03 PM   #9
Distinct70
Registered User
 
Distinct70's Avatar
 
Join Date: Dec 2013
Posts: 448
Reputation: 0 Distinct70 is on a distinguished road

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

To isolate the leak, I have wrapped and jammed in paper towel between the motor and the solenoids as well as around the collar of the reservoir.

I dried up as much as I could and I will check to see where the leak is coming from. I doubt it is the reservoir because I don’t see it dripping down from the reservoir on to the assembly.

Is there any issue with driving with the paper towel in there? Its not going to catch on fire from heat?

Jump to top Distinct70 is offline   Reply With Quote
Old Mon, May-20-2019, 11:54:54 PM   #10
Texaz3
Registered User
 
Join Date: Dec 2015
Posts: 1,992
Reputation: 0 Texaz3 is on a distinguished road

United States




Default Re: SMG Pump Maintenance/Troubleshooting: Complete Guide

Very cool. Thanks for putting this together.
__________________
“Aerodynamics are for people who can't build engines.” - Enzo Ferrari
Jump to top Texaz3 is online now   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT. The time now is 04:31:55 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
M3Forum.com and M3forum.net is in no way sponsored, endorsed or affiliated by or with BMW NA / BMW AG or any of it's subsidiaries or vendors.
BMW and M3 (E90 M3 | E92 M3 | E93 M3 | E46 M3 | E36 M3 | E30 M3) are registered trademarks of BMW AG.
M3Forum Terms of Service
Copyright ©1999-2017 M3Forum.com
Discussing SMG Pump Maintenance/Troubleshooting: Complete Guide in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)