Bill51sdr

Paul, have you checked to see if the fuses you are putting in are the correct amp rating? Wondering if a PO put a higher amp one in place of the correct one to hide a current draw that was blowing the fuse? Could be the problem causing the excessive draw has gotten worse.

Mongo

Could it be wires touching behind the board too?

bernard farquart

I had the whole fuse panel out a couple of months ago (when I took that picture) for an unrelated issue (tracing fuel pump no power issue).

The connections, and wires on the back of the board were all looking pretty good at that point.

I have had this car for ten years, so the 25 amp was in there for a decade with no issues, I can't blame the P.O. for this one.

The fuse in the holder that originally melted was a 25 amp, the one I used to replace it was a 16 amp (that was what I had on the side of the road) that fuse also melted, but did not blow. I have a 16 amp in now, which is still in place, but have not had time to stick my head in there and clean it out.

928 at last

Make time.
Sounds like a potential car-b-que.

WallyP

I'm not sure that the message is getting thru...

Heat at the fuse is always poor contact on one or both fuse contacts. Usually between the fuse and its connectors, but sometimes between the connectors between the fuse holder and wires behind the panel.

An over-size fuse can melt wires if the fuse rating is much higher than the ampacity of the wires. An oversize fuse will not cause heating of the fuse. Your problem is virtually certain to be resistance at the fuse connections, with the resistance causing heat at the fuse. The connectors may be loose or corroded.

Alan

What Wally said - Stop trying to make it something else... heating at the fuse body IS ALWAYS A POOR CONNECTION (high resistance) issue- it has little to do with the power consumption of the circuit being protected - though having a much higher fuse value installed may mean there are issues there also - however they are unrelated to this heating issue. You need to fix the connection issue - its mostly a cleaning, tiightening and quality fuse replacement strategy...

Alan

bernard farquart

I just re-checked the last fuse I put in. it is holding up well, and I ran the fan for awhile and had my finger on it, with no warm up. I think the top spring holder is a bit tweaked, i will have to re-bend it when I have more light.

Since I think the start to this issue was the crappy new fuses that are too long, does anyone know of a properly designed brand currently for sale? Bussman is out, as they are now making GBC fuses too long.

Alan

No this is not the way it works. The fuse element is not what melts fuses... they melt from the ends because thats where they get hot due to contact resistance at the places they connect

I know you and most people think differently - but its wrong. The small size of the fuse element is such that even the plastic dissipates the heat sufficiently before it blows. In these cases of heating the total circuit current is actually below the fuse limit - well below usually - because the heating is due to excessive in circuit resistance that lowers the normal circuit current. However a voltage dopped across a resistance means significant power dissipated where there should be basically be none...

AND Fuses are not supposed to get excessively hot in normal operation

Alan

Landseer

Well said.

Now the long fuse are indeed a huge problem for these CE panels.

We did a refurb a few weeks ago on an 84 and had to remove and discard the brand new long fuses. Actually, we never got more than 7 or 8 installed before we realized it was fruitless. Damaged 6 or 8 more in the process. Almost impossible to install without damaging the ends and they absolutely do not seat uniformly on the bases. So that can easily be contributing to your issue, in conjunction with dirty contacts. We had to go back and rebend the upper contacts. Real PITA.

Get VW fuses.

Btw, they aren't likely melting, they are bending as the ends overcompress. Seen dozens like this. That little spring clip has exponentially more force on it as its opened to accept the longer fuses and the little semi hollow ends deform, compressing the filament, especially if you spin them a tiny bit to seat them. With time and vibration in the panel, they probably bend further.

Landseer

Happen to have examples, doesn't seem like much of a problem but it was for us.

The other problem is consistency. We didn't measure that set we tossed, but we saw some very long ones.

Here, in a pack of 6, check out a white Buss, yellow Buss, blue Buss vs White 928 (copper colored filament).

Note the last few pictures of the yellow one, measured after test install/removal.
See how the end deformed a bit? You can't spin these to seat them without ripping them and the metal seems softer.


What we pre-85 guys need: A Short Bus