I will mill the gear face on the lathe to remove scratches. I will fit the housing to get the desired tolerance

What should be the clearance between the housing and gears (big and small)

Haynes manual states that there are no service limits given, and also no operating pressures are stated, only the minimum pressure range that causes the oil pressure light to come on (3 - 7 psi).
As for the pump internal end clearances, I suggest for a gear pump of that size you need to aim for aroun 0.05 mm (0.002") maximum end clearance (gear face to cover). Check it using Flexi-gauge, do you know the stuff ? Looks like plastic spaghetti and is available in different measurement ranges. Place it in the space (hold with grease), assemble components dry, dismantle and use the scale on the packet to measure the flattened width, which translates to the thickness. The final oil pump assembly must be done very carefully in respect to achieving an oil tight joint at the front engine face. This is a high pressure joint (full pressure before the relief valve). BMW states 3Bond 1209 I think. I used Loctite 515 Master Gasket with the mating surfaces primed with Loctite Primer T and allowed to cure. Do not touch the primed surfaces before applying the 515.
Good luck, hope this helps.

Using Loctite activator (now is 7471) is necessary?

I can only speak from my own experience with my water/oil pump rebuild. I tried twice to effect a seal without priming, but no luck, oil still weeped from the joint, can be felt by poking little finger in the hole the oil pressure switch wire emerges from.
The primer chemically etches the surfaces, preparing them for the curing process for the 515 Master Gasket.
I experimented with the effectiveness of the primer by applying it to 2 zinc plated bolt heads then applying the 515 and allowing to cure, vs just applying the 515 to 2 other bolt heads. The difference in force required to break the seal is quite amazing.
Loctite products cure by removing the air (anearobic curing process).
I couldn't obtain the 3Bond product, so the Loctite had to do, that was 2 years ago, no problems since.

In service manual K1100LT BMW don't say anything about Loctite between the engine and oil pump housing...

I know it's not an argument...

Loctite 518 this Loctie is quite stronger

or Loctite 5188

Now I have all of the issues sorted and had a good ride on the bike today it has decided I need to spend more time with it by dumping some oil on the garrage floor. From the hole in the water pump.



Being a low km 85 model I expect the water pump shaft will be the old style so I have a question. Has anybody cut the thread off the end and drilled and tapped it to take a bolt? I don't have it apart yet so don't yet know if the design makes this possible.

Another thought, it's leaking out of a hole big enough to fit a small finger into next to the sender, not the drain hole at the bottom of the sump??????

oh bugga !!! peter ....

i wonder if thats the hole for the temp sender on the rt models ....is it threaded ? ....(might have to clean it out with some dereaser to see properly )

Found this pic on the net. Leaking out of the hole to the right and above the 2 machined holes. The machined holes are the sender and drain I think.

pjjms wrote:Another thought, it's leaking out of a hole big enough to fit a small finger into next to the sender, not the drain hole at the bottom of the sump??????

I`ll guess your weep hole is blocked, then the oil searching other ways to get out.

Inge K.

I'll almost gaurantee you have a leak at the joint between the pump casing and the engine. The hole you speak of is where the wire for the oil pressure switch threads through and when the joint leaks oil runs around the pump casing and collects in that void space. This happened to me 3 times when I rebuilt my water/oil pump. In the end I managed to get a seal by using Loctite Master Gasket 515 and preparing the surfaces with Loctite Primer T. The manual states a 3Bond product (can't remember the number).

Remember, this joint is under full pump pressure, unlike most other joints on the engine, that's why a high pressure sealant which is not brittle is required. Don't try normal RTV silicone, it will leak, and so will Permatex (both my experience). Hope this helps.

ah ! mystery solved dennis .......good work

Dennis wrote:Don't try normal RTV silicone, it will leak, and so will Permatex.

Could be that I`m just a very lucky guy, had this problem 16 years ago.

And did try 3 or 4 different sealants (did not have the recommended one at hand),
all started to leak after some time.

The last one I did try was Permatex blue RTV, at this day the pump is still dry.

Inge K.

You were right Dennis. Took the pump off this morning, resealed and so far no leaks. Used Loctite 510.



Thanks for the help guys.



Peter

I used Loctite 5920 Premium Copper silicone on mine over a year ago, and 5000 odd miles later it is still oil tight.

Dredging up an old thread to ask "Would Permatex High Heat Red RTV possibly work to bond the pump assembly to the engine block (given Permaex Blue worked at least in Inge's case)?" Reason is I have this in the chemicals drawer in my workshop.

I have used it for that exact same job and all is well with the pump still, just be careful with the oil drain hole.

I am a bit too far from home to check my sealant draw but used a red sealant on the water pump that I think was Permatex Red. It came via a big company that used radial engines which was used to seal against oil not coolant so should be good.

Crazy Frog wrote:

This is the mine
https://drive.google.com/file/d/1bw1fmaox4J76DHogkdg0cEfus3_L906J/view
https://drive.google.com/file/d/1br03h1dA6leigGZ08kKREYGLaQ6RVYLj/view

can i reuse it?
Thanks

Zisco wrote:This is the mine
https://drive.google.com/file/d/1bw1fmaox4J76DHogkdg0cEfus3_L906J/view
https://drive.google.com/file/d/1br03h1dA6leigGZ08kKREYGLaQ6RVYLj/view

No images are being displayed in your links.

Now?
https://drive.google.com/file/d/1bw1fmaox4J76DHogkdg0cEfus3_L906J/view?usp=sharing
https://drive.google.com/file/d/1bpgBUwTbkGqDlFkHJ6fKxFMDdBuSXgyS/view?usp=sharing
https://drive.google.com/file/d/1bpetyGH0-ra4-E_FuhsfUUi_oj8NT4Uu/view?usp=sharing

The images cannot be seen.

Zisco wrote:

Crazy Frog wrote:

This is the mine
https://drive.google.com/file/d/1bw1fmaox4J76DHogkdg0cEfus3_L906J/view
https://drive.google.com/file/d/1br03h1dA6leigGZ08kKREYGLaQ6RVYLj/view

can i reuse it?
Thanks

From the images below (in your 2nd attempt) I'd say your waterpump shaft is 'toast', will not seal successfully, and will tear up a new seal.

Zisco your shaft is so so shafted best to use it for a paper weight,motorworks will find a good S/H unit for not a lot of money.That is what i had to do for my K.

Thanks you very much, I will a new One buy.

Hi everyone, I have another question regarding the spacer bush...
I bought a new shaft seal and new slip ring, but in reassembling something seems to me wrong, the spacer bush I have not bought a new one, I used the old one because it looks like the same but I have the impression that it is too long for the new slip ring.... 
If I tighten the bolt the spring of the slip ring, is compressed so much that it blocks the shaft and does not make it turn, however, loosening everything is fine and I have the impression that the spacer Bush is 2mm too long.... I'm doing something wrong or I need to buy a new spacer bush?
thanks

Are you installing a stamped metal impeller or a cast metal impeller?

Laitch wrote:Are you installing a stamped metal impeller or a cast metal impeller?

I already had the stamped one as standard

Zisco wrote:. . . the spacer bush I have not bought a new one, I used the old one because it looks like the same but I have the impression that it is too long for the new slip ring..

When installing the new style seal, a different bushing must also be used as in this illustration. It is a shorter bushing

Thanks for confirming, the old one is 13mm while the new one seems to be 10mm from the picture, I can’t see clearly... could I miling the old one on the lathe and lower it by 3mm what do you say?

Zisco wrote: could I miling the old one on the lathe and lower it by 3mm what do you say?

I say if you have the skill, the equipment and the measurements, do it but replacing these seals is not a job you'll want to do, or buy parts for, twice although some of us have. 

Laitch wrote:

Zisco wrote: could I miling the old one on the lathe and lower it by 3mm what do you say?

I say if you have the skill, the equipment and the measurements, do it but replacing these seals is not a job you'll want to do, or buy parts for, twice although some of us have. 

I have a friend who works with the lathe by profession, so it is not a problem but I should know the precise measurement, if 10mm or 11mm because the image does not show well…

I have already replaced the seals and everything went well… only this spacer bush is missing to close everything

[size=32]11 51 1 464 902 bushing is an approximately 6 Euro/$10 bushing which fits many '70s-era BMW cars and Bricks.[/size]

Two Wheels Better wrote:[size=32]11 51 1 464 902 bushing is an approximately 6 Euro/$10 bushing which fits many '70s-era BMW cars and Bricks.[/size]

Yes but with ship 6+6= 12€
my friend would lathe it for me for free

Based on unknown dimensions, yes. 

I'm just about to rebuild a pump. It had the old type seal - at least I think it did - it was destroyed when I heated the bush in order to remove it from the impeller shaft on disassembly. The new seal should be with me tomorrow. Last time I did a 'new for old' rebuild was a good few years ago, but I do remember that Motorworks recommended that I replace the bushing and that's what I did.
This time I have a lathe to alter the old one, which is 13mm as mentioned. I'm working on the theory that there'll be a small about of axial leeway viz the length of the bush, courtesy of the spring within the seal. Therefore (theory again, sorry) I'll aim to place the lip of the new seal over a good bit of the impeller shaft - and I'll do this by shortening the bush to suit.

Pics to follow, dimensions of the shortened bush also. This may help, or it may be a load of codswallop 

Two Wheels Better wrote:Based on unknown dimensions, yes. 

that's why I'm looking for the dimensions otherwise I don't do it and buy the new original one…

chris846
Pics to follow, dimensions of the shortened bush also. This may help, or it may be a load of codswallop 

I look forward to the photos of the change you will make goes thank you very much

Have a squiz at this:
K100 Forum Water Pump Seal thread

Hang on hang on guys - my memory is duff and it's been a long time.

....been reading about this 'cos something doesn't seem quite right, so please, advise or confirm...

The short bush in the pics in theis thread, is 3mm shorter (ish) Is this the SAME 3mm that at one time guys were machining off the old type cast impeller so's it could be used with the new type SEAL?

...In which case a pump with the later pressed steel (thin) impeller....uses the longer bush.

Put another way:

Cast impeller + v early type seal (that everyone's forgotten about) + 13mm bush = okay (original design)
Cast impeller + later (longer?) seal = shorter 'conversion' bush required (this setup occurs with a repair)
Pressed impeller (3mm thinner than cast impeller) + later seal = the 'normal' i.e. 13mm bush

Help needed. I know this has been done to death, but I have been researching old threads as I should, and this is the conclusion I'm coming to 

Chris, that is what the old boys at the Beemer workshop used to do with the cast impeller situation twenty years ago, yes. 

New, longer bush, 'new' type seal, stamped impeller. I've spent my six Euros worth fussing already.

Cheers TWB
So the short bush in the service bulletin (post 104) was a 'special' to allow repair fitment of a new (longer) seal to the old cast impeller - for the guys who didn't have the wit to stick the impeller in a lathe?

...I must seem really thick.

Maybe I am 

Losing it...

The cast impeller doesn't have a spacer at all (haynes manual).

Machining 3mm off the cast impeller (TWB's post plus other, old posts) must've been done so's the 'new' seal could've been fitted.

The pressed impeller has a 13mm spacer bush (it's on my bench in front of me)

....so what's the short-looking bush in post 104 for? It's got the smaller diameter spigot on it, which fits the oversize hole in a pressed impeller, to centre it. Therefore, it seems to be for use with a pressed impeller?

And why does Zisco's pressed-impeller pump seem to need this shorter bush too?

Where's Scooby, Shaggy, Jeff, Daphne and the other one when you need them?

 "Twat!"

I try to explain this with my bad english…

I have a k100 16v and this it already mounts a pressed impeller and not a cast impeller… 
however the water side gasket has been changed, now there is the new model with the spring which is longer than the previous model, which is why the spacer bush is shorter than my long spacer bush (13mm), so theoretically shortening my spacer bush by 3mm everything should fit well…

Should've known....check with Anton 

http://largiader.com/articles/waterpump/

Now gone, but still saving the day, God bless.

Basically:

Cast impeller + old seal = okay (early OE setup)
Cast impeller + new type (longer) seal = shorten impeller by 3mm in lathe 
Pressed impeller + 13mm bush + old seal = okay (later OE setup)
Pressed impeller + shorter bush + new type (longer) seal = okay (final OE setup)

You can either buy the shorter bush, or shorten your own to around 9mm overall length (per Anton)

thanks chris this is very helpful

The below just confirms what Anton describes in the link:

 The original bush is 13mm (the pump that I'm fixing therefore had the pressed impeller, and the old, shorter seal)

 The counterbore in the 13mm bush measures 9mm 

 With the seals installed in the pump, and the shaft drawn through the water side seal until the gear (on the other end of the shaft) is flush with the rear face of the pump, the shaft projects 6mm through the seal.

 This requires 3mm to be machined off the rear face of the bush....

 ...to give a new counterbore depth of 6mm.

 Well it all seems okay!

if you remove 3mm you have a total of 10mm .... Anton was talking about shortening it to 9mm ....
in the afternoon i took the space Bush to my friend to do it 9mm.... he won't have done it yet, but I don't think 9 or 10mm makes much difference