What's in the workshop? Gareth's Tree-find

MikkiJayne · #1 31st October 2020, 08:42 PM

Yeah thats feasible

A frustrating day today. I got the front panel back on and filled all the fluids. Still no brake hoses so I can't finish the brakes and so can't check the gearbox properly, but the engine starts up with no leaks

However... the replacement fan bearing failed immediately on startup and became loose and rattly

I had to pull the fan, belt etc and replaced it with a good OE one which is all I had available. I will investigate getting a proper FAG or SKF bearing to replace the no-brand one the part comes with, and just use the housing.

After this was all back together the engine was nice and quiet but I noticed the TCU would go in to limp on every startup with a low voltage code

When the code is cleared it's then quite happy, but at every power-up it gets the error so starts in limp every time. Swapping the TCU solved it, which is extra frustrating as I sold my spare S8 PRNDS TCU to Scott the other day to fix his tiptronic problem

I do have a PRND432 TCU spare though so that'll go in for now while I seek a proper replacement.

Finally, I pulled out the jumper I had put in the starter interlock relay before it went on the lift, confident that the replacement wiring harness would solve the lack of a neutral signal from the F125, but it was not to be

Still no start with the relay back in, so the F125 needs to come apart for inspection. At least that doesn't take long on an S8, especially one that's just been apart.

No leaks though...

ainarssems · #2 31st October 2020, 09:54 PM

Quote:

Originally Posted by MikkiJayne

Yeah thats feasible

A frustrating day today. I got the front panel back on and filled all the fluids. Still no brake hoses so I can't finish the brakes and so can't check the gearbox properly, but the engine starts up with no leaks

However... the replacement fan bearing failed immediately on startup and became loose and rattly

I had to pull the fan, belt etc and replaced it with a good OE one which is all I had available. I will investigate getting a proper FAG or SKF bearing to replace the no-brand one the part comes with, and just use the housing.

After this was all back together the engine was nice and quiet but I noticed the TCU would go in to limp on every startup with a low voltage code

When the code is cleared it's then quite happy, but at every power-up it gets the error so starts in limp every time. Swapping the TCU solved it, which is extra frustrating as I sold my spare S8 PRNDS TCU to Scott the other day to fix his tiptronic problem

I do have a PRND432 TCU spare though so that'll go in for now while I seek a proper replacement.

Finally, I pulled out the jumper I had put in the starter interlock relay before it went on the lift, confident that the replacement wiring harness would solve the lack of a neutral signal from the F125, but it was not to be

Still no start with the relay back in, so the F125 needs to come apart for inspection. At least that doesn't take long on an S8, especially one that's just been apart.

No leaks though...

2 things,
1) could it be aged capacitors in TCU that resulting in low voltage error and be replaced and
2) can it be updated from PRND432 to PRNDS with a software update.

MikkiJayne · #3 1st November 2020, 04:01 PM

Quote:

Originally Posted by ainarssems

2 things,
1) could it be aged capacitors in TCU that resulting in low voltage error and be replaced and
2) can it be updated from PRND432 to PRNDS with a software update.

1, good idea - worth looking in to

2, yes but I have no idea how. The TCU I'm using is actually an A8 FL1 but it's running S8 FL1 software. But, there is no facility to do that with VCDS and the traditional ECU flashing apps like Nefmoto don't appear to be able to do it either. I wonder if a specialist could read the map directly from the board and then flash it back? It used to be possible to get remaps for these TCUs so there's clearly some way to do it but how is a mystery...

I might open it up and see what's on the board

MikkiJayne · #4 14th November 2020, 12:16 PM

Back on this after a little time off for pre-lockdown organising and some other stuff which came up. Working on the bumper this weekend. The first job is to get the bumper supports out.

To remove the rebar from the plastic all these plastic rivets need to come out

We need to save the bracket

and will sacrifice the bolt to do so

Headlight washers out

the hose is clipped in, which can be removed once the rebar is out

with all the rivets out and the headlight washers out, the bar just lifts out

then the headlight washer hose can be unclipped

Cut the heads off the bolts

then unscrew the bracket at the top

and lift out the bracket complete with the shank of the bolt

bumper supports now freed

Bracket in the vise, lots of WD40 on the thread, and mole grips on the shank

The first part is to wind the bolt *in* to the bracket. Doing this, we get clean threads in to the aluminium bracket, and the seized part comes out of the top. This is critical to saving the thread.

You can see the galled aluminium stuck in the thread. If this was forced out this galling would tear the thread out of the bracket and destroy it

Cut off the bad bit, lots more WD40 and then the clean thread of the bolt can be removed with the mole grips.

The other side was more stubborn and needed flats grinding on to the bolt shank to get enough torque on it to break it free

and this is why - the top three threads are stuck to the bolt!

With the bolts out, the threads are cleaned up with a tap, then the brackets can be reattached to the bumper bar

johnny_quattro · #5 14th November 2020, 02:46 PM

Loving the detail on this lock-down V2.0 thread. The bumper pictures from the inside have provided a very useful insight into how the headlight washers are rigged up. I'm certainly going to feel more confident at tackling this long-overdue job on my own car. One jet is dry and the other just dribbles. I wish I had a garage like the one at MJ Towers, I'd never leave!

MikkiJayne · #6 14th November 2020, 06:20 PM

That's usually an airlock after the bumper has been off as the pump doesn't run long enough to clear it. Hold the passenger's side jet down while someone operates the wiper control repeatedly until the driver's side pops up, then repeat the other way round, and that should then bleed the system enough for them both to work.

johnny_quattro · #7 15th November 2020, 11:18 AM

I've not had the front bumper off during my ownership of the car. I forgot to mention that I'd always thought that electric motors raised the headlight washers but having seen the photos, I now realise that it must be the water pressure. Bearing in mind the Covid-19 situation, I'm going to try to do this on my own, armed with a roll of duct tape! Thanks for the advice.