Astra electric surging....

Anyone tell me what could possibly be wrong with my astra? Its a year 2000
1.7 dti with 115k on the clock.
The problem came about a 3 weeks ago. When sitting with the engine running
at tickover and the lights on they seem to have a small power surge about
once or twice per second (evident by the lights dimming and then getting
brighter). This is also evident in the noise of the fan and the dash
lights. When the engine is speeded up it doesnt dissapear until about 70mph.
Its now getting to the stage where it it quite annoying. The battery has
been changed as I thought that it may not have been holding its charge. No
warning lights are showing in the dash and its getting to be a pain to drive
slowly as its now affecting the drivability at low revs. It starts and runs
OK with everything working as it should but I dont know whats causing the
slight power surging....HELP!

 

my gut reaction would be to change the alternator,
however, it could also be say a faulty rad temp switch for the rad fan
or really anything that takes alot of power , might even be a postive wire
somewhere rubbing to earth

try pulling the leads off the rad sensor first and see if it still
misbehaves.

these are the only two ideas i can think off that would give such signs

certainly won't be ecu related.

mike

 

Is the air con on when this happens, as when the air con motor kick's in it
took a lot of power on my 2001 Astra 1.7dti, but no where near as bad as
what your describing, I old used to notice it stopped at traffic lights, and
the head lights would dip slightly and the revs would dip for a spilt
second.

Rich

 

Hi. Tried pulling the wires off the rad sensor but nothing different
happened. The car doesnt have air-con so it could`nt be that. Checked all
the wiring where at all possible and seems OK. Could only be the alternator
now but I thought it would show on the dash light if it was
faulty.....Gordon

 

might not ,
now you could be really brave and disconnect the alternator (start the car
first)
then see if it still does it.
that would be the acid test

mike

 

Interesting idea. Dont know how you mean by disconnect though. if you just
unplug it, not sure if you will damage it when it starts to turn when u
start the engine. probably at least the rev counter will not work. if you
remove the drive belt, might have brake problems as some alternators have
the vacuum pump on the back end to drivr the servo.

just occurred to me now-perhaps problem might be with the (electric) power
steering? they can consume a lot of power and if its a bit out, the
corrections you would have to do to the wheel might explain things.

just guessing tho'

Mike

 

good idea, it could sadly be 1001 things but it must be something taking a
good few amps to make the headlamps dim.

it is quite safe to operate the alternator whilst not electrically connected
, but yes, I forgot to mention keep the belt on!

mike

 

part of the problem here is that we are talking about parts that are a bit
too expensive to just replace on the off chance....

Mike

 

I believe Ive found the problem. It boils down to the alternator. With a
multimeter attached to the battery, it gives out 13.6v then 2.8v at the
corresponding times as the lights dim and brighten up again. How or why its
doing this is a mistery to me, so It looks like I will have to replace it.
Does anyone know what type and make it will be and the relevant part number?

 

ah sri i did realise you have a wee bit of savvy else i'd have suggested the
meter testing.
you could pull it aparti bet it will be the diode pack or the dreaded spade
terminals inside
if it's that type.
if it were me i'd haul it apart, you might find a broke wire or WHY
i've repaired quite a few that way
it's a shot to nothing if you are going to exchange or buy new anyhow


mike