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Nick Jones

Soot Monster

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4 hours ago, PaulAA said:

20 litres/100km = 14mpg according to the computah!

Lordy me...… and from an unclean diesel too...…. Tesla next?

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One of the "joys" of owning the same car for many years and doing lots of miles in it is that you get to repeat some jobs.

It seems that A6 C4 front wheel bearings last about 100k, so a few of weeks ago a familiar groan starting to make itself heard above other noises.  I ignored it for a bit.  It got louder.  I checked it wasn't getting hot or getting slack.  It wasn't, so I ignored it some more.  However, with a mission to Heathrow looming (250-ish fast miles) I thought I maybe ought to deal with it.

It's a bit of a cow of a job if you do it the factory way (remove whole front leg and use a press).  The first couple of times I did it this way and it took at least 6 hours.  Last time I cheated and did it on the car.  This involved breaking up the bearing in situ then running a couple of hot beads of MIG weld around the inside of the outer bearing race.  As the weld cools it shrinks the race a  bit, the housing expands and you can wack it out.  You can then also quickly remove the new bearing from the freezer and tap it in whilst the housing is still roasting hot.....  Works, but a bit high-stress.

This time I had a secret weapon in the form of an on-car press-set.  I've seen them used on Youtube (aways in the USA) but never been able to find one at a sensible price this side of the Atlantic.  Dunno why you can buy them in Harbor Freight for $60 but here they are £ 400+.  Anyway, finally found one at a sensible price over here  (<£60) a couple of years back and bought it.  I planned to  change an A8 wheelbearing with it, but that was too big and I had to improvise and only used some elements of it.

This time I was able to use it as intended and the job took under two hours from start to fully tidied up finish.......

P1180847s.jpg

Work in progress - new bearing going back in.  The fit is so tight on these they don't bother with a circlip......

P1180848s.jpg

The set

P1180849s.jpg

No more groaning......  That's 6 front wheel bearings the car has had including factory fit.....  The LH rear is still original!

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Well done, Nick!

I suepect that the kit works because it doesn't come in a Red Box!

John

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So having made the front quiet.... all was well until a couple of weeks back I started noticing a new moaning noise from the rear at certain speeds and on smooth road surfaces.

didn't change much for a while, then a longish run down to Plymouth and back definitely made it worse and by the end of a fastish 250 motorway miles last week it was really starting to shout, though it still wasn't getting hot.  As usual it wasn't very obvious which side was to blame.  As the LH is the original factory bearing (almost 321k) and the RH has done under 20k I was inclined to blame the LH.... however, twiddling the wheels suggested I should check out the RH first......

P1190262sc.jpg

That hasn't lasted well :down:  No wonder it was making a racket!

No obvious reason why.  Crappy part presumably.  New ones are SKF so ought to be ok.

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MoT looms...... and the LH handbrake has been sticking on.

The latter is that the LH rear caliper has formed a habit of sticking on if the handbrake is firmly applied. It can be manually released - by reaching behind the wheel and poking the lever, but this isn’t very convenient. We had a bit of a moment in Plymouth a couple of weeks ago where I had to apply the handbrake firmly to do hill start out of a steep T-junction and then had to literally do a full scale burnout to get the car to leave the junction. Being in thick city traffic I couldn’t really pull over and deal with it so we then had a couple more embarrassingly over-dramatic departs from uphill traffic lights before I was able to pull over and deal with it, by which time the brakes on the rear left were smoking vigorously.

Annoyingly the caliper is not old. Crap parts are not unique to Triumphs. I removed and stripped the caliper but could not get it to work smoothly, so I’ve ended up overhauling the original which has been sat on my scrap pile - and its working well at the moment. Unfortunately the Plymouth incident had killed the disc and pads so the rears are all new now.

While grovelling under the car I also noted that the “new” exhaust hanger rubbers that replaced the saggy 22 year old originals exactly 12 months ago had failed completely (which explains the odd noises), so I’ve replaced them too.

Hopefully this will be enough to appease the MoT man on Friday.....

She ain’t young no more...... very nearly 326k as I write and another 200 ish tomorrow.

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Another MoT pass.  The 16th in my ownership.... :blink:

I'll never find anything as tough again according to the tester.  I fear he's right!

I then had to go straight home and fix my younger son's 2004 B6 A4 Avant which had suffered a "failure to proceed" the previous evening due to water in the throttle position sensor (the accelerator pedal one).  Fortunately he was able to dry it out enough with a spare sock (!) to allow the ECU to reset and carry on his way.  This is a known issue with this model and this particular car has previous history having been evicted from my brothers household for similar behaviour.

It stems for poor design decision making by Audi in placing the ECU box over a large hole in the scuttle, in a trough, directly below all the water run-off from the windscreen.  They also made it in two sections with two seals to double the leak opportunity and then placed a whole raft of critical electrics directly under it as well as the ECU itself in the box.  In this case the leak was small but perfectly positioned to run down the wire to the accelerator pedal potentiometer.  It apparently was caused by a knuckle-dragger professional garage chimp being tasked with mending the windscreen wiper mechanism which is only accessible after removing said box.  After mending the wiper mechanism (it bears the scars to this day) he then managed mangle the lower seal when refitting the box.  Successive professional garage chimps have never got any further down than the upper seal and (although it shows now sign of ever having leaked) simply smothered that in sealant.  I've now had the whole lot out, re-seated both the seals with sealant and bolted everything down carefully.  I also regreased the wiper mechanism while I could get at it and fully mucked out the bulkhead/scuttle plenum area which is a fine leaf-trap.  This involved removing the battery as one of the drains is directly under it.  This in turn involves undoing a 6mm allen bolt holding the battery clamp buried 150mm down the narrow gap between battery and firewall below the engine wiring loop and brake pipes.  The actual clamp has a long moulded tail on it to give you a slim hope of retrieving it and repositioning it - presumably added at the prototype stage after much shouting from the poor sods who had to work on the cars.......  Having undone that you then have to wriggle the huge (diesel engine) battery out of its lair while standing at least 4 feet from it.....  Write a back-safe method of removal for that one!  Genius design  - not!

We then had to work out how to return some semblance of smoothness to the throttle assembly which had had all the grease washed out of it and was creaky and jerky as hell.  WD40, 3 in 1 and even silicone furniture polish all made it even worse and eventually, having chickened out of full disassembly of it in case I broke it and immobilised the car I went to the scrapyard and got another....... and then having proved that worked I got braver and successfully got the original apart, cleaned up and silicone greased.  So now I have a spare as well which should mean that I've cured the original leak and well never need it.....

The job then left was to change the thermostat, which in the usual VAG fashion only lasts a couple of years and is very inaccessible.  Though having said that, in spite of the dire stories on the internet I managed it with minimal dismantling and only minor bloodshed......  The older A6 is definitely alot less irritating to work on!

While on the subject of irritating Audis, a good friend locally has a V6 TDI quattro version of the B6 A4 Avant, which is a fairly rapid machine when its working.  Sadly, after a mere 200k (and a high quality service history) it suffered cam failure.  Turns out this version of the V6 TDI has hollow, hydroformed steel cams with the actual lobes shrunk on. After a while, the lobes come loose and move around, dislodging followers, which dislodge other followers.....  There are four cams and 24 valves.  Access is awful......  Horrible job, proven by none of his usual trade contacts even bothering to quote.  Amazingly he's bitten the bullet and swapped the cams himself (parts are not cheap either), including new timing belt etc.  Trouble is, now it doesn't start or even have any compression, on any cylinder....... He's got the proper locking kit and as far as we can tell the timing is right....... WTF?  Suspect the hydraulic followers are keeping the valves open, but don't understand why.  It stood two days between fitting and first turning over.....  I shan't be buying anything with the V6TDI in it!

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Following up on the V6 TDI story....... I was lucky enough to spend the morning trying to work out what the issue was.  He'd partially stripped it again.  It takes about 2.5 hours to get to this point - if you've done before.

IMG_3913.jpg

It's a DOHC V6 with 24 valves. One cam on each bank is belt driven from the front with the second cam being gear-driven by the first.  The cams act on the valves via roller rockers with one end of the rocker supported on hydraulic adjusters. To mess with your head, the inlet and exhaust valves are shared between cams. 

First discovery was a broken rocker on the RH bank.  We were then carefully compared the profiles of the new and old cams paying special attention to the gear driven cams.  At this point the penny dropped.  You can't mix up the belt driven cams because they are clearly different.  The gear driven ones though, look the same and are physically interchangeable, but have different timing....... you can see where this is going right?  Yep.  Gear-driven cams fitted to the wrong bank.  With the cams removed it can be seen that 3 rockers are broken on each side because the valves hit pistons when the engine was first turned by hand (very little force needed apparently!).

Balls..... :down:

IMG_3914.jpg

Really the heads should come off at this point and another set of rockers/hydraulic adjusters ordered.  However, the owner has really had enough of it so the ghetto decision was taken to reassemble using the best of the old adjusters and rockers on the gear-driven cams, fitting the correct cam to each bank this time.  This fiddly-ness of getting the cams timed right relative to each other is enormous as the producers of the parts don't mark the cam gears with their relative positions, forcing you to rely on the timing lock kit, which is hidden in a confined space under the bulkhead when working on the LH bank...... plus the gears have a strongly spring loaded anti-backlash arrangement making it hard to guess the final position when you first offer them together...... There was cussing..... :growl: The ancestry of the designers was thoroughly questioned and found lacking .

Sit rep when I left.  Belt was back on and the engine had been turned over (very carefully) by hand with no tight spots, no suspicious noises and best of all, noises of compressed gas escaping slowing past piston rings showing that the engine is now pumping air and building some pressure, so probably the valves are ok...... probably.  Maybe.  Hopefully....... :confused:

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I am in awe! The only items I recognised from your first photo were the dipstick, battery conditioner and lamp (and I strongly suspect the latter two were aftermarket items!).

Back in the dunce's corner.

Miles

 

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1 minute ago, MilesA said:

I am in awe! The only items I recognised from your first photo were the dipstick, battery conditioner and lamp (and I strongly suspect the latter two were aftermarket items!).

Back in the dunce's corner.

Miles

 

I’m with you Miles. Modern   engines ....It’s a mystery to me .

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On 10/11/2019 at 11:15 PM, Nick Jones said:

It takes about 2.5 hours to get to this point - if you've done before.

 

Nick

It took me about 8 secs to get to achieve the same level of access to the V6tdi:

DSC_4002.thumb.jpg.bf6ffdb3a6b746d743ab492b5503f96c.jpg

:mad:

Paul

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1 hour ago, Hamish said:

I’m with you Miles. Modern   engines ....It’s a mystery to me .

It's finding the bloody engine under all the other gubbins which is the main challenge......

Paul's method is a bit drastic is a bit extreme though.  That's going to need a BIG bottle of T-cut :confused:

We were also playing a game while working on the engine which was "count the number of individual moving components in the valve train".  Got to 352 starting at the cam pulleys and ending at the valves.  If you also count the individual rollers in the roller rockers that adds another 240....... :blink: flippin' heck!  There aren't that many parts in a whole Triumph 6 and probably the gearbox too!  Worth remembering that Audi also do a V8 with 5 valves per cylinder that has rather similar valve gear - so that will have nearly double the count.  Miracles of production engineering but not surprising that things sometimes go awry.

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21 minutes ago, MilesA said:

Does it need to be this complex

Beats me.....  I have the previous generation straight 5 2.5TDI in my A6.  Single overhead cam and only 10 valves. 140 bhp rather than 180 bhp (though they "chip-up" to 170) and it's rather better on fuel than the V6.  The S5 is also renowned for extreme durability.  I guess it's an emissions thing and particulates/NOx at that as the S5 probably has lower Co2 emissions.

I won't be buying anything with the V6 in it.

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IMG_3913.jpg

Nick,

Re your pic above.    Is that the fuel pump in the middle, between the cam sprockets and above the idler?   What drives that???

John

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Yes, that’s the injector pump. It’s driven by another belt from the cam pulley on the n/s bank. Neither belt nor pulley are fitted in that pic.

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