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Discussion Starter · #1 ·
Removing the PO's sealant job from the plastic drain plug on my 82 GL500's radiator, that plastic head came right off at the sight of my spanner. So, soldering iron came out and I melted a groove good enough for a flathead. Easy-peasy and no resistance in the screw (it was the source of a coolant leak, so not surprised).

After looking at other member's use of steel replacements, I looked nearby for M12x1.25mm screws, found none, then called True Hardware who had a 2" bolt with a 1 1/4" head. No thanks! Autozone, though, after I explained to the guys where the plastic piece came from, showed me the oil drain plug for a nissan. Same thread size and 14mm vs. the 12mm plastic. Well, it comes with its own washer, so I thought I'd give it a go doubling up with the original rubber gasket.

This picture illustrates the damaged plastic drain plug next to the new part. Then, the thing installed. Have since run the engine, topped the fluid back up, did the reserve, no leaks. Wind and rain came in hard tonight so, she doesn't run until the morning.
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I was able to obtain a 12 x 1.25 drain bolt for my GL650 from the Salvo Auto parts store... I have since then just ordered a new Honda drain plug (plastic) as I am a bit concerned about galvanic corrosion issues with the steel plug...

19013-415-004 VALVE, DRAIN $6.24
 

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'84 CX650E that is evolving into a GL500
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Honda used a plastic drain plug for 2 very good reasons 1) no galvanic reaction and 2) you will twist the head off before you damage the threads in the rad (plastic drain plugs are always cheaper than rads).

No matter which drain plug you use you should absolutely never put a socket wrench on it. The torque you apply to a bolt is a function of the force you apply and the length of the lever (wrench handle). In the case of a drain plug threaded into a brass radiator the optimum handle for most people should be about 6" long.

On the subject of overtightening & wrench lengths:
In my shop I have a rule that sockets are only for removing fasteners and that (unless a torque wrench is called for) combination wrenches or box end wrenches are always used for doing things up. The idea is that a smaller wrench should be shorter because it takes less torque to snap smaller bolts. In the rare cases when I have to use a socket to tighten something (like the spark plugs) I have a stubby ratchet (about 4" long) - it provides more than enough torque for any socket up to 14mm, especially when followed by the torque wrench.
 

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Discussion Starter · #4 ·
Torque responsibly, always
 

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I was able to obtain a 12 x 1.25 drain bolt for my GL650 from the Salvo Auto parts store... I have since then just ordered a new Honda drain plug (plastic) as I am a bit concerned about galvanic corrosion issues with the steel plug...

19013-415-004 VALVE, DRAIN $6.24
The plastic draincock is available at all my local auto parts stores. I bought the Dorman (in a "HELP" brand blister pack) one at Pep Boys yesterday for $4.
 
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