golf mk4 gti

[mase001]

hi guys,

recently had a problem with the car where when it starts from cold and the engine is warming up, all the lights and electrics in the car would dim for a second intermittently every 5 seconds or so and the engine seemed louder and with a high pitched whirring noise. once the car was past the initial minute or so warm up stage everything is fine.

so, i got a new alternator as i needed one anyway, and a new battery, with no luck. i got my cousin who does my car work to do some research and he said it could be the earths, he cleaned them all and the problem seemed to sort itself out.

During this time, i haven't had a stereo in the car as it would drain the battery and cause the car not to start, so i thought now it's all sorted i'd be able to put it back it. As soon as it was back in, the problem started again, took the stereo out, problem still persisted for a few days. Now it seems ok some days, and the dimming and whirring every other.

any ideas, i'm at my wits end now!

thanks!

 

[Burnerman]

I still reckon you have an alternator problem (i.e a chargingproblem) but if the alternator is new ( and not a scrapper one) then the fault has to be in the connections or earths.
Put a multimeter across the battery terminals when its getting huffy - I guess you'll see the volltage dropping off as the lights flicker.
Check out any large fuses around the positive battery terminal (if there are any - depends on how old your car is) and look for wiring/chafing issues where the alternator wires are around the sump area. Another popular one is the engine to bodyshell earth straps.
John

 

[mase001]

yes that's what i thought my cousin had already checked, he said the engine to bodyshell earth was really rusty so he cleaned it up and reterminated. hmmm, maybe i'll take it back to him to double check them and get him to look at the wiring around the alternator.

thanks a lot Burnerman; you're the only person across a lot of different sites who's had any ideas at all!

 

[Mursal]

Those Bosch alternators are usually on rubber and need an earth strap?

 

[SaladFingers]

The loud whirring will be the auxiliary air pump. Perfectly normal and nothing to worry about. It pumps air to lean the exhaust gasses whilst on fast idle.