Mercedes-Benz Forum banner

PSE Pump Troubles

9K views 16 replies 7 participants last post by  shimshon 
#1 ·
In my 1993 S320L my soft close doors and trunk don't ever work. Also my two front door locks don't work either. Today I took my back seat bench off to check the pump and to do a quick experiment I opened the trunk and closed it and the pump seems to work for the trunk handle mechanism but not the door locks or soft close doors. What do you guys think the issue possibly is? I was thinking wiring or the valves inside the pump are sticking.
 
#2 ·
Soft close is not the PSE. Its the closing assist pump. Pull the fuse in the trunk (think its number 9) and put it back in. This resets the assist pump protection. See if soft close works. If it fails on any door after 2 cycles, there is a problem with that circuit. Door locks are the PSE pump under the seat. Given that neither close assist or door lock works, it could also be a microswitch issue.
 
#3 ·
Hello Ethan,

The PSE is the doorlock pump under the seat, and the problem is most of the time is a motor that goes bad. Here are a few threads:

http://www.benzworld.org/forums/w140-s-class/1585361-diy-pse-pump-post-mortem-resurrection.html

http://www.benzworld.org/forums/w140-s-class/1827546-pse-pump-needed.html

The other problem with door locks is the vacuum motor that drives the door mechanism goes bad-The snaps tabs break off, but one can seal them with cable ties..

http://www.benzworld.org/forums/w14...ock-actuator-installation-question-video.html

http://www.benzworld.org/forums/w210-e-class/1497717-diy-door-lock-actuator-cheap-fix.html

Hope it helps,

MArtin
 
#4 ·
Just to throw my 2 cents in.

I did this about 2 weeks ago with a Johnson Electric 12V DC Motor - High Torque Output - 6 oz. in. - 6600 RPM 9167AK motor off ebay ([URL="http://www.ebay.com/itm/281656938778"[/URL]). Was super simple. The only mods I made were:

1. Grind or file a flat on the knurled shaft
2. Solder extension leads to the motor (it's shorter than the original)
3. For safety, put an inline 15A fuse with one of the motor leads.


Cheers
 
#5 ·
Scott,

As I understand the motor terminals and PSE wires are not color coded for positive and negative. How did you decide which way to connect them? Did you simply get lucky the first time around? As I understand if connected in reverse you would need to redo and swap the leads if a particular circuit pressurizes instead of vacuum.

Also, did you verify the pressure and vacuum obtained to calibrate your screw adjustments e.g. not too tight and not too loose? If so what specs did you use?

Seth
 
#6 ·
Seth,

While there is a correct polarity, this motor is driven in both directions (vacuum and pressure). Just temorarily hook it and and see if it works (door locks and reverse rods). If they don't, it's backwards.

I have not checked the system for pressure and vacuum specs. That I was planning on doing later this week. As I've just got my ventilation system working, I was planning on running through the PSE and climate computer diagnostics to see what other parts might be bad.

I have to say, having a MightyVac is essential for these jobs. Replacing the motor was one of the easier jobs I've done. The hardest part was actually getting the electrical plug off the PSE housing. Mine actually broke, so I spent time repairing it.

And seriously consider the fuse. I know the original motor was uni-directional, but was used in a reversing manner, so the brushes would jam and overheat. I didn't take apart my new motor, for I suspect the brushes are the same design. I flipped out when the motor in my ebay PSE that I installed went up in smoke. Luckily, the back seat was still out, and the foam cover over the pump was pulled back. I was doing other work on the engine at the time, and thought the smell of burning was coming from the hood. My chamba boy was that one that started yelling that smoke was coming out of the back set. Cheap insurance. Even though this motor should only require a 3 or 4 amp fuse, I've found that startup and reversing surge require a 10 amp fuse. I had to put a 15a in there before the new motor was broken in.


Cheers
 
#7 ·
OK let me share the PSE pressure and vacuum specs.

These specs are critical for pump longevity since if assembly is too tight the pump will wear prematurely due to excessive friction and if the assembly is too loose the pump will wear out prematurely due to extended running time associated with leakage. So we are not just looking to get the system working we are looking the the new pump to LAST.

Pressure Spec is 0.3 to 0.6 BAR which is 4.35 to 8.75 PSI

Vacuum Spec is -0.3 to -0.6 BAR which is 8.86 in Hg to 17.7 in Hg

MAVA or others please comment if you don't agree.

Seth
 
#11 ·
Seth,

From the motor it self I expect 20" or better from the pump head. Anything else I do not bother with that motor. If that does not work, I change the pump head after the cleaning. I look for no load current of the pump of under 2Amps. Over 10Amps(loaded) start over-Align the pump head parts/ Clean the pump head / New motor(get another new motor). This is the reason Scottpetered had the fire.

One can get the pressure, but at what cost, so the current draw is super important.

Martin
 
#8 ·
OK for all of you folks who claimed to have successfully rebuilt these PSEs via motor replacement I ask:

What PSI and in-Hg specs did you use for pressure and vacuum post integration of your new motor?

What torque specs did you use for the screws atop the motor vane plate?

Seth
 
#9 ·
I haven't done mine yet,the motor just arrived and is sitting right in front of me.

My service manual doesn't have specs like you are asking for. Testing the pump by itself with a reservoir : greater than or equal to 450 mbar in less than or equal to 0.7 seconds for pressure and less than or equal to 1.1 seconds for vacuum. There is a p/n for the reservoir but I've never been able to determine the volume. There are also some system functional tests - the spec for Central Locking is is less than or equal to 3 seconds to lock the doors.
 

Attachments

#13 ·
I'm glad to hear Martin's input on the current draw. I have one of those nifty ammeters that plug into a fuse socket. After I installed an in-line fuse on the PSE motor, I measured the current. While this meter does not offer a peak current measurement capability, I could see it go over 10amps on startup, then settle down to 2A.

I am hoping tomorrow to have time to measure the vacuum and pressure of the pump.

Cheers
 
#14 ·
I'm letting out the trade secrets :grin... Each-One-Teach-One :nerd

It is sustained current-not start up-Wait ten seconds for the reading.

Remember how each vane came out-One long side will flat square edges, and the other long side will be round(beveled round at the thickness side). From time to time very wobbly motor will round the rounded long side causing the pump head wear the pump head, and cause it to leak-not generate enough vacuum(or pressure), yet I always test for vacuum(easier for me).

To find the right polarity:

A) Apply 12v to the motor it should pull vacuum(if not, reverse it).

B) The +12v lead is where the red wire from the pump is soldered too :nerd

Martin
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top