SwaitsySG

Well, another thread revival, this time not so positive. After some extensive testing, which initially seemed OK, the problem does in fact persist. The brake caliper is still sticking on intermittently. So that's the rusty section of pipe replaced, the flexi hose, and a new caliper. No change. So I'm guessing at this point, it's going to be a sticking valve in the abs pump itself 🤔

Well, first off happy new year to everyone. Hope Christmas was good. For the sake of tidying up this thread with a conclusion, I've since gone ahead with the brake line repair. I cut the steel line just past the corroded end section, chamfered and reamed the end of the line, made it all neat and tidy, threaded on a union nut and flared the line. Corroded section of steel brake line has now been replaced with a new piece of cupronickel line with a flared union to the steel one. To the end of that I've replaced the old flexi hose with a new Brembo one. The bracket itself was solid, it has a quick tidy up but I may return to that and give it some better protection. Brakes re-bled to finish off. So far no leaks at the union, no fluid loss from the reservoir and more importantly no hot wheel or smell of brake pads. It's early days so I won't say problem solved yet. A short motorway run to my nearest services will give me a better idea. But so far, so good.

Cheers Gareth, appreciate the concern. I have new Brembo hoses there. Beyond that, there needs to be a balance. Replacing the full line (correct me if I'm wrong for thinking the fuel tank needs to come out? I read that on here somewhere) pretty much means the vehicle is probably scrap. Which is a shame as its got plenty miles left in it. I'll give it some thought before making a decision on what to do. I made this very repair to an old Merc once, where I replaced the knackered end of the brake line with a new piece, double flared and joined with a union. It passed its mot without issue and never gave me any bother.

I think they'll be ok if I'm honest. They look worse than they are. If I can carefully persuade the flexi hose out, I'll give the lot a good clean and some rust converter. Then get the ol'Dinitrol on it, preserve it for a wee while longer.

Well Cliff, my two mot advisories were for this and the offside rear. So I'll replace the ends on both rear lines. I'm not going to touch the front. Fifteen year old car with 254k miles, I'm not doing any more to it than I need to.

Well, that's gubbed. Whether it's the cause of the sticky brake or not is still not confirmed. But I'm not going to attempt to loosen it. So the plan now will be to cut that whole end off and replace it with a new piece of pipe.

Cheers Stevey. That's optimism i can live with, and I've plenty plusgas 🤣 I've a set of ring spanners but not any dedicated brake spanners, so maybe jump online the night and have a look for some 👍🏻

Thanks lads. I don't believe it's the abs unit Stevey. Not when the hoses are a tenner a pop. I'll try them first. I was curious about whether being solid externally or not at least gave some sort of indication as to whether they were bad. It's an old car, and the brake pipes are going to be rusty where they meet the flexi hoses. So trying to remove them could be a world world of pain in itself.

For the sake of opinion. Cheers.

Not something I'd considered, but it's possible. How firm should the flexi-hoses be?

Rear brake binding after caliper change Afternoon all. Think anyone could shed some light on this? So more often than not, but not all the time the nearside rear brake seems to stick, causing the wheel to heat up and the pads to smell. I'd initially changed the pads, cleaned the slider pins, filed the caliper carrier to clean it, and replaced the pad shims. I also added a thin smear of anti seize grease to the backs of the pads. No change. I've now changed the caliper, so that's brand new. Still no change. I might add at this point there's no squeaks or squeals, no fault codes for the braking system, no issues at the pedal end, no dash warning lights and the EPB appears to be functioning as it should. There was also no issues during the mot test, which the car passed two weeks ago. Any suggestions folks?

Just thought I'd post a quick update on this. What are we, 6 months later roughly? Racked up around 4000 miles since the repair. New plug is right where I left it, no leaks. Guess that's about as good as you could ask for.

I'll need to look into the water temp sensor theory Stevey, cheers for the suggestion. I agree with what you're saying about the coolant flow rate. Mine has sat quite happily idling in traffic on hot days without problem. I've never had an overheating issue with that car. Though I can't say I've ever held the revs at 2500+ for extended periods of time. As far as the emissions test goes I dunno. That's just what the man said. Needless to say the mot has now been done and the car has passed. Regarding the AC as i say, the old fan did nothing when I switched it on but as mentioned the system needs recharged. I don't know whether that affects matters, but certainly from an electrical standpoint switching it on did hee haw. As far as 'knowing' the fan was goosed, I didn't. I just figured it was, between the faults and the lack of any sort of life. Never had an A6 before now but the fan used to kick in on my 2017 Leon ST quite frequently. Wasn't unusual to hear it whirring away as I parked up after decent run. Newer car and a later gen 2.0TDI though so maybe not a fair comparison.

Thanks for the reply Gareth. So basically while doing the emissions test the temp gauge started to creep up during the test. Technically 'overheating' in so far as it crept above normal operating temp, high enough that the fan should have kicked in but didn't, but not high enough to be catastrophic. Not into the red. So the test was abandoned, the tester airing on the side of caution. Under normal driving conditions the temp has never gone above normal operating temp. Gauge has always been rock solid. Sorry, I should have made that clearer. With the replacement fan technically working, albeit on the full time the engine is running, the car is going back to the same chap to complete the emissions test. And yes, 2500 revs. Or at least I assume he was running it stationary at 2500. I was unintentionally vague there. When I said higher revs I didn't mean top end. I forget that the revs generally only ever reach 2500 for a second or two at a time while changing up through the lower gears. Usually i change gear slightly before that anyway. Normal daily driving it never sits that high consistently. 70mph in 6th on the motorway you're looking at 1900rpm. Cheap is a misinterpreted word in this context. Inexpensive would have been better. Prestige Motor Services. (Dunno how good or bad their rep is within the Audi community. If any). They describe themselves as specialist Audi breakers, to use their words, that deal mainly in new and used Audi parts. I'll admit used electrical part - a gamble. Fair enough. With your advice in mind, I won't be getting any more parts until I've done more testing on what's already there so I'll look into AC pressure sensors following that. I'll add at this point that the fan will run continuously regardless of whether the AC is switched on or off. The AC needs recharged but if its switched off I'd have thought that wouldn't affect the fan. Its the single fan unit. So a main rad fan on one side and louvres on the other.

Aye, so it went like this; The old fan didn't work. The chap at the garage was reluctant to complete the emissions test on this basis, as it wasn't kicking in when holding the engine at higher end revs. When the car is out on the road the temp gauge sits where it's supposed to and the car runs quite happily. Its never overheated. But static in a garage, held at high revs for the emissions test, he was concerned that the engine might get too hot as the fan wouldn't kick in, so the test wasn't completed. My OBD scanner brought up a low control circuit fault and a blocked/difficulty of movement fault. There was no physical obstruction to the fan but the module terminals were quite corroded. Admittedly I only tested continuity of the power cable from the plenum chamber to the fan plug. That was fine and corrosion free. I sourced a replacement unit from an Audi motor factor as it was inexpensive, included both the fan and module, and tested and deemed to be 'in working order'. It could well be that this is at fault but I took a punt, two birds with one stone and aw that. I'd thought maybe a relay was the problem but was told it's in the fan motor itself on this particular setup. (CAGB 2009 2.0TDI with single fan). Installing the replacement fan and module, the 'new' fan comes on about 10 seconds after the engine is started And stays on until a couple seconds after the engine is switched off. There's no fault codes showing for the replacement fan. In fact, there's no fault codes coming up at all. Not for the fan, or any sensors. No lights on the dash either, such as for a dpf regen. There's two temp sensors on this engine, both on the back I believe. The main one is easy enough to reach though a mirror is required as there's no direct line of sight when changing it. That may be worth testing, or even changing as it's a quick job and costs buttons. But again, no fault codes relating to that. The sensor on the rad, which has also been known to contribute to misbehaving fans is the AC pressure sensor. Again no fault codes. That brings me to where i am at the moment, if that builds a better picture.