Pelican Parts
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   Pelican Parts Forums > 1- Porsche Technical Forums > Porsche 911 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Mar 2011
Location: Cape Cod, MA
Posts: 59
914 Alternator

Pelicans,

I have a 1973 914 with a 2.0. When driving on the highway at relatively constant RPM we have noticed that the headlights are flickering. I measured the voltage across the battery with the engine off. It measured 12.5 V. With the engine running at low idle it measured 12.0 V. When the RPMs were increased to 2000-3000 the voltage increases to 13-14 V. I am trying to understand if it is an alternator or voltage regulator problem. I understand there is a way to short the D+ and DF to see if the alternator is functioning correctly but I am uncertain how to do this. Any help would be appreciated.
Old 07-12-2018, 12:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Oct 2008
Location: Denver, CO
Posts: 1,644
can you measure voltage when the headlights are flickering? On 911s, the "flicker" is usually caused by high voltage spikes (16-18 volts) that correlate to the flickers and are indicative of a failed voltage regulator.

Unfortunately, the spikes can be very transitory and the alternator would generally show 13-14 volts at rpm like you're seeing. Amazon/etc sell voltage meters that plug into the cigarette lighter socket for constant monitoring, or, some of the better voltage regulators will record high reading spikes if left connected for a while
Old 07-12-2018, 12:59 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Jun 2013
Location: Orange County, Ca
Posts: 69
Regulators are cheap, I would replace that first.
Old 07-12-2018, 01:26 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Oct 2015
Location: SE Pennsylvania
Posts: 118
Garage
I have seen this issue before and VR replacement corrected the problem. You know your alternator has output since you are getting 13-14 V at running speed.
Rob
Old 07-12-2018, 01:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
porsche930dude's Avatar
 
Join Date: Sep 2006
Location: Upstate NY
Posts: 4,696
Garage
and a new voltage regulator will be solid state which is nice
__________________
82 SC , 72 914
Old 07-12-2018, 02:36 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Oct 2008
Location: Denver, CO
Posts: 1,644
At least with 911 alternators, a failed VR was generally also complimented by worn brushes and slip rings (both fixed through an overhaul by an alternator shop) -- no clue if similar issues exist with a 914 alternator/VR and/or whether the 914 has an internal VR (like my later 911) which requires alternator removal to replace.
Old 07-12-2018, 03:32 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
porsche930dude's Avatar
 
Join Date: Sep 2006
Location: Upstate NY
Posts: 4,696
Garage
Quote:
Originally Posted by darrin View Post
At least with 911 alternators, a failed VR was generally also complimented by worn brushes and slip rings (both fixed through an overhaul by an alternator shop) -- no clue if similar issues exist with a 914 alternator/VR and/or whether the 914 has an internal VR (like my later 911) which requires alternator removal to replace.
Nope the VR is on top on the relay panel and simple to replace. The alt on the other hand is quite the opposite in both regards
__________________
82 SC , 72 914
Old 07-12-2018, 03:45 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 04:46 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.