Previous winter the car was having trouble starting, changed battery. Checked glow plugs and relay. Starter and alternator both rebuilt. Cleaned all body and battery grounds. Seems to still have problems with keeping charge in battery. Have found no parasitic drains. Defrost fan and headlights very dim unless step on throttle. Tac also goes way down. Any ideas?

Did you replace the brush pack (voltage regulator) when the alternator was rebuilt?

You should be showing about 13.5V at idle using a multimeter, anything lower points to the alternator or voltage regulator being on the outs. My money is on the regulator.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Actually yes new bosch brushes at rebuild. Sorry but i am one of the O.E.M. only type people. I have been overhauling mercedes diesel for a while and have to many problems with aftermarket parts. Granted in my area most of my work is done on older vehicles and dealer support is hard to come by most work is done by trial and error.( hopefully not to many errors) In all respects i hope someone has seen something i havent the car has a 1 yr old 900 amp interstate battery ( I like those batterys) but lately i have felt a little dischouraged with that brand.