T4 Oil Pump Comparisons, Stock . Schadek . Melling Options

[McMark]

I was looking for information on the stock T4 oil pump and couldn't find anything helpful. So I disassembled on of mine today and took some comparison pictures.

Here is the stock pump:





Once you remove the four nuts on the back, you can use a 6mm x 1.0 bolt and a U shaped piece of steel to pull the guts:


In order to 'blueprint' this oil pump you would need to pull the four little studs, a small alignment ring, and then carefully mill the inside face of the body, thereby tightening the clearances between the flat sides of the gears and the body.

Schadek and Melling pumps are much easier to 'blueprint' because you can simply deck the face using something as simple as sandpaper on glass.

The stock pump does match up with the oiling bores in the case much better. Here is a stock pump. If you look closely, you can see the small variance: the case hole is slightly smaller than the pump hole.


Here is the Schadek pump body. Notice the much larger variance.


Finally, here are the numbers.

Body Height Measurement:
Total Height Measurement:

And finally, I'm not making any recommendations or judgements about anything here. This thread is simply about posting facts. (IMG:style_emoticons/default/biggrin.gif)

[DNHunt]

All of the oil goes through the filter. With the stock oil system when the pressure gets very high the bypass valve in the oil filter mount lets unfiltered oil into the main oil passage. A type 1 pump allows an assortment of covers and it is possible to plumb to a remote filter and block off the stock filter. In this system all of the oil must be filtered.

The drawbacks are external lines, full oil pressure to the filter and another level of complication.

To be honest, it is possible to do full flow with the stock pump by tapping the galley plug between the oil pump and the oil filter mount and then blocking off the oil filter plumbing, but then the same issues that Mark raised with the stock pump are faced. It is tougher to blue print.

The Type 1 pump is not without problems. In addition to what Mark raised, to plumb it for full flow the outlet must be plugged. Cam bolts need to have the heads relieved or the pump housing needs to be relieved. If these procedures are not done, the cam gear bolts hit the pump. If it is an engine rebuild the best solution is to relieve the cam bolts. The pumps I have seen need to have the shaft that drives the pump off of the cam pressed into the gear a little farther, so there are plenty of places to screw up.