 Crack, or normal casting? |
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| 74ravenna |
 Sep 24 2016, 10:04 AM
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Member  Group: Members Posts: 471 Joined: 19-October 14 From: nh Member No.: 18,032 Region Association: North East States 
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Is this a superficial blem in the casting?
Once magnified it appears to be but I just want to get some knowledgeable folks opinion. TIA Steve  |
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| earossi |
Sep 25 2016, 11:35 PM
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Member Group: Members Posts: 210 Joined: 8-December 11 From: Chicago, Il Member No.: 13,878 Region Association: Upper MidWest |
QUOTE(veekry9 @ Sep 25 2016, 10:56 PM)  https://www.youtube.com/watch?v=AiYnDskFxTo Burning metal! (IMG:style_emoticons/default/blink.gif) VW/Porsche made the Type4 engine from aluminum for it's tensile strength,not for it's 'unflammabilty'. (IMG:style_emoticons/default/dry.gif) Heated magnesium castings to fit interference bearings,circa '70s,did not catch fire back then. Intentionally lit hair-thin magnesium and titanium turnings,and without the added heat of the torch,went out. A puddle of molten magnesium can be lit up with an oxygen rich atmospere and added torch heat. So,yeah,the metal can light up,but,it isn't like it will spontaneously combust. Putting a torch to a casting long enough to melt,will result in a puddle of magnesium on the floor. It would be very difficult to ignite a casting such as the VW cases,the wall thickness and mass too great. Welding the material with ox-ac in the past was a difficult job,no doubt,but quite possible tho. https://www.google.ca/search?q=oxygen-acety...gA&dpr=1.75 https://www.google.ca/webhp?sourceid=chrome...er&start=10 https://www.google.ca/webhp?sourceid=chrome...agnesium+solder https://www.google.ca/webhp?sourceid=chrome...ing%20magnesium https://www.google.ca/webhp?sourceid=chrome...sting+magnesium https://www.google.ca/webhp?sourceid=chrome...e+sand+casting+ https://www.google.ca/webhp?sourceid=chrome...s+burning+metal https://www.google.ca/webhp?sourceid=chrome...e%20ingredients The round spots on the die-cast magnesium engine parts: https://www.google.ca/search?q=ejector+pins...RLODYQQ_AUIBigB / Without this turning ugly, I suggest that you Google "magnesium fires". If you go back to the early days of the Beetle, VW used magnesium for its cases. The magnesium did not "spontaneously combust". Fires usually started from other faults such as fuel leaks or electrical fires. Once the engine saw fire, the magnesium would combust. I saw one burn like that when I was in college back in the 60's. And, water will not extinguish a magnesium fire. You let them burn until they run out of fuel. Or, you can foam the fire, though I never did witness that. And, I believe that VW went to aluminum because it was less expensive than magnesium, and more stable. Not for its combustibility as you pointed out. |
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Posts in this topic
74ravenna Crack Sep 24 2016, 10:04 AM
stugray casting imperfections.
They are covered in them. Sep 24 2016, 10:08 AM The Cabinetmaker What is that we are looking at? Sep 24 2016, 10:08 AM
dangrouche
What is that we are looking at?
looks like under... Sep 24 2016, 05:16 PM injunmort is that the cylinder spigot? Sep 24 2016, 05:24 PM earossi Appears to be a surface crack in the spigot on a c... Sep 24 2016, 07:15 PM stugray
Appears to be a surface crack in the spigot on a ... Sep 25 2016, 01:28 AM veekry9 Shrinkage of diecast surfaces,a subject of depth a... Sep 25 2016, 02:09 AM 74ravenna Its the top of the engine where the cylinder head ... Sep 25 2016, 04:51 AM rgalla9146
Its the top of the engine where the cylinder head... Sep 25 2016, 05:50 AM earossi
Its the top of the engine where the cylinder hea... Sep 25 2016, 06:27 AM veekry9 Not a crack,it's a 'shrink riser'.
The... Sep 25 2016, 06:48 AM 74ravenna
Not a crack,it's a 'shrink riser'.
Th... Sep 25 2016, 07:03 AM 76-914 I think it happens on all Aluminum engines. The Su... Sep 25 2016, 07:16 AM Mikey914 Only one way to tell for sure. File the imperfecti... Sep 25 2016, 09:47 AM bretth I read about using a torch to briefly heat up a su... Sep 25 2016, 10:53 AM Mikey914 Wouldn't personally use a torch on this, too m... Sep 25 2016, 02:17 PM earossi Hitting magnesium with a torch will ignite it; so,... Sep 25 2016, 02:38 PM veekry9 AiYnDskFxTo
Burning metal! :blink:
VW/Porsch... Sep 25 2016, 09:56 PM ThePaintedMan
Without this turning ugly, I suggest that you Go... Sep 26 2016, 07:16 AM veekry9
Yep,that is why we had the specialized fire ex... Sep 26 2016, 12:49 AM Beach914 Magnesium solids will not normally combust when ex... Sep 26 2016, 07:50 AM mbseto In college chemistry, we had a stash of magnesium ... Sep 26 2016, 08:08 AM Mikey914 You can light them with a flare, so it takes a goo... Sep 26 2016, 10:55 AM veekry9 George,you have attributed those words to me,a res... Sep 28 2016, 01:39 AM bretth I didn't think someone would take a torch to a... Sep 28 2016, 04:30 AM |
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