Type 4 oil pump rebuild, Comparison of OEM vs. Samba CNC pump Options

[Superhawk996]

Playing with the idea of what it will take to rebuild a type 4 pump.

The pump that came out of my 2.0L engine is trashed from pumping rust. Both the gears and the housings are seriously scored.



I figured I'd roll the dice and see what might be on Ebay. Took a gamble and bought a used pump hoping I might get some core parts that are useful.



I did end up with a good housing outer. However, the gears are pitted and it the inner housing plate either has a serious casting flaw, or some sort of galvanic corrosion that pitted it. I always struggle with this kind of thing. It really would have minimal effect on the pump and it probably worked OK for a lot of years. However, I'd just like to know that it is perfect going before going into a engine.





It looks like new inner plates are available but at a cost of $150+.

I decided that since I have a donor "scrap" pump, I have nothing to lose by experimenting with machining it.

[Superhawk996]

Given that I'm a mechanical masochist I haven't given up on the Type 4 Pumps.

In fact, I've begun collecting them.



Previous Roll call:
1) from my original engine - pump is garbage. Heavily scored from pumping rust.
2) E-bay purchase. Pitted gears and a housing plate that has a defect or corrosion.
3) Pump from GA000099 engine - In great shape and reusable.

But I still need a good pump for my original engine. I haven't given up on the machining of the housing plate and pinning the shaft. In fact, I will pin the shafts of both engines regardless.

But rather than get deep in the machine work at the moment, I purchased two more pumps here on the forum to see if I could find more good parts to mix and match a 2nd good pump.

So I opened up the dirty pump first -- This is like Christmas for me. I love to see what is in the box for the 1st time.



And what a great Christmas it was. Another usable pump in great condition. (IMG:style_emoticons/default/piratenanner.gif)



Only the lightest of scoring on the gears and the housings. Perfect to reuse after I pin the shaft.

The second pump is a bit of a mystery.

On 1st inspection, it's clear that something isn't quite right. the stationary gear shaft is sitting far too deep in the housing plate. (IMG:style_emoticons/default/WTF.gif)

For the record - I have no issue with the seller on this. If you're not familiar with these pumps it would be easy to miss. Plus as always, you never quite know what you'll actually get and I didn't ask any questions since the price wasn't a concern. This was intended as a parts grab bag anyway on my part. (IMG:style_emoticons/default/biggrin.gif)



Opening up the pump was a mixed bag. The external housing is in awesome shape. and is immaculately clean. I think it was probably vapor blasted. it is that nice. (IMG:style_emoticons/default/smile.gif)



I will need to do a little measuring just to make sure the gap between the gears and pump bore is right but this part looks unused and amazing visually.

The internals are a mystery. I think the gears are 24mm Type 1 gears. They are in great shape & look brand new.

However, what is clear is that the shafts (both driven & stationary) aren't Type 4. They are definitely too short. I suspect Type 1 but really don't know enough about the Type 1 to be sure. (IMG:style_emoticons/default/confused24.gif)



However, this is sort of a blessing in disguise. I hadn't considered the possibility of being able to swap a new gear onto the driven shaft.

Now I have new toys to play with. (IMG:style_emoticons/default/happy11.gif)

I suspect what I'll do is mix and match enough parts to produce another good 3rd pump using the immaculate housing, a machined housing plate, and probably some swapping around of gears.

The gears that I think are Type 1 seem to measure exactly the same as Type 4 gears for both OD and height. I need to do a better comparison of the tooth profile but it really wouldn't matter as long as they are kept as a pair.

New science project work ahead.

With 5 pumps on hand and two ready for use, this Oil pump rebuild project will likely get shelved for a bit other than a quick update later on when I finally pin the shafts of the two pumps I'm going to use for rebuild of GA000099 and my original engine.