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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Nothsaw on May 18, 2020, 11:32:19 AM
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Hello all first post. Recently bought my first K-Bike, an 87 k75. When I bought it, it had oil/coolant leaking out of the weep hole under the oil/water pump mainly when hot. After some research I decided to replace the seals. Once replaced the oil/coolant leak stopped for about a week. Noticed another puddle under the bike. This time it's still coming from the weep hole but is only oil. No indication of oil in the coolant or vice versa. Also it seems to leak even with the bike on the stand for a few days. I'm assuming this means it doesn't have to do with anything specific to when the bike is running. Any ideas? Any help would be much appreciated. Don't really have any mechanical background and this is my first time wrenching on a bike. Please be gentle lol. Thanks all.
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After some research I decided to replace the seals. . . . Don't really have any mechanical background and this is my first time wrenching on a bike.
Does this mean somebody else replaced the seals the previous time?
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I changed them myself after I noticed the first leak that was coolant and oil.
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OK, then. This is your second time wrenching on your bike. :laughing4-giggles: What exactly did you do the pump the first time? Which parts did you replace? What was the condition of its impeller shaft?
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Haha I guess you're right. The shaft was in great condition. I replaced the oil seal and the coolant seal both were in awful condtion it looked like PO just shoved them in there with a flathead screwdriver, the impeller itself because it was the old cast iron one. New one came with a spacer. A red o-ring on the coolant side as well as a tiny o-ring that was on the end of the smaller drive gear on the oil side. Used "The Right Stuff" RTV to seal it all back up. Also had to replace some of the bolts that mount the pump as they were way too stretched out for my liking.
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If you're certain that leak is coming from the weep hole, you'll be joining the ever-expanding group of members who have needed to do this job more than once to get it right. Thorough surface cleaning and patient assembly are requisites. Which resource were you using for instruction?
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I used this handy video from the University of Youtube. https://www.youtube.com/watch?v=nzxdMe8ICYU
Now that you said that, it has me thinking. I wonder if the leak is coming from the oil filter cover and because I have it on the center stand it is running forward near the weep hole being deceptive... At work currently once I get the chance I'll clean the belly and watch it to see where it's coming from and report back.
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As I suspected it is coming from the weep hole. boohoo
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Laitch, do you suggest replacing the seals again or just re-doing the RTV?
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I refer you to Reply #5.
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Just figured I would follow up with this.
Ordered a new oil seal and a new Coolant seal.
Spent Saturday morning mostly looking for shade from the AZ heat.
Once I found enough shade I got to work.
Meticulously took apart the pump and replaced the Seals.
Spent a couple extra hours just being careful.
Put everything back together and took it for a test drive.
I thought the guy next to me just wanted to race but when I returned home I realized he was trying to warn me about my loose hose clamp. I was spewing coolant all down the street 44271
Checked over everything once again and tightened the hose clamp. Took it for another spin. Was fighting ladies off left and right.
Returned home once again and voila, no oil leak! Seems the issue was the oil seal wasn't properly seated because of my "rushed" first repair.
Thanks for the guidance.
On a side note, does anyone know where to get some of the extra long bolts and mount the pump from inside the coolant side? Noticed one wasn't in the best shape.
Thanks again for all the help!
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On a side note, does anyone know where to get some of the extra long bolts and mount the pump from inside the coolant side? Noticed one wasn't in the best shape.
Thanks for the followup. 112350
The bolts are listed as 8.8 M6x60 in the BMW fiche. Zinc-plated should be ok, but if the old screw is holding, whose going to see it? Is it rusting out? Home Depot advertises them online. Probably Ace and the rest have them, too; otherwise, it's money to your favorite dealer.