My Basic Full Flow Filtration Plan

Basic Type 1 Engine Full Flow Diagram
Fig 1. Basic Type 1 Engine Full Flow Diagram

So once I pulled the oil gallery plugs on the case, I was more or less committed to at least ensuring the case was truly clean and of course, having to tap and plug them again.

I was back and forth in terms of just putting the plugs back in for this rebuild, but the entire point of this exercise is for me to do things I’ve never done before and quite frankly, the lack of true oil filtration on Type 1 engines has always been one of the weak points.

Now there’s a few ways of going about it, with some kits out there requiring no case mods, and even one that makes no sense to me in which in the inlet and outlet on the pump is more or less the same path.

I’ve opted to follow the basic common method (Figure 1) for adding full oil filtration, which basically is similar to how they ended up adding it to Type IV engines.

Instead of modding and plugging the original oil pump I took out, I purchased a brand new Schadek 26mm flat cam gear pump that isn’t even capable of returning oil to the case through the stock path. All my research has lead me to believe that Schadek seems to make the best oil pumps so I may as well steer clear of EMPI ones if my stock originals cannot be used.

NOTE: I had a real difficult time with either the choice of the stock 26mm gears or the so called “heavy duty” oil pumps with 30mm gears. I literally could not find a single conclusive argument in the the VW forums and such as to exactly what size of engine would dictate the shift to 30mm. Answers were all over the place, with some people running them with stock 1600s, other saying they’d never run anything other than a 26mm even on larger displacement engines, and even a lot of people saying that you don’t even need the 30mm ones for doing external oil coolers!

Sample Mounted Filter
Fig 2. Sample Mounted Filter (not my pic)

I’ve gone with a basic aluminum pump cover with a single outlet that’ll attach to a hose that’ll run down and under the fender to a filter that will mount to an adapter up under the driver side rear fender. There’s a simple attaching mount that holds it all to the existing bolts of the bumper.

The return line then will follow the supply line back towards the engine, and reconnect at the main oil gallery that I’ve opened, drilled, and tapped for an appropriate fitting.

Now I haven’t decided if the “under the fender” placement will be the final placement for my full flowing yet. I mean, a lot will depend on ultimately what I want the engine bay to look like in the final restored car. I’m thinking that it can easily go up in the engine bay now, thereby shortening the length of lines to and from the filter.

I assuming that any engine I build, with the exception of may ones I intend to sell after breaking in (the AR engine maybe) will have full flow filtration. There’s just no possible way an engine such as a Type 1 that relies on oil for both lubrication and cooling should not be properly filtered. I imagine that with a filter, and proper maintenance schedules, the kind of horrors I found when I opened up the AH engine would have not occurred.

No doubt I’ll go with standard rubber oil hose lines for the first engine but I’m thinking that given the exposed nature of the lines in their placement under the fender, I’ll eventually want to to something stainless like in Figure 2.

Eventually, when it comes time to make sweet sweet love to Murbella’s AJ engine, I’ll explore one of those non-mod setups for her. That way, the only drill and tapping that needs to be done is to the stock oil pump itself.


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