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Glemon · Joined: 05 Jan 2016 Posts: 267 Location: Lincoln, NE

Who has the good ones? I got a set off Amazon and my 25 amp fuse melts the plastic but doesn't pop the fuse. Started going down a rabbit hole, a lot of them advertised as ceramic or bakelite are in fact plastic these days. No local Porsche dealer if that is your answer. Thanks, have been off the board awhile, hope y'all are doing ok.
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88 924S
68 TR250
02 IS300

safe · Joined: 18 Mar 2017 Posts: 708 Location: Sweden

Not an answer, but maybe you can use an old one an pop on the metal part from a new?
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

924RACR · Posted: Wed Aug 24, 2022 8:26 pm Post subject:

Step one: don't buy Chinese.

I've experienced the melting a number of times myself.

Now, the hard part - finding a source that isn't Chinese (or other) junk.

Last time, I ordered mine I think from McMaster-Carr (mcmaster.com). Have neither blown nor melted one since... which is only half the answer...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Glemon · Joined: 05 Jan 2016 Posts: 267 Location: Lincoln, NE

Thanks, learned my lesson about buying the cheap ones, have some of what appear to be new old stock coming from eBay.

Got a kick out of your last line. I suppose if one had the right equipment and spare fuses you could test them for spec on doing their job.
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88 924S
68 TR250
02 IS300

924RACR · Posted: Thu Aug 25, 2022 10:18 pm Post subject:

safe · Joined: 18 Mar 2017 Posts: 708 Location: Sweden

Search ebay for NOS torpedo fuses and you can find old (unused )fuses. This is an item that can get expensive in the right unmolested package.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

The interior fan fuse keeps melting on my 85 924, i replaced the fan itself thinking that its probably tired and eating a lot of power...however even after replacing that the fuse kept melting..so i'm sure that its the plastic body of the fuse that does not tolerate the heat that well.
I'm going to look for some ceramic bodies and transfer the metal part from the new fuses.
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Supercharger and EFI kits
https://www.the924.com

safe · Joined: 18 Mar 2017 Posts: 708 Location: Sweden

Clean the posts so the fuse has good connections. If it's oxidized you get resistance and that generates a voltage drop and heat over that resistance.
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/Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

Beartooth · Joined: 05 Apr 2022 Posts: 316 Location: Roberts, MT

The situation with fuses really gets me. It's pretty clear that a ceramic fuse with a copper conductor are the ideal choice. Mercedessource used to sell such fuses, although I'm not sure they were ceramic (the ones they currently sell are thermoplastic). Apparently the better quality fuses available use anodized aluminum, and hopefully a more temperature-resistant plastic. Cheap China fuses are going to be plain aluminum and the cheapest plastic available, a recipe for failure. Keep in mind, the best fuses you can get anymore may be made in China too; I haven't bought any in a while, so I'm not sure. For any car with a corroded mess in the fuse box, pulling all the fuses, cleaning everything up, and reinstalling the fuses with a light coat of silicone grease is a good idea.

As for the best available fuses, it seems Flosser or Bosch would be the brands to stick to. Mercedessource sells a kit with enough fuses to replace all the old ones, plus cleaning brushes and silicone grease. https://mercedessource.com/store/1968-1995-most-models-fuse-box-ultimate-service-kit Not sure who makes the fuses, but I'd think they're the best available. Anyway, going back to the beginning, I can't see why nobody's making the best possible fuse anymore. Sure, what's available is cheaper than ever, but I think all of us are willing to pay a few extra bucks to keep the gremlins at bay. If somebody could at least make a replacement conductor in brass or copper, that'd be helpful; you could re-use the body of the old fuse. Unfortunately, I don't see the situation getting any better; we might just have to make fuse block maintenance a regularly scheduled event.
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1980 931 diamond in the rough