Mercedes benz charging problems

I am currently having problems with my 1985 300sd it seem that after i start the car the altenator does?nt start charging the battery right away like there is a relay not working properly i notice at night that the lights stay dim for a long time then suddenly they turn bright also some times they never turn bright and the battery goes dead i replaced the alterator and the battery but did not help the problem it seem that there is a relay that after you start the engine it switches from the battery to the altenator thats not working properly can not locate any thing in the repair manual NEED HELP :?: :?:

Reply to
DIESEL
Loading thread data ...

The "brains" of an alternator is the voltage regulator which is an easy to fix add on thingy on the back of the alternator.

It's a cheap enough part to replace ($18 or so) but can be rebuil;t with $2 worth of brushes you get from any alternator/starter place.

Here's how:

formatting link

Reply to
Richard Sexton

That symptom is because of huge draw of power by your glow plug system. It means your alternator is failing. So I'd put in a new regulator on it to see if you can still keep your alternator. Two screws on back of the alternator... very easy job.

Alternator must provide at least 13.5V at idle to charge battery... Otherwise, it will just drain the battery further.

How old is your battery? Maybe you should have the charging system checked by Autozone... free of charge.

Reply to
Tiger

:lol: Thanks my battery is new but i think i have found the problem i think that the glow plug relay was failing some times it never stoped heating the glow plug even though the yellow dash light was out other times it worked properly when it failed it would drain the battery dead i installed a new glow plug relay and i (so far ) can notice a difference THANKS DIESEL

"Tiger" wrote: > That symptom is because of huge draw of power by your glow > plug system. It > means your alternator is failing. So I'd put in a new > regulator on it to see > if you can still keep your alternator. Two screws on back of > the > alternator... very easy job. > > Alternator must provide at least 13.5V at idle to charge > battery... > Otherwise, it will just drain the battery further. > > How old is your battery? Maybe you should have the charging > system checked > by Autozone... free of charge.

Reply to
DIESEL

The glow plug system is supposed to keep glowing for 3 minutes after starting... so check after 3 minutes.

Reply to
Tiger

Checked after 3 minutes and original relay was failing some times staying on continuously draining battery, installed new one seems to have solved the problem so far notice now that after 3 minutes when relay shuts off all lights brighten THANK

"Tiger" wrote

Reply to
DIESEL

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.