Author Topic: final drive vent/weep cap  (Read 289 times)

Offline k75_oakland

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final drive vent/weep cap
« on: May 12, 2022, 10:53:05 PM »
I have a new-to-me k75 that I immediately changed the fluids on upon buying, including final drive. I filled per the shop manual. I just noticed that a little bit of the oil is weeping out of the little black cap atop the final drive. Given that I have just read this is called the "vent/weep cap," perhaps this is stupid question, but is it normal for it to be weeping some oil? Just wondering what that indicates.

thanks
  • Oakland, CA
  • 1986 K75C

Offline Laitch

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Re: final drive vent/weep cap
« Reply #1 on: May 12, 2022, 11:22:19 PM »
I haven't had that occur on my Brick yet. I change the rear drive fluid every year. What type of fluid did you use, how much did you use, and was the rear drive warmed up when you drained the old fluid?
  • Along the Ridley in Vermont.
  • 1995 K75 80,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline k75_oakland

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Re: final drive vent/weep cap
« Reply #2 on: May 12, 2022, 11:50:48 PM »
I used a synthetic hypoid gear oil that met the spec in the shop manual. I followed the directions in the book, but now I can't remember if it was warm--I changed the engine oil when it was warm, but it may have cooled off by the time I changed the drive oil.

What effect would that have--if it wasn't warm? Would the oil level be too high (hence the weeping)?
  • Oakland, CA
  • 1986 K75C

Offline Laitch

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Re: final drive vent/weep cap
« Reply #3 on: May 13, 2022, 12:59:47 AM »
I used a synthetic hypoid gear oil that met the spec in the shop manual. I followed the directions in the book . .  .
I was hoping for a less vague answer, but let's move on.  :laughing4-giggles:

Lubricants drain from components more efficiently when they're warm. I change engine, gear, rear drive and fork oil after I've taken the moto for a ride. I let components drain thoroughly then refill them. To reduce obsession about this, I suggest you take your motorcycle for a ride, drain the rear drive again, then refill it. Use a measuring container but don't refill it above the lowest thread in its filler opening regardless.
  • Along the Ridley in Vermont.
  • 1995 K75 80,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline frankenduck

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Re: final drive vent/weep cap
« Reply #4 on: May 13, 2022, 05:24:08 PM »
In decades of playing with K bikes I've never seen gear come out of the final drive vent cap. (Except- for the first time I took one off without draining it and laid it on its side without emptying it. DOH!)

Did you fill it to the bottom of the threads on the final drive filler hole?
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Offline k75_oakland

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Re: final drive vent/weep cap
« Reply #5 on: May 13, 2022, 05:29:27 PM »
 
Quote
was hoping for a less vague answer, but let's move on.

sorry, I know that I gave a vague answer, I was just being lazy because I didn't want to go down a few flights of stairs to see the bottle.

Bel Ray Hypoid gear oil, 80W/90

Yes, I filled it to the bottom of the threads in the filler hole. Seems like I should open the filler and check to see where the level is now...
  • Oakland, CA
  • 1986 K75C

Offline Laitch

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Re: final drive vent/weep cap
« Reply #6 on: May 13, 2022, 06:32:26 PM »
Sure, look at the level when its cold. Adust it if necessary. Clean off the vent and ride. I always drain lubricant thoroughly and measure carefully, but I'm just an instruction-following drone. :laughing4-giggles:
  • Along the Ridley in Vermont.
  • 1995 K75 80,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline k75_oakland

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Re: final drive vent/weep cap
« Reply #7 on: May 13, 2022, 07:46:45 PM »
Is it better to check when cold or warm? Your first response made it sound like it should be filled when warm. Or is it just drained when warm?
  • Oakland, CA
  • 1986 K75C

Offline Laitch

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Re: final drive vent/weep cap
« Reply #8 on: May 13, 2022, 11:07:41 PM »
Is it better to check when cold or warm? Your first response made it sound like it should be filled when warm. Or is it just drained when warm?
I drain the components when the moto has been warmed up by riding it. I check levels when it hasn't been ridden or when it has cooled down for a few minutes after operating it. My Brick has not leaked, weeped or consumed engine or drive line lubricants, or coolant either. I did have a Rambler station wagon once that used a quart of oil every ten miles: that one needed infusions of fluids regardless of whether it was hot or cold. :laughing4-giggles:
  • Along the Ridley in Vermont.
  • 1995 K75 80,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Past-my-Prime

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Re: final drive vent/weep cap
« Reply #9 on: May 14, 2022, 10:35:11 AM »
Although I've not had fluid leak from the top vent I did have a leaky seal at one point, leading to FD fluid on the rear wheel. Seal replaced = no more leak. (I got a local motorcycle repair shop to do it).
Are you completely confident that the oil is coming from the vent? Might it have leaked when you took off the FD in order to lube the splines and may have laid it on its side?
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Offline k75_oakland

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Re: final drive vent/weep cap
« Reply #10 on: May 14, 2022, 01:29:08 PM »
Itís definitely coming from the ventójust a small amount, we arenít talking a lot of fluid. I havenít lubed the splines yetóthatís next on my list of maintenance.
  • Oakland, CA
  • 1986 K75C

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