[Johnalfa]

Just replaced the terminal block for fan fuse on my 94LS. When I took out the old bar fuse, it's labeled 80A! I've had the car for a year; guess I'm lucky nothing melted down. Haven't had a chance to drive with the 40A fuse. My question is, why would the 80A fuse have been there, and what damage could it have done?

John

 

[SpiralArchitect]

Just replaced the terminal block for fan fuse on my 94LS. When I took out the old bar fuse, it's labeled 80A! I've had the car for a year; guess I'm lucky nothing melted down. Haven't had a chance to drive with the 40A fuse. My question is, why would the 80A fuse have been there, and what damage could it have done?

John

Probably someone had a 40A fuse blown and decided an 80A fuse would be more durable. You are indeed lucky nothing melted. When I got mine I went through all the fuses to check if they were OK, I remember finding a 20A in place of a 7.5A.

Is some part of the wiring modified? If it were a diesel someone could have installed a straight vegetable oil kit with a fast electric heater. Since it's not... I can't justify it.

 

[Michael Smith]

I once had a car "repaired" by a "professional" mechanic with a 30 amp fuse in place of the 5 amp "to stop it from blowing all the time". Two days later the trailer hitch wiring (installed by that same "professional") caught fire and literally pinpointed the cause of the problem. The back of the female connector (facing forwards) was totally unsealed and salty winter spray was getting in and shorting out the 5 amp fuse, harmlessly. In the shop the water dried out and "no fault found".

Never, under any circumstances, put an oversized fuse in a circuit unless you absolutely know that the entire circuit protected by that fuse can take the additional amperage safely.

I also recently had a trailer hitch installer put the fuse at the rear of the car instead of at the battery when directly wiring power from the battery to the female connector at the rear bumper. This is not rocket science but there is inexplicably a lot of ignorance about electrics in the car repair business. My truly professional mechanic wired in a second fuse at the battery, for free. Double protection!!

I know from actual experience that the Honda fuse works (45 amp I think it is, instead of 40 amp) and it seems because you need to bend a curve into it to fit the terminals that it lasts longer. I believe the curve allows for the fuse to cycle through heating and cooling without fracturing.

 

[Johnalfa]

80A Fan Fuse

Guess I really lucked out on this one. If I hadn't gotten a new fuse block to replace the old one with a broken retaining tab? When I pulled the old fuse i noticed it felt thicker than the new one supplied with the fuse block. The 80A marking was barely visible under the light on my workbench.

John

 

[Del]

"you need to bend a curve into it to fit the terminals that it lasts longer. I believe the curve allows for the fuse to cycle through heating and cooling without fracturing"

I totally agree. That's been my thought all along as well. Have had one like that in my 91S for years. When fastened down tight at both ends by nuts, the flat strap just gets too loaded with thermal stress fatigue cycling, mostly due to the 40A being just a little too small and getting hotter than Alfa had guessed at. 45A or 50A would be ideal, using more would risk burning up wiring somewhere.

Had a friend with a Merkur XR4TI with a short in the window motor wiring. Local dealership couldn't figure it out, so they just bypassed the fuses for that and straight wired everything. Needless to say, poof, there went the wiring loom. Cost the dealership a lot of time and money to replace the loom. Morons are everywhere.

 

[SpiralArchitect]

Don't you love those "so it doesn't keep blowing all the time" sort of electricians? They're everywhere!

A few months ago someone asked me to take a look at an industrial cart-sized battery charger. Instead of having two 80A fuse "blades" between the two posts leading to the +24V wire, it had a bunch of fencing wire rolled around them! The poles got so hot the insulators were charred to bits! Needless to say the transformer core windings were destroyed.

Later the same guy asked me to take a look at another 12A charger. I inspected it and said the protection switch (a thermal breaker) had to be replaced and I might need a few days to find a suitable replacement. His answer was "bypass the switch".

I obviously refused to do it. Do these people ever think about consequences? Both fuses and switches do the same: avoid fires. It's cheap insurance.

 

[goats]

want to see

if anyone else remembers this; house fuse boxes

In the old days, there were fuses (not breakers) for your house circuits. There was a screw-in type fuse called a BUSS fuse that happened to have the same diameter as a US penny.

I can not tell you the number of houses I worked on / troubleshooting electrical issues, back in high school, that had a BLOWN fuse --- BUT behind it, was a lincoln penny!!!! When you asked the homeowner about it- the obvious answer was-- to keep the fuse from blowing! Then, when you went upstairs to check that circuit --there was a 1000 watt electrical heater, and an extension cord that had a 500 watt (tube ) radio, and in the next room, was a hot plate or toaster, etc etc etc

3-4 K watts of stuff on the circuit drawing (at start up ) 25 amps or more on a 15 amp circuit-- and the house wiring (copper in those days) never seemed to burn up.

Nowadays-- dont try this at home!

 

[SpiralArchitect]

3-4 K watts of stuff on the circuit drawing (at start up ) 25 amps or more on a 15 amp circuit-- and the house wiring (copper in those days) never seemed to burn up.

Nowadays-- dont try this at home!

Are newer houses wired with aluminium around there? I've never even come across aluminium wire in any store. Copper supplies are getting scarce. Estimates say it will run out in 25 years.

 

[Michael Smith]

We used aluminum (as we call it) for a number of years but are back to copper. Aluminum was found to creep out from under mechanical fasteners as it flows under pressure. Oxidation also created high resistances at connectors. A few house fires put an end to aluminum for home wiring.

As we also use 110 volts instead of 220 our house wiring is heavy gauge as well.

 

[Johnalfa]

I've driven the 164 for two days now(approx. 100 miles) with the proper 40A fuse. Fan has been operating normally and fuse is still intact. So I still don't know when or why the 80A fuse was installed, but I'm glad to be rid of it.
John

 

[SpiralArchitect]

"So it won't blow again."

You will probably find that even 40A is much more that it carries most of the time. I'd bet it won't blow unless either someone messes up the electrics or there's a short.