Went to the BMW rally in Maryland this past weekend. Was a great time. Lots of good folks and nice bikes. had an issue when was leaving. Had a coolant leak. pulled her apart and found a friggin mouse nest on top of the motor! couldn't get to it without yanking the faring off. Anyways too decided to go for it. Stopped halfway and checked didn't loose anything. Got home, took the faring off and removed the nest. Found oil on the top of the motor. Looked like some new, some old. Cleaned it off. Ran the bike for 20 minutes and no oil or coolant leaks.  Any idea where it may be coming from? As for coolant I am ordering a set of new hoses. Looks like a Grand time replacing them. My buddy was giving me a very difficult time over my "old" bike. Then she decided to start pissin all over the place!  Was very helpful.

Oil could be from the crankcase breather that goes into the airbox.  From there the oil can get out through the holes for the screws that hold the box in place.

Why are you replacing the coolant hoses?  Are they deteriorating?  The only damaged hose I have replaced was torn in lowside slide.  The coolant hoses on the bikes I have owned have held up very well over the years.

Let your buddy bad mouth your bike.  Bricks and cockroaches will be the only things still working after the apocalypse.

Hello .75, The hoses don't look bad but I had a pretty good leak going there for a while. Am going to look them over again today and see if they look cracked at all on the connections. The leak seemed to be coming from the long hose behind the radiator that goes across the top of the block. It just seemed to go away though. Hopefully the oil is just that breather. Am going out to check it out. Put cardboard under it on center stand. Should let me know if anywhere else shows leakage.

My buddy has a 22 GS850. There was a bunch of this style bike there. There were only a few bricks and only 1 1985 K100rs (mine). She got a lot of lookers.

fishboy316 wrote:The leak seemed to be coming from the long hose behind the radiator that goes across the top of the block. It just seemed to go away though. 

What's the level of the coolant in the reservoir beneath the seat? Is the level tube still transparent?

Hi Laitch. No it is not transparent. I did look in and it was 1/4 or so full. Rode it home 85 miles and lost a tiny bit from the radiator. Pulled off lower faring's and cleaned all the messes up. Maybe this will show where it is leaking. Looking today nothing seems to be leaking. 

Thanks 
Bill

fishboy316 wrote:I did look in and it was 1/4 or so full. Rode it home 85 miles and lost a tiny bit from the radiator. 

That isn't enough coolant in the reservoir. Have you flushed and replaced the coolant system since you've owned this relic? If not, you probably should get on that. In the meantime, fill it up to the Max level indicated by embossed letters on the tank's side and by the green arrow in the attached photo. Replace the tube so you can see what's going on in there. You don't want to be running with a low coolant level.

I have found a small leak. It is up front at the radiator where a couple of hoses meet. The long hose with the 90 on the end. Appears to be a small drip. Looks like a couple hoses meet there. What is confusing me is that coolant seems to gather in the coil cover and drip from there. At least that is what it appears to be doing when on the side stand. Could be more than 1 leak I guess. I am about to do the flush when I find the leak and take care of it.

Thank you for your help. Both of you guys.

Bill

Clean the area real well and get some talcum powder from the drug store.  If you can, get the stuff in a spray can.  Then dust the area with the powder.  Take the bike for a ride and when you come back the leak(s) will be easily visible in the powder.

fishboy316 wrote:I have found a small leak. It is up front at the radiator where a couple of hoses meet.  What is confusing me is that coolant seems to gather in the coil cover and drip from there.

If the coolant from the front leak isn't flowing over the block to the rear then dripping as Earth rotates on its axis, look for a leaking freeze plug—a dished, flat-bottomed, circular plug recessed into the rear of the engine block left of the coil cover. In the attached photo, the oxidation from a freeze plug leak on a K1100 left a trail on the block. When the engine wasn't running, the plug would leak when the radiator cap was removed. The coil cover is at the upper right; the spark plug wires are visible. Your engine's freeze plugs might slightly differ in appearance and location.

Laitck, I only see it when it is running. That could be it though. It is certainly in the right place. 
I will powder that area also. On a bright note have been parking on a piece of cardboard to see if any oil leaks and so far nothing. 2 days. Rode about 25 miles last night. 

Thanks

I am not getting the leak anymore. I did find that the Z-hose is all cracked up. Ordered one for replacement. Checked the coolant and none seems to be gone. I am sure it will happen again.
Also filled to max.