BimmerFest BMW Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
I have a E65 745Li '02. I am having a problem with the auto boot opener. When activated either by the internal or external boot switch, the key fob or the remote, the boot will open for just a second then close. If I hit the external boot switch (at the boot lid) and lift the boot a little bit, it will continue to open fully using the hydraulic motor, and similarly it will close perfectly. I have replaced the fluid (with AeroShell Fluid 41 as per the instructions on this forum) and have inspected the supporting rams and springs ... all look fine. One of my hydraulic cylinders (passenger side) has a small weep ... but I don't think that this is the cause. Is there a sensor or micro switch that triggers the boot hydraulics to lift that could be stuck ? If I screw out the rubber bump stops the boot will open, but the force at which this occurs is certainly not normal operation. Any help would be greatly appreciated.

Cheers
 

·
Registered
Joined
·
89 Posts
When I first got my car ('04 745Li) it worked perfectly. From the key fob & the local switch. Then after some time, it would do what you're saying. Open, then close. I had to use a stick to keep it open while working in the trunk.

Then all of a sudden, it started working right again. Staying up all on it's own, for however long I needed it open. Then it went back to not working right.

I figured I must be doing something wrong. After experimenting with it a bit (I obviously have nothing better to do) I've come to the conclusion that if I close it manually, it stops working. If I push the button to lower it, it will work right. So I suggest you open your boot lid, doesn't matter how. Then use the button inside the trunk to close it. Let it close on it's own.

Then it should be working "right" from now on, when you need to close it, use the switch. Never close it manually again.

Just yesterday I had it open with a charger on the battery while I was reading codes with DIS. The wind was blowing pretty good & sure enough it closed the lid. I opened it again & sure enough, it wouldn't stay open. I was just about to put the stick in place (I keep it in the trunk now) & just happened to see the switch & remembered.... I pushed the switch, it closed the lid. I opened the lid again with the button & it stayed open.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #5 ·
Thanks for your post Thunderkyss ... but I think your issue is with the two gas struts that support the boot (...trunk !!!) lid. These struts commonly fail and the symptoms that you have described fit perfectly. There are a couple of DIY videos on Youtube that will help ...

I am now looking at the angle module ...
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #10 ·
DMAX745i ... if you use ATF the seals in the hydraulic pump will fail in time. If you contact the manufacturer of the pump ... Germany company from memory (not BMW) ... they will explain that AeroShell Fluid 41 is the ONLY hydraulic fluid to use. Yes, normal ATF will work ... but then again you can put salt water in your radiator to cool your engine as well ... it will work ... but for how long, and what damage is it doing to your system ...

Nygel, thanks for your suggestion ... but I have replaced the entire fluid contents of my hydraulic system ... it is not low... or were you commenting on Thunderkyss' problem ... if so ... then, if the reservoir was low the pump would fail to pump correctly and not lift the boot lid from the start. As fluid is pumped in on one side of the ram, fluid is withdrawn from the other irrespective of the motion of the ram. The volume of fluid in the reservoir changes little between cycles.
 
1 - 10 of 10 Posts
Top