oil pump rotor and annulus replacement

[Frank]

Morning people,

I had problems priming the oil pump in my S1 after putting the engine back in the car and took the oil pump cover off for a look. I found that the annulus (hope I got the right term here) was split neatly into 3 pieces as in the photo. I don't know how long its been like that probably for some years but its a wonder it worked at all. I purchased a new set but Im having trouble getting the rotor off. I have removed the spring clip that holds it on and thought it would slide off but it wont move at all.

Is there a trick in getting this off? I have searched the archives but cant find any reference to anything specifically around it and I don't want to apply too much force.

Any help or advice gratefully received.

 

cheers

 

Frank

 

 

[JerryS]

Hi Frank,

I’ve found the centre rotor to be a very tight fit and when dismantling I’ve always had to remove the whole shaft through from the pump end. The drive pulley, woodruff key and circlip have to be removed and the end of the shaft deburred first (to protect the bore), I guess this is next to impossible for you at this point.

It must be tempting to just fit the new annulus but even if it does appear to mesh well and the clearances are correct there’s still the need to test fit the housing and spin the rotors to check there’s no binding present.  

Did you strip down the aux housing as part of the overhaul? I’m just wondering if any excess play in the aux shaft got focused at the pump end leading to the failure. Or perhaps the pump was already binding - I’ve heard of extra gaskets being needed to pack out the pump body.

- Jeremy

[JMK-S4S]

Not sure how this is fixed to the shaft but we had a variety of problems like this on ships and warming the piece that comes off usually did the trick. Keep the shaft cool and use gentle heat - an oil bath so the temperature of the piece comes up slowly and no stresses or other heat related issues are created. 

Obviously this may not be possibly because it depends what you have stripped off and the gear you have access to but the principal is sound

I do not recommend or suggest open flame heat - that is a NO NO!!

good luck

Edited January 13, 2018 by JMK-S4S
Correction

[Frank]

Hi there Jeremy and James,

Thanks for the responses. James, I did try using a heat gun on the rotor but it wouldn't move and its not in any sort of position that you can cool the centre. I had some success previously with the heating method before particularly the rear hubs.

As Jeremy said its a bit challenging to try and move the rotor while the engine is in the car as I'm pretty sure it hasn't been off since new. I think the annulus has been broken since at least 1988 as when I had the belt changed then the mechanic said that the base of the distributor is cracked and I should get a replacement, the distributor wasn't and now I know he must have been talking about the oil pump. Its a wonder it held pressure for so long. So after some careful consideration  and lots of drinking coffee and staring at it fI decided to fit the annulus onto the existing rotor. I packed it with Vaseline and tested to check that it rotated freely and spun it up with a drill and it primed in no time. I have never been so pleased to see oil leaking out underneath the filter (I hadn't fully tightened it )

So thanks for your help and advice guys, its great to be able to get info and advice from someone who has insider knowledge and done it before to make sure Im not missing a trick.

cheers

Frank