5 replies to this topic

[blackoctagon]

Does anyone have an insight as to why the z22yh (and other post-se engines) oil pump is considered better than the z22se one?
I can find find lots of posts across z22se and here about it being better, but no detail on why.

I'm sitting here with a disassembled z22se oil pump unit and there seems to be no change to the timing cover, the pump backing or the georotor assembly in the photos I can find of other, later model's pumps.

The georotor seems interchangable in other family engines, and is not hardened like the GM Motorsport part. The pickup and discharge ports are the same. The volutes in the casing appear the same. The only source of difference that's been hinted about is the pressure relief value being lower (and this may more due to speed-efficiency issues than oil flow volume or pressure delivery ones.)

I've spent a while researching, but i'm begining to think it may be a perpetuated myth, perhaps only based on part number changes.
Can anyone tell me the detail changes?

[vocky]

the earlier z22se oil pump assemblies had smaller pump gears, not interchangeable. 

 

the weak point in the oil pump assembly is that the pressure relief valve can stick / seize. The later spec oil pumps had better gears and relief valves.

 

 

[blackoctagon]

I appreciate the response - I was really struggling to see the difference from photos.

The crank diameter on the gear appears to be the same. Is the outer diameter of the georotor larger on the later pumps? Or have they thinned the wall and used a larger diameter gear?

The relief valve in this one i'm disecting had a lot of 'stiction' from what appeared to be a light mixture of congealed oil and some dissimilar metal corrosion.
Given the state of the engine otherwise it was probably well looked after but led a low rev/low load life, so it probably never saw relief.
Polishing it brought it back to life quickly to an extent i'd be happy to reuse it, if I really had to.

[chris_uk]

i have both here in the garage i can measure them up for you tomorrow but i think they are the same size, they certainly look it. 

 

[blackoctagon]

I'd be grateful if you would.

[piwo]

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Edited by piwo, 20 December 2020 - 11:15 AM.