newbie question on 82 240D fuse box, etc. - PeachParts Mercedes-Benz Forum

showme · #1 01-30-2008, 11:49 AM

Hey, everybody, this is my first post, and I have a question about the 240 we just bought our daughter for a "college car". The previous owner told us that the heater doesn't work, and he had the blower taken out and checked, and all is well there. The problem is evident though. The #8 fuse has blown in a big way, and, although the lower brass tab is still there and in good shape, the upper one is gone, and the plastic casing on both sides of the fuse holder are a bit melted. It's fried. The rest of the fuses are in good shape, and a fuse still fits neatly in the spot. My question is, can I repair this single fuse holder without changing out the entire fuse box? Possibly bypass it for the winter with an in-line fuse of some sort? What is the procedure for replacing a box, if necessary? Anyone know of any links with pics? I just need to get it on the road for my daughter, Eliza. Right now, she's biking back and forth to work and the metrolink for transportation for school till I get this done.
It also has a problem with shut-off. When the key is switched off, it keeps running, even when you push the 'stop' handle under the hood. (I shut if off by putting it in gear and killing it by letting off the clutch). Other than that, and a generous amount of body rust-thank you New Jersey- it's a good running and well kept little car. I do have to thank the posters at Greasecar.com for referring me to this forum. What a plethora of information. They gave me some good advice, but I'm still not getting enough to solve the problem. Thanks so much for your help. By the way, my wife has an 81 300D that is a great car, except that I haven't installed the block heater and she has to put a drop light under the hood on these cold Missouri nights. I drive a Suburban that is diesel\veggie oil powered. Thanks in advance for any help on the 240 problems. I look forward to absorbing all of the knowledge available here!

ctaylor738 · #2 02-01-2008, 05:16 PM

My .02 is that it would be a huge hassle to replace the fuse panel, and that you would be better off to re-wire with an in-line fuse. But you need to find out why it fried the panel in the first place.

BTW, my wiring diagram (Haynes) for the 82 240 shows the blower powered by fuse 10. Fuse 8 powers the rear window defroster.

You will be better off posting your shut-off problem on the diesel forum.

Good luck.

showme · #3 02-01-2008, 10:19 PM

Thanks, Chuck. Yes, I saw the same thing in my manual. But in my daughters car, it's the #8 that's gone, and in the owners' manual that came with it, it shows the 8 as the blower. I went through the Haynes' book the other day, and even traced the schematic to all points touching the fuse, and it seemed plausible that that was the one. But when I opened up the box before writing the post, I saw that it was #8. The previous owner had said that he had the blower taken out and tested, but after reading quite a few posts on the habit of these blowers running , but pulling more juice due to dragging and wearing out, I think that it may be the one. I think I need to replace the blower, but I have to find a way to insert a fuse in this circuit, or change the box. I'm just not sure how to jump the box fuse with an inline fuse. How would you find the correct wire to jump to? I'll check diesel, but I figured the tech section would be the place to look for electrical problems. Thanks for your reply. I was beginning to feel invisible. Lee

280EZRider · #4 02-02-2008, 02:11 AM

As you have noted, this blown fuse thing is quite common on the w123 cars. It isn't always the fault of the blower however. It does draw a lot of amps, but also many times the fuse itself is at fault. Cheaper fuses are made of plastic w/a cheap coated metal for the current - they melt easily. The better ones are ceramic and soild metal for the current.

If you have an extra bus on the fuse box, you can remove the box and transfer the wires to that bus to avoid having to buy a new box or doing a cheezy wire job on the burned out bus. To remove the box, disconnect the battery, remove the fuses, remove the 1 screw holding the box, and carefully detach it from the firewall, twist it to where the face is upward, and pull it further toward the engine compartment. You can't pull it far, but just enough to work on.

showme · #5 02-03-2008, 11:19 PM

Thank you! That's what I was looking for. Even if I don't change a thing, I'd still like to know what's in (behind) there and then, after evaluating it, decide what to do.

ctaylor738 · #6 02-04-2008, 08:31 AM

Didn't mean to leave you hanging, but we were out of town this weekend.

The 1983 123 wiring diagram shows the blower powered from fuse 8. It shows a 2.5 mm red/yellow wire from the ignition switch to the fuse. A black/green/pink wire runs from the fused side to the blower switch.

So however you choose to do it, you need to install an 8 amp fuse between those two wires. I personally would make the choice based on what is least disruptive to the car's wiring.

Mustang_man298 · #7 02-04-2008, 09:38 PM

Quote:

Originally Posted by 280EZRider

As you have noted, this blown fuse thing is quite common on the w123 cars. It isn't always the fault of the blower however. It does draw a lot of amps, but also many times the fuse itself is at fault. Cheaper fuses are made of plastic w/a cheap coated metal for the current - they melt easily. The better ones are ceramic and soild metal for the current.

If you have an extra bus on the fuse box, you can remove the box and transfer the wires to that bus to avoid having to buy a new box or doing a cheezy wire job on the burned out bus. To remove the box, disconnect the battery, remove the fuses, remove the 1 screw holding the box, and carefully detach it from the firewall, twist it to where the face is upward, and pull it further toward the engine compartment. You can't pull it far, but just enough to work on.

I agree and second this. You should have an extra space or 2 for options that aren't used on a 240, (I believe the very far end 2). I too had a bad experience with plastic fuses on the blower circuit, 1-2 per week until I figured it out (fuse remained intact but plastic body melted and let it squish away from contacts, Buss brand). I knew the motor wasn't the issue because the fuse element didnt burn and the motor was just rebuilt. I now use only ceramic fuses or wrap the elements front the cheaper fuses onto the ceramic bodies from the originals. As far as what fuse it is, there should be a paper card in the fuse box lid which would describe functions and values for each fuse. I can get you a pic of the one in my 82 if you need. If the top part of the holder failed, and all else is ok, most likely what happened was a corroded or loosened rivet on the buss in the fuse block that caused heat. The upper side of the fuse holders is the "hot buss" side, so the fingers are riveted to a copper buss rail in the block to the feeder wire for that group.