M52 Water pump pulley bolts

A query for you all to ponder over.

I have just bought a new water pump (OEM) for my E39 from Euro Car Parts for the sum of £37.71 inc vat.  Henry Bros want £70.50 for a BMW one.

Looking at in the box, I have measured the spaces between the 4 bolt holes that secure the pulley onto the hub.  The 4 holes are not located at the corners of a square but at the corners of a rectangle. Two of the bolts holes are the same distance from the centre of the pump spindle which id different from the other two.

This means that the water pump pulley can only be bolted to the hub in two positions and not four.

This seems a bit strange to me as I would have thought the bolt holes would all be at the same distance radially from the centre of the pump spindle but they are not on this new pump.

I was under the impression that my car has the bolt holes at the same spacings.

Can anyone confirm this before I go and strip out the old pump tomorrow morning?

Andrew

Thanks Sleeper.

I phoned up ECP and they told me it was the correct pump for all 6 pot M52 BMW engines regardless of age. I am aware that there is a change of things in Sep 1998 which is just after my build date so I was worried I may have a slightly different pump but I don't so everything is tickety boo!

Andrew 

sleeper wrote: no sweat - I did one last weekend and went through the same thing!! Cheers!

Any other special tips as to how to get the viscous fan off i.e how to stop the hub from turning, apart from hit the spanner with a hammer to try and shock it off?  Which is what you told me last time I asked.

The reason I was checking about the bolt centres is that I was thinking of making a tool up from flat bar to hold the pulley still while heaving on the hub nut.

Andrew

tips, err the one I've just done wouldn't knock off with t'hammer either  so I locked the pulley with a big flat-blade screwdriver and tapped it off.

...and yes, I am an octopus! (it is possible)

BTW - I use a ground-down sink spanner from B&Q - big cast alloy fella, and it works a treat!

I'm sorry to hear you're having trouble with this. I've only ever changed them using this method and I've done a few. It does need quite a belt though and a heavy hammer is best.

It's a stupid question cos I think on earlier postings you've said you were aware of it being a reverse thread but you're definitely hitting it the right way? (clockwise when facing the engine)

Perhaps it's just a tight one and you do need to make up a tool to stop the pump pulley turning - it's never a nice feeling using a hammer on a piece of precision engineering! I think I'll probably do that in future if the 'whack it hard' method isn't 100% successful as I thought it was before this

Thanks guys,

I was hitting it in the correct direction,  Left hand thread and all that, me and the old boy, striking the end of the viscous spanner with a 2lbs hammer and nowt.  Stuck fast.

Andrew

gilescooperuk wrote: I don't have one of these cars but.... why not undo the pump bolts and remove the pump and the fan at the same time, then with the now scrap pump on the bench separate it by clamping the impeller in a vice so it can't twist. Just seems that if you are taking the pump off why fuss with trying to remove the fan in the engine bay. Giles

You can't get to the water pump to block bolts as these are hidden behind the water pump pulley.  You can't remove the water pump pulley without first removing the viscous fan coupling I'm afraid.

In other words

Have a look at your 1989 525i E34 and you will see what I mean.  It will be of similar construction I would think to my M52 lump on my E39.

Andrew

try some 'plus-gas' disassembly spray, works on everything...

http://www.frost.co.uk/item_Detail.asp?productID=7973

easily done though chas, especially working from below....

Chas C wrote: Makes you wonder if someone previously tried to remove it assuming it was a normal thread...

Doubt it.   The previous owner was religious in getting everything done at BMW, even tyres.  I have all the receipts for everything and they are all BMW and none of them are for work which would have required removal of the fan.  I would like to assume that if BMW had a shot at removing it they would have done it correctly. 

Emm maybe not going by my experience of my Local Main $tealer!

I think with nearly 8 years of 6 cylinder heat the nut has welded itself to the pulley spindle.  It will of course not been greased when it was assembled by BMW.  Had the nut been greased then I bet there would not be this problem.  Any nut or bolt I remove from any car gets greased before it gets put back.

Andrew

Edited by Andrew Rolland