1994 discovery battery is overheating(cooking)

[shultz74]

i own a 1994 discovery and i am having major electrical problems.headlights keep blowing out, no interior lights, power windows don't work, tach don't work, heater blower motor don't work, clock, etc.... if i am driving and let off the accelerator sometimes it will just stall out. when i am driving on the interstate, sometimes it runs ok, but most times when i accelerate it hesistates pretty bad. it has been hesistating like this for awhile and i would change the plugs and wires usually twice a year and it seems to run better but i don't think this is the problem. so anyways, i was in NYC this weekend, and it shut off right at the toll booth on 678s.. i had no power at all, so right there at the toll booth with 100's of cars behind me, i popped the hood, wiggled the battery cables alittle and i got back power, but now my battery was starting to smoke with alittle bit of water coming out from around the caps.........so i got to my destination, embarrased, and really ****** off because i don't know whats going on here.........and comments or helpful hints would be very much appreciated

 

[joey]

Bad alternator, change it fast before it cooks your entire vehicle.

 

[shultz74]

do you think i have a bad ground also and including a bad alternator? or just a bad alternator?

 

[joey]

Sounds to me like a bad Alternator... could be a ground issue, but I doubt it from what you described.

 

[shultz74]

ok. thank you, very much. today i drove it to the parts store, popped the hood and looked at the 100 amp alternator fuse and i discovered that the fuse actually melted and the fuse box cover started to melt. so i had to have it towed back to my house cause the little time that it sat while i was in the store, it totally drained off all of my battery. i put a new fuse in it, and while i tried to start it again the fuse got real hotttt. so, it still wouldn't start and ended up having it charged. now, im looking for an alternator on ebay.

 

[DigitalNY]

I don't presume to know more than Joey considering his experience and history but I'd check elsewhere before purchasing a new alternator. Also, you should be able to find a parts shop that will test your current alternator.

When you mention that the fuse melted I assume that the fusable link itself (the metal strip) melted, but from the sounds of it the plastic fuse casing and some of the fuse holder melted also.

If you have a significant battery voltage drop with the vehicle off and alternator fuse blown or removed then I'd venture a guess that there's probably a short or increased resistance somewhere in the electrical system.

I'd perform the following tests and would try to do it in as short a period as possible to reduce the chance of frying further sensitive electronics.

I would start poking around with a multimeter and check voltage at the battery with vehicle running ~2000 rpms and accessories on (headlights for example) , (use the throttle cable adjustment under the hood to bring the rpms up to around 2k while testing). It should be 13.8-14.6VDC.

Check voltage between battery positive and chassis ground using the same running conditions as above. (brush a bolt in the engine compartment, connected to the chassis clean with sandpaper or wire brush and use it for the neg side of the test). Results should be the same as above.

Check voltage between alternator positive output (the big fat cable) and chassis ground using the same running conditions as above. Results should be the same as above.

If you get differing results of more than 0.3-0.5VDC then you'd have to start checking the path between these components. I'd also take a look at the negative ground side of the connection where the battery cable meets chassis and take a look at the circuit board in the under hood fuse box, their prone to corrosion.

Above all I'd have the alternator tested. You should be able to find a shop that will test your alternator outside of your vehicle, just call around and ask. Also ask if they know of anyone in your area that rebuilds alternators. A rebuilt alternator if it's done correctly is just as good as new. In your case if it is the alternator I'd say that there's about a 85% chance that it's the integrated rectifiers or voltage regulator, not the windings, and should be a relatively easy fix if the windings are in good shape. The only parts necessary to bring the alternator back to spec would be the rectifiers / regulators, brushes and possibly bearings.

DigitalNY

Disclaimer: Nothing I say is my fault.. Nothing you do is my fault.. etc.. etc.. These are just the ramblings of a rover newbie...

PS- If you get results that are outside the 13.6-14.8V range post them here, I'm curious.

 

[DigitalNY]

Also, if your looking for an alternator and don't want to use e-pray you can try:

http://www.autopartsgiant.com They carry reman'ed Marelli 100A Alternators for your vehicle for $160.16 plus $60 core charge that you'd get back when you send them the old alternator.

Just a thought...

 

[shultz74]

ok. thank you. i will also check those grounds out and under the fuse case under the hood. i will let you know my results. i bought a fairly new alternator on ebay for $50 shipping included. i am also going to take the old one off and have it checked out too. thanks