Power Seats Come With Issues As They Age
Seats are not a super-frequent issue that come up for BMW owners, however they do have a set of problems that commonly occur on higher mileage vehicles. At one point I had a problem in both my driver’s seat, and passenger seat on my E36. Typical issues for an E36 include leather deterioration, power seat failure, and manual latch failure.
Several of these issues I recently resolved on my 1996 BMW 328i, so I wanted to describe a few of the common issues, and how to fix them. Luckily, e36 seat repair are typically well within the scope of everyday diyer’s and can usually be repaired in the space of an hour.
Repairing your seats is also a great opportunity to vacuum some hard to reach areas. I think of power seat repair as an investment, as I typically recover up to $10 worth of coins.
In this article I will discuss various common failure points of E36 seats, how to repair them, and include some resources to help you along the way.
Front Seat Removal
Almost all repairs involving power seat adjustment or folding latch adjustment involve removing the seat. It’s surprisingly very quick to do. Two nuts in the front, and two bolts in the back is all that holds down the seats. You will need a size 5/8 (16mm) socket for all four fasteners. This is the same whether or not you have power seats. The nuts and bolts are concealed by plastic covers, which can be popped off with a screwdriver.
Optionally you can choose to disconnect the negative terminal on the battery or not. Disconnecting the seat wiring can cause an airbag light to appear upon starting the car at the end of the job. My airbag light was already on before I started this repair, so I didn’t care.
Afterwards you should be able to push the seat back in order to disconnect the wiring underneath the seat. On the passenger seat there’s usually three wires, two for the seat motors and one for the airbag. On the driver’s side there should be two for the motors.
Once you’ve disconnected the wires you can lift the entire seat assembly out of the vehicle, alternatively you can flip it over the center console.
The large plastic kick plate at the bottom of the seat is held on with a single T30 torx bolt. Remove it and the plate will fall out.
Power Seat Recline Failure (Video)
Video on replacing the recline seat gear on a BMW.
The E36 series was a mixed bag for powered seats. Some models came with power seats, while others did not. Although, power seats are a luxury to have, they do need repair as they age. One of the most common failures is the power seat recline feature.
The typical symptom is that you hold the reclining switch forward or backward and the seat remains motionless. You should also hear a whirring sound coming from underneath the seat. If this is the case, than 99% of the time you will find that there is a plastic gear inside of the recline gearbox, and it has shattered into pieces. If you don’t hear a whirring sound (unlikely), than most likely you’re recline motor has taken a turn for the worse and failed.
Luckily this repair is rather simple and accessible to perform for most diy’ers. When you remove your seat and flip it upside down, you will notice that there are two gearboxes underneath the seat, and three motors. The larger gearbox with two motors is the one that you’re after.
Both motors need to be removed. They each have two T25 torx screws holding them onto the gearbox. The motor on the top will have to be removed first. I was able to remove and re-install the motors with an L-Shaped torx tool. I found that the space was too tight to use a socket.
Sit both of the motors to the side and out of the way, ensure that they aren’t simply dangling by the wire.
The gearbox has six T20 screws holding the lid on. Take note that the two rear screws are larger and much longer than the other four. I also used an L-Shaped torx tool to remove these screws.
Once they have been removed, you can carefully pry the lid from the gearbox. This may take some persuasion, but remember that some of the gearbox parts are fragile.
There are two plastic gears inside of the gearbox, a white and pink gear. The white is the one that actually controls the recline adjustment, and the pink gear controls the bottom of the seat. Typically when your recline feature is faulty, the problem is in the white gear. Overtime the gear will either break into a bunch of small pieces or it will develop a large gash.
These gears typically cost around $25 – $35 apiece, I was lucky and my local O’Reillys store sold it to me for $20. I highly recommend replacing both of the gears, even if only one is faulty. That way, you don’t end up doing this again in six months when the other gear breaks.
Generally when you purchase gears they do not come with the threaded rod already pressed in. This means that you will need to press it in yourself. You can use a bench press or a clamp to press the gear in.
I pressed the gear on with a rubber mallet and a solid piece of wood. I placed the gear on the wood, and tapped the rod into the gear with the mallet. You want to tap the rod in just far enough out of the gear so you can insert the c-clip. Remember to only tap on the shaft, do not hit the gear with a rubber mallet.
After the gear is successfully pressed, re-insert the rod and gear into its spot in the box. This may take some play to ensure that it fits properly. At this point I would advise not to touch any of the other gears, unless you want to replace the pink gear. Simply re-lubricate the inside of the gearbox with grease, and re-assemble everything.
Latch Repair (Video)
Video on replacing the manual latch cable on a BMW
The plastic folding latch is a common issue on higher mileage BMWs, especially on the passenger side. There is a long cable that runs all the way from the latch, down to a mechanism at the bottom of the seat. Unfortunately BMW did not make these cables as strong as they should have been, and they tend to snap eventually. When the cable snaps the latch becomes useless. You can pull it up or down, and nothing will happen.
The vast majority of seat latch issues can be attributed to the cable snapping. The unfortunate part about this repair is that the latch cable itself is ridiculously expensive in my opinion. I couldn’t find it cheaper than $50 online, so I bought it from BMW for $60 because they had it in stock.
You need to remove the seat to replace the cable. I have heard of some people removing the backing by sitting on the back seat and replacing the cable, but I think this is a lot harder than just pulling the seat.
Removing the back is pretty simple, first you’re going to want to remove the headrest. Simply pull up quickly on the headrest and it pops right out.
There are two small torx screws on the bottom of the back, remove them. Afterwards, remove the levers on either side. They are unbelievably easy to remove, simply take a flathead screwdriver and pull them out.
Same goes for the lever cover. Except you’re going to want to be a little more careful prying out the cover, as it is held in with plastic tabs that tend to break.
At this point the cover pops right off, and you have access to the Bowden cable. You should be able to identify where it has snapped, either at the top where it attaches to the plastic mechanism or the bottom.
To remove the Bowden Cable you need to pop it off at the bottom, and remove it from the lever at the top. You will probably find that it is zip tied in the middle. Once it’s unattached, snake it through the bottom.
Installation is simply the reverse of removal, take care when working with the plastic lever mechanisms, as they are fragile.
Other Common Seat Issues
The seat may refuse to go forward or backward, if you can hear a whirring sound like the motor is spinning it’s probably the plastic drive gear. If the seat is at least trying to move, check the rails at the bottom. Look for any debris or any pieces that might have gotten stuck in the rail.
If there is no sound at all after holding down the switch, than more than likely one of your motors will need replacement.
Leather Worn Out
This is especially common on the convertibles, as they typically get more wear and tear on the seats. The leather cracks overtime, and falls apart eventually. New seat covers range in price, but typically you’re looking at $400 – $700 for the covers. Replacing the leather can be a tough task for a diyer and unfortunately there’s not a ton of information online to help with replacement.
Alternatively, there are some diys online about restoring leather seats. This involves sanding the damaged leather and filling serious problem areas with leather compound, and then applying leather dye to the seat.
*Convertible top owners, the best way to maintain your leather seats is to repair the window corner leak as soon as it begins to occur. It’s ridiculously common on convertibles, and overtime that water leaking on your seat will fast-track it to cracking.*
Overall, manual seats are certainly more reliable than motorized seats, but there’s always a trade-off for more luxury. Luckily for us, seat repairs are typically simple, quick, and cheap. The one exception in my mind is leather work, which can be quite expensive.
Check out some of my other BMW Articles!