Still having problems....starting to get desperate
Symptoms: Car won't start up (slow engine turn over) after several weeks of stop and go city driving. Starter will turn over very slowly, lights dim etc. and voltage will drop to 8-9 volts when this happens. Car driven primarily in the city (HOT 90-100F) & R-134 Retrofit AC on continuosly full blast (california weather).
When this happens I jump it with a portable battery pack and I'm in business. I then charge it overnight adn then ready to go the next morning.
So far tried:
1) Two alternators (one MBZ and bosch rebuilt from fastlane)
2) Two batteries (both Sears Diehard)
3) Tried voltage regulator and removal of the capacitor (see above).
Still no avail.
-Highest charging voltage at full throttle is 13.5
-Idle voltage is 12.5-13.0 usually dropping to 12.0 at idle with AC full blast.
-Startup voltage is 11 volts (rising to 12-12.5 volts at idle with AC. The startup voltage will rise to 12-12.5 after approx 3 minutes as I think the glow plug relay (newly replaced bosch from fastlane) stays on until that time and then cuts out--- a warmup feature I think)
Contrary to all the posts I have read, I have never seen a full 14.5 volts charging at idle on either car. Belt tension is firm.
Turning on the A/C + Blower seem to knock off a good 1 volt on my car (i.e. 13.5->12.5) etc.
Here's what I think might be the problem:
Six months ago I had replaced the glow plug relay with the kit from fastlane. it seems to have a feature that keeps it glowing on for 3 minutes....its a warmup feature probably good for cold climates but it causes a massive current draw dropping your voltage to 10-11 volts at idle (especialyl with AC, lights) for the first 3 minutes. After it cuts out the voltage drastically improves!
...wonder if anyone's had problem with these "newly improved" glow plug timers....especially in the peak of summer when you need your full battery capacity.
This is further coumpounded by short distance driving which causes the battery to just keep getting drained trying to supply current to the timer x 3 minutes.
Anyway, dug up the old relay (there was nothing wrong with it as it turns out I had a loose connector to the relay that was causing the light not to glow. Installed it back in, and the voltage has greatly improved to 13v idle and 13.75 at 2000 rpm (that's on a partially drained battery from the problem earlier today). This is much better than the measly 11 volts I was getting with the "upgraded" relay.
Is this a known problem with the updated glow relay? I would recommend sticking with the original relay (does partshop or fastlane have the original stock one?) in hot climates and city driving with AC on (like my car does).
Anyway, will go drive around some more and see if this clears up....unfortunately I had bought the same relay for the other 300SD about a year ago too...it too seems to have the same problems on startup/warmup voltage.
