Harley Davidson Stripped Drain Plug Thread Repair - Do's and Don'ts

WiseAutoTools.com © Summary: This article covers several options for repairing stripped threads for oil and transmission (Primary or Secondary) drain plugs on Harley Davidson motorcycles. 

Harley Davidson motorcycles obviously vibrate a lot which may lead to the drain plugs loosening over time. If they loosen up any, thread deterioration may occur. Aluminum threads can also get damaged and stretched if drain plugs are overtightened a little.  

It does not matter if it’s a Harley Davidson, Honda, Kawasaki, Suzuki, Can Am or some other motorcycle, they have one thing in common; they have aluminum pans or housings. Some vibrate more than others, like the Harley, but stripped threads can be fixed as long as there is enough metal remaining. Loose plugs will most likely cause a leak.

Don't do this.

Longer Bolt – If the pan doesn’t have enough meat on it, a longer bolt does no good. Plus even if the longer bolt would grab a little further in, who wants to trust only a couple of threads to hold all their oil or transmission fluid in?

Teflon tape – Really? Just a temporary solution at best. Once the bike vibrates a little the tape will wear against the damaged threads and the drip (or worse) will return. Teflon tape could also end up in the pan and get drawn into the pick-up screen. That could cause more problems.

Silicone – Silicone will NOT adhere to anything oily. And how do you clean the oil off a constantly dripping hole? You don’t. Also, just like the teflon tape idea, the vibration will cause problems resulting in a recurring leak. Then there’s the problem of dealing with re-siliconing every time the plug is removed. Silicone is just not a good idea when comes to stopping a leak from a stripped hole for a oil or transmission drain plug.

Expandable rubber plug. I’ve tried this type of plug before. Carmax where I used to work kept them along with the nuts and bolts assortment. This is a waste of time. The rubber will not mate up perfectly to a hole with damaged threads. Without getting it just right, the result will be a drip. Also different temperatures may cause the rubber to expand and contract resulting in.. you got it! A DRIP.

Oversize drain plugs. These used to work OK for metal pans. I used single and double oversize drain plugs years ago when I worked at Goodyear, but that was when there were no aluminum pans. Just steel. Oversize drain plugs are NOT a good solution for aluminum pans or housings. First of all, the oversized plugs have to be installed perfectly straight. Also with aluminum housings/pans there’s the risk of cracking the pan or housing when forcing the oversize plug in. We recently had someone return one of our Time Sert kits because he discovered that when he previously tried installing the oversize plug he had unknowingly cracked the pan. Once the aluminum housing or pan is cracked, there’s no repairing it. So stay away from oversize drain plugs.

Heli-Coil. A Helicoil is a thin winding of wire. The coil has gaps between every spiral of the wire which does nothing to stop fluid. The Helicoil is held in by the outward force of the spring tension. That might be OK for some less critical applications, like repairs that will not require frequent removal of the bolt. The fact remains that the HeliCoil may come out when removing the drain plug. That’s not something anyone wants to deal with when doing oil changes. Also the risk of it leaking makes HeliCoils a bad choice for this application.

Do This.

Use a Time-Sert professional thread repair kit. It’s easy and best above all it’s permanent. We all know that steel is stronger than aluminum. It’s 10 times stronger. Time-Sert uses carbon steel. It’s also a solid threaded bushing which is not going to allow leaks between the threads. As long as there’s room in the area in front of the drain hole to use the tooling, the pan or housing does NOT need to be removed. The kit comes with a guide to line up the tooling straight. That way the drain plug and washer fill sit flush so there’s no leaks when the repair has been completed. The original size drain plug is used.

For current pricing on the kits mentioned in this article see 0122A 1/2-20 kit or for the M14x1.5 size or for the M14x1.5 size see the 1415C.

Question: How do I get a stripped drain plug out? I have a 2005 Harley Fatboy 96ci. The primary housing drain plug hole is stripped out. It only spins. How do I remove it and what is the best repair?

Answer: If the plug just spins and won’t come out, I would try vise grips. Attach them to the drain plug and turn it to the left (counter clockwise) while pulling outward. Once the plug has been removed, use the 0122A DLT which is a Time Sert 1/2″ by 20 thread repair kit. This kit will make a permanent repair by installing a solid carbon steel insert which will accept the original size drain plug. The threads will be upgraded to steel instead of aluminum which will hold up much better making this a superior repair compared to trying to use an oversized plug which could crack the housing. If an oversized plug has been used previously, you will need to go up a little in the outer diameter. You could use a 1415C kit which is M14x1.5. The 14mm size is a little larger than the 1/2″ so that will work well. Just pick up a replacement 14mm drain plug from a parts store if you go this route.

Question: What about all the metal shavings from drilling and tapping?

Answer: The metal in the bottom of the pan (or housing) is flushed out by putting in oil (new or old your choice) before finally installing the drain plug. Once the oil starts coming out metal free, the flush is complete.

Question: How do I know what size drain plug I have for sure?

Answer: One option is to look up a drain plug on-line for your vehicle/motorcycle at NAPA online or your favorite parts store. The plug size is usually found when looking up the drain plug. Don’t want to look it up yourself? Call a parts store or dealer and ask them to look it up for you. Another way is to take the old drain plug to the parts store and find a nut that fits, or match it up with a replacement drain plug sold at the store. Tap and dye sets can also be used to determine the size just as you would any other bolt by finding a dye that is the correct size and pitch.

Question: What size is Harley drain plug?

Answer: Most are 1/2-20. If unsure use a nut from a parts store from their nuts and bolts selection to verify the size. Or contact a Harley Dealer to have them look your plug size up by application. We also have a partial application list on the Time Sert 0122A product listing.

Question: What causes a stripped oil drain plug?

Answer: Normal wear on threads can lead to loose threads. Over tightening can stretch and distort the threads also. Once a certain amount of threads are worn the drain plug may strip remaining threads. Most of the time the steel drain plug threads are fine but the softer aluminum threads sustain the damage over time.

Emails to and from a recent customer.

Jeff: There is no room for a drill on my 1998 Harley Road King. But maybe if I put the drill bit in a socket and go slow, maybe that could work. And use a socket for the counter sink and the tap. Cause, taking the oil pan out is a huge pain. Rear wheel has to come off. With no proper bike jack and stand, that's not a simple task. Your article says do NOT try an oversize self tapping oil drain bolt. But it sure is tempting. Lol.

Our response: Yeah the drill bit (reamer) does have a square on it so you could use a 12 point socket on it. It is the longest tool in the kit measuring about 4 inches. Yeah, I can see it would be tempting, but we've had customers crack the housing with oversized plugs.

Jeff: Fingers crossed. And yes, I hear you about the oversized drain plug. I should have just pumped the dang oil out, like on a small sailboat diesel. These aluminum oil pans are just asking for trouble. Which is what I'll do in the future. Even after installing your time sert. Last question. If I'm gonna do this, I might as well do the transmission drain hole also, or at least make sure I have the proper sized time sert on hand. Does the kit come with more than one insert? I believe the trans drain plug is also 1/2-20. It is positioned straight downward, so access is not an issue.

Our response:  Good idea about using a fluid extractor. Many Harley's come with the 1/2-20 drain plug for both the engine and trans, it's best to verify though. The 0122A kit comes with five inserts. The common length insert is included with the kit. The insert can't be too long or it will stick up inside preventing all the oil from draining out.

Jeff: Thanks. Its gonna be close. Cant get a drill in there for sure. Likely cant get a socket in there either. Can I buy a short drill bit in the size that comes with your kit? Or is that bit a non standard size?

Our response: We only have the one length available. It's a 33/64th bit.

Jeff: Just wanted to thank you for the help. The kit came in and I was able to do the job without removing the oil pan on the 1998 harley road king. The tools were perfect. Very sharp and easy to use with a 10 point wrench. No drill. (No room) Took some time to get the off-set done with just a 10 point wrench, but it worked. Its rare these days to find a quality tool. So much junk coming from china. The job is done! Thanks again. Jeff

We've been selling thread repair kits since 2005. Call for assistance in finding the drain plug thread repair kit at 800-734-8665 or provide us your drain plug size and type of motorcycle by using our Contact Form.