MGB-GT BGT just died - I'm stuck Panera Bread

[tdskip]

Thank goodness for WIFI!

So the BGT just died after a period of surging and going through what left like the brakes a being put on and off.

The electrical system is totally dead - nothing. When I checked the battery connections the (+) wire it sparked badly.

I stink at electrical, but this seems like I have a ground somewhere I shouldn't. Yes/no?

Ideas?

Anyone want a sandwich?

 

[100DashSix]

I'm not sure how much help I can be, but can you further describe how the car died and how you checked the + connection? If I understand your first sentence, the car surged powerfully as if the brakes were being pumped, then cut out and drifted without that surging?

 

[tdskip]

So here is what happened. She started surging, or more accurately, feeling like the brakes where being lightly tapped on and off. This has been happening for the last week, and I assumed the carbs were needing a rebuild. (hey, I'm learning as I go here)

On the way home tonight she was doing the same thing until she just cut out on thw highway - totally dead. No power to fuel pump, clock, lights, nothing. Totally dead.

When I went to check the battery connections and the + lead sparks badly any time I move/touch the lead. It makes enough sparks that I decided to just have her towed home rather than fool around with it on the side of the road in the dark.

She has a one modern battery rather than two, and the ground line is connected and appears to be well connected to the chassis still.

Thanks for the help!

 

[Keoke]

Yes it sounds like you have developed a hard short in the hot side of the battery power. Prior to developing the hard short it seems you were getting intermittent ones cutting the engine power off intermittently.--Fwiw--Keoke

 

[Kimberly]

Wiring diagrams are available at https://www.advanceautowire.com click on stock schematics. Start at the positive post on the battery and methodically check the wiring for damage.

 

[Scott_Hower]

Tom-

Very first things to check are the battery terminals. They need to be clean and tight, no wiggle. The cables should be securely connected to the clamps, with no corrosion. Sometimes people cut the lead and install new cable clamps and they corrode after a while (BTDT).

Next, check the -ve ground lead to the chassis from the battery. Same deal, it should be clean and tight against the chassis. I always wrap my wrench in electrical tape when working in the confines of the B's battery box. One misstep on the +ve to ground and you'll weld the wrench to the car. Not fun.

Next, trace the battery +ve cable forward from the battery under the passenger floor pan to the starter solenoid lug. Check carefully for damage/cracks/whatever. The cable ends at the starter solenoid and should be, you guessed it ... clean and tight. Sometimes the copper stud on the solenoid is stripped or corroded or both. Disconnect the -ve battery terminal before you attempt to remove and clean it.

That ought to keep you busy for an hour or two. Report back what you found and we'll go from there.

FWIW, this summer I replaced the main battery cable on my B with a pre-made assy from British Wiring. It fit perfectly and only took an hour or so to install. Might want to look into that. The new cable was a bit thinner. Just for the heck of it, I cut off the the coroded ends of the old cable and measured the resistance against the new one. The new (slightly thinner) cable was *half* the resistance of the old one, which suggests corrosion inside the sheath.

 

[tdskip]

I have a direction now to go pursue.

Thanks guys!

 

[Jack_Long]

With all that arcing, I suggest that you disconnect the ground wire first and then visually inspect the main cable from the positive post all the way forward. Less chance of shocks or melted wiring.

 

[jlaird]

yep, would do as Hap says first, also have a fire extengiser handy in case the smoke wants out.

 

[tdskip]

in case the smoke wants out.

LOL.

I'll be careful.

 

[DrEntropy]

Sounds more like what Scott explained than a ~short~... That'd fry the harness or parts of it. Likely an intermittant connection or corrosion as the culprit.

 

[Steve_S]

This is so funny! No, not your breakdown. I'm in South Carolina right now. My wife and I ate at Panera Bread today and loved it. We were trying to figure out if there were any on the west coast, especially in our area. Now we know!

 

[tdskip]

Steve - come to Irvine for the food. Stay for the BGT repair. LOL.

Hope you are having a good trip Steve.

Actually I just fixed it. The PO had a battery relay that was exposed joint that was bouncing around (hence the intermittent power loss) and eventually got stuck and partially fused to the bottom of the battery well.

Simple fix thanks to everyone coaching.

Thanks again guys!

 

[DrEntropy]

Oddly enuff I had a bank run planned this afternoon... set off inna Alfa, got around the block and the bloody thing "hiccuped"... another few yards, a bump and another stutter. That time I was watching the instruments: Charge light blinked on, voltmeter dropped like a stone to 0 volts and back to 14... intermittant power connection! limped gingerly back to the hovel and found: Battery + side clamp ~slightly~ loose, removed the "snoot" from the back of the alternator and found OAK LEAVES packed into the vent holes, and (AH-HA!!) a poor crimp connection to the alternator +V supply. Total time, 20 minutes. Bank run made with no further incidents. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

Your fault, tdskip... I was pondering your post as I set off! /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

 

[Bugeye58]

Ah, the joy of Magneti Marelli! And we thought Lucas was bad!!
Jeff

 

[DrEntropy]

NO Sh**!!!

A dim starboard headlamp (an H-4, no less) had me scramblin' last month. Worried that low voltage would eat a $10 bulb... Turned out to be a piddle-poor connection right at the spade connector on the ground wire at the lamp. A resolder rectified it... but it weren't soldered at factory. Crimped! It's solder'd NOW, by Joe.

Marelli, umm.... well, Marelli ain't Joe and th' Boyz.

 

[Bugeye58]

Doc, on my Fiat, the Marelli ignition uses a GM module! At least it's easy to get parts.
Jeff

 

[DrEntropy]

I deep-six'd the Marelli "mist/fog vulnerable" dual point dizzy and schtupped a Bosch unit in the 1750... VW POINTS!!!

MWUHAAHAAHAAA!!!!!! Buck-ninety-eight a set!


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