In this post i will describe standard problems and the ways to fix it and also the ways to retrofit it back to simple trunk shocks.
Premium option S316A for e65/66 was hydraulic trunk lift. Yes its very comfortable and convenient, but with years these nice options give more headaches, than luxury feeling. This Option includes:
-electro-hydraulic pump (located in the rear right panel) (8) -rarely just low on fluid due to leaks
-hydraulic piston or actuator, which lifts the trunk (3)- fails often, leaks onto NAVI unit
-Trunk lid shocks (23) -fails often
-electronic module (12) -rarely fails
And what fails? Everything, except for the pump (it has safety prevention valve).
TRUNK LID SHOCKS FAILURE:
So if your trunk lid still opens after you press the button (remote, interior, trunk button), but it wont stay open or barely stays open especially on the hill
– YOU NEED NEW TRUNK LID SHOCKS (23), they got upgraded with silver coils vs old black ones which always fail. NEW upgraded P/n: 51247201461. So even if your old ones are still working i strongly recommend newer springs, because it will help to reduce stress from hydraulic cylinder as well.
Hydraulic Cylinder Leak:
Well, this is the worst and most expensive…. So if you press the button and nothing happens or you can hear the pump is trying to lift the lid but it shuts down right away, it means 2 things:
-Hydraulic fluid is low and therefore it stops the pump from failure. Sometimes BMW says you can loose some fluid over the time due to evaporation, aging etc…. but in my experience it means Cylinder leak. You can add some fluid into the pump on the left panel, but most likely it will leak out soon.
-Cylinder leak. In this case it explains where the sticky red fluid leaked and created mess in your left rear panel, usually you see SVS, NAVI unit covered in oil.
Options? Well you need new hydraulic cylinder kit p/n: 51247202868, which is quite expensive ~300$. Plus you need new shocks 160-180$, 500$ in parts!! Lots of hassle to install it as well.
OR IF YOU ARE TIRED OF THIS (300$+160$(SHOCKS))AND WANT JUST A SIMPLE TRUNK OPTION, I RECOMMEND YOU FOLLOWING STANDARD TRUNK LID RETROFIT:
-you need to remove trunk shocks (use sharp pick tool to remove shock lock)
-disconnect hydraulic cylinder and remove it including lines or simply move it out of the way.
-disconnect hydraulic pump electric connector or disconnect hydraulic trunk HKL module. You can code it out using NCS, but not necessary.
-buy and install standard shocks 80$ each p/n: 51247201463
-DONE! Enjoy standard hassle free trunk lid with soft close feature. I know its not that luxury, but 500$ still in your pocket and you should be happy, bc no more worries it will leak again and flood your expensive modules. BMW says not to leave your car in the open sun, bc it makes things worse for hydarulic cylinder causing premature failure.