The standard OE rear main seal on a 2.0 TSI Volkswagen is, for lack of a better word, complete trash. Here's how to replace it with a better, more robust option from iAbed.
I may be the designated "BMW guy" at FCP Euro, but that doesn't mean I don't work on other cars. As of late, I have found myself working on quite a few Audi's and VW's. The most recent vehicle I have worked on is a MK6 GTI with a 6 speed manual that had recently been tuned. Needless to say the stock clutch wasn't up to snuff and would slip like crazy. One thing I have learned about the CCTA/CBFA TSI engines is the factory equipped rear main seal leaves much to be desired, and that's being nice about it.
The rear main seal that VW decided to use for the TSI applications is very thin and is adhered to a stamped sealing flange. Generally speaking a thin seal that is adhered is not a great choice for an oil seal where crankcase pressures are involved. It seems to me that this seal is almost intended to act as a fuse if crankcase pressures are too high. Speaking of which, if your TSI's rear main seal has failed it is highly recommended to also service the PCV valve and check the hoses for any clogs as this is the most likely cause of the failure. In addition, the rear main seal failure if severe enough can also cause a variety of rough running conditions including P0300, P0301, P0302, P0303, and P0304 fault codes indicating a vacuum leak and lean running conditions.
iAbed has developed a solution to this common problem with their rear main seal flange kit. Below are two pictures of the OE seal and the iAbed kit side by side for direct comparison:
You'll note several major differences—the OE seal is a complete unit with the mounting flange and the seal being "one piece". The OE seal is actually internal to the engine, meaning the seal faces the engine block. The OE seal is also a formed seal that is then adhered to the mounting flange. All in all, a pretty cheap design that also happens to be pretty weak. Compared to the iAbed seal you will notice it uses a more traditional square style seal with spring retention. The mounting flange is also beefed up from the OE design and is made from billet aluminum. You will also see that the seal goes from being internal to external in the updated design as well. As a whole, the iAbed rear main seal kit is a much more traditional rear main seal design.
Installation outside of removing the transmission and corresponding parts is pretty straightforward. Simply remove the eight bolts securing the OE seal in place and pry off the engine block. Next, clean up any sealant on the engine block from the original rear main seal housing. Use clean shop towels and some brake parts cleaner to remove any oil film on the sealing surface. You will need to install the new seal into the billet housing. I used a press and a cup to evenly press the seal into the iAbed housing. This isn't required but I chose to do it this way to make sure the seal pressed in evenly. Once the seal is pressed in evenly and completely lay a bead of oil resistant RTV in the groove machined onto the backside of the iAbed housing. VAG recommends to use silicone sealant, sold under p/n D174003M2, but I use Loctite 5970. Once the sealant is applied slip the new rear main seal assembly over the crankshaft and against the block. Install the supplied hex cap screws with the iAbed kit. I tighten these screws in a criss-cross pattern to ensure the housing is evenly pressed to the engine block. I then torque the hex cap screws to the OE spec of 8Nm
Overall, the iAbed seal is a nice kit and definitely worth the price premium over the stock seal. Personally, I'm not a fan of dropping transmissions more than I absolutely need to. Installing the iAbed rear main seal kit is truly a peace of mind solution in my opinion.
