oil change concerns

[Dan89FLSTC]

I have a question...trying to understand the problem with the o-rings (my bike is an `89 so it does not use o rings on the drain plugs). On the plugs that use the o rings, is there a recess that the o ring fits into, or does it just get flattened between the plug head and the case?

 

[RetiredJake]

The design for this o-ring is not optimal. There is a relief on the threads for the o-ring, but no groove for it to sit in. As a result, it gets flattened between the head of the plug and the case. This is the reason it should never be reused, no matter what it looks like. If you resuse it, it will look like the one above and there is a very good chance it will leak.

 

[Joyflyin]

The design for this o-ring is not optimal. There is a relief on the threads for the o-ring, but no groove for it to sit in. As a result, it gets flattened between the head of the plug and the case. This is the reason it should never be reused, no matter what it looks like. If you resuse it, it will look like the one above and there is a very good chance it will leak.

Jake, thanks for that explanation. Now I know why the o rings end up looking the way they do. I mainly replace them because I was told that it was best to do so, and it worked well for me, so I don't argue with what works. :s

 

[PigSnot]

Reading this thread, thought I’d go measure how much was drained from the primary chain case after I’d siphoned out 4 oz previously to address the clutch drag. There was a total of 48 oz. Guess that explains how 4 oz made such a significant difference on clutch drag. Bike came this way.

After doing the comp sprocket install, added 45 oz of Formula + for a dry fill as per manual, 07 Road King. (Normally would be 38 oz) Level is just above bottom ring of Clutch basket, and clutch is fine, no drag. Just thought I’d share this, as per posts above.

I’m having good success without pipe dope; New O ring on drain plug every time + torque to spec -> no leaks or weeping. Drain plug O rings (PN11105) are available separately.

I too always find explanations most interesting and helpful. Leads to understanding the why’s. Thank you all.

 

[greasit]

don't be surprised at what you find when you pull your drain plug, or look at anything else. While my bike was in for starter repairs under warranty, one of the techs changed the oil on my bike by mistake. I don't like the syn3 they use, and it was within 100 miles of the oil change/service i was going to do anyway, so i changed the oil the next day. The 3 attached photos show what i found. The o-ring had not been changed, pipe dope was used to excess. This is the mark of a lazy tech, much easier to slap some pipe dope on it rather than clean the plug, pull the o-ring and slip a new one on.

Note the pipe dope partly covering the magnet

sorry for the focus, but the white area way back inside is pipe dope

this o-ring is definately older than 2 days

it looks like the most common mistake in applying teflon tape was made on the plug in the picture. It should be applied down a couple of threads from the end to prevent the end of the tape from tearing off and going in the oil sump. Also why would you apply tape on a straight thread to seal when the o ring does the sealing against the tank? The tank should be counterbored or beveled to accept the o ring and not tear it. But again i said it should be. If the o rings are getting torn, its a lousey machining job on the tank. Most hydraulic fittings with o rings can be tightened and reused over again until they loose there flex, they shouldn't tear or they will leak. You should be able to wind the plug in until the o ring hits and then just snug it to compress the o ring.