I'm Prejudiced Against Allen! I Hate Allen!

Catbert

Catbert

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I have to admit it. I'm prejudiced. I'm prejudiced against Allen. I HATE Allen! I hate all Allen wrenches also know as hex keys. If I were a real Halloween warlock I'd cast a hex on Allen wrenches.

Why oh why do automotive companies use Allen oil drain plugs on their vehicles? To save 10 grams in weight? No. Does anyone know?

The AI wizard says auto companies use them to lower the risk of using oversized tools to avoid rounding the edges of a traditional hex head plug. Well, that's exactly what my gripe is all about except with Allen keys. When you need to apply force you are limited when dealing with the feeble Allen key to avoid rounding the inside edges. When that happens, you're screwed.

Yesterday, I went about changing the oil fluids (engine, trans, differential) on my new classic car. BMW has had a love affair with Allen keys on their drain plugs for decades. Naturally, the 19mm Allen plugs I needed to loosen were stuck like they were welded on. That tells me the oil hadn't been changed in a long time or someone with Schwarzenegger arms tightened them.

I first used a hammer, difficult as that is when lying on your back under the car with your arms folded and trying to hold the Allen key straight with one hand while swinging a hammer in limited space with the other. Not fun. Then, I used a makeshift pry bar using 3/4" pipe that the Allen key end fit into. After a few tries that finally worked.

So... Allen key? You're out! Finished! Excommunicated! Deported! Hex head plug... we're lifelong partners.

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You need to get a Milwaukee m12 impact driver (yes I’m partial to the brand, the smaller size is nice but of course any brand will work) Find them on sale at Home Depot, get a 3/8” and can use it for a lot of the work on the car as well as removing lug nuts. Do NOT reinstall the drain plug with it, but it’s very helpful for removing stuck bolts. You may also then want to replace it with a male hex plug rather than the female type you have currently. Then you can use a regular socket.
 
e9Leveque said:
You need to get a Milwaukee m12 impact driver (yes I’m partial to the brand, the smaller size is nice but of course any brand will work) Find them on sale at Home Depot, get a 3/8” and can use it for a lot of the work on the car as well as removing lug nuts. Do NOT reinstall the drain plug with it, but it’s very helpful for removing stuck bolts. You may also then want to replace it with a male hex plug rather than the female type you have currently. Then you can use a regular socket.
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I have an impact drill. The problem is, most Allen plugs are mounted to the side with no room to use a drill. I convert all to a hex head when I can as I am doing with my CSi.
 
BTW... upon removing both Allen plugs on the gearbox and draining the oil, this is what I found on the drain plug magnet. I don't know what most experience and I don't know how long it's been since my gearbox oil was changed, but this was more metal filings than I would expect to see.
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The CV axle bolts are my favorite version of allen.

I'm not a pro but a few pieces of metal on the trans magnet seems normal to me, at least the manual.
 
an old BMW mechanic i know, once showed me his MB tool that was like a boxed end wrench with a one sided allen key in the other. he had one at 17mm and one 19mm - they were only 1/2 " thick or so.
 
You really shouldn't replace a tapered plug with a straight cut one. The tapered plug seals as it gets tighter. With the straight cut plug it is only grabbing the first threads and might strip, plus there is probably no flat sealing surface on the transmission for the washer to seal on.

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starcruiser said:
You really shouldn't replace a tapered plug with a straight cut one. The tapered plug seals as it gets tighter. With the straight cut plug it is only grabbing the first threads and might strip, plus there is probably no flat sealing surface on the transmission for the washer to seal on.

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I doubt that the oil plug in m30 blocks are tapered.
In the parts book they are specified as an M22x1,5 thread (metric), and that by definition isn't tapered. Secondly, the partsbook show a crush ring which would then be a second barrier which is unlogical. Also, a crush seal can't seal if the required compression isn't reached, which is tricky to get right with a tapered thread: it then would need to be cut so that the plug depth would be an exact value, which is contrary to the concept of tapered plugs.
Generally tapered is choosen to overcome tolerances; if the hole /plug dimensions are a bit off from nominal, you just set the plug deeper/shallow.
 

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i have an allen socket but the post is too long to get into the space. you could only do it with a torque wrench on a bench when it was removed from the car ...
 
Not tapered.
Tapered plug requires too much torque for aluminum pan.
 

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Very late e24 side loader differentials have 3 plugs
Two in the rear and one on the bottom

There is no fill plug on the side like early differentials
 

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