Question about junp starting a diesel car

[cobb]

I am not sure if this belongs here or the battery forum, but will try it here.

Anyway, I had a second glow plug fail Friday last week and replaced it. My car would go from starting right up to having to grind the starter for it to catch, then it would have a miss for a few seconds.

Anyway, replaced that, so back to 4 glow plugs working in the 4 cylinder engine. Anyway, Tuesday I felt it again require me to grind the starter to get it started as another glow plug failed. I ordered 2 more at the local auto store. They do not sell bosch and the autolites have a 2 year warranty.

Come Thursday, a second plug failed and it would not start unless i did a lot of cranking and adding some ether.

Friday afternoon it would slowly turn over and not start. I decided to use my second jump starter device that hooks to the battery and is supposed to give 450 amps. Of course I also had a 200 watt model plugged into the cig plug from a few years ago I purchased to use for portable power. It works and hooked it up after I left my light on a few weeks ago as it seem to help me start up faster.

Long story short, the past 3 times I have started it, even with a new 850 amp battery from the 700 amp battery it had in it, seemed the jump starter
rated at 450 amps helped it to turn right over, where as nothing else would.

Not even a new battery with another 150 amps. The charging system seems to work as the battery voltage is 12.74 off.

Anyway, installed two more glow plugs and got one returned and two more on order. It started right up tonight just after the idiot light went out.

Other than that strangeness, I find with the new proper size battery for my mercedes 240d the lights do not flicker at a 40 hz rate like they did since Ive owned it. Plus at the adjusted jacked up idle, the lights do not dim slightly either at idle.

The idea of replacing the alternator has crossed my mind, but I aint rushing out to replace a 50 amp model with another 50 amp model. I want something 2 to 3 times that size.

 

[icecube]

The alternator is quite unlikely to be the cause of your problem relating to starting, as in general the alternator cannot get even close to the current demanded to crank the starter, much less a diesel setup. 50amps ain't 250+ for just the starter.

Have you checked the glow plug control circuit? They shouldn't burn out like that, I wonder if they're on anytime the ignition is in the ON/RUN position.

 

[WNG]

Well since it's a Merc, it is likely a Bosch alternator, and they are notorious for lousy regulation, poor idle voltages and heat related issues.
The regulators are nothing but PITA in my old Audi.
So, the alternator can have an effect on his starting....the alternator isn't pushing enough amps and voltage (13.8, to 15V during extrem cold temps) to keep the battery topped off. I'm not a diesel guy, but I remember those glow plugs need a lot of wattage.

 

[jayb79]

Try this site http://www.mercedesshop.com
They where a big help for me when i had a benz.
Sounds like you could have a dirty conection somewere. Pull the plug off the back of the alt and check that then follow the wire up to the fenderwell and check the juntion there to.

 

[z96Cobra]

If the alternator isn't bad, you should check both battery cables to see if they have good connections (at both ends). It almost sounds like the negative battery cable isn't grounded to the frame very well. Could also be the charging wire between the battery and the alternator.

Roger

 

[cobb]

I kind of suspected something was up with the alternator, but the body is so rusted, the car is flexing making doors not shut tight and the trunk, that I just want to nurse it along til I can buy another one in better shape or another car.

Seems the engine maybe in a slight bit better shape and diesels are just hard to start in the cold, not to mention one with over 409 thousand miles on it. Ive adjusted the valves, checked out the GP system and replaced plugs as they have died. Seems they drop dead vs slowly going bad. I have a real budget issue or I would of replaced them all at once or buy bosch.

Anyway, seems the car has GP relays. One that controls the idiot light on the dashboard and the other that powers the plugs. The one that powers the plugs in its stock configuration powers the plugs for 45 seconds, unless you decide to crank the engine. At that incase, it cuts the power to the plugs and will not recycle til you restart the engine.

This colder weather in VA I have been waiting 30-45 seconds to crank it as it does need a bit of grinding of the starter to get it to catch with 4 working glow plugs and an adative in the tank. I think that has what caused the plugs in it and the few I have replaced die early.

Myself, I thought a larger battery would make it start better and wanted one sicnce Ive owned the car in July of last year. A few weeks ago I left my lights on and 4 hours later it was dead. A jump failed to start it. AAA, used a 650 amp unit and started it, tested and had me restart it. AAA said it was ok, but I was again, unable to get a battery installed at advance auto, nor did they have one in stock. So, I bought the second jump starter thing to ensure I could get started that night for the new years weekend.

Since I had installed the 200 watt unit that feeds through the cig plug outlet and it seemed to help it start a slight bit quicker with less cranking.

I am just wondering why with either the old undersizd battery and the new proper sized battery, that in both cases the 450 amp jump starter hooked to the battery added enough umph to make it kick over in its condition. Maybe I just need another 450 amps to fire it up in colder weather and wasted 80 bucks on a new battery a few days ago?

Ive visited a few benz forums. They arent that all helpful. Now the idea of replacing both cables to the battery has crossed my mind and was thinking of running a new ground right to the engine. Of course it could likely use a new starter too with upgraded alternator. Ive heard you can use a gm (gasp) or saab alternator on it if you swap the housing.