New Battery, New Alternator - Car wont start after 2 weeks - PeachParts Mercedes-Benz Forum

Thecorrupterx · #1 05-09-2008, 04:32 PM

just 2 weeks ago I replaced the battery and the alternator. two weeks have gone by and it has had some trouble starting and it has been getting progressively harder and harder to start. I have been riding around for the last 2 weeks with no electrical on, except for head lights, and now it will barely start at all. and even after 20-30 mins of driving, which should charge the battery, it wont start with out a jump

. I dont have a volt meter, so I cannot give the voltage drops for when the glow plugs are running or when the car is cranking, but it cranks slowly and sometimes it will try and speed up. but once it gets cranked everything is fine, no strange noises or anything. This is getting to be bad.

now for the questions; is the starter bad? every "i dont know about diesel" fool i have come across says "sounds like your not getting fuel" but I dont believe them cause it still runs fine, if i can get it cranked, Does anyone thing it would be a fuel problem (both filters changed 4 weeks ago and still looking clean)?

Anny suggestions would be appreciated, thanks.

kerry · #2 05-09-2008, 04:37 PM

You need a volt meter to determine if the alternator is putting out voltage. It sounds as if the alternator is not charging the battery.

bustedbenz · #3 05-09-2008, 04:37 PM

As it's a diesel, it doesn't need electrical power to operate once it's running, so I wouldn't expect anything odd once it's running. Slow operation of the starter motor is not caused by a lack of fuel. Normal speed cranking, but a longer period of cranking before the engine starts, COULD be a fuel issue.

Your electrical issue can't be adequately diagnosed without a volt meter, plain and simple. You can get one for five or ten bucks at Radio Shack or Lowes. That'll tell you if your battery is defective and/or if your alternator is not charging. New doesn't necessarily mean functional. It usually does but not by default.

JenTay · #4 05-09-2008, 04:39 PM

my money is on the OVP. i had the same symptoms and the over voltage relay fixed it.

Thecorrupterx · #5 05-09-2008, 04:43 PM

I had access to a volt meter when I first had the new battery and alternator put in when running it read 13.3v and off it read 12.4v no load so it seemed like it was working. all of the connections are still good, the alternator is still plugged in and they were new not two weeks ago so I think that they should still be working. I should bring a volt meter with me when I go and try to get the car running when I find someone to give me a jump. I keep leaning towards the starter is going out because even when I am getting a jump it still wants to turn slow and it gets faster and will eventually crank. also I never try to start it for more than 10 sec burst every 30-40 seconds.

If it is the starter which would be better to get; a big non-gear reduction starter, or a gear reduction starter.

Where is the OVR - over voltage relay, and is there anyway to work around that problem without buying a new part? or is new part going to be the only way to get this beast running.

bobodaclown · #6 05-09-2008, 04:46 PM

What's the voltage at idle, and 2000 RPM? Do you have a battery charger? Actually you can bring it to AutoZone or one of the more popular auto parts places and they will test your battery and alternator for free.

Good luck.

Thecorrupterx · #7 05-09-2008, 05:04 PM

I only have a trickle battery charger and I have been leaving it on the car overnight every night since it started doing all of this. I got dropped off at the house, my car is at walmart (friends like these) we could not jump it because my friend has a saab, and they are so retarded that you cant access the battery so no jumping.
bobo-the alternator and battery are BOTH brand new, 2 weeks ago I replaced both of them and I even had autozone re-test it after I had them put in and they came up fine. So at this point I dont know. I think its the starter, but I dont know, I am looking on imput. I am getting a ride to go and try to get it started in a little while, but I want to see if there is anything else I can do to improve my chances of starting it before I go back out there. and once I get out there I can tell you more about what is going on, like the vboltage drops from both the glow plugs and starting the car.

BoomInTheTrunk · #8 05-09-2008, 05:16 PM

have you checked to see if you have a short somewhere in the electrical. get a test light and start checking the fuse terminals. it might be that the alternator is working correctly but you have some sort of sort in the electrical.

Thecorrupterx · #9 05-09-2008, 05:25 PM

I dont have a test light. also what are the voltage drops for when the glow plugs are on and for when it is running the starter so I can see if there is a strange amount of voltage drop during those actions. I am at a complete loss right now, dont know what to do or how to get rolling again.

Thecorrupterx · #10 05-09-2008, 06:31 PM

so my battery reads 12.8V while standing and off, after the ride back home, I put it back on the trickle charger. it reads 13.1V when idling and I did not test the voltage while at 2000+ RPMS. so the way it started when I jumped it this time was; first i ran the glow plugs like 5 times when my friend put the cables on it, then it took only 4 seconds of cranking, it went slow for about a second and then picked up and cranked at normal speed.
the voltages as I try and start it as are follows. 12.8v sitting, 12.2v when glow plugs are going (only went for 2 seconds) and 10.6v when the starter is running. any idea of what that indicates?

cphilip · #11 05-09-2008, 06:40 PM

Sounds almost normal to me except the slow turning and the only 13.1 Volts running. I would expect closer to 13.5 running. I normally would expect to see 12.5 V sitting... but... those are not far off.

But the slow turning sort of makes me wonder about the condition of your cables and if you have a clean ground.

By the way... what size and group battery did you put back in the thing?

bobodaclown · #12 05-09-2008, 06:44 PM

Sounds like a weak battery. Whats the CCA (Cold Crankning Amps) and Group size of the Battery? could be that you got one not enough CCA. I believe you need a Group 49 battery.

Thecorrupterx · #13 05-09-2008, 06:52 PM

850 CCA/1000A battery and a 55A alternator, I want to go and upgrade to a Saab AL129X Alternator as a possible fix, would there be any parts on the starter that would go out or make it act like this that could be replaced without yanking the starter.

cphilip · #14 05-09-2008, 07:57 PM

I thought the alternator rating in these with stock Bosh type was 65 Amps? Not sure about the 81 300D though...

I certainly would clean and inspect all cables...

bobodaclown · #15 05-09-2008, 10:01 PM

The 55Amp Alternator works, Unless you've got abnormal electrical demands. The starter is a high torque motor. Ususally they just go bad. Works or doesn't. Wehn you installed the battery did you clean post off and clean the connectors? Are they nice and tight. Same with the alternator? Are your trips very short where the battery isn't getting charged? There is no need to upgrade the alternator unless you've got more electronics running drawing current.