Can a 964 oil pump be rebuilt?

[iamjackyla]

Does anyone know can a 964 oil pump be rebuilt? Can I find the rebuild kit somewhere?

The oil pressure on my 964 is a bit weak,(around 0.5 bar on oil pressure meter), so we open the oil pump and found the gap of the gear is bigger.

Thanks!

[VFR750]

Supertec performance rebuilt my 3.0sc pump a year ago. If you are suffering low pressure, they may be able to determine if the rotors and casing are worn out.

They are so simple inside, it is all about the clearances in the gear mesh and housing to gear tip.

I would think you need special tools and a flow bench to properly inspect a gear pump.

[chris_seven]

There are not many parts available for 911 pumps although you should be able to find bearings.

To try to understand what is wrong shouldn't be too difficult but needs a bit more information.

What is the engine speed when you see 0.5bar pressure and at what temperature and type of oil? (I assume idle speed when warm)

What pressure does it deliver at 5000rpm when hot and have you checked bearing clearance?

There are only 3 ways that the pump can 'spill' and lose delivery/flow which will mean that the pressure drop will reduce.

The first is axial clearance and this show up as excessive end float of the rotor and wear on the end casing.

It may be possible to rectify this issue with new bearings and re-machining the end plate to remove scoring.

The second is the radial clearance and this should be evident from scoring or wear patterns in the housing.

Again bearing wear can cause contact between rotor and the housing and this should be easy to see. If the engine has had previous problems it could have ingested some broken parts and scored the housing and even chipped the teeth. Repairing chipped teeth could be difficult.

It should be possible to repair scoring to the housing and even wear using some of the modern metal filled epoxy resins used for the repair of slideways on machine tools.

Some of these compounds are hugely strong and great adhesion.

The last area is wear in the mesh and therefore leakage through the mesh.

This is very rare as bearing issues which would allow the teeth to mesh incorrectly would normally damage the housing before tooth wear became significant.

I am not sure if the tooth profiles in a Porsche pump are involute and how they may have been corrected so making measurements over pins could be tricky as it is difficult to know how they started out.

If you have photographs of the radial face of the housing would be valuable.

[Mark Henry]

Originally Posted by chris_seven

There are not many parts available for 911 pumps although you should be able to find bearings.

Bearings??

[G450X]

Originally Posted by Mark Henry

Bearings??

Yep, 964 oil pumps are more "advanced" I guess you'd say, and they have bearings...

Carefully inspect the magnesium housing - they have been known to develop stress fractures...

[Mark Henry]

Originally Posted by G450X

Yep, 964 oil pumps are more "advanced" I guess you'd say, and they have bearings...

Carefully inspect the magnesium housing - they have been known to develop stress fractures...

OK, I couldn't find a pic of them apart and I thought they looked just like an earlier pump with the shaft running in the casting.

[chris_seven]

[Mark Henry]

Thanks,
I'd call that a bushing, which is a type of plain bearing, but the terminology had me confused.

[chris_seven]

So is a main bearing a bush

GBB define all of their products as plain bearings and then also add the term bushing: Plain Bearings & Self-lubricating Bushings | GGB Bearing Technology - EnPro Group

I think that the steel backing with the bearing alloy coating tends to define these parts more accurately as bearings.

I have always considered bushes more as spacers which are not subjected to high loads and speeds but agree that there is a degree of confusion but in this application I do believe it is working as a bearing.

It could be more of a US-English vs English debate that I don't think we will ever resolve.

[KTL]

You can adjust the end play rather easily. Thanks to Scott Kinder for sharing how he does it

Internal Oil Pump

And yes it's a good idea to check any pump that is of unknown origin. A free spinning pump doesn't tell you anything about how it looks inside. This pump spun nicely even after it ingested a bunch of bearing debris.



You want the inside of your pump to look like this- virtually no signs of junk scraping the walls

[Mark Henry]

Originally Posted by chris_seven

So is a main bearing a bush

Yes, I would call it a bushing. I wouldn't call a rod small end bushing a bearing. I'd pretty well call any press in plain bearing a bushing.
When you said bearing I was imagining a roller bearing with some sort of seal.
To me a main bearing is a crank bearing. A rod bearing is for a rod and a cam (intermediate) a cam bearing.
I know they are all plain shell bearings, to me it's such common knowledge I'd never call it a plain or shell bearing.

Almost 30 years aircooled performance engine building (mostly VW) experience.

Here's something I'm testing, DFL or Dry Film Lubricant.
The processing for DFL actually makes the material grow slightly making for a tighter tolerance.

[h.wong]

Contact Glenn Yee at Glenn Yee Motorsports... in San Dimas, CA. 1 909 592-1510

He blueprints 911 oil pumps for Ollies and many others...cheap insurance.

Good Luck,
Harry