Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-28-2009, 12:35 PM
Registered User
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 22
More mysteries in the Charging System (1985 300D)

Seasons Greetings, All!

My 1985 300D has a ghost in the charging system. My alternator is a new Bosch, new voltage regulator and the battery is new as well. I can drive around for days during the day with no symptoms. It would seem the battery maintains its charge just fine, and then the battery will suddenly turn up dead, usually at night. I'll run an errand, come out and the car won't start, after driving fine for a week or so, day and night.

I did tests on the system yesterday and everything looked fine. Results similar to this morning's tests below. I drove the car for three miles, checked voltage at the battery with the car running (idling, at 2000RPM, with headlights, without) and the highest reading I could get was 12.4 volts.

Could it be an intermittent short?

The battery light on the dash illuminates, and here are my multimeter tests:

Car Off cold: 12.12 volts
Cold Idle: 13.6 volts
1500 RPM cold: 14.25 volts
Warm Idle: 14.3 volts
1500 to 200 RPM warm: 14.4 volts
Idle w/ high beams: 14.04 volts
Idle w/ high beams + blower: 12.05 volts
2000 RPM w/ high beams + blower: 13.9 volts
Idle w. high beams + fog lights + blower: 12.03 volts
Car Off after 15 minutes of testing: 12.4 volts

Thanks for any input...

Chip

Reply With Quote
  #2  
Old 12-28-2009, 12:38 PM
Craig
Guest
 
Posts: n/a
I had a similar issue, it turned out to be a bad connection inside the plastic connector on the back of the alternator. The wires were almost disconnected from the connectors inside the plastic piece. I figured it out by wiggling the cables and watching the voltage fluctuate.
Reply With Quote
  #3  
Old 12-28-2009, 12:44 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
... your blower motor is toast. pull it soon.
your car can catch fire and end it's own life if you wait too long.
also, your battery is not full, and it may be bad. have it tested ASAP. you should be reading 12.7 or better on a fresh charge with the car off.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #4  
Old 12-28-2009, 12:50 PM
Banned
 
Join Date: May 2002
Location: Blue Point, NY
Posts: 25,396
Quote:
Originally Posted by vstech View Post
... your blower motor is toast. pull it soon.
Why?
Reply With Quote
  #5  
Old 12-28-2009, 12:58 PM
Registered User
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 22
I'm guessing he says that because is seems to drop the reading 2 volts when idling, although it only drops it .5 volts at 2000 RPM.

If you could elaborate, I'd appreciate it.
Reply With Quote
  #6  
Old 12-28-2009, 01:00 PM
Registered User
 
Join Date: Nov 2009
Location: Austin, TX
Posts: 22
Quote:
Originally Posted by Craig View Post
I figured it out by wiggling the cables and watching the voltage fluctuate.
I'll check that again. I actually did wiggle that connector and saw no fluctuation in the reading, but it's worth another wiggle.
Reply With Quote
  #7  
Old 12-28-2009, 01:14 PM
Craig
Guest
 
Posts: n/a
Quote:
Originally Posted by Chip View Post
I'll check that again. I actually did wiggle that connector and saw no fluctuation in the reading, but it's worth another wiggle.
It might not be your issue, but it stumped me for a while until it got bad enough to be obvious. If you want to be sure, remove it and take a look.
Reply With Quote
  #8  
Old 12-28-2009, 05:20 PM
LuckyEddie's Avatar
Registered User
 
Join Date: Mar 2008
Location: Wilmington, NC
Posts: 202
Are the pulleys in good shape??? If they are shiney in the bottom you can not tighten them enough to stop the slipping.
Reply With Quote
  #9  
Old 01-09-2010, 04:58 PM
Registered User
 
Join Date: Aug 2009
Location: Jacksonville, North Carolina
Posts: 7
I've got a similar problem that I'm sorting out. While driving at night (headlights on, blower on) the "antilock" light comes on and all my lights get dim. When I turn off the blower everything goes back to normal. I just did my testing and the blower drops the volts by about 1.5 My blower has been making a lot of racket lately and it probably is the culprit. BTW, everything getting dim last week made me immediately suspect the alternator so I changed it. Next night I drove, same problem. Oh well, at least I have a new alt now. Let me know what your solution is to this problem. Is the blower motor able to be fixed, lubed, reconditioned? Thanks
__________________
1985 300SD 241k "Woogie"
Reply With Quote
  #10  
Old 01-09-2010, 06:42 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
Is it possible that sometimes your glowplug relay is sticking on?
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #11  
Old 01-09-2010, 11:06 PM
dagObx's Avatar
Registered User
 
Join Date: Jan 2008
Location: Outer Banks, NC
Posts: 382
Assuming alternator problems, what is the advisability of installing one of those single wire type alternators? I know it isn't pure Bosch, but sometimes a guy has to do what he has to do.
Reply With Quote
  #12  
Old 01-09-2010, 11:22 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 51,042
Quote:
Originally Posted by dagObx View Post
Assuming alternator problems, what is the advisability of installing one of those single wire type alternators? I know it isn't pure Bosch, but sometimes a guy has to do what he has to do.

Not a single wire type but I have a Delco Alternator on my Volvo. The origional is an SVD of something like that; it was not a Bosch.
Mounting it was not 100% good as it is hard on the Belt due to some misalignment.
However, I have been driving since 1993 like that.
But, how it mounted was similar to the Delco.

If you can fabricate a good Bracket for a Single Wire Delco I but you could sell some.
The trick is to the older Delcos are larger; and to a lesser extent the pulley size/grooves.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #13  
Old 01-09-2010, 11:32 PM
Craig
Guest
 
Posts: n/a
I currently have a 65W denso alternator in my 300D, it's been doing well for 100K+ miles.

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 12:47 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page