blower fuse started a fire in my engine compartment!
 

I was driving down the road today in my '93 400E with my A/C on and my blower "hiccuped" for a second. About a minute later I was slowing down at a red light when I noticed smoke coming out from the drivers side of the hood. I immediately pulled into the turn lane with my flashers on and turned off the blower fan. I popped the hood and the blower fuse was completely gone and all of the plastic around it was on fire. :eek: I blew it out after a couple tries. The hood pad even melted. What should I do? I'm afraid to even try the A/C now.

This has got me worried because the '88 300E I sold to my neighbor had the same thing except the only thing the fuse melted was the plastic cover that goes over the fuse.

I saw this melted fuse/hoodpad earlier in the day, and it looks as bad in person as it does in the picture...maybe worse. If I wouldn't know any better, I would say the plastic fuse holder erupted like a mini volcano.

The only theory that I have so far, is that there was a hairline crack...seeing as how there is so much current, it was able to bridge this hairline crack, and at the same time because it was bridging this gap, the metal started to heat up/ turn red, which then caused the subsequent melt-down.

Or....a cockroach was sitting on the metal strip, and when the current went through he hung in there for a while until he finally blew up, and what you see it actually cockroach guts.

I think I will stick by my first theory, and see what y'all come up with. I have a keen interest in knowing the cause, since I have a '94 E420.

-Larry

*** bump ***

At the risk of annoying anybody...

I would really like to know if anybody has had this happen - I have a E420 and would like to know if there is something that I can do to prevent this from happening to me.

I am sure that other 400E/E420 owners wouldn't mind preventing fires under the hood as well.

thanks! - Larry

I would guess that if the fuse was the right size and did not blow, than the fire/heat was on the line side of the fuse. Maybe you had a bad connection from the wire to the fuse spade, or between the fuse holder and the fuse spade. The fuse would not blow in this case.
If the fuse did not blow, make it blow on purpose using a jumper wire from it across the battery. Just to make the sure the fuse blows. If it blows, then I am certain you had/have a loose connection of some sort on the line (battery) side of the fuse.

My independent mechanic told me that he originally suspected that my blower motor had frozen up and that caused the subsequent fuse to blow/fire. He has since taken my blower motor out and verified that the motor was not bound up.

When the initial blower "hiccuped" I know for a fact that the blower was still running even while the fire was burning. After I saw the smoke, I turned the blower fan off and then after putting my flashers on, I turned the car off and popped the hood. After extinguishing the fire, I started my car up and of course since there was NO fuse the blower motor did not run. Does fire conduct electricity? Although, there was NO fuse while the fire was burning, I KNOW the blower motor was running.

Anybody know if fire will conduct electricity?

tkamiya,

Thanks for your reply. I did not assume that you were accusing me of anything. As a matter of fact, my independent mechanic replaced that same blower motor fuse about 6 months ago. That time, however, it was merely that the fuse blew and the blower motor quit. I know he put in the right fuse because I watched him install it. That is the only reason I knew that the fuse area was on fire when I originally had the problem. The blower motor "hiccuped".

Thanks again. Sometimes it is frustrating on this forum because you can ask a question AFTER you have searched the archives and yet still nobody answers your post. Not even to say "hey, I feel for you. Same thing happened to me."

Blower motors are nasty little creatures sometimes! When they go bad they will start pulling amps like gangbusters and if you have any problem whatsoever in the circuit where it can pull from, it will. If the circuit has a weak point it will heat it up. Not easy to tell exactly what happened without seeing the actual spot where it erupted, but I have seen some of those auto fuses heat up before and melt to the point the 2 poles connect together, this would create the weak point, or the failure. It is not the fuse or the circuit, but more likely the blower motor going bad and drawing too many amps. I feel bad for you because it is likely you will have to replace your whole fuse block. When you buy a car, always look in the fuse block, check the fuse sizes to the specified size on the chart and make sure no funny business is going on in there. The fuse should have stopped the motor, you had a very rare unfortunate incident. The fuse block has a lot of wires in there. If you are not comfortable replacing it, get someone else to do it. Did you open the lid to the fuse box yet? It looked as if it were still closed? What about the big fuse and relay box behind it? You have a lot of work to do, you will have to replace your blower motor and likely the harness to it, also you very likely could have a problem with your climate control assembly. Good luck!
Brian

That is probably more likely than my theory, I don't know a lot about he E class cars, I didn't know it had a fuse link independant of the fuse block, That is good news though as he will only have to replace that link and not the whole block. Thanks !
Brian

I've seen this and there was a very simple cause. One of the screws that held the fuse was either too long or overtightened till it hit the fender under the holder; taking the power side right to ground. Bang!

A bit of an update (I went to the mechanic that is working on fz500sel's E400).

Seems it was something in the ignition switch that caused the fire. I looked at the removed switch, and noticed that X15 was broken.

What is this connected to, that would cause a fire?

Weird....

Fuse fire on my w124
 

Hello, your post is of great interest to me as this has just happened to our 1990 300E. Under hood, after the fire looked similar. We put the fire out with a blanket. We have had the paint work repaired. We have wired in anew 30 amp fuse, the type most new cars have, not mercedes fuse link, and the fan at any speed continues to work and not blow the fuse. The fire was caused directly by MB fuse due to its location. It, and it alone, started the hood material on fire,including other wires to catch on fire. With the hood closed it more or less touches the hood lining.
I have no trouble with fuses blowing due to any cause.The fuse is supose to 'burn out'> Its sole perpose is so that wires/cars do not burn to the ground. Right? I do have a big problem with M.B. over this 'add on' fuse link. It was an quick fix for the earlier smaller fuses in the fuse box. Do you know of a good law firm? My pictures are the same. let me know what you think please. warm regards........miglenda

fuse fire-miglenda
 

Hello Larry, thank for the link. In our case the fuse was red hot and did not to what a fuse should do. It ignited the hood liner. After the fire was put out and our B.C.A.A. towed the car first to our home prior to phoning our insurance company. At home I started the car up, hood open, and it again was started arking and spitting small fames. It never melted the plastic holder!
Just the arking from it created the other fire. your thoughs. Maybe a small debt court would help us all out?.

regards
michael---miglenda

fuse fires
 

Hello Brian,I have a post under miglenda-fuse fire. Our car is as new through out and under the hood is spotlessly clean. This inline type fuse was stock and nothing in its mounting shorted it out. I acutally saw it arking through the plastic connector. The fire was caused due to its mounting on the shock tower. When your hood is closed your hood liner is is more or less just about touching it. It should get hot and burn out, not keep arking and burn the car down. It is none other than a bad design and location. We have a large fleet of Hwy trucks and from time to time fuses burn out. Some bigger than 30 amp. Never has a fire been started due to this.They were mounted properly.
regards
michael.

I've seen this a number of times. In all cases the problem was either a wrong too long screw on the feed side or a continued disreguard for a high resistance connection till the point where the heat allowed the circuit to melt down allowing the screw to touch the body on the feed side.

Tight clean connections of original specification have no problems even with shorted components. The fuse will blow.