Gday all, I am in the process of putting my old 8/85 K100RS back on the road after i parked her 21ys ago.  I have had it running and with usual issues.  ( minor rat damage, speedo gears, master cylinders etc)  
I ran her up on the stand while testing the rear brakes for sticking on.  I didn't notice the fan had not kicked in until the over-temp light came on.  Yes was hot but plenty of coolant.  A check of the coolant showed it was down a little, nothing obvious in the oil sight glass.  When i topped it up via the radiator cap i noticed a few small blobs of black/dark brown oily traces on the top of the coolant.  
The oil/water pump hole appears to be clear.  (stuck a plastic zip tie in there and no coolant or oil traces there).

I have ordered now water/oil pump seals but am a little concerned that i may have injured the head gasket.

Looking for some ideas please on what to test or which way to go?

Cheers
Kev

It's the water pump. K bike head gaskets don't fail.

duck wrote:It's the water pump. K bike head gaskets don't fail.

Tell that to Smithy but it is the exception and will almost certainly be the oil/coolant pump.

Thank you. I'm hoping to get a look at it soon. Work has been getting in the way.. . I'm looking forward to getting back on the road.
New fan and coolant hoses on the way. Thought I would cover those bases while the radiator is out. (The old fan has fried a brush)

Cheers
Kev

Rick G wrote:

duck wrote:It's the water pump. K bike head gaskets don't fail.

Tell that to Smithy but it is the exception and will almost certainly be the oil/coolant pump.

I do know one head gasket failure - at 215K miles on a K1100LT that spent life dragging around a hack.

Just waiting on parts from Western Australia...  god bless Aussie Post.    The hole was blocked also,  hence no warning sign of the leak.    Cheers all
Kev

Yeuk. Looks like a PO has been in there and couldn't be arsed to fit a new seal. Search the forum on how to do it BEFORE trying to have a go. Two things will happen otherwise:

- you won't get all the old seal out
- you'll break the new seal trying to seat it.

Here you go: https://www.k100-forum.com/t886-oil-water-pump-rebuild

Thank you... full kit coming and with your info and Dr Google, I will give it a crack. Thanks again.

Once it's all back together give the coolant system a couple of flushes with a non foaming detergent like a dishwasher detergent to get any oil residue of the internal surfaces. The oil wont dissolve in the coolant and slows heat transfer to the coolant.

Copy that mate, will do.

Cheers