oil pump, which one Options

[trojanhorsepower]

All,
I am looking to change the oil pump as a way to up my oil pressure. I understand that this may well not help, but having a new oil pump around is OK.
With that in mind, what are my options? I will pull the motor but hope to not split the case. Is this even possible? Which pump?

Thanks

Peter

[Superhawk996]

Ok so let’s summarize:

That is a pretty decent pump from what I can see in photos. Would be ideal to do the whole Samba “blueprinting” procedure to make it perfect but recognize that isn’t possible right now with the tools, time or patience you have. No shame there.

What would I do?

I wouldn’t hesitate to use that T4 pump to swap for the existing T1 pump. At a minimum it will solve the problem of the T1 pump internal leakage problem that is widely acknowledged with undersized T1 pump bodies.

If it solves your oil pressure problem you will have also verified the effectiveness of the previously used pump. If it makes good pressure hot and cold - you’re good to go. Keep it in there and (IMG:style_emoticons/default/driving.gif) Think of it as troubleshooting. If it doesn’t solve your pressure problem you are no worse off and will eventually have to split that case to get to the root cause.

With respect to the idler shaft being so much deeper. I have seen this before.



I’m not going to pretend I know the whole history of these T4 pumps and how VW may have changed or updated them over year and models including T4 bus and 411/412, etc. if anyone knows more detail on how the T4 pumps evolved - please post. I’m leaning new stuff even after all these years.

When I saw this on one of my T4 parts I assumed it was someone swapping in T1 parts (idler shaft and gears) but perhaps there was a lot of variation in these parts as VW recognised the potential migration issues? (IMG:style_emoticons/default/confused24.gif)

Having the shaft deeper may be an engineering fix for the bad failure mode where the shaft can migrate into contact with the cam rivets if the engine is overheated.

Overheating expands the aluminum oil pump end plate hole faster than the steel idler shaft. This loosens the press fit and potentially allows the shaft to begin to migrate as oil pressure gets behind it.

By shortening the idler shaft it effectively makes it much less likely the shaft could migrate far enough to begin to touch the cam.

Per the Samba procedure - pinning or peening the shaft addresses this. The T1 idler shaft isn’t fundamentally different. The T1 pumps I’ve seen have a factory peened shaft

I would peen the T4 pump end plate idler shaft bore (just to be safe). I prefer pinning but recognize you don’t have to tools to do that.

How to peen the shaft:
Use a hammer and chisel / cold punch and just deform the end of the shaft hole such that if the shaft were to ever migrate, it would encounter an undersize hole that will then limit the shaft from moving further.