Distilled White Vinegar & 928's
10-09-2008, 12:55 PM
#16
Just a follow up on my vinegar bath. The vinegar took off most of the oxidation with the exception of areas that had other coatings (dielectric grease?) on the edges. I am tempted to try phosphoric acid during my next dunking to see if it penetrates better.
Dennis
Dennis
10-09-2008, 01:45 PM
#17
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Dunking the panel will result in liquid being drawn up inside the wire insulation through capillary action. Whatever gets in there will probably never rinse out, though acetic acid would eventually evaporate out. Applying a dielectric may create a barrier that prevents any residual acetic acid from evaporating.
10-09-2008, 02:09 PM
#19
Chronic Tool Dropper
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The original fuses in my 356 were beryllium coper alloy, placed into holders that were similar metal but tin plated. An annual spinning-of-the-fuses ritual was needed, but that was all that was needed. Using acids, even acetic acid, on the fuse panel is a first step down a very slippery slope to disaster. Need to get perceived oxidadtion off the fuse-holder blades? Use a pencil eraser. A new one, not that hardened rubber rock that's been sitting on your office shelf since you switched to mechanical pencils ten years or more ago. Fuses ugly and trashed-looking? Buy new ones. Get some genuine-something brand with copper elements, not the cheapo ones that corrode easily. Buss makes a glass tube replacement fuse with pointed copper ends tin plated, much better than what came in the car as far as long-term durability.
Dielectric spray... Stay away from that stuff if you can. It's intended to limit moisture penetration into high-voltage connections, where the dielectric properties are needed to prevent flashover protection. The only place it has a use in the 928 is on ignition components. I know many are deluded into thinking that it needs to be included in every connection to prevent corrosion, but that's simply not the case. If you have something that's causing serious corrosion issues in your fuse panel (besides the acids mentioned in this thread...), fix that problem. The protective barrier that most 'protective sprays' might provide also limits the electrical connection. "High dielectric strength" is exactly not what you want in a low-voltage (car) circuit, between metals that you expect to conduct freely.
For strong mechanical connections like battery terminals and ground points, clean and assemble them snugly, then dab a little Vaseline on them to seal the edges against moisture and possible chem vapor intrusion. These are joints that can also stand the spray connection protectors, but only after they are assembled and tight.
Don't use acids on anything electrical that you want to have working later. Phosphoric is nothing you would never want to get near anything on your car, unless you wre thinking about chemical milling the body to reduce weight.
Dielectric spray... Stay away from that stuff if you can. It's intended to limit moisture penetration into high-voltage connections, where the dielectric properties are needed to prevent flashover protection. The only place it has a use in the 928 is on ignition components. I know many are deluded into thinking that it needs to be included in every connection to prevent corrosion, but that's simply not the case. If you have something that's causing serious corrosion issues in your fuse panel (besides the acids mentioned in this thread...), fix that problem. The protective barrier that most 'protective sprays' might provide also limits the electrical connection. "High dielectric strength" is exactly not what you want in a low-voltage (car) circuit, between metals that you expect to conduct freely.
For strong mechanical connections like battery terminals and ground points, clean and assemble them snugly, then dab a little Vaseline on them to seal the edges against moisture and possible chem vapor intrusion. These are joints that can also stand the spray connection protectors, but only after they are assembled and tight.
Don't use acids on anything electrical that you want to have working later. Phosphoric is nothing you would never want to get near anything on your car, unless you wre thinking about chemical milling the body to reduce weight.
10-09-2008, 08:40 PM
#21
Rennlist Member
Good luck with your adventure.
10-09-2008, 09:25 PM
#22
Try reading the ingredients on the can. Don't have a coke can handy, but the Dr Pepper can I just emptied says phosphoric acid. At my age, I take any adventure any way I can. 
Dennis
Dennis
10-09-2008, 09:49 PM
#23
Rennlist Member
I meant no offense. Certainly you can buy a phosphoric acid cleaner and dilute it to the same pH as Coke. I don't drink Coke. I think there are two acid components to carbonated soft beverages. One is carbonated water, or weak carbonic acid. It is found in Coke, Pepsi and club soda. The flavor or "nutritional" syrup does indeed contain other ingredients which are listed on the can, including phosphoric acid, in Coke but not Pepsi, also citric acid and others. The acidic content is essentially the same for Coke and club soda, club soda having no phoshoric acid, and coke very little.
Best of luck,
10-09-2008, 10:11 PM
#24
Dave,
No offense taken. I purchase, sell and use phosphoric acid in my tile business. It is not considered hazardous by the EPA even in the concentrated shipping containers. It does evaporate like acetic acid, hence the odor when using it. And last but not least, it won't damage the glaze on tile like many other acids, even in the concentrated form.
BTW the board I'm using it on is an old, tired spare.
Dennis
No offense taken.
I purchase, sell and use phosphoric acid in my tile business. It is not considered hazardous by the EPA even in the concentrated shipping containers. It does evaporate like acetic acid, hence the odor when using it. And last but not least, it won't damage the glaze on tile like many other acids, even in the concentrated form. BTW the board I'm using it on is an old, tired spare.
Dennis
10-09-2008, 10:15 PM
#25
Rennlist Member
Dave,
No offense taken. I purchase, sell and use phosphoric acid in my tile business. It is not considered hazardous by the EPA even in the concentrated shipping containers. It does evaporate like acetic acid, hence the odor when using it. And last but not least, it won't damage the glaze on tile like many other acids, even in the concentrated form.
BTW the board I'm using it on is an old, tired spare.
Dennis
No offense taken.
I purchase, sell and use phosphoric acid in my tile business. It is not considered hazardous by the EPA even in the concentrated shipping containers. It does evaporate like acetic acid, hence the odor when using it. And last but not least, it won't damage the glaze on tile like many other acids, even in the concentrated form. BTW the board I'm using it on is an old, tired spare.
Dennis
10-10-2008, 12:20 AM
#26
Rennlist Member
... For strong mechanical connections like battery terminals and ground points, clean and assemble them snugly, then dab a little Vaseline on them to seal the edges against moisture and possible chem vapor intrusion. These are joints that can also stand the spray connection protectors, but only after they are assembled and tight. ...
My experience with Vaseline has been that it melts and runs off at underhood temps, so I started using high-temp grease. I've also been happy with the red & green felt pads for under the posts. A FLAPS item.
10-10-2008, 02:32 AM
#27
Chronic Tool Dropper
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I have the best part of a a gallon of CRC marine preservative. a product that does wonders for stopping corrosion. Get it at better auto parst places, and also at boat supply stores.
10-11-2008, 08:39 PM
#28
Rennlist Member
I came this close to mentioning the different environment in which the 928 battery lives, never thought of high-temp conductivity (though neither do I see why it's a problem if it stays located), hadn't thought of melting as a positive thing but take your point, and everything wipes off with solvent. 
As for Vaseline washing off easily - have you ever made the mistake of using Vaseline at Halloween? I swear it took me 2 hours in the shower and a jar of shampoo. OTOH, I made a small gaggle of oblivious 16yo girls scream when they turned their attention to me after I opened the door.
I'm glad to know about the CRC stuff. Thanx.
ww
As for Vaseline washing off easily - have you ever made the mistake of using Vaseline at Halloween? I swear it took me 2 hours in the shower and a jar of shampoo. OTOH, I made a small gaggle of oblivious 16yo girls scream when they turned their attention to me after I opened the door.
I'm glad to know about the CRC stuff. Thanx.
ww
The high underhood temps don't seem to plague the battery out in the back where Porsche motors 'normally' live. High-temp greases do generally contain metals, so do sometimes conduct. Meanwhile, Vaseline melts low and flows into the exposed connection parts. Washes off easily when you need to remove it, unlike better water-resistant greases.
I have the best part of a a gallon of CRC marine preservative. a product that does wonders for stopping corrosion. Get it at better auto parst places, and also at boat supply stores.
I have the best part of a a gallon of CRC marine preservative. a product that does wonders for stopping corrosion. Get it at better auto parst places, and also at boat supply stores.
