MkIV Underbody Plugs

Check your underbody plugs to avoid rust inside the frame.

Related Parts

Underbody Plugs


In this video I’ll show you how to check the underbody plugs on your mk. 4 jetta, golf, or new beetle. Underbody plugs are plastic caps that are put in the frame of the car to prevent water or debris from getting inside the frame. If these caps are damaged or cracked they’ll allow moisture to get in and the frame will start to rust from the inside out. So we want to check all these plugs to be sure they’re in proper condition and replace any that are missing or cracked.

We’re going to start out on the side of the car. Right where the pinch well is here you’ll see a whole collection of these plugs. Some are oval and some are round. On this car these two look alright, this one has some cracking—we’ll replace that round one; this round one is missing its outside completely; all these ovals look OK. There’s going to be a collection of them on the side here, and a main one on the frame rail here. There are small caps all along the underbody of the car.

Now we’ll check along the pinch well of the other side of the car. These look good, but this round one is destroyed.

The last ones you want to check are located in the back where the spare tire is. There will be two. One of these is missing and the other is broken

We looked at this car and determined we need to replace three of the oval ones and none of the round ones.

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