[T3] 21mm Oil Pump Inlet Size

Bobnotch bobsnotch at aol.com
Tue Jan 23 13:54:00 PST 2018

Also check the fit of the pump in the case. There have been reports that the newer pumps don't fit tight when the case halves have been tightened to spec. This can cause an internal oil pressure issue.

-----Original Message-----
From: Jim Adney <jadney at vwtype3.org>
To: type3 <type3 at vwtype3.org>
Sent: Wed, Jan 17, 2018 11:51 am
Subject: Re: [T3] 21mm Oil Pump Inlet Size

On 16 Jan 2018 at 14:48, Jaime Gurrola wrote:

>   I'm rebuilding a 1600 and the oil inlet hole on the new 21 mm Schadek
> oil pump is about 2mm smaller than the original 21mm pump. The new pump
> inlet size is 13.8mm and the old pump is 15.8mm.

The size of the hole is not as important as the location. Check the size AND
location of the matching hole in the case, as VW changed that location at
one point, so that, IIRC, we can no longer buy pumps that mate up correctly
to '70 cases. Check both the inlet and outlet holes.

If the locations don't match up, it may be possible to find another pump that
will work, or you might need to have a machine shop make a new bore in a
better location. Don't just make a groove; bends in the oil flow path,
especially on the intake side, make a big difference to the final flow rate. The
oil should have a straight shot from the case to the center of the pump,
especially on the inlet side.

Sometimes the holes are larger on one part to make sure that they overlap
the whole hole on the mating part. That small change in diameter is a very
minor problem.

You can't assume that everything will just be okay.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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