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Re: Thermostat/Oil Cooler (long... but maybe useful...)


Hey Simon- 

> I have followed this thread with some interest and concern.  Most of 
> what has been said is beyond my depth.  Nevertheless, I thought I should 
> pick up on one thing. 
> 
> I do not understand why Volkswagen AG have persisted with magnesium 
> alloy cases for Type1/Type2 engines (the basis of the Type3 cases) even 
> to this date.  I understand that, compared to aluminium cases, magnesium 
> cases are virtually impossible to satisfactorily weld when cracks have 
> occured and that magnesium cases are a nightmare when it comes to fire. 
> (I once gave up helping a Type 3 Variant owner try to put out a fire in 
> his engine compartment - the burning magnesium flared spectacularly and 
> two small fire extinguishers were useless.  Heaps of sand only slowed 
> the fire.  We just had to watch it burn itself out.) 

Ouch - that doesn't sound like it was much fun... 

> For these two 
> reasons I like the Type 4 engines and the Wasserboxer engine.  Their 
> cases generally will outlast a magnesium Type1/Type2 case and can 
> usually be 
> rebuilt many times. 

True!  I've never played with wasserboxers, so I don't know about them, but 
with the Type 4's I've seen I have yet to see a case that needed to get an 
align bore (except for the ones that had holes in them thanks to a thrown rod 
:-). 


> The other reason why I do not understand why Volkswagen AG still 
> persists with magnesium alloy in Type1/Type2 cases is that the very 
> first Type 4 engine (the 1969 "V" series which I have in my 1969 411) is 
> made of magnsium alloy just like the Type1/Type2 (and Type3) cases. 
> Yet, VW made the change for the 1970 model year to aluminium alloy cases 
> for all Type4 cases thereafter.  If the costs of changing over from 
> magnesium to aluminium were so high for Type1/Type2 engines, why did 
> they do it with the Type4 engine? 

Good point!  Hmm...  Perhaps they determined that it just wouldn't work for the 
T4.  Or, perhaps it had to do with Porsche's involvement in the 914 project 
that debuted in 1970. 

I've never seen a magnesium T4 with my own eyes, just heard about them 
second-hand.  I have a question: are there any noticable differences between 
that case and an aluminum T4?  Does it use the same through-bolt design?  Also, 
does the right-hand side of the case have two transverse seams on the top?  I 
never could figure out why that side of the case had these two seams but the 
left side didn't, especially considering that the left-hand side is more 
complex than the right-hand side.  If the magnesium T4 case doesn't have these 
two seams, perhaps it'd be a clue to this mystery... 

Does anyone here have experience with producing Magnesium AS21 or AS41 
castings?  Do they typically run at a lower temperature than they would with, 
say, Aluminum 356?  Do they require heat-treatment?  Do they require much 
re-finishing (minus, of course, the required machining)?  Just curious to find 
out the overall cost... there must be some reason why they didn't change over. 

Do you suppose it could be legal - back somewhere in the 30s, 40s, or 50s, VW 
signed an agreement with some magnesium-producing company for cheap material 
and an agreement to use that material on that engine forever?  Or is that idea 
far fetched? 

I've heard "rumors," take them only for what they are, that VW ran a small 
number of aluminum T1 cases as prototypes around the same time they developed 
the CT 1600 case (this was a magnesium case similar to a T1, but it had 
hydraulic lifters, a cast-in oil filter mount kinda like a T4, and a pancake 
cooling system that was used as a cheap alternative to the wasserboxer in 
Europe from about 79-82 or so...). 

> Can anyone enlighten me? 

I stand beside thee, awaiting similar enlightenment from the metal casting 
gods... 

Take care, 
Shad 

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