Passenger battery boiling

krys2130

New member
May 14, 2010
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I have a 2004 Chevy Silverado 6.6. When I bought the truck I put new batteries in it and after a few months the passenger side battery started boiling, I checked the alternator output and it was reading 14.7 so I changed the battery thinking maybe it had a bad cell. A few months later same thing, so I put in a new alternator and batteries. Then a while later once again same thing passenger side battery leaking, and starter not engaging so I put in a new starter and battery. My question is what is causing my passenger side battery to boil over? is there a isolator switch on there that I should be looking at or some type of relay? I am stuck here...I just can't seem to find the problem and hoping to get an answer soon.

Thanks, any suggestions would be appreciated
 

JMK777

16's, but i keep em clean
Mar 20, 2008
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sounds like your over discharging the battery. could be bad cables/connections
 
Last edited:

rick67

New member
Jan 20, 2010
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Indiana
It sounds to me like the right batt is doing all the work. I would check cables, connections, etc. to the left battery.
 

Ridin'GMC

I like red
May 20, 2010
620
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MA
When one battery goes bad, it can cause the other to do all the work, hence the boiling. It's better to change both battery at the same time when one goes bad.
 

Josh2002cc

That Uncle
Apr 2, 2007
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He has replaced the batteries and the alternator already. So unless he got a bad battery and it just so happens the drivers side battery was bad when sold or bad after install is unlikely.

I bet on rain water/car wash water is the culprit. ;)
 

Wolverine68

New member
Jun 9, 2024
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16911108ast
Only the pass side battery?? I'm willing to bet that your issue is that your windshield drains directly onto the top of that battery. If it is a flat top maintenance free battery, the drainage gradually overfills the battery. Poor some water on the pass side windshield and I guarantee that it drains directly onto that battery. I had the same issue. I put some duct tape on the top of the battery where it drips and built a little duct tape dam so it drains off and I've had no issues since.
 
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Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Only the pass side battery?? I'm willing to bet that your issue is that your windshield drains directly onto the top of that battery. If it is a flat top maintenance free battery, the drainage gradually overfills the battery. Poor some water on the pass side windshield and I guarantee that it drains directly onto that battery. I had the same issue. I put some duct tape on the top of the battery where it drips and built a little duct tape dam so it drains off and I've had no issues since.

It’s a 14 year old thread my man, I’m betting he got it figured out or sold it
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Could those AI bots be starting to infiltrate here now? They're really bad on other forums.