Water pump bolt snapped

[Supershooter]

I decided to check the impeller gear, I placed the socket over the nut and it twisted off with almost no torvue applied to it. Any advice on how to get it apart now? I was thinking a big channel lock.
Supershooter 

[Laitch]

If this were my problem, I'd apply some heat to the hole and shaft head, soak them in Liquid Wrench, rap on the shaft stub with a punch, wait 10 minutes then drive it out with the punch. A bolt of smaller diameter could serve as a punch.

[Martin]

As per Laitch heat and penetrant (NOT WD 40), which might have to be applied more than once.
Regards Martin.

[Supershooter]

Thanks for the advice guys, a little PB Blaster and a punch. It came right out. It’s really unfortunate that someone in the past doctored up the gear. I’m glad it didn’t come apart while I was riding it.
Thanks again.
Supershooter

[Supershooter]

Where is the most economical place to purchase the gear?
Supershooter 

[The Mighty Gryphon]

First place I usually look for repair parts is ebay.  You might be able to get a complete pump assembly for less than just the broken part from a dealer. 

You could try taking it to an automotive machine shop to see if they can get the broken bolt out.  I wonder if someone used red LocTite on it and it needs to be heated.

Otherwise, you can look for a used part.  That gear was used in the K100, K75 and the K1200, but not the K1100.

[Laitch]

That looks like a nut that broke the threaded end of the gear's shaft, rather than a bolt that broke. Is that correct? Besides a new gear/shaft assembly, you'll be replacing the cast impeller with a stamped impeller and installing the latest seals, spacers and a bolt, too. It's a job that take patience and a thorough understanding of the process.

As Gryph indicated, a search for a replacement shaft or pump might turn up something suitable.

[The Mighty Gryphon]

Laitch, Looking at the fiche, it looks like a bolt that goes into a threaded hole in the end of the shaft.

There is no indication in the fiche as to the thread direction.  Judging from the price($39.48), that is a very special bolt.  Possibly with a left hand thread?


12311460853_1_N.jpg (1.13 kB . 97x75 - viewed 475 times)

Maybe someone who has been into the pump can chime in, why is there a self locking nut going over the head of a bolt?

[Laitch]

Laitch, Looking at the fiche, it looks like a bolt that goes into a threaded hole in the end of the shaft.

I've looked at the fiche. I believe early models had a threaded shaft then the assembly was revised with the tapped shaft. What I see in his photo is a nut with some threads on its inner circumference and a chunk of metal within it. Supershooter is likely to answer my question and set me straight.

[Laitch]

Maybe someone who has been into the pump can chime in, why is there a self locking nut going over the head of a bolt?

I don't think there is. Maybe this thread will clarify things.

[volador]

Water Pump
pre-1986-87? original design pump 11411461177 with 'threaded stud end' of pump geared shaft and SELF-LOCKING HEX NUT-M8-8-ZNS 07129964675 superseded by 07129904002 securing the cast impeller/rotor 11511460024

Superseded by pump 11412325850 design changed to 'tapped' geared shaft 11411461183 with Z=32 teeth gear with Z=14 teeth drive shaft
changed to stamped impeller/rotor 11411461173 secured to 'tapped' geared shaft with 12311460853 SCREW-M8X22 (bolt)

Superseded by pump 11417676366 same tapped geared shaft 11411461183 with Z=32 teeth gear with Z=14 teeth drive shaft

latest pump 11517676371 design change tapped geared shaft 11411461793 to Z=19 teeth gear with drive shaft Z=12 teeth 11411460282 DRIVE SHAFT renew O-ring

SB 1100102_Slip-ring seal for water pump

Sealing Combination Coolant/Oil Pump SB 11 046 91 2458

Rebuilding pump 'press in bushing tool' 11 6 724 - PRESS IN BUSHING  83300401628 PRESS-IN BUSHING NLA

OIL & WATER PUMP PRESS TOOL/ENDURALAST/EME

[The Mighty Gryphon]

Regardless, you gotta love those guys at Motorrad. 

$39 and change for a friggin' screw that can only be used once! 

Geez, that's as bad as that clutch boot that's as fragile as a butterfly wing.  I'd love to know what makes that screw so special and why it can't be reused.

[volador]

Geez, that's as bad as that clutch boot that's as fragile as a butterfly wing.  I'd love to know what makes that screw so special and why it can't be reused.

Do you reuse your 6-clutch pack bolts? Probably no reason not to reuse that one. Motorrad just "recommends"...

'In oil pump applications, this is is a one time use only bolt. BMW recommends replacing this when rebuilding any "old" style but serviceable K bike pump'.

12 31 1 460 853 $32.50 EME

[The Mighty Gryphon]

Must be made of irridium or something real special.

[Supershooter]

In my haste to get advice, I miss represented my problem. I have a shaft with a threaded end with a nut , that held the water pump impeller in-place. It’s left hand thread, and snapped when a very small force was allied to it.
I was shopping for parts online and started to wonder if a local machine shop could cut off the treaded end of the shaft and tap the shaft to accept a bolt. Am I wasting my time with this thought process?

Dustin

[volador]

Its a great idea if the geared shaft is in good condition, not worn, scored or corroded from use.

If you know the proper length of the coolant side of the shaft your proposition follows the OE progression of water/oil pump design change as is mentioned above.
Proper coolant side shaft protruding will ensure the seal is not disturbed.

[Laitch]

If I were in your position, I'd be looking for a used pump with a stamped impeller while measuring and determining if modification of the existing shaft will work.

What symptom moved you to disassemble the pump? Were you looking for the source of the oil at the intermediate housing?

[Supershooter]

Is there anything that you see in these pics that I should be concerned with?

[volador]

certainly got your moneys worth from that seal

[Supershooter]

I've decided to order a new impeller, is there a cheap place to buy the bolt that holds it in?
Supershooter

[The Mighty Gryphon]

Ummm...you broke the OEM bolt, and now you want to replace it with a cheap one. 

[Supershooter]

Ummm...you broke the OEM bolt, and now you want to replace it with a cheap one. 

No, the shaft that holds the impeller on was threaded with a nut on the end. Now I need to buy a new gear /shaft that is is tapped to receive the bolt on impeller.

Supershooter

[The Mighty Gryphon]

Oh, I got confused by the thread's title.  I'm easily confused now in my declining years.

[Laitch]

I've decided to order a new impeller, is there a cheap place to buy the bolt that holds it in?

What you're seeking is a serrated flange head 8mmx22 1.25 bolt. Googling that will bring some much less costly options. One difference separating the BMW bolt from others is that swell just under the flange indicated by the arrow in the photo. That might be a design feature that increases security of attachment. Another question that might arise is whether those serrations on the bolt flange are really necessary. That's the fun part of being a pioneer; you'll find out yourself, indisputably.

[Supershooter]

Laitch,
I was hoping another pioneer had already experimented and shared his results...
Supershooter