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I don't see anything in the TSB's suggesting there was a problem. As I said with other mag parts I highly doubt that the mag is warping. If properly cast and heat treated it will have the same strength as an aluminum cast counterpart. Mag will dissipate heat faster than aluminum also. Once in heat treated condition it is very hard to get mag to move without breaking it and would take considerable force to do so.
I see a lot of leaking timing chain covers but not too many leaking between the case and the housing. I have found that in some cases when they were leaking the nuts were not to factory torque specifications. Applying the appropriate torque seemed to eliminate the problem without replacing the gasket. The other issue is the cam seal leaking. Odds of or the need to spend the money on aluminum housings and covers IMO doesn't seem warranted. Although if you want the piece of mind any new part will be more of a guarantee than reusing the old be it mag or aluminum.
The only issue I have seen with these housings are the gasket is stuck in place and has bonded with the magnesium. When you remove the gasket it will leave small voids that could allow oil to leak by. I just did one for a friend and so far no leaks despite the pitting of the casting surface.
Do you know what year they switched to the aluminum housings. My 96 Vram 993 engine has the mag ones.
Appreciate your experience on this. That's exactly what we are seeking. Is this as real an issue as, say, the mag valve covers? What is the "failure rate" so to speak ?
Appreciate your experience on this. That's exactly what we are seeking. Is this as real an issue as, say, the mag valve covers? What is the "failure rate" so to speak ?
Hoping to gather more impirical data...
I might be breaking down a 90 C2 engine in a few weeks. If I do I will post what I find. We did an 89 C4 with 108k miles IIRC a year ago and the housings weren't a problem. The owner drives the car almost daily since and so far not a single drop. We also used the original mag valve covers.
Another point to be considered. If an instance of warped housings is discovered it would be good to note if the engine was run extensively without its heat shields. I always kept mine on the back since I ran a muffler across the back. I removed them from the sides since I have the heat shield by the cat and I am also running a smaller less restrictive unit on one side and nothing on the other. Although they didn't use heat shields on turbos.
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I see the mag part is still available. I would assume if it were a problem it would have been superseded with the aluminum part. Interestingly the aluminum part is more expensive than the mag part made from same tooling. Mag is more expensive to produce as well.
A few people have posted that the magnesium cooling fans coming from PAG are now made of aluminum, I wonder if this is more of the same? The part numbers you posted were in-use prior to the end of the 993 production (they show as dropped/replaced in a 1998 PET) when they were still magnesium. It would be interesting to see what the casting date is on the inside of the box (PAG used an indexable mold date insert).
A few people have posted that the magnesium cooling fans coming from PAG are now made of aluminum, I wonder if this is more of the same? The part numbers you posted were in-use prior to the end of the 993 production (they show as dropped/replaced in a 1998 PET) when they were still magnesium. It would be interesting to see what the casting date is on the inside of the box (PAG used an indexable mold date insert).
If the fans are painted how are they determining that they are aluminum vs mag?
I wish I still had my foundry. I worked with another foundry a year or so ago to help them develop a revolutionary new sand mix that was both environmentally safer, breathed better and made a mag casting better than I have ever seen. Although the sand is water based it requires no water additions. the mix created its own water through a chemical reaction in the mulling process resulting in a mix that required a maximum of 3% water vs 5-7%. The resulting casting was as clean as an investment casting and the parts we made I still have sitting outside for over a year now with no signs of oxidation....yet. Parts were cast in AZ91E so it is a low corrosion mag used mostly for navy applications.
Unfortunately he does not want to get involved with the DoD so finding an application for this is not easy and he has done nothing with it.
If the fans are painted how are they determining that they are aluminum vs mag?
They no longer come painted maybe? There was that time when a great number of people were convinced the chain box covers were phenolic... It would be really interesting to compare the weight of these to confirm. Porsche does not do a part revision, no matter how minor without a corresponding change in part number, not at least since the late nineties. I suppose there is always the chance that people are confusing uncoated magnesium for uncoated aluminum (not sure I could tell the difference)? I see people on the beach down here picking up lead keel weight thinking its silver treasure all the time. I'm almost convinced that the airline companies are seeding the beaches with the stuff so that tourists will have to pay extra for overweight baggage on their return flights home!
They no longer come painted maybe? There was that time when a great number of people were convinced the chain box covers were phenolic... It would be really interesting to compare the weight of these to confirm. Porsche does not do a part revision, no matter how minor without a corresponding change in part number, not at least since the late nineties. I suppose there is always the chance that people are confusing uncoated magnesium for uncoated aluminum (not sure I could tell the difference)? I see people on the beach down here picking up lead keel weight thinking its silver treasure all the time. I'm almost convinced that the airline companies are seeding the beaches with the stuff so that tourists will have to pay extra for overweight baggage on their return flights home!
LOL.
It IMO would be pretty irresponsible for Porsche to supply a magnesium part without some form of preservation. If they aren't painted and supplied that way then people need to be informed that painting is required. At a minimum a chrome acid pickle would help but then they would be more gray to gold in color.
As you noted untreated magnesium looks nearly identical to untreated aluminum without any passivation. I can tell but I worked with the stuff for 30 years.
I have heard stories how engine tins are coming from the suppliers in primer. Again this is not the product people are paying for and if this is what Porsche classic plans to feed its customers there will be a lot of unhappy Porsche owners.
As you said weigh the two side by side. Aluminum weighs approximately 1/3rd more than aluminum all things being the same. They wouldn't need different tooling to make them in aluminum so they would look identical. Aluminum and mag have the same shrinkage factor. Just like the aluminum valve covers are made from the same tooling as the old mag ones.
It IMO would be pretty irresponsible for Porsche to supply a magnesium part without some form of preservation.
That's what I figured but maybe a year or so ago I read about some new magnesium alloys that don't require painting or coating.
Originally Posted by cobalt
I have heard stories how engine tins are coming from the suppliers in primer. Again this is not the product people are paying for and if this is what Porsche classic plans to feed its customers there will be a lot of unhappy Porsche owners.
I know going back to at least 2000'ish, that the engine tin (like all body parts) have come in primer.
That's what I figured but maybe a year or so ago I read about some new magnesium alloys that don't require painting or coating.
True the WE alloys were designed to be corrosion resistant and are widely used in the aircraft and automotive industry. Although they are not like the aluminum based mag alloys used in these cars. I doubt they would change the alloy.
Sikorsky wanted me to convert over to WE43 about 25 years ago when Mag Electron was first pushing it. The cost to add all the necessary equipment to melt it was prohibitive for me.
The aluminum based alloys are pretty basic and are the oldest form and most commonly used up until recently. The rare earths alloys like EZ33A and ZE41A have their own level of complexity and benifits. I specialized in both the Aluminum based and Rare earths alloys. I never got involved with the WE alloys.
04-10-2017, 11:27 AM
Timing Chain Boxes - Aluminum Model?
