I smell sulfur
 

I kept wondering what that smell was, getting in and out of the truck. Smelled a bit like that stuff they put in propane so you can detect leaks. Then I realized it was sulfur. My battery box is right under the driver's step.

Told the owner of the truck he's going to be needing batteries, and he seemed dismissive.

What say ye, O Wise CADsters?

Overpowering rotten egg stench emanating from the battery box area means bad ju ju, dunnit?

What is the reading on your truck's volt meter when operating?

Should be in the neighborhood of 14 volts when the engine is running.

If the voltage is significantly above that level the gas coming from the batteries could be due to extreme overcharging. If this is the case , get the alternator checked, as the internal voltage regulator has probably failed allowing the alternator to go "wide open". This excessive voltage can also cause premature failure of lights and electronic components.

I have seen cases where the alternator's voltage regulator failed and the gauge was pinned!

If the voltage reading is normal, then the smell is probably caused by batteries that are near the end of their lifespan.

I have had batteries short out before and start boiling. It is easy to tell which one by removing the battery box cover and looking for the one that is wet on top or by which one is hot. Be extremely careful as battery gas are explosive. If you do find one is bad, wait until it has cooled down and remove it from the system. The truck will be fine until you can get the defective battery replaced.

yup, heat is the #1 clue.

Remove it, maybe have it tested.

I'd just change all of them.

Me too, though it didn't stay pinned long enough to do much damage. The alternator seized up very shortly afterwards.

I'll never forget that night. I drove another 100 or so miles back to the yard running the extremely dim headlights off the batteries, with the button on the fuel pump screwed in.It is (a little on the low side of normal at that), so I'll go with this explanation.

Thanks for the input everybody!

Owner checked the batteries with a tester. They all listed as bad. New batteries, no more problems.

You sure that W wasn't driving your truck last???