DDK - Die Deutschen Klassiker

Original factory built engine possibly up for a total engine rebuild.
How important is the oil bypass mod to be done during rebuild preparation?

What units is "important" measured in ??
I understand it's relatively easy and cheap
It helps (I am told)
Why would you NOT do it if you are "in there" ?

Did it to mine

James, diy with hand tools?

Mike Bainbridge did it

I remember Rob on here did his recently, I'll look at how he DIY'd his.

911hillclimber wrote:Original factory built engine possibly up for a total engine rebuild.
How important is the oil bypass mod to be done during rebuild preparation?

It's actually minimal work, the parts cost less than £100 and it improves engine longevity... but i think the engine runs fine without it.

I think it's more important if you have hydraulic tensioners and piston squirters.

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The engine in mind is still factory build from 1973 and 140K miles and runs well but leaks oil from somewhere, source to be sorted and if needed a full engine rebuild will follow.

The engine iirc has stock '73 tensioners.
Thanks for the link, saves me searching your thread!

I would argue that if you are not going on track with the car, that you are probably not stressing the engine to the point where you'd actually need it.
However, I had it done during my rebuilt, "whilst you are in there". I'd also follow the recommendation to replace the oil pump with the stronger 4-rib model.

we fitted a later oil pump at the same time too

This engine runs well, maybe a bit of tlc needed in the injection manifolds (possibly corroded fuel drillings etc).
It has an oil leak that is embarrassing, and the plan is to remove the engine to try to find the source of the leak.

If it is under the cylinders, or the case slit line etc rather than the rockers etc then the engine will come apart.

If this is the case then the crank out rebuild will becon the by-pass etc mods.

This lovely car is not thrashed.

Are you asking for a friend? I thought you had a 3.0 in your 911?

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Yes, a friend's engine.
My yellow 911 has a 3.2, factory build, never been apart and leak-free, about 140K miles.

Mike B did mine for me when we had the engine rebuilt. The oil pump is from a 930

markm wrote:Mike B did mine for me when we had the engine rebuilt. The oil pump is from a 930

When I looked into it, the 930 is the best if you can find one, but they're all better than the early pumps. Something to bear in mind, with the oil bypass mod they could get away with a smaller scavenge side so the later pumps are bigger on the pressure side but the scavenging doesn't scale up to the same extent.

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