Starter motor/Poly belt/Parasitic drain

[B7RS4]

So how it started (no pun intended). Drove the RS4 for about 400 miles on and off and no dramas really.

1st problem - Starter partially engaged a few times (horrible noise) then started fine. 

2nd Problem - Squealing poly belt on tick over (still working but annoying.)

decided to take the car off the road for a few months and do both jobs.

 

Anyone looking to do any of these jobs be aware it a little more work then your average.

 

1) poly belt,

jack car up and take belly pan etc off.

Then you need to slide the front of the car forward, (Audi S4 4.2l alternator belt and tensioner replacement DIY by Edge Motors)

Fog lights out

Bumper off

watch the video! easy job but make sure you have a long pole or breaker bar to take tension off belt.

 

NEXT

Starter motor, (what a !Removed! of a job) Audi RS4 B7 - 4.2 V8 - Starter Motor change

One of the engine mounts Allen bolts near the exhaust is a pain but doable.

 

Stripped and cleaned starter motor. engaging shaft was all carboned up, cleaned and lubed and works like a dream out of the car.

heat shield was put back on but maybe not as well as it was when i took it off due to its age. (Might be a problem)

 

So poly belt installed and works fine

Starter motor works every time .............................

When the car is warm after a run it wont start. Clutch pedal down (audible click) and no joy, Leave the car for 10/15 mins to cool down starts straight away! Assuming the heat shield may be making the starter solenoid overheat and not sure if it tells the car not to start if its to hot?

 

Also if car now left locked up over night it drains the battery.

1) Charged battery and it hold charge fine. leave it disconnected over night and didnt lose any charge

2) did a parasitic draw check. car unlocked and drivers door open, drawing about 4 milli amps

removed all relays from under steering wheel and no change to draw.

car running battery doesnt drop so alternator is charging.

3) Once locked and left it drops to 1.6 milliamps

is this bad?

my thoughts are before i did starter and poly belt it was fine so its something i have done.

 

Any ideas what may be drawing?

Bad earth from starter?

Bad cables from starter?

Heat shield hot starter sending signal?

bad earth or something not on properly attached?

any help would be appreciated.

 

Plan on getting the car back on axle stands and getting access to the starter again, check all the plugs and leads

wrap exhaust near the starter and try and make a better deal with the heatshield.

Hopefully i notice something!

 

 

 

[Steve Q]

Great advice and great jobs done. Sorry to hear you've got a power drain. Keep us posted on how you get on. 

Could it be the imobiliser? 

[Magnet]

Hello David,

Seems like you have your mA in a twist.
Power consumption when the car has fully shut down (possibly in excess of 30 mins after being locked) should be around 50 ish mA, so 1.6 ma must be wrong.

My guess is you are talking amp figures here rather than mA. 
Try disconnecting the alternator output plug - might be discharging through a faulty diode. 
Regards,

Gareth. 

[B7RS4]

perfect thanks, I've jacked her back up and found a slightly loose starter earth but surely that wouldn't be it. i will disconnect the alternator plug and check the draw. ill keep you updated. i will have closer look at the multi meter to get the amps in the correct power. seen as i've only fiddled with the starter i assumed it would be that but alternator could be a shout.ill update tomorrow once ive had a fiddle about.

[Steve Q]

please keep us posted on how you get on 

[cliffcoggin]

18 hours ago, B7RS4 said:

 I've jacked her back up and found a slightly loose starter earth but surely that wouldn't be it.

A loose motor earth could easily explain the poor starting, but not the power drain.

The 1.6 mA drain you reported is not believable. A car in good order and locked loses a few dozen milliamps normally, some 30 times your reading.

[B7RS4]

Evening all, soooo (bangs head on coffee table)

As you are aware by now i,m more mech based then electrical! below are images from multi meter connect in series with the battery. 4.48 is with all fuses in

1.86 is with just the radio fuse removed. |( not sure why the radio would be a problem now?)

with the loose starter earth removed made no difference, all fuses out has no draw at all which is expected i assume. 

It has to be something i have fiddled with? the heat shield from the engine mount was touching the back of the alternator point so not sure if that would

have an impact?

immobiliser? how do i check that? i haven't taken any plugs off the back of the alternator yet so not sure if that is drawing power? that will be my next job,

leave all fuses in and just disconnecting alternator to see if the draw drops. 

 

After that i'm not sure where to go?

 

Thanks in advance.

[Magnet]

Images of the scales are too in distinct to offer any  advice.

Really didn’t  expect the earth to make any difference to the drain.

Reserve judgement until, you have removed the alternator plug and checked if the battery still runs down overnight.

If that doesn’t sort it, I would seriously recommend you seek the assistance of a trusted local electrician. You really don’t want to be playing with the electrics on these unless you are experienced in doing so. 

[cliffcoggin]

David.

Zooming your pictures shows the meter to be set to the 0-20 amp scale, so the readings refer to amps not milliamps. That information confirms there is a significant power drain and explains the battery going flat overnight.

Previous similar problems on this forum show that pulling fuses has not helped in diagnosing the fault, so I suggest you get the car to an electrician who will be able to test individual circuits.

Before doing that please confirm you have not fitted any auxilliary equipment such as a dash cam or sat nav etc. that is connected to a permanent live supply, i.e. a supply that is not switched off by the ignition key.

[B7RS4]

I will disconnect the alternator and see if the draw drops off, If it does then it might be the alternator leads. Yes if it does in fact begin being a pain i will get it booked in somewhere and bite the bullet. Also i have nothing after market on the car that has been installed since it was working fine.

Edited 3 hours ago by B7RS4

[Magnet]

Good. Disconnecting the alternator has been recommended as a next stage.

What is your logic for thinking it’s the leads if the parasitic drain drops when the alternator is disconnected ? 

[B7RS4]

starter motor out all leads disconnected from alternator, still drawing 1 amp when doors closed and just boot open to get to battery.

 

radio fuse removed, I'm thinking it must be the immobiliser? at least i can reinstall starter and reattach alternator leads.

something is stealing my amps when at rest

[Magnet]

If the boot is open, then the car will not shut down, and so any readings you take will be meaningless. As I said, car can take in excess of 30 mins to go to sleep.

Use light insulated cables to set up fly leads off the battery, then close the boot lid. Measure current draw once car has been locked and left for 30 mins.

My view is that you would be wise to now engage the services of a local mobile auto electrician, before something goes wrong.