Crossflow Starter Motor Problems - Any Ideas?

[Dieter7S4]

Help!!!!

I have a prob with my starter motor(s) on my 7 which is proving decidedly annoying!.

History is - blew the electronic ignition unit last summer, this has been replaced and has tested fine, and works (car will bump start)

Starter will not turn over fully (sounds like a knackered battery), so we have tested battery, tested wiring, all earths etc, still have the problem.

I then bought another starter motor, still have the problem, I have tried both new and old to the same result. We then applied a separate power source directly to the starter motor, (battery physically taken out of the tin top, pos lead straight to the starter input, neg to the block) we still have the same symptom. Anyone have any idea whats going on?

Thanks in anticipation.

Mike

[Murph7355]

Have you tried the direct power to both starter motors? Do they spin at all? Was the new starter brand new and/or guaranteed fully operational?

[Dieter7S4]

Hi Murph,

Yes, yes and reconditioned. I've got the old one in there at the mo, the strange thing is that it spins up like a good un, every now and then!

Mike

[Eugene7]

Hi Mike,

What happened when you went direct to the starter with power and earth (earth to starter body, rather than engine block/bell housing)?

Did you also try the earth isolation, and disconnecting the alternator?

I really am stumped with this, as we have discussed via Skype...

I guess it could be a teeth alignment problem between the starter bendix teeth and the flywheel teeth. Have you checked they engage correctly?

Would love to hear any other ideas!

[davidball]

Do you have an earth directly connecting the battery negative terminal to the chassis?
My problem with bad starting was solved by this.

[Richardsix]

I had similar last year prior to knackering my crossflow, rebuilt a new lump and use the same starter and it wizzes it over, so I know the starter is not at fault, all I can think is timing a bit out or compression ratio too high???

[Murph7355]

When you say the starter's not turning over fully, do you just get a partial revolution and then it jams? Or does it turn all the way, just very slowly?

Do you hear any clicking/grinding etc?

When you bump it, does the engine run OK? Freely, idle OK etc ??

And have you tested different earth points/wires are only the same ones each time?

[Dieter7S4]

Thanks for the help so far!

The starter turns but very slowly (as if the battery is almost flat). it does this even when power from an external battery is applied directly to the starter.

When I bump start the car, the engine appears to run freely, pick up is good etc. Idle is smooth at 900rpm. The timing may be slightly out as we replaced the ignition unit, and bench tested the whole system including the dizzie beforehand, it's not far out though.

Earth straps checked and cleaned are the main strap direct from battery to chassis, the strap from block to chassis and the strap from the ignition unit to chassis.

An interesting symptom is when we connect a Draper external battery pack to the starter (either in situ or out of the car) it indicates reverse polarity! When connected to the battery it doesn't!!!

Cheers

Mike

[Murph7355]

What else was changed when the ignition was replaced? Did you put it back together or someone else?

Have you got access to a multimeter so you can see what voltages etc the starter's seeing?

It might be worth getting an auto electrician out to it...

[Eugene7]

Mike, seen this thread on BC?

HERE

Do you know the battery voltage drop when turning over?

[Eugene7]

So Mike, going to tell everyone what the fix was???

[Dieter7S4]

OK, Cleaning all earths meant that it jump started from the Audi, having f*cked around with both new and old starters.

Blatted about 120 miles over the weekend, still unsure about the strength of the battery and still had light probs (1 sidelight out and rear indicator)

Left the car for 2 days this week and no joy!

Bought a new battery and all (I think) is good!! I still cannot explain why connecting power directly to the starter was not working - I can only assume that dirty earths were messing things up!!!

Thanks for all the help, by the way, Steve, owe you a few more beers

(Seems to be the story of the last 20 odd years )

Edited by Dieter7S4 on Thursday 28th April 21:42

[one eyed mick]

Possible collapsed cell in battery ? you would get 12v on meter but would drop when put under load ,been there replaced 3 starters [2 new] all leads extra earths, nothing, replaced battery[premium] no probs [touch wood ] for 3 years .Load tested battery after 48 hrs charge 13.5 v dropped to 8.5 in 10 secs with one cell fizzing like crazy . hope this helps some one who is gerring close self destruction