Your oil pump will fail., And it will kill your engine. Options

[Valy]

I'm rebuilding a 2.0L and posted a lot of pictures in a different thread.
One of the pictures showed the oil pump and Jake immediately noticed that the pump failed. Went back to the engine and saw how the oil pump touched the cam gear and shred off the nits holding it.




Being such an anal guy, I took same time today to understand why did the oil pump fail?



The red axle in the picture above it the one that protruded through the pump cover. There's nothing that holds it in place except the friction between it and the cover!
So Why does it move?
This red axle goes into a cavity of the oil pump case (rightmost in the figure). The cavity is almost snug-fit to the axle but oil can infiltrate around the axle into the cavity. When the pump works, there is a bit of oil pressure in the pump that causes the oil in the cavity to push the axle out; just like a hydraulic piston. The force is small but it's constantly there. As the axle moves, more oil flows in and that keeps pushing the axle out.
Over the time, that axle is pushed out of the pump cover until it starts touching the cam gear, shredding the nits that hold it. Eventually, the nits will brake or the axle will block the movement of the camshaft and something else will brake or your camshaft bearings will give due to the vibration inducted by the hits.

The aftermarket oil pumps are build differently, with no axle that can protrude into the motor, making them a good upgrade to your old original pump.

Make yourself a note to replace that old oil pump at the first occasion. I will even recommend to create that occasion before it's too late.

[HAM Inc]

to say every stock pump is to blame or to be a potential failure of a motor would be an absolute and not necessarily accurate in every instance.

Clearly they aren't all failing. I don't think anyone is suggesting that. While Jake had a nice size mound of failed pumps, it is likely that statistically thay represented a minority % of the total pumps still in service. Some majority are likely still in service with out this failure.

But the truth is that professionals who see a lot of these engines see enough of the failure to look for an alternative. If an individual wants to take a chance with his own engine and re-use the pump, more power to him.

But a pro who does that knows that at some point he is likely to suffer a failure, because even if the failure rate is only 5% it still means that one out of 20 of the engines he builds is going to suffer with this issue. No thinking pro who plans to make a career in this business would take those chances. That's the sort of thing GEX does and we all know about them.

It's the same reason I replace every valve seat of every used T4 head I reman. All of the O.E. seats won't fall out, but enough do that the community knows of the problem, and as a business man I know that if I don't replace every seat once in a while a customer is going to lose one and end up very unhappy.

When a trust-worthy pro recommends replacing a 30+year old part he is not necessarily suggesting that everyone will fail if not replaced.

You can debate the statistical chances of failure and ponder the life-cycles calculated 45 years ago by the engineers. It's a fun academic exercise. But the bottom line is that when you build your engine if you reuse some of these old parts there is a reasonable chance one of them will fail.