6 replies to this topic

[Mini_Rob_Cov]

Hi guys
I have a little problem, not to mayjor. I noticed last night on my way home from work, that when i stopped for lights etc, the power in my car would almost go off. The radio would turn off and the dash lights and headlights would dim. If i rev the engine they go bright again.
The fan belt has been slipping (despite being changed) so could it be a problem with the battery not getting charged enough? Thing is, the problem only occures when the car in stationary with the engine running, its fine with the engine off.

Any ideas from the wise people of tmf?

[Jupitus]

I'd certainly say fix that fan belt first... then check again

[998dave]

this would suggest poor charging, so fan belt adjustment, altearnator output, OR battery and earth connections.

With engine stopped chack voltage at battery terminals. then start engine, and check again. should go from about 12.8 to about 14.0

Check quality of engine earth strap, and battery earth strap.

Check connections at starter motor solenoid where battery positive lead connects.

Check & adjust fan belt.

D

[Mini_Rob_Cov]

Well i've just changed the fanbelt about a week ago, but it's still slipping (for some reason only at nighth ) The belt is as tight as the altenator will pull it but still slips. i know the belt is the right size because it took me 3 attempts to find one the right size. I think i'll go to my mates dad later, he's an electrician so i can borry his multimeter.

So i should check the battery, engine off and on
Starter solenoid - engine running?
Anything else i should check while i have the multimeter?

[998dave]

starter solenoid, either, it should have the same voltage as the battery positive terminal, as it's a straight cable from one to the other.

If he has a PD Meter that'd be better, but unlikely as they're expensive, and a bit specialist.

If fan belt still slips i'd look at adjusting again, did you loosen the bolts at BOTH ends of the banana to adjust?

You have
two 1/2" nut + bolt sets on top of alternator.
one 9/16" nut + bolt set at bottom of alternator to banana adjusting arm.
one 9/16" or 5/8" nut + bolt set at rear of banana arm.

Loosen them all, tug the alternator up tight, then holding it up get someone else to retighten, starting at the top two bolts, and working down.

Always hold the left hand end still and pull up with right hand end when tightening these, as the lever moment will pull alternator up, rather then pushing it down...

Hope you sort it out!

[Mini_Rob_Cov]

Ahhhhh, i didnt know about the bolt at the rear of the banana arm. Thanks for that, i'll try ajusting that now, see if it helps

[998dave]

Good stuff, let us know it it helps, I wasn't aware of it first time I looked either, but unfortunately the alternator never moves in the arc of the banana.

Dave