Hi,
A local bike breaker has a K100 water/oil pump for sale, thinking of getting it as a spare, to rebuild.
Is the pump fitted to a K100 the same as one on a K75C?
M

The pump itself is the same, front cover is different.
Pumps from before -90 have better capacity.

Turns out the breakers bike is post 1992, and mine is an 85 - so doesnt look like it will work.

Why was I looking? well I noticed a tell-tale stain on the garage floor, after putting the K75 back into service (and done a few hundred miles), this stain appearing underneath the weep hole.   

Possibly to be expected, on an older bike, but a little frustrating. Sofar I have done a routine service (oils/filters) and regreased the reardrive shaft splines; fitted fork gaiters...wonder how long this list will get  

I guess this was/is another 'area' that can be problematic on the K. Anything else spring to mind   

I see on here http://www.largiader.com/k75/ its says: "...Look for oil seepage from under the oil/water pump and also from the rear of the engine; usually on the left side. Rebuilding the oil pump is not always successful..." gulp    

Looked in the Clymer/Haynes/BMW manuals as well as/after reading several posts on here. [Wot a great resource - some links with the pictures seem invaluable, hoping fitting/repairing is achievable - some posts have given the encouragement that it might be...]. :| 

.....and have taken the plunge and have ordered a seal-kit and impellor. I may try and fit this myself or may entrust this to a locally (respected) mechanic/engineer....that might be more sensible than me 'having a go'; a little scared to be truthful  :suspect: 

Hopefully it will be repairable (and succesfull!).

Wish me luck!
Mark

Also ordered the "rubber boot" for the clutch pushrod near the actuating arm....might as well swap that out too, as it seemed a bit messy/oily around there as well. I guess I will have to assume the actuating arm pin will be seized, although clutch feels ok. Not sure I am brave enough to do that as well...just yet!   

mhsilverw wrote:Turns out the breakers bike is post 1992, and mine is an 85 - so doesnt look like it will work.

Why was I looking? well I noticed a tell-tale stain on the garage floor, after putting the K75 back into service (and done a few hundred miles), this stain appearing underneath the weep hole.   

Possibly to be expected, on an older bike, but a little frustrating. Sofar I have done a routine service (oils/filters) and regreased the reardrive shaft splines; fitted fork gaiters...wonder how long this list will get  

I guess this was/is another 'area' that can be problematic on the K. Anything else spring to mind   

I see on here http://www.largiader.com/k75/ its says: "...Look for oil seepage from under the oil/water pump and also from the rear of the engine; usually on the left side. Rebuilding the oil pump is not always successful..." gulp    

Looked in the Clymer/Haynes/BMW manuals as well as/after reading several posts on here. [Wot a great resource - some links with the pictures seem invaluable, hoping fitting/repairing is achievable - some posts have given the encouragement that it might be...]. :| 

.....and have taken the plunge and have ordered a seal-kit and impellor. I may try and fit this myself or may entrust this to a locally (respected) mechanic/engineer....that might be more sensible than me 'having a go'; a little scared to be truthful  :suspect: 

Hopefully it will be repairable (and succesfull!).

Wish me luck!
Mark

Also ordered the "rubber boot" for the clutch pushrod near the actuating arm....might as well swap that out too, as it seemed a bit messy/oily around there as well. I guess I will have to assume the actuating arm pin will be seized, although clutch feels ok. Not sure I am brave enough to do that as well...just yet!   

The 92 pump will work with the 85 engine. If the pump has not been changed/upgraded on your 85 then it will have the water pump impeller held on by a nut on the end of the shaft. This arrangement is very weak, and will probably break when re-assembling it. This means that you will have to remove the shaft again, thus destroying the new water pump seal in the process. The later pumps (from sometime in 86 I believe) have the impeller held on by a bolt threaded into the shaft. If you pull the front plate off the water pump you can check on what is in there. If it is the old type you will need to replace the shaft as well.

For what its worth I just did mine, 84 K100 RT. When it was opened up the shaft was in s**t too. I got someone to do it but he had disagreed with my instruction to order up the complete new pump and not just the seal kit as we were ordering parts before going off road. We then had to order the shaft and some more parts which was annoying. I would follow Avenger GT's advice.

Interestingly afterwards there was a small drip after starting up, that has since stopped and seems fine. No top up needed in 2,500 miles.

my 85 k100rt had a leak too. it only had 25k on it at the time
had a spare engine off a 91lt, it was a later design but the shaft was all pitted and goughed up.....
i ended up buying a new shaft/impeller/seal kit.
not a drip in just over 3k miles.
i also had a leaky clutch boot, the one on the 91 was good.
fix it right the 1st time so do you not have to worry about it miles from home.

I also did the clutch boot and a new clutch cable. My RT came to me with 36k miles.

Chances are your shaft is kaput too.

Avenger GT wrote:...85 then it will have the water pump impeller held on by a nut on the end of the shaft. This arrangement is very weak, and will probably break when re-assembling it....

It was and it did (the mechanic/engineer doing this called me today to advise it broke, when dismantling) so a new shaft ordered    to accompany the seal kit I'd already acquired.

Mark

mhsilverw wrote:

Avenger GT wrote:...85 then it will have the water pump impeller held on by a nut on the end of the shaft. This arrangement is very weak, and will probably break when re-assembling it....

It was and it did (the mechanic/engineer doing this called me today to advise it broke, when dismantling) so a new shaft ordered    to accompany the seal kit I'd already acquired.

Mark

At least it happened on the way out. Mine happened on re assembly. Ended up fitting a later type new pump.