Battery Dying After Engine Swap

[1984CuttySupreme]

I just recently had a 4.1 V6 Buick motor put in my Cutlass that had a 3.8. Since I've gotten it back from my mechanic the battery keeps dying. Even after installing a brand new battery the power windows & everything electric seems sluggish and soon after the battery dies and the engine won't crank. The alternator is relatively new as well. Any ideas what might cause this? I have several other questions but I figured I'd get the most important one out of the way first. I installed new battery terminal connectors today and have the battery on a charger so I'll test that tomorrow. The positive terminal was maxed out and was cracking in half.

 

[breeaad]

Sounds like you have an electrical drain. With everything off, and key turned off, put a current meter across the positive and negative posts of the battery. Any reading will show you have a drain. Have a buddy watch the meter and start pulling fuses until the current goes away. That will tell you where the drain is. If there is no drain, I would start by looking at items associated with the swap. A bad drivetrain to body ground could be a culprit. Perform a voltage drop at all connections by connecting a voltmeter to both sides of the connection. The readin should be zero. Hope this helps!!!

 

[84GP455]

Since it was an engine swap i bet a ground strap was forgotten. Check the engine to chassis ground strap in the back of the motor, there should be a braided metal strap going from the block to the firewall. If not you need to put one there, they are easy to forget to put back on when doing an engine swap.

 

[79loserbluebu]

Make sure your alternator is charging. A simple test would be to run the car and test voltage at the battery. It should read 14V. Anything less and you may be running into a problem with the voltage regulator circuit.

 

[1984CuttySupreme]

Thanks for the tips. I'll give 'em a try today and let you know what I find.

 

[1984CuttySupreme]

Since it was an engine swap i bet a ground strap was forgotten. Check the engine to chassis ground strap in the back of the motor, there should be a braided metal strap going from the block to the firewall. If not you need to put one there, they are easy to forget to put back on when doing an engine swap.

Would the engine be able to crank at all if this was missing?

 

[86 regal]

grounds can do some really funny things!

 

[84GP455]

Yes it definitely could. You need grounds from the negative battery to the frame and from your engine block to the chassis.

 

[84GP455]

you bet it could and you could drive it like that for years like i did before i found out my engine ground strap was not on there.
When i did my swap i forgot to replace the ground strap and i went through many alternators until i installed a stereo system with multiple amps then it totally died, so i did a little test. I opened my door with the interior light on which was very dim, then i took some jumper cables and put one on the engine block then i grounded the other end to some metal on the frame and viola! the interior light got 10 times brighter. Then i installed a ground strap from the engine block to the firewall and all my problems were solved.

 

[1984CuttySupreme]

Well I charged the battery last night and so far it's been fine cranking up and driving throughout the day. My mechanic did a light test this morning to check for any drains on the battery and we noticed something very low voltage is drawing some power. But he said it shouldn't be enough to drain the battery unless it sat for an extended period of time. There's a bit of a wiring mess so I'm not sure where to start looking... also I noticed one ground strap unattached on the firewall. I'm not sure where on the engine to attach it though... here's a pic: