replace all fuses?

[dmwallace]

A blown fuse during a trip last week (naturally it was the AC on a 97 degree day) has me wondering about the condition of the rest of the fuses on my '89 3.2. The other fuses in the front fuse box look kind of cruddy but I have never looked at bullet-style fuses before. I also have no idea how old the fuses are (could be all original?).

I am thinking it would be a good idea to replace all of the remaining fuses - does this make sense?

Is there anything I need to pay particular attention to during the replacement, beyond doing 1 at a time and replacing with the same amperage fuse according to the listing on the fuse box card and in the Bentley manual?

Do I need to loosen the terminal screws before changing the fuse or just pull out with a fuse puller?

Does the battery need to be disconnected?

Are there any other fuses located elsewhere in the car that I should replace?

Thanks,
David.

[coloradoporsche]

Unless there is some unusual corrosion on those fuses, I wouldn't bother. If you moved into a 17-year-old house would you replace all the circuit breakers?

[Wil Ferch]

Not the same thing...bad analogy...IMHO....

The German "suppository" fuses are bare aluminum strips on plastic or ceramic bodies....and suffer long term corrosion and vibration effects.

If you can find the right sizes...it might not be a bad idea to replace them. Your alternative is to remove/inspect each one individually, and "abrade" ( pencil eraser) the end-tips to be clean...also clean the fuse holder contacts and make sure they have enough "tension" to hold them securely. A little dielectric grease smeared on the tip ends and maybe the body might not be a bad deal either.....

- Wil

[dmwallace]

Thanks for the advice, Will. I guess I should also clean the fuse box contacts with a pencil eraser when I replace each fuse.

Re. finding the right sizes - I did find the 25A fuse at a Advance Auto store which also seemed to have a good selection. So I just need to total up the quantity of each size fuse needed and I should be okay.

One other question - are there any other fuse locations besides the trunk fuse box that I would need to check?

Thanks,
David.

[Wil Ferch]

Two things..... the yellow ( 5A ) style are hard to find for some reason.

If your 89 is like my 85 ( I think it is)...there are also 3 fuses in the engine compartment left cover...for rear defroster, etc.

If you swing open the trunk smuggler's box, there should be a relay mounted to the inside wall. The 88 update shows an external 16A fuse piggy-backed on the relay, too.

-Wil

[dmwallace]

Thanks for those extra location suggestions, Will. I was just looking at the smuggler's box recently contemplating some AC upgrades so will look for that fuse and also in the engine compartment.

[ruf-porsche]

Originally posted by coloradoporsche
Unless there is some unusual corrosion on those fuses, I wouldn't bother. If you moved into a 17-year-old house would you replace all the circuit breakers?

Yep and upgrade to a 200amp service, but thats me.

[randywebb]

find a post by Warren or (Sherwood?) re pickling vinegar to clean the corrosion off

some have replaced the box with a modern one

[coloradoporsche]

Maybe this is a matter of philosophy....

I certainly don’t mean to rain on anyone’s parade regarding a fun Porsche project. And who am I to argue with Will Ferch?

But replacing fuses prophylactically? Never heard of such a thing. Most people just carry a few in the glove box. Like I said, if they show signs of severe corrosion, that’s another story. But hey, knock yourself out if you are looking for a project.

You guys don’t like the circuit breaker analogy? OK…maybe we should all replace the headlights every year. They do have a tendency to burn out, you know That fuel pump relay is probably next…better just get a new one. Call me crazy but I just replace pluggable electronics when they wear out. That’s why they have sockets for crying out loud!

And Dmwallace didn’t ask if he should clean them, he asked if he needs to replace ALL the fuses! I say no.

That’s my story and I’m sticking to it.

[dmwallace]

Coloradoporsche:

I was soliciting opinions on this and appreciate your perspective. I am not really searching for a fuse project, but on the other hand replacing fuses at $.25 each at leisure instead of a replacement on the side of the highway does sound good for a "all thumbs" P-car owner especially given that I don't know if any replacements have been done previously.

[Wil Ferch]

I say what I do for a "reason"....if you look how poorly designed the Porsche electrical system is..and how poor ( in principle and execution) a "suppository" fuse is...then maybe you'd think differently.

Look at the Tech Articles and search for hot running fuses for 930 fuel pumps and A/C...for example ( Lee Rice article ?)...I've seen the same thing on the 25A A/C circuit when it runs so hot it distorts the fusible link within the fuse...enough to give it an "S" shape"...but not enough to "blow".... can still cause problems..

Yeah....call it prophylactic replacement if you must.... but it gives you chance to "renew" these heat-stressed parts and at the same time let's you check for fuse ( and fuse holder) condition.

I would be less concerned if these were ATO style or glass-encapsulated fuses in a proper design that doesn't overload the system.....

BTW....anyone can argue with me...I'm nothin' special ...just a poster like you !! ....

We're here to present opinions, hopefully based on facts or experience. No problem.

- Wil

EDIT--> Lee Rice Article here--> http://www.pelicanparts.com/techarticles/rice_ramblings/rice_ramblings-2.htm

[dmwallace]

Will,

Thanks for the pointer to the tech article; I had not yet checked those and the tip about the redoing the AC power is something I will look into. Re. the existing fuses - considering cost and time vs. some level of risk of being stranded or otherwise inconvenienced during a long trip (or at night or a storm) I will definitely be changing out the fuses in the short term.

Regards,
David.

[Por_sha911]

Two things: 1) at the very least, have some extra fuses and a relay in your glove box. It took me a while to find the 5A yellows. 2) Wouldn't the dielectic grease be a problem with making it easier for the fuse to pop out (expecially if they aren't put in properly or if there isn't sufficient tension)?

[Wil Ferch]

Suppositories need grease !!!....LOL !!!

- Wil

[randywebb]

Fuses or circuit breakers in a house carry a LOT of current, making minor surface corrosion not such a terrible problem.

In contrast, many auto fuses carry little current, hence the surface corrosion could be more of a problem for some fuses/circuits.

A second reason the analogy above is not the best one, is that if a fuse or circuit breaker goes out on your house, you take some form of transport to a store and get another, or you just flip the breaker.

In contrast, if a fuse blows on your car, it may interfere with your driving. And... it could leave you stranded in a remote location with no help. Potentially, you could run out of water or shelter/warmth and die before getting help. Depends on where you drive. Some of us drive little used used roads in the boonies in our cars - esp. those in the West.

I have not replaced my fuses or box, but I did go thru and clean/inspect each one.

[defcon65]

Clean 'em with a pencil eraser and do the fuse box contacts, too. If the copper element is bent, you might want to replace the fuse. While you're in there is a good time to check the wire connections and tighten them up. Disconnect the battery first, of course!
BTW, salt and vinegar will clean all the oxidation off copper. Makes a good potato chip, too. Rinse with clean water and spray with WD40 to protect against future corrosion.

[randywebb]

I have not been able to find any potato chips that are just the right shape to get into the fuse holder. If anyone knows of a source of cone shaped potato chips, maybe they could post it.

[defcon65]

Try Bugles, Randy.

[randywebb]

no vinegar with the salt...