Have disassembled the pump and am at the re-assembly stage. Regarding the impeller shaft pitting; Mine shows distinct grooves around some areas, but they do not correspond to the critical sealing surfaces in the tech article,
http://www.ibmwr.org/ktech/water-oil-pump-rebuild.shtml
and the pitting is approx the same. I was thinking of doing some sort of salvage job with a thin layer of JB weld and some fine grade wet & dry. Good idea, or am I mental?
Also, do I have to replace my old cast iron impeller with the more "angled" version in the article (presumably with the spacer that comes in the re-build kit)?

Hi there, I dont think its a good idea, youll have two diferent metals in an allready corrossion sensitive area, this can increase corrossion rate. And if the filler goes off it will destroy the seals. If the working surfaces are compromised is safer to change the shaft.
Regarding the impeller, if the old one is not worn I´ll use it, in fact I did not change mine, and its been working for the last 4years (25000kmts), I also think that cast iron is better impeller material than steel sheet.
Best regards
JAP

Yeah, new impeller shaft then!! I'll put back the cast iron impeller as well if there is no need to change it. Looks good to me!
Cheers then JAP!

"Yeah, new impeller shaft then!! I'll put back the cast iron impeller as well if there is no need to change it. Looks good to me!"

When you fit the new type water seal you will find that the cast iron impeller will not sit down fully on the end of the shaft, and will press on the seal if you tighten it. This is not good to say the least, as it will damage the seal. You will have to grind or machine about 4mm from the back of the impeller to let it clear the seal and sit down fully on to the shaft. I reckon that it would work OK having done this, I just didn't get a chance to try it. Check out my posts in link below.

http://k100rt.aforumfree.com/t1112p45-waterpump-seal-special-tool

Oh blimey!!
Well, if its not to expensive, then I might as well just get the pressed steel impeller then. I've already got the spacer anyway. Not sure if I can be bothered to put back the cast iron one if it involves altering the part.
Great advice from everyone! Thanks! Why can't we run countries like this?!

Just been told my parts have to come from germany and will take another week. Bike standing with no oil and water. This is probably not good for it re bearings etc. Any wisdom out there?? While I'm at it, what spec oil should go back in, and it is supposed to be silicate free coolant in the cooling system..the luminous orange stuff?

If the bike was recently running then there will be no problem with it standing idle with no oil. Remember, things like the crankshaft, output shaft, cam shafts etc don't lay in oil, they rely on oil being pumped through them when the engine is running.
As for the coolant, standard green stuff is ok, about 50% coolant and 50% water I think.

Oops, sorry, forgot about the oil - I use 15W40 high detergent diesel engine oil, all year round. Good for the starter sprag clutch as well. Change it and the oil filter every 5000 K's and shell be sweet. Remember, Dennis' golden rule - never ever cane it when the engine is cold ! People who do this (to any engine) should have a slow and painful death inflicted upon them !

I try to pass this important piece of info along to friends too. Warm it up or drive away slowly. I reckon people nowadays think it's OK to press the pedal to the floor or give it too much stick moments after startup because modern fuel injection fools us into thinking the bike or car's running alright even when it's stone cold, not like the olden days when we had hand chokes or even a carbie with a choke we had to set. The engines ran like a turd until warmed up enough to go well and that somehow made us more aware of the engine's lack of proper operating temperature. I suspect that fully synthetic oils are doing a better job of lubrication when cold than 'traditional' oils.

As an aside to this discussion, I do a bit of casual work at a local Subaru/Mitsi workshop and noted that recently Subaru has begun to use 0W20 oil all year round in the newest versions of the Boxer motor. Talk about tight tolerances!

The Dodge dealer I retired from went to 5w20 several years ago and before M-Benz left and pulled the Sprinters they were 0w40 Mobil One.

yes, all those manufacturers have reduced the internal clearances over the years, thanks largely to better materials (metallurgy), better tooling and CNC machines. But remember, none offer Nicasil cylinder linings or hard chromed crankshafts. This is the reason the K's were not cheap to purchase, at the end of the day we have an "industrial strength" engine which is full of typical German over-engineering, including a huge cooling system and heaps of oil with a big pump (forgive me if I sound like I'm going on about this but at the end of the day this adds up to one thing - Quality).
Still, it doesn't matter how well it's been manufactured, cane it when it's cold and you'll kill it ! Long live the K, and lets get the bloody Tee shirts happening,..................... 'nother red wine,.............. ....... ..... ... .zzzzzz

Lots of cooling and lots of oil volume always made a very robust engine aka industrial diesel engines.

At the moment I do not know if its poss to source another impeller. None in UK. Not sure about germany yet!! Thinking of making the old one good again. I'm gonna ask an engineering Co. to build up the shaft and then grind it back to its original spec. What d'ya think?

Any good machine shop will be able to do that for you, in my years in the car business I've seen our local shop do some amazing repairs.

Where are you trying for the parts? Did you try Motorworks or Motobins? Both of them should have what you need.

Hi, have you tried maxbmw? wen I repaired my pump I used the old impeller with a new old model shaft and didnot had to modify the impeler, also didnot brake the water seal. There are two new style (slip ring) water seal models one for the 19 teeth safth and one for the 32 teeth shaft. If you check the pump diagrams there are two of them. In my case I also called seller to be sure that nothing was missing.
Best regards
JAP