New Engine Shorting Out the Battery??

[mtnbob]

Just replaced my engine. It runs well, but the battery is shorting out. New battery, new alternator, both check out perfect. When I hook up my multitester, take off my positive clamp, and but one lead on the battery terminal and one on the clamp, I am pulling 12.9 amps. When I pull one fuse at a time, nothing changes. When I unhook all electrical connections on the engine, one at a time, nothing changes. I have to unhook my battery at night to keep it from discharging

Any suggestions on the next step??

[burn_your_money]

Did you unhook the 12v power cable to the alternator? Did you pull all the relays?

[Rabbit79]

Sounds like you're on the right track, you just need to move further upstream. I'm not sure on a MK 2 but on mine there's a single wire that provides power to the fuse box, hooks up to the 'H' terminal IIRC. If you could disconnect that you could eliminate the fuse box and most of the wiring. I'd also pull the wire off the starter to see if that's where the problem lies.

[mtrans]

I'd also pull the wire off the starter to see if that's where the problem lies.

X2 for your 12 Amp.

[8v-of-fury]

12A Jesus!

I had 1.16A kill my battery over a 24 hour span.. 12A.. that is brutal.

[mtnbob]

Ok, I haven't pulled my relays yet. I have pulled my starter wire. I'm not sure about where the 12 volt main wire is??

[Rabbit79]

In some cars I've seen them come off the starter relay instead of right off the battery, but if you've pulled your starter wire you've eliminated whatever comes off of there. What I would do is disconnect every wire that comes off the positive side of the battery one at a time until the amperage draw goes away and then you'll have it narrowed down to one particular circuit. Then you can start tracing it out and see where it goes. Bentley wiring schematic would be very helpful for that part if you have it.

[Toby]

I suspect that the alternator has a shorted diode. The easy way to check that is to hook up the battery on a cold car and check back in 1/2 an hour. If the alternator is warm, you have found the problems.

[mtnbob]

Hmmmm interesting!! I will check it out. I pulled all of the relays under the dash, but it keeps pulling 12.8-12.9. The alternator was rebuilt and put in with the motor a month ago.

[R.O.R-2.0]

Ok, I haven't pulled my relays yet. I have pulled my starter wire. I'm not sure about where the 12 volt main wire is??

the main power feed is one of the 2 smaller power wires off the battery.. i believe one is for the glow plug system, and the other is for the fuse panel..

[mtnbob]

Ok ty, I have definitely pulled that!!

[theman53]

Hmmmm interesting!! I will check it out. I pulled all of the relays under the dash, but it keeps pulling 12.8-12.9. The alternator was rebuilt and put in with the motor a month ago.

Just because it is new doesn't mean it isn't a problem, especially electrical stuff. I just wonder for 12amps if something wasn't hooked in backwards or something crazy.

[mtnbob]

Anything is possible, since I did it myself

[Toby]

Did you ever check to see if the alternator is warm on a cold engine?

[mtrans]

I`ll check (unhook)starter motor and when alt.