Stripped Oil Drain Plug: What to Do?

 

On most vehicles, the engine oil drain plug is located on the oil pan, which is typically made of steel. In these cases, any ol' auto tech at "Wherever Garage" can hardly screw it up. And even if they did, the worst-case scenario would be having to replace the oil pan, which isn't that big of a deal.

On all flat-four aircooled and watercooled Vanagons (except for inline four cylinder Diesel), the oil drain plug screws right into the aluminum engine block. The thread size is 14mm, and it only takes about 10 ft.-lbs of torque and a new crush washer to seal the drain plug. There is nothing special about the crush washer, and no special tools are needed for the job. However, as easy as this job sounds, it's even easier to screw it up. That's why we NEVER recommend "Wherever Garage" for oil changes on these vehicles. You need to take your vehicle to a shop that understands the amount of torque and the crush washer needed for the job. It will make all the difference.

The majority of the engines we get in to rebuild have damaged or totally stripped-out oil drain plug holes. The hole is almost always repairable, with a helical insert, commonly referred to as a 'helicoil.' A helicoil repair is the least intrusive method to fix such a failure, and the resulting repair is better than new. In other words, once a helicoil is properly installed, the hole is almost strip-proof. The repair yields a threaded hole that is 5 to 10 times stronger than original. All the engines we build get a helicoil installed in the drain hole, whether or not it is stripped.


Still, an overzealous mechanic can strip out a helicoil, and then the hole will be too big for another helicoil repair. At that point, a metal insert called a "time-sert" is required, and even then, that can get stripped out. Both a helicoil and time-sert repair can be done in-vehicle. But, if the hole gets too big, the hole will have to be welded up and re-drilled and re-tapped, which can only be done on a completely disassembled engine.

You may have heard that helicoils are kind of hokey, and the “proper” repair is a time-sert. Nothing can be further from the truth!

Helicoils have been used since WWII on aluminum aircraft engines. In fact, many threaded holes in aircraft engines and aluminum parts have helicoils installed from the start. Porsche engines employ them all over the place. Furthermore, time-serts are problematic for this repair. If the shoulder at the top of the time-sert is too large for the crush washer to cover, the oil will leak around the insert, around the crush washer, and right out. Also, time-serts often come out with the drain plug! Heli-coils simply do not back out. Why some knowledgeable and otherwise well-educated/experienced professionals continue to bad-mouth the heli-coil is a mystery to us. 

The fact is this: The helicoil repair is the way to go, and every GoWesty rebuilt engine gets one, stripped hole or not!

Note: GoWesty does not sell helicoils. They come in a variety of sizes, and any good auto or tool supply shop should have them.