Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
Burning/Coolant smell & loss, and strange induction sound
Hi Everyone,
I've not been on here much the last few months due to world events, and more importantly our new D4 behaving itself. (Till now...)
Over the last week or so I've noticed a couple of things with our D4 that are worrying me. It started when I noticed a weird burning/hot smell after a run. Not like burnt oil or exhaust fumes, and for a little bit I couldn't place what the smell was. There is no smoke/steam under the bonnet and no trace of anything dripping under the engine bay either overnight or after a run.
Over the weekend I spotted that the coolant level is dropping slowly and the penny dropped that the smell is like coolant leaking somewhere and likely evaporating off. The smell comes mainly from the passenger (left) wheel-arch area after a run. I can't see any obvious leaks yet but haven't had a chance to do more than lift the bonnet.
More worrying, the car has suddenly developed an induction noise at part throttle. It sounds like an issue as the first turbo spools up as it disappears at full throttle. It's not quite a whistle, more of a rasping sound (almost like a wastegate on a petrol turbo engine.)
Any suggestions on what I should be looking at/checking for?
It's a 65-plate car and only done 46k miles with FSH at main dealer. It drives well and is hitting high 20's mpg on very mixed driving. No smoke out of the exhaust that I can see.
Are there any known issues with the turbos and/or the coolant system that could be likely candidates?
There were a load of historical fault codes that I've now cleared and will monitor to see if anything is thrown up in the coming days - this might help with the induction noise but likely less so with the coolant issue (assuming they are different issues.)Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
27th Jul 2020 12:03 pm
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
Anyone, any thoughts/suggestions at all?Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
29th Jul 2020 10:18 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
It might be the N/S EGR cooler (part of the EGR) or a hose since you think the smell is from that side.
Temps get pretty hot at the EGR and often the leak has evaporated before you have a chance to confirm it. Monitor as best you can and keep coolant topped up, it may become more obvious over time.
A workshop with a water jacket pressure test kit should be able to determine where the coolant loss is occurring.
As for the other issue, monitor the dtc's and record them before you delete, there may be an answer or clue in there!yµ (idµ - eAµ) ψ=mψ
29th Jul 2020 12:49 pm
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
Thanks for that. At least I have somewhere to start the investigation now.
Am I imagining that some garages will put a UV dye into the coolant and use that to help trace leaks? Might give that a go if it makes sense.
I checked the fault codes again and nothing has been logged yet...Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
30th Jul 2020 10:36 am
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
Sorry, to add - is the EGR and cooler accessible from the top of the bay with the engine cover off? Or do I need to go through the wheelarch or underneath?Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
30th Jul 2020 10:37 am
KostasA
Member Since: 23 Aug 2015
Location: nairobi
Posts: 286
also i wouldn't disregard the water manifold on top of the V. mine had splitter slightly and was leaking on the warm V.
a good way would be to pressure test the cooling system if you cant trace the leak.
30th Jul 2020 11:38 am
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
When you say "on top of the V" do you mean on top of the engine, in the middle of the two banks of cylinder heads, i.e. under the engine cover?Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
30th Jul 2020 11:53 am
KostasA
Member Since: 23 Aug 2015
Location: nairobi
Posts: 286
yes, where your main coolant pipe goes 'in' the engine.
30th Jul 2020 11:56 am
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
Brilliant - thanks. Will check...Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
30th Jul 2020 12:00 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
wizbongre wrote:
Sorry, to add - is the EGR and cooler accessible from the top of the bay with the engine cover off? Or do I need to go through the wheelarch or underneath?
A bit of both! Heat shields in the wheel arch and Battery box need to come out to get any decent access.
The engine water coupling is rarely a problem but is prone to cracking in warmer climates.yµ (idµ - eAµ) ψ=mψ
30th Jul 2020 1:28 pm
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
"A bit of both!" - of course, why would I think it would be easy. Thanks Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
30th Jul 2020 3:25 pm
jamesinyk
Member Since: 22 Nov 2019
Location: UK
Posts: 25
Are you sure the induction sound isn't because the viscous fan is running harder than usual? Mine is more audible when the engine and in particular the ambient temperature is hot, especially on hot start.
31st Jul 2020 10:32 am
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
Definitely not the fan - that's a completely different sound. This is definitely (famous last words) an induction/turbo related noise.Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
31st Jul 2020 11:03 am
wizbongre
Member Since: 26 Oct 2013
Location: Liverpool
Posts: 690
I've not spotted anything obvious yet.
I bought some UV dye and blacklight torch to see if that helps me spot where the leak is...
No new fault codes yet either on the turbo side.
Are the intercooler hoses on the D4 just as prone to failure as they were on the D3?Cheers,
Gareth
'57 D3 2.7 TDV6 HSE gone and soon to be forgotten!
‘15 D4 3.0 SDV6 HSE Luxury
'64 Audi A6 3.0BiTDi Quattro S-Line Black Edition with lots of toys
12th Aug 2020 8:47 am
darrind
Member Since: 04 Jul 2008
Location: In A World of My Own!
Posts: 2863
Quote:
Are the intercooler hoses on the D4 just as prone to failure as they were on the D3?
I get the impression it is less regular than the D3 but they do split. Heres some pictures of the split on mine -
From the inside -
Repaired on the roadside with superglue and electrical tape
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