Starter Motor failure

[skyegtb]

Hello! A little under a year ago I had a few issues with the starter on my car intermittently not engaging. I thought it might have been battery related as it only seemed to happen after the car had sat for a few days, but like all intermittent problems over the last year it actually seemed to disappear and started on the button every time. Anyway, I didn't use the RS6 for the last 3 months and it sat in my garage. On the 30th Sep I tried to start the car but the battery was flat.... I forgot to turn on my battery conditioner. DOH. So, I charged it overnight and next day she started perfectly. I took the car for a 70 mile drive then parked it overnight. Next afternoon I jumped in and she started perfectly again, I remember thinking that the starter was turning nice and fast. I drove to the shops, loaded my shopping and F*cks sake, she would not turn over. I tried probably 30 times but no cranking took place (ooerr). Battery voltage was over 12V and everything else in the car worked, all lights illuminated, fuel pump ran etc. So, I called the AA and waited 10 minutes, then gave it another go, and lo and behold she fired up beautifully! I called the AA to cancel then drove the car home and put her straight up on the car lift. I scanned for fault codes, and no faults to report... I turned the car off and tried to start it again, and again no start. I waited 5 minutes and was then able to start the car 10 times in a row with no issues.

So, (by the way, sorry for the long report above!) I am almost 100% sure it must be the starter solenoid that is defective, or perhaps the starter motor is occasionally seizing, so I am looking to buy a replacement. Before I do, is there anything else I should check? I want to look at the wiring too, but as it is completely buried I don't think it could be checked until the starter was removed anyway. As mentioned, the only issue is the occasional non cranking, otherwise everything electrical seems fine and the scuttle panel behind the engine in this car is bone dry etc. but I also plan to remove the expansion tank to check the big fuses that are hidden under there too.

Next, any recommendations of a supplier for the starter? Should I go genuine parts: Bosch 0 001 110 130 / OEM 077911023F , or are there better / equally as good alternatives out there?

For the replacement I have found a few guides on here and it sounds fairly *easy*, certainly no worse than any other job done without removing the engine!

[Shoppinit]

I had something similar. It’s a trap you can fall into with a battery conditioner. When the battery is on its last legs, the conditioner gives you the impression that it’s fully charged but there is very little capacity left in it. The voltage reads OK and there is enough charge to start once, but after that nada.

Before changing the starter motor it’s worth checking with a different battery if you’ve got one handy.

[skyegtb]

I had something similar. It’s a trap you can fall into with a battery conditioner. When the battery is on its last legs, the conditioner gives you the impression that it’s fully charged but there is very little capacity left in it. The voltage reads OK and there is enough charge to start once, but after that nada.

Before changing the starter motor it’s worth checking with a different battery if you’ve got one handy.

Excellent advice. The battery in the car is around 8 years old, so probably due to be changed soon anyway.

[Mɐʇʇ]

I've had the same. Battery conditioner meant that it supported a knackered battery enough for....1 start....but a couple of hours disconnected and it couldn't start the car.

[skyegtb]

Right, 1st purchase a new battery! Unfortunately I don't have any options to fit a spare, but no worries, I feel 8 years is a pretty good run for a battery anyway.

[skyegtb]

OK, battery ordered, I'll give that a go first and report back. If the battery doesn't fix the intermittent starting then I'll swap out the starter next.

[skyegtb]

I also plan to remove the expansion tank to check the big fuses that are hidden under there too.

Glad I did, turns out that even though the area below the expansion tank was bone dry and free of debris, (and pretty much always has in my 11 years ownership of the car as it is always garaged), seemingly in the past it must have been wet in there as the large live wire that connects to the (lower) 200amp fuse was seriously corroded and eaten away and just a small strand of copper from the crimp was left making contact here. I have to assume that this wire and fuse are most likely related to the car starting / starter motor (can anyone confirm?). Anyway, I removed the defective crimp, cut the wire back a touch - luckily the wire was actually perfect, and have ordered some M8 x 16mm2 crimps and a heavy duty crimping tool to hopefully put things right. I also bought a new battery, a Varta OEM from Tayna batteries for £120ish so will swap the old battery out as well.

I'll add some pics later when I get home.

[Shoppinit]

Yeah, that could totally explain the problem. Good find. Surprised at the corrosion given it's been garaged. Mmm. Maybe I'd better check mine.

[srichards]

I assume some drains could block up and then let water drip down there somehow.... I'll be checking mine too!

[skyegtb]

Here's the pictures of the dodgy crimp / cable.

[Mɐʇʇ]

Definately upduck.

[skyegtb]

OK, success! In the end I had to add a 3" extension to the existing wire with a new crimp on the end and the car now starts perfectly every time. The new battery probably wasn't needed, but I think the previous one was probably due for a change as it was near 10 years old. Next issue was I changed the oil and filter while the belly pan was off, no problem with that, but when I scanned the car afterwards the following code has now appeared steadily: 17985 - Right Engine Mount Solenoid Valve (N145) P1577 - 004 - Open Circuit. The car drives absolutely fine with the code, full performance etc, but I can't help thinking that when I removed the filter the connector might have got soaked in oil, or perhaps I even knocked it off, so next time i put the car on the lift and have the belly pan off I will firstly check the connector and take it from there. Reading posts about this on the internet suggest that it's quite a common failure that can be lived with, but I don't like error codes.....!

[skyegtb]

Fu*k and b*llocks!!! Just took the car for a nice drive, stopped for petrol nice and happy. Went to re-start the car.... Nothing. Tried for about 3 minutes to no avail then waited for another couple of minutes and finally it turned over. Now it's back on my car lift and I'm going to swap out the starter. Seems the defective wiring below the expansion tank was a red herring. The only thing that is clear now is the issue is only there when the car has been driven and is fully up to temp etc. When a cold engine or cooling down it seems to work fine. The only other thing I can think it might be is something relay related but I have no idea where the starter relays are. Oh well, I'll try to take pics of the process of swapping the starter to make a DIY.

[Shoppinit]

I would definitely check the electrics first before going to the trouble of removing the starter.

There are a couple of starter inhibitor switches, too, like the switch in the gear selector. Worth checking.

[skyegtb]

Yep, I'm going to check everything I can, but my gut is telling me its the starter. Due to where it lives on the engine, so close to the heat of the turbo I can't help but feel it has probably been heat damaged over the years. I'm kind of struggling where to check in the electrics though, but I hear what you're saying about the gear selector / foot on brake thing. The problem is that now the engine has cooled the car starts fine again....