A freewheeling alternator?

Jimmy

Veteran Member
Joined
Feb 24, 1999
Location
Canada
I read this at:
http://www.autotruck.net/ms/archives/1998/898/898bug.asp

It says near the bottom:

"The alternator on stick TDIs features a freewheel disc, which works only during cecel (<-- this must be a typo, Jimmy) when the glow plugs are operating and there's a big electrical load. It cuts out the charging system and allows the rotor to freewheel. Something else that's unique to manual trans versions is a second set of glow plugs that are used to heat the coolant."

We know about the coolant glow-plugs but what's this about a freewheeling alternator? If this is true, we need to keep close tabs on the battery. During winter startup the electrics may not be getting any help from the charging system for a short while and a dud battery will be a serious no-no.
 

JeffT

Veteran Member
Joined
Oct 4, 1999
Location
Diesel is diesel is diesel!
There was a thread awhile back where people were noticing their headlights dimming for a split second then normal. This happens to me after I start up and the engine is cold.

Wonder if it has something to do with this freewheeling alternator?
 

ThinkDiesel

Veteran Member
Joined
Oct 31, 1999
Location
Northern Virginia USA
I'd be willing to bet that it has more to do with the electrical draw of the glowplugs "afterglow" phase. That would make sense with a cold engine, too. BTW I have noticed the same thing

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Ryan

1999.5 Jetta/Bora GL TDI
Atlantic Blue/Gray Studio
 
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