I recently installed new oil pump gears as preventative maintenance since my discovery is an 03 in the bad vin range. The old gears looked fine but, since I was already in to it I replaced them. I have it all back together and everything seems to be fine but, as an after thought and for future reference is there an up side or downside to the gears? Is one side supposed to be face down in the cover and the other facing the timing gear? There was no markings on the gears and to me both sides looked the same. I was reading some random post on a forum about the gears having a specific up and down side. Any thought or opinions on this?

 

I e-mailed EAC parts and they sent me this reply
"Good morning.

No, there is not any difference between the two sides, either way round is ok for fitting. The original manufacture type was sintered so this mark may have been to do with that process or as indentification over similar parts, cannot think of any other reason.

Regards

Steve

S. P. Hall

Evolution Automotive Components Ltd.

17 Lythalls Lane (Unit 1)

Foleshill

Coventry CV6 6FN"

 

To start with, All gerotor pump gears are sintered; for the seller to be implying that his aren't, suggests his advise is not to be treated as gospel IMO...

If the annulus in the pump he sells is chamfered on both sides, then it is symetrical. If there was a chamfer on only one side, then this should have been fitted 'facing into' the bore that you dropped the pump into.

Reason for this, is that you can't realistically machine a perfectly sharp internal edge in a production environment... You always end up with a radius, because the sharp corner on a cutting tool quickly bluntens to an (admittedly very small, but still relevant) round, hence the pocket also has a round between the cylindrical surface and the face.

If you put a sharp-edged component (the annulus) into this bore, it will bind as the edge digs into the round. Adding a chamfer, GUARANTEES there is no chance of this happening. You use a chamfer instead of a round as it is easy and fast to create,,,It is just basic engineering fundamentals.

 

Dave, neither side of the gears looked chamfered to me, unless it just wasnt evident to the eye?

 

It doesn't matter how you install it as long as it is not original "factory" pump. Only factory pumps have marks on them that decide how they go in. As long as you got one from AB for example, it doesn't matter. I went through this a few months ago.

Hope this helps.

Cheers!

 

Thanks! There is nothing worse then second guessing something thats already put back together. Boris_ Were your gears cracked?

 

Outer ring was cracked in 5 places. Out of the VIN range as well.

Cought it just in time.