Annealing a vw engine case?

[raygreenwood]

[oprn]

What Gene Burg described that VW did to cases back then was absolutely true except for the annealing. I have no way to confirm or deny that. Yes the original engine in our '69 Bus only lasted 34K miles but the re-machined by VW case went another 80K under our ownership in the same car without any further issues or rebuilding. I would definitely say it was as good as new when they were finished with it.

As for annealing softening up the case material, I cannot see that as being a good thing in the bearing saddle area. They are too soft to start with as far as I am concerned!

If modern machine shops can only get few thousand miles out of an align bore like Gene Burg suggested then they are doing something wrong!
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

[oprn]

As for a factory fix, the case we sent in for repair all those years ago never left Canada. As I recall it was post marked Quebec. I highly doubt VW had an engine manufacturing facility there!
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

[BFB]

[Nitramrebrab72]

There are different annealing processes, some done cold some for coating a surface some for changing molecular structure of certain metals, some for making samurai swords. The one I think you mean is the following process. With a special hardened forged high tensile strength steel bar the size of the bearing holders fit the bar in place of the bearings holders, clamp the case together with external claps above the bearing holders.
Heat to over 700°f and cool the case repeat the process until the bearings holders are pulled and pushed into line. It realies on different speeds of contraction and different volumes of different types of expanded metals .
It is an extremely high level metal working stroke engineering process that only few know of and even fewer can get right that needs to use the right temperature and right cooling process for good results.

[modok]

There is no right answer if it's a good idea or not without knowing what is wrong with the particular engine case.

If it was welded or has suffered a BURNED UP main bearing that's caused it to warp in a unhealthy way..... then it becomes necessary to stress relieve, to relax the ABNORMAL stress in it, so it doesn't warp later in service.
Becase otherwise it absolutely will. It will stress relieve itself over the course of the next few years and then be all out of shape again, and we don't have time to wait 5 years before fixing each engine case.....
or do we?

But relieving ALL stresses is not ALWAYS best.
Half of why the concept of "seasoned" parts is because castings do shift a little after being subjected to normal stresses of being bolted together and and run and it's better to leave those normal residual stresses alone.

One thing I do see as a pattern is guys who prefer to bake every engine block ARE DOING a full re-manufacturing type process. Which sometimes makes sense, especially if the aim is to build many engines exactly the same, using all the same machining processes and setups and parts, RATHER THAN individually inspecting each engine case to see specifically what's wrong with it.

The mass production way is not how I prefer to do things or was trained to do things, but I understand the utility.
For instance you can reface a valve as quick as you can check if it's bent, so your just wasting time checking the valve to see if it's bent, but, you know what.....? You can't deny more energy efficient to not fix what ain't broke!
And I like measuring things anyway. It's interesting. Working in a factory doing the same thing over and over isn't as interesting to me.


Quite a difference in philosophy between the two far ends of the spectrum of remanufacturing and individual repair.

But anyway, for what most of us do around here with the VWs
If the saddles aren't warped and you didn't weld on it, then, it's good to go. And if it is warped and you welded on it, may be better to just call it dead, or, let somebody else fix it, like. send it to gex

[oprn]

[raygreenwood]