Did I Ruin my Jeep's battery by adding oil?!

February 12, 2008 4:30 PM

Jeep Repair: I have a 97 Grand Cherokee (actually, the badge reads "Cheeroke" for undetermined reasons). I performed some recent seemingly-unrelated maintainence./ Why isn't it starting?!

I was doing some routing cleaning and maintenance yesterday when I found that the oil level wasn't even appearing on the dipstick. Not at all comfortable/familiar and yet suspicious of cars, I decided to put a little bit in at a time to see if I could get it to register on the dipstick. The Vehicle Information System is supposed to read when your oil level is low, but hasn't piped up. So I took a chance. After about 1/4 quart (cup?), the oil began to register on the dipstick, well below the "Add" section. I kept adding it in slowly, checking often to avoid putting too much in, which is specifically warned against on the dipstick. I put the entire quart in, drove it around the block and parked it where I could get enough light to repair the liftgate, which had stopped working (apparently pretty common). Some scraped knuckles later, I successfully jimmied the hatch open and could now remove the interior rear panel to actually fix the problem of the lock, but by this time the sun had gone down and so I put everything inside the car and closed the hatch, sure that I would be able to get it open now that I have the rear panel off.
Today I went out to finish the job, and lo and behold. The car won't start! The diagnostic readout said Error 12, which means that the battery has been disconnected sometime within the last 50 startups. Ok, so maybe it's a battery problem, I thought, but the lights were coming on (though dim). Did removing the rear panel, which as far as I could see had NO electrical connections drain my battery? Did adding (too much?) oil?
I got a jump start later this evening - the hood light lit up quite a lot more after I attached the cables, which is a good sign. The engine wouldn't start as I turned the key, except when I was giving gas, and as SOON as I stopped pushing the pedal, the engine stopped completely. If I turn the key with no jumpstart assistance, I get a rat-a-tat-tat machine-gunny sort of sound and also bupkis.
So, not being a car person, I'm throwing myself upon the askMe altar: Can someone help or point me to a good place to ask a newbie?

posted by hoborg to travel & transportation (14 comments total)

I have a '94 Grand Cherokee Limited. There's a security system that is armed when the power is drained. Try locking and unlocking the liftgate with the key, not from the dashboard, and see if it starts normally then. (The manual says that locking and unlocking the driver's door with the key should reset it too, but on mine I usually have to do the liftgate.) Good luck!
posted by nicwolff at 4:52 PM on February 12, 2008

OK. reading more carefully, if you've trashed the liftgate lock, try locking and unlocking the driver's door with the key. If not, the liftgate lock disassembly may have messed up the security fuel-feed lockout, and you'll have to pull the whole anti-theft system which is behind the right side of the dash. Here's a good page on the anti-theft system that I think is what you're dealing with.
posted by nicwolff at 4:58 PM on February 12, 2008

The oil had nothing to do with anything; you did a fine job there. It sounds to me as if something simply drained the battery overnight. Is there a chance that the hatch wasn't fully closed, causing a dome light or some similar light near the hatch to remain on?
posted by jon1270 at 5:32 PM on February 12, 2008

On top of the security system, it sounds like you are dealing with a low or dead battery -- that ratatat sound is what you get sometimes when there is enough power to activate the starter solenoid but not enough to operate the starter. I think you should finish up the liftgate situation before replacing/recharging the battery, in case you have a short circuit or some sort of current drain back there.
posted by Forktine at 5:36 PM on February 12, 2008

make sure you have plenty of gas. my jeep cherokee gas guage was way off.
posted by cda at 6:14 PM on February 12, 2008

Once you jump start a completely dead battery, you need to run it a bit while still connected to the donor car, without letting the RPMs drop to idle, or it'll stall. It takes a few minutes to build up enough of a charge in the battery again to sustain itself.

Alternatively, let the donor car charge your battery for 5 minutes or so before you try to restart yours.
posted by M.C. Lo-Carb! at 9:29 PM on February 12, 2008

My bet is that that you accidentally shorted the battery to ground through something electric in the liftgate. Is there a lightbulb in the liftgate? Or does yours have an electric lock?

In car electricity, the entire body is "ground" and any wire that supplies electricity (to a light or whatever) is a potential short.

Btw, the measure your oil level when the engine is cold. It takes a while for oil to settle back in the pan after the engine's been run. Too much oil can be a bad thing, depending on the engine design.

And, no, there's no connection between your oil level and your electric problem. You've posted a perfect example of "post hoc, ergo propter hoc" :)
posted by jdfan at 9:47 AM on February 13, 2008

Ok folks, tried the jumpstart again. Thanks for all the great help. I really suspected it was the security system, because it fits the symptoms perfectly. I locked and unlocked all the doors with the key and then tried it. Again, if I was hooked up to a donor battery, the engine would start, and if I gave it gas and kept it at 1000rpm or higher, the engine would run, though it'd sort of surge every so often, but if I let it drop below 1000, it'd just die. There wasn't, as far as I know anything on, the headlights and everything turn off after a certain amount of time, and I double checked this morning to see if anything was still lit up. It would be, because there's definitely enough power to light up the console and interior lights.

cda - I have plenty of gas, though my gauge is off too. I virtually never drive and filled it up on the trip prior to this. Good tip though. Could have been a real head-smacker ;)

M.C. Lo-Carb! - how long is "a bit"? I ran it for maybe 30 seconds before my gaz-guzzling car made me feel guilty for going nowhere at 3000rpm.

jdfan - I did do the oil when it was cold. VERY cold - as I say I typically don't drive it. Maybe once a week. I didn't REALLY think it was the oil, but working with computers has made me question everything when something goes wrong.

I think what I'll do is take the excellent advice to put my liftgate back together (though all I did was remove the back panel...), even if it means not having it work still. If I wasn't running it at above idle for long enough, I'll try that again. I sort of miss the sound of the engine rumbling like that, rather than sputter and choke and die.

Thanks for helping a dude out. I'll check back and keep this thread posted for future reference, and buy everyone a beer once it's working.
posted by hoborg at 4:07 PM on February 13, 2008

I'm not sure what kind of idle air actuator a Jeep uses, but I'm sure that their idle control software will have some kind of integrator memory that learns the proper warmed up idle air position/amount. When you disconnected/shorted the battery, that learned memory was reset, and your vehicle may need more air than the default unlearned value. Try revving it up and very slowly returning to idle a few times, so that the system has plenty of time to react and learn up.
posted by rfs at 8:06 PM on February 13, 2008

It's possible that you might have to be in drive with the engine warmed up for this learning to occur.
posted by rfs at 8:09 PM on February 13, 2008

I'm n-thing the "shorted something out in the lift gate" theory.

I'm posting to say that I'd love to see a photo of your "Cheeroke" badge.
posted by qvtqht at 5:17 PM on February 14, 2008

I took the alternator out and trekked (literally. I have a Trek bike.) to the Auto Parts store with it. They tested the alternator, and it came out fine. I've returned the liftgate to it's original working order and feel fairly confident that a new battery should get the thing purring like a lion again. So I removed the battery and am waiting to borrow a car. Schlepping a 10lb alternator in a backpack is one thing...

If the battery works, I will let everyone here know, and be extremely happy, though probably not in that order.

qvtqht:


posted by hoborg at 10:49 AM on February 15, 2008

Oh, I see, askMe. Work in the preview, but not in the post. What's the point?
Cheeroke
posted by hoborg at 10:52 AM on February 15, 2008

Ok, apparently it was just a superdead battery, and not jumpstarting it correctly. All in all, a lot of consternation over nothing, but I did get the liftgate working (with some broken plastic bits), so I guess that's good. Thanks everyone for your help - I'm going to go let out a Cheeroke.
posted by hoborg at 6:12 AM on February 16, 2008