Car stuff – Gilbert Serex

By the end of March, the car had been moved out of the old location and the drive down my narrow road was epic. Not only that but the neighbour had otherwise decided to drive up the lane as I was going down…. No problem just reverse right, well… The transmission kind of refused to “R”, turning it to a bit of a panicky moment. Anyway the neighbour managed to reverse and we squeezed past each other, she gave me the “look” (she’s nice) but I don’t think she recognised me and though “what the heck is this guy doing down MY road!” lol.

Anyway. Then the transmission decided to actually reverse, go figure. Just another oxidized episode I guess.

Wipers

First job working out the wipers or lack thereof, removed the wipers unit from the car. One of the the motor brushes was not connecting. Gave it a good clean and the motor and gear work as intended but the gearbox was making a whirring noise. Ordered a cheap compatible motor with different connector. Had to open the old gearbox to figure out the way it worked, then trial and error to make the new motor work the same way, quite easy when you know how!

Innards of the wiper motor gearbox — This is what I had to do to figure out the system.

Old vs. new motor wiring order

Then the mechanical side of it had to be modded also.

New motor in…

Plenum

The plenum which sits in front of the windscreen and contains air intake and more importantly the ECU box, was filled up with tiny polystyrene balls caused by the house roof being insulated with that stuff years ago, it was everywhere, and more than 6 months later, I still find them! In addition to this, lots of organic matter was also accumulated. It took me about 2 hours of using compressed air and vacuuming to get most of it, all drains were cleared.

ECU Box

The ECU box was very worring, there were traces of moisture and the ABS ECU was showing great signs of water oxidation, Thanks to the great folks at audiworld.com Forum for their recommendations to double my efforts I think I might be able to get to the bottom of the issues plaguing the electrical gremlins. I spent a whole day de-oxidizing all the ECU box connectors and sockets (a total of 18 of them!),

How to clean heavily oxidised connectors?

Take white vinegar and a load of table salt (saturated, which means cannot dissolve anymore) preferably warm.
Dip or brush connectors one by one in the solution for about 15 minutes
Neutralize the acid with warm water with lots of baking soda, again to saturation,
Compressed air dry
Optional contact cleaner

Resulting in a car starting (almost, see below) and all engine and Transmission Faults cleared and staying so!

However, I still was facing issues regarding the main relay which prevented the car from starting, strong smell of fuel, wiggling relays in the passenger foot well remedied the situation, probably doing the same clean up exercise there would definitively help also.

Few issues still, the orange rubber seals on the box marked “Benzin” in the ECU box was giving me trouble and had to smother them both with silicone to facilitate the connectors’ insertion, as they were losing their shape when inserting the connectors.

The surrounding rubber seal of the ECU cover does allow water to seep through at the cabin side due to the fact that this cover slots into catches and does not seem to provide good seal, my tip: add atop layer of plastic sheeting slide it between the lower windshield frame and said box half way to the front and tape it on on the forward side, so far seems to sort the water ingress.

The only fault remaining after is the “606 rotation rate sensor-Faulty” which is the black thing under the passenger seat, ordered a second hand one from Latvia and voila! ABS light cleared!

Botang’s Hole!

For those in the know, this has to be the weirdest bit of Teutonic engineering I ever got to face ever. Mr Piesch, were you on holiday that day? How could you let this slip up. Basically the Botangs hole is a opening located in the back of the plenum under the AC piping (and for a RHS steering), under the ECU box, that is covered by a bit of card board painted over, that’s it! Over time, this cardboard fails and water penetrates in the cabin, on the footwell electrics, like relays and connectors making the whole left hand side of the car footwell under the carpet a swimming pool!

The infamous location of the Botangs Hole!

Proceeding to patch that hole completely eradicated the problem, except that there is also the issue with blocked AC drains by the transmission tunnel, on both sides. Yet another German engineering blunder, probably a Friday afternoon design devised around the pilsner Keg Ach, as the car had sat for 9 years, there was a lot of debris in the air system, which translate to hearing the sea when the fan is running and the passenger getting a foot shower when turning sharply to the right. The easiest side to drain the excess fluid and clean the pipes is on the left hand side, bearing in mind there is a drain on the left also! Bah. Whassever.

Still, had to contend with moisture under the rear left passenger carpet, I still don’t know where the water came from, perhaps the door seal is not too good, but it is not overly worrying, everything is dry where it matters now.

Sunroof

The sunroof was not working, the button does nothing, all I hear is a click, I tried to help the rood by nudging it from inside and outside, all I can hear is a “click”. It now works. But I had to do a manual override it was quite hard to get it unstuck. Doing so I managed to strip the 4mm Allen bolt using a impact river, I since discovered that tool to manually overide is in the fuse box cover located in the footwell.

I still to this day have water ingress when the car is parked facing up a slight hill, must be the rear drains that are quite difficult to reach, am thinking putting Tees on each side of the rear pipes in the boot (once you remove the side covers they appear, I fin d the system at the end of each drains to be a mystery as to why they thought this was a sort of clever way to end them, they seem to get clogged so easily. I tried to have a go at them from the inside at the rear of the car but all I managed to achieve is ripping the lining from the roof off the substrate and now have a sagging liner 🙁 I need to find out about clearing drain holes but it is not an overly big problem IMHO.

HVAC drainage

What is this idea following the sunroof and front plenum draining system also badly affects the HVAC drains, especially after a long period of standing still, dirt accumulates in the bottom of the HVAC pan and the drains gets easily blocked, there are two drain on other side of the transmission tunnel, it is well documented, but I fail to understand the logic in creating bottlenecks for dirt to get stuck into and having to do a manual clean every now and then, still thanks to the option though, If you do have blocked (and you will) drains, you end up with a rather annoying car pissing on your legs every time to turn sharply left or right. I decided to keep the left hand side trans tunnel cover off to ease access and monitor the clogging, so far after two episodes it seems to be OK.

Steering column adjuster

The electrical assisted steering column adjustment was totally stuck solid, not a movement to be seen, after working tirelessly for several hours I managed to free the system up and it is now working as expected. A video or two is better than a million words….

Rear transmission shaft seal

There was another problem regarding an oil leak reported on previous MOT back in 2016, transmission oil leak, this was the rear shaft transmission seal at the back of the gear box, new seal from Audi sorted it, no need to remove any catalytic exhausts, simply shove the prop shaft aside…

Long term trim, system too lean/rich

After fixing most of the technical issues, leading to an unexpected sailing through the MOT with a couple of minor advisories, my last sporadic issue was fuel trims, lots can be the cause:

Faulty MAF sensor
Faulty Fuel Pump
Dirty fuel filter
Dirty injectors
Faulty O2 sensors

I proceeded to get a new MAF after many many other tests, like fuel pressure test:

Fuel filter replacement

fuel cleaner additive.

The problem is not too problematic, I drove 800 miles with a faulty MAF and the ECU corrected the fuel supply (lean) at around 15%, but best not to have this for ever as one get the EML (engine management light) on pretty much all the time.

I replaced the MAF with what I though was a compatible item only to discover that the EML turned back on as the engine was running to rich,; right the opposite(!).

Subsequently doing another 800 miles roundtrip to England running “rich” with EML on all the way. No ill effects.

I now have a correct MAF and all fuel trims are perfect!

Secondary Air Injection

The very last persistent problem I am still faced with throwing a EML is the SAI or Secondary Air Injection system, a nonsensical historical piece of technology that sparked the madness of modern cars ever race with “clean air” regulations that emblazon all new vehicles with excess weight, sadly but a necessary evil in this age of “we are all gonna die” mentality. Basically the SAI “blows” air into the Cats like blowing onto a fire to increase temperatures to make them work better at limiting pollutants exiting the tail pipes. What a silly thing only needed in cold weather when the engine is cold, something one will never e failing in the UK MOT tests as engines are well warmed up before any emission testing! So this can technically be deleted. However this causes the EML and ECU to react, and seemingly needs reprogrammed, I am still working on a solution…

Transmission

Coming to a browser in front of you soon…

The story begins in early March 2025, the first steps was to check if the car would fire up. Obviously the battery was totally dead and had to be replaced.

First thing first, replace the battery and try to start it. Result: lights came up in the car and upon trying to start the car, smoke started to billow out of the engine bay.

Suspect No 1: alternator, proceeded to disconnect it and the smoke stopped.

After replacing the alternator, the car started and moved forward and backward with a few red lights on the dash, main one was ABS second was traction control, the long process to clear all the DTC (Diagnostic Trouble Codes) started. As the car had sat for 9 years in all sorts of weather, luckily under a partial roof, it was not too bad, however the level of corrosion, especially in the ECU box located in the plenum at the back of the engine firewall, was major.

The main error was linked to the transmission and brakes system. Mainly caused by water ingress and connectors corrosion, I checked and dried the ECU box, protected it somehow from further water ingress – on a a side note – why would the engineers at Audi design a system that is right where most of the water coming from the windsrceen would end up flooding this plenum is difficult to understand. If so, make sure that the box is providing a very good seal, which is not the case; it merely is splash proof at best.

Other items that were found not working well or at all:

Alternator shorted
Windscreen wipers motors dead
Wing mirrors folding not proper operation (since stopped working all together)
Transmission (mainly corroded/unused contacts and ABS fault related)
Rear brakes calipers seized
Very very Mushy brakes.

First Start

The first start was epic. But I was far from “start up and go”, the next few months would be quite challenging, the first major step was to move the car from the car port as I needed to repair the roof. So I hired a trailer and planned the move back home.

The first main problem was brake pedal / gear shifter relation ship. As you can see in the video below the car dash sometimes failed to indicate what position the trans was in, the red icon did not light up but the car got in R or D or N no bother, then it beeped.

Moves… Just!

Second issue were the mirrors, they didn’t unfold…. If I manually unfolded them they stayed unfolded but power cycling the car made them fold back. Both mirrors could be adjusted up down left right but the “fold” option did not work, Me was thinking that I had maybe not been using the feature properly; the dial rotated all the way to 6 o clock and nothing was happenings.

Mirror, Mirror on the A8!

Third issue was the sun roof, the button did nothing, all I heard was a “click”, I tried to help it by nudging it from inside but no luck there, subsequently found out about the manual override it was quite hard to get it unstuck. But doing so I managed to partially strip the 4mm Allen bolt, tip: don’t use an electric impact screwdriver, I also found the key to operate this roof in the back of the fuse box in the footwell.

I also thought that the drain holes of said roof needed cleaned as the footwells where quite soaked in. Especially the left hand one. turns out it wasn’t, more on this later.

Fourth, the steering wheel adjustment was not working. All I could hear was a clunk but nothings was moving, more on this later as well.

Lastly for the time: Windscreen wipers were also dead… I though the motor probably had seized and fuses had blown…. It was a bit challenging to say the least.

Before moving the car more seriously , I had to work on the brakes, most importantly lack thereof, the pedal was going to the floor and after a few pumps it kind of “prevented” the car from moving, not good enough, so only one thing for it, flush the whole system.

Went to Halfords and got a few bottles of DOT4 brake fluid, also bought a basting pipette to extract most of the old fluid out of the tank and proceeded to flush every single corner, starting from the rear left (furthest away from the master cylinder – Engine Running btw!) and so on. There were a lot of air in the lines, which made sense, after a good litre of new fluid in the system, that replaced very old and dirty fluid. The brakes were finally back to good old firm. However the ABS/ESP light were still coming on even after clearing the faults with my cheap Bluetooth dongle, I was not getting much details about anything so I decided to get a more advanced diagnostic tool.

Initially acquired an Autel, but it was still quite basic. So I returned it and got a Chinese XTool, which had a bit more features, still, had I known, I should have gone for a VAG Tool straight away; as it obviously IS the best system for these cars. But that [VAG] came much later, when i really decided that needed the thing to extract most of the faults accurately.

Lots of faults! — Lots and lots of faults!

Xtool report, a bit more readable. but still… Should’ve gone for a VAG tool in the first place!

After clearing most of the faults, the ABS light kept coming was back on but the ESP one had gone (was flickering and I cleaned the abs pump connector seems to be doing the trick – for a while). I wasn’t at the end of the ABS warning light saga.

Maybe the cause of the ABS/ESP light being on?

Category: Car stuff

2 – Moving Home – 2001 Audi A8 Barn Find Restoration