BMW M5 Forum and M6 Forums banner

1 - 20 of 179 Posts

·
Registered
Joined
·
1,855 Posts
Discussion Starter #1
So for a couple weeks I have been occasionally getting the 4A and 4B codes which indicate a problem with the Bank 2 Intake Vanos control. I reset the light a few times and never really saw any performance issues. This week, the car started running rough, and the SES light came on. I had the 4A and 4B codes as well as 71 and every misfire code for cylinders 5-8. These were identical symptoms that I had two years ago and I found I had a broken wire on one of the Vanos solenoids. I didn't document it then, so I am doing it now. I'll leave the solenoid removal "how to" to others who have documented it well. I will add that I remove the entire filter box to get better access and leave the coolant hoses in place.

Time to do something about it so out comes the driver's side Vanos board. I immediately see that there is a cracked solder joint on one of the leads that goes into the coil from the little board.


So, I clean the board up, re-solder that joint and all the others ones, adding additional solder to reinforce the weak little trace between the pads.


Back into the car, clear codes, start it up...still the same. FARG! Take the board out, I must have missed something. Now I break out the meter and my power supply. I thought the cracked joint was a slam dunk but I was mistaken.


I found the coil that did not respond, right away. This wasn't the case last time, I had to wiggle connections to get it to fail then. Desolder the little board and my problem becomes apparent. The lead has broken off flush where it enters the coil potting. Just like last time.


So out comes the Dremel, files, and X-acto knife and I start carefully hacking away to expose the wire. This is tedious and the epoxy is tough. You must be careful not to damage the lead wire more than it already is. I exposed about 2mm and stop because I don't know how deep I can go before hitting the winding. It doesn't show well in the picture, but it is there.


I then took a section of solid core wire that is 1mm(.040") thick and using a small drill bit as a mandrel, I bent a tight loop on the end and then put a curve in it to match the other one. The hoop was pushed over the stump and soldered on. When I did this the last time, I threw away the little board and soldered the wires directly to the solenoid leads. The unbroken one was no problem because it was long enough but the short bit of wire was difficult to connect the wire to. The first attempt broke after two weeks and I had to redo it with a bigger blob of solder and that repair has lasted over a year and a half. So this time, I decided to fix it so that it was stronger from the start. The loop of wire provided much more surface area and I think this will be a good repair.


Now the little and big PCBs were prepped for assembly by using solder wick and a solder sucker.


The parts were then fit together and I started by soldering the wire lead that wasn't broken to the little board. I then soldered the wires back into the main board and finally the repaired wire lead. I felt that in this way, I would have the least stress on the repaired lead and the repair wouldn't move if it re-melted when soldering the wire to the small board. It seemed to work. A little bit of shrink tube was used to repair the insulation on the yellow wire. And that is it.


The board was tested and installed with no problems. The car once again runs like it should, or at least as well as it ran before. In this case, the board failed in two ways. First, the solder joint broke on the black wire and then all the mechanical load went to the other wire which finally broke. This solenoid board is a pretty poor design execution and invites failure. I'm afraid it's not the last time I'll be in there. The newer solenoid cover with the screws may reduce the movement of the solenoids and the have fewer failures like this, so I may have to look into that. Everything I did here could be done by anyone with basic skills, so don't be afraid to give it a shot and save yourself $1500 in parts and labor.
 

·
Registered
Joined
·
4,488 Posts
Great write-up, gzig5. Thanks. I resoldered the obvious joints a while back but now I have a 71 code, so this may be my problem.
I have a early 2001 and the solenoids are firmly clamped in place by setscrews. Are you saying they are loose on yours and can move around?
 

·
Registered
Joined
·
1,855 Posts
Discussion Starter #3 (Edited)
I don't know when they did the change, but the early cars don't have the set screws. So the coils are free to rattle around on the end of their tethers, which are the wires. I think this is why they are breaking. The upgrade is probably as simple as bolting on the new covers, but I may modify my existing covers if there is enough meat for the set screw threads.

 

·
Registered
Joined
·
9,876 Posts
Nice job! The extra surgery is excellent! I think if I had found that I would have been forced to buy a new noid, not any more.:cheers: thanks much
 

·
Registered
Joined
·
1,760 Posts
Nice work. I gave myself a good fright when I broke a wire off mine but work like this helps everyone to see it's not brain surgery if you can solder a bit and have the right tools. What power supply were you using there btw?
 

·
Registered
Joined
·
84 Posts
So for an early model year is it as simple as buying the updated cover so they are not loose? Anyone know the part number for it?
 

·
Registered
Joined
·
1,855 Posts
Discussion Starter #8
Nice work. I gave myself a good fright when I broke a wire off mine but work like this helps everyone to see it's not brain surgery if you can solder a bit and have the right tools. What power supply were you using there btw?
It's made by Power-One and has +12, -12, +5, and +24 VDC outputs. I can't remember where I got it, but probably from a machine retrofit years ago. Lot's of supplies like this at salvage shops and online. Another good source would be a 12 VDC wall wart from an older printer or something like that. You can use a car battery, but there is a lot of current capacity there and one of these little supplies will fold back if there is a short.
 

·
Registered
Joined
·
6,918 Posts
Great write up, especially the level of details, and nice to see circuit diagrams used in practice.
 

·
Registered
Joined
·
6,918 Posts
What wattage soldering iron should be used for this repair? I have a 35 watt kit that melted the usb port when I tried it on my HTC cell phone.
 

·
Registered
Joined
·
9,876 Posts
Wattage question is a good one, but is subjective. 35 watts is maybe a tad high for boards an a like but not really for an experienced user. I use a 20w but sometimes don't get good heat recovery. The wattage is best thought of as heat recovery, the higher it is the faster the tip will reheat when heat is transferred to whatever you touch. So if to low you must hold the tip on to long to have the temp come back to melt the solder. So more heat ends up transferring into the board so you melt things, if it heats to quick the same thing happens if the operator is slow. Truly it is all about the speed of the operator. You need a drop of solder on the tip to make good heat transfer then make contact and quickly add more then remove. I use the 20w because I don't do it everyday, so my skill is not high.
 

·
Registered
Joined
·
1,855 Posts
Discussion Starter #13
I agree with Sailor, and there is a lot of "personal" experience that goes into it. I typically subscribe to the more is better path and that is also how I was taught to solder. Get in there with enough heat, and git 'er done, quickly. At home I've got a couple of different irons from 15 - 400 W and usually chose the iron more by the size/shape of the tip. The 15W is just about useless IMO for anything but ant poop sized components. To me, the size and shape of the tip is more important than the power. I'm also fortunate in that I have access to the Metcal and Hako soldering stations at work as well as the microscopes to see the fine details. The solder stations have a bunch of interchangeable tips that automatically get to the temp you set. The last coil I repaired after I wrote this DIY, had the coil winding wire, which is REALLY thin, break off the output post. I would have been hosed without the 8-30x microscope to show the tiny detail. I'll see if I can find the pics of that at home and update the thread.
 

·
Registered
Joined
·
236 Posts
Excellent write up

I have seen this failure on many S50B32 engines as well.

Preventive bridging of the pcbs might help, and I wonder as well about something simple like hot glue to support the pcb and prevent vibration?

I have not verified this yet, but the solenoids look to be identical to those found in some abs units from the 90s... It may be that these could be cheap sources for replacement solenoids vs time consuming repairs too.

DIY - ABS Hyraulic Unit Repair - BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3)

This is just a thread showing that 3 of the 6 solenoid look to be a match. One of these days I'll rip a pump apart and see if there is a way to confirm they are interchangeable.

Has anyone thought of this before? Is it old news?

Well presented!
 

·
Registered
Joined
·
236 Posts
ABS part number request

I'm a little hesitant to give you a part number you could pull off realoem, you might mistake that for me saying that the swap is valid and it is a replacement.

I have not pulled one apart yet, but it sure looks like it is worth investigating.

I will try and compare one to the Euro vanos solenoids I have all over the place, but I've not got my S62 in the garage yet, so I've no basis to compare directly to the S62 part.

Alex.
 

·
Registered
Joined
·
9,876 Posts
you might mistake that for me saying that the swap is valid and it is a replacement.

Euro vanos solenoids I have all over the place,

Alex.
You don't know me very well, no matter what you have decided or say, I will not be satisfied until I have tested it and confirmed it for myself. Sorry just my nature to prove and verify. So you had little worry of me blaming you or even assuming you were correct. Thanks for the lead I will do it myself.
WTF is a euro vanos solenoid?
 

·
Registered
Joined
·
236 Posts
Can't PM yet, so sorry about possible waste of BW

If you were local, by now we'd have met and be good friends I'm sure. If you were in chicago, I'd hand one over, let you pull it apart, and just ask for the bits back.....I'm not selling off my ABS pump supply because I have long had a hunch it might be a good source for replacement solenoids on my Euro engines as well as for my S62 plans...I'm a hoarder!

I think almost all the 90's abs pumps were the same pretty much, but I showed in the pictures what I think is one from a 95 M3 US spec.

It is almost certainly identical to any other 3 channel pump, though, to think about it, maybe that is a 4 channel 97+ M3 pump as there are six solenoids.

In the USA, we are very ethnocentric so a "Euro" is reference to the Euro M3, or S50B30/B32 engines we never got. I've imported perhaps 70 of these over the past 8 years for resale to enthusiasts. This was the first appearance of vanos as you know it on the S62.

In the S50B30 the intake cam only had a pair of these solenoids, they hit the vanos unit from the S50B30 with an ugly stick for the B32 and made it dual vanos. Eventually this stuff showed up on the V8 too in the form you recognize.

You probably knew all this, just not what I meant by Euro.

Gee, I typed all this into a PM, and my count is not high enough to have sent it. Now I'm one closer.... whoopeeee?
 

·
Registered
Joined
·
9,876 Posts
Not a worry I can get one of those pumps for $40 likely, part # would have saved time, could have called Bob and read the # off your post, but I can look it up.
This is gold to me so thanks for the lead.
 

·
Registered
Joined
·
72 Posts
Vanos

I no the thread is a little old but please let me no how you make out. The entire "VANOS" is scary knowing they are $4800.00US for both banks to replace. I just got back from a BMW dealership to price one out just in case I need one in the future. Keep me in the loop. Great article.:applause::applause::applause::applause::applause::applause::applause::applause::applause::applause::applause::applause::applause:
 
1 - 20 of 179 Posts
Top