|
|
|||||||
| D2 - Engine Bay Everything under the bonnet |
 |
|
|
Thread Tools | Display Modes |
|
#1
3rd April 2009, 06:05 PM
|
|||
|
|||
audi S8 1999 AQH 360bhp overheating problem
hi,i have a 1999 s8, The engine code is AQH. The temp guage sits at 90 then rises to 100 then back down but just goes up and down from 95 to 100. I have replaced the viscous fan, did the carrot test and the fan just stopped, Replaced it with a new item from euro carparts, replaced the electric fan as this wasnt working at all also replaced the two temp switches,, audi replaced the timing belt,waterpump and thermostat etc 2 years ago at 120k, mileage now showing 155k.The electric fan works when the ac is switched on, but when the heaters are on the fan kicks in, but if i turn the heaters off the fan turns off is this right? im not sure what else to check now but im assuming maybe my waterpump could be gone.
help please? 
|
|
#2
3rd April 2009, 07:42 PM
|
||||
|
||||
|
Was the water pump changed with the cambelt? If so then I doubt it would be that. If not, there is a good chance.......
Welcome to the forum btw.
__________________
Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light. 
Last edited by Conan_the_Librarian; 7th April 2009 at 05:27 PM.
|
|
#3
4th April 2009, 08:21 AM
|
|||
|
|||
|
waterpump was changed at the same time as the timing belt this is why i doubt the pump is at fault but still not convinced. the two problems are that car rises from 90 deg to 100 and fluctuates up and down,water level is fine. 2nd problem is the electric fan kicks in when i switch the heaters on and when i switch the heaters off the electric fan turns off.
|
|
#4
4th April 2009, 09:18 AM
|
||||
|
||||
|
Do you have VagCom? If so, is it throwing up any codes?
I'm thinking it may be a thermostat problem for the 90 - 100 degrees heat fluctuation. They are reasonable easy to change. The fan issue is a new one on me. If you have access to VagCom do an output test and se if there are any anomalies.
__________________
Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light.
|
|
#5
4th April 2009, 10:04 AM
|
|||
|
|||
|
I had the same problem and replaced water pump, thermostat & viscous fan but overheating remained. Turned out to be a seriously restricted radiator. Mileage at the time very similar to yours. To be on the safe side I had the rad replaced but you may be able to get away with some serious flushing. It's certainly worth a try before incurring any more significant expense!
Mike 2001 Ming Blue S8 g
|
|
#6
5th April 2009, 11:19 AM
|
|||
|
|||
|
im gonna change the thermostat as this is the cheapest option and at the same time flush the radiator.the water has always been clean with antifreeze. how easy is it to replace the thermostat?? any guidence much appriciated as i will attemp this tomorrow!!
regards
|
|
#7
5th April 2009, 01:43 PM
|
||||
|
||||
|
__________________
Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light.
|
|
#8
5th April 2009, 01:44 PM
|
||||
|
||||
|
If you have access to Vagcom, see what temperature the engine ECU is showing.
There is a 'dual temperature sensor' on these V8's, one sensor is for the ECU, and one is for the instrument cluster. They fail frequently and give false readings. If the instrument cluster is reading one thing, and the ECU another, change this part. Its about £25 I think... I'd treat the fan problem as a seperate issue until thats been checked..
__________________
For parts enquiries and Forum User Administration please contact customer services directly, not me  - enquiry@a8parts.co.uk, www.a8parts.co.uk, or call 01642 783537The Daily Town Car - 2023 Tesla Model Y Performance. Black with Black. Giant ipad screen, huge sunroof, 4 wheel drive, Tow bar, lots of ooomph and made in China, so actually built properly unlike the Californian ones. The Family Wagon - 2018 Tesla Model X. Black, 7 Seats, Towbar, Homelink, Enhanced Auto pilot with Summon and self park, Heated front seats, CCS Charger upgrade, MCU2 Upgrade, Falconwing Doors, Self opening / closing doors, Netflix, Spotify, toys, Air suspension, alcantara roof + lots of other stuff...... The 17 year old Driver Wagon 2015 Skoda Citigo Monte Carlo. Alloys, Power steering, Aircon, Leccy windows, Sat Nav, bluetooth, central locking, cup holders, 59 whole bhp. Million times better than my first car. Well jealous..... The First 20 Audis: 2001 D2 4.2 QS Silver, 1997 D2 S8 Silver, 1999 D2 4.2 Silver, 2002 D2 S8 Dolphin Grey, 2003 C5 RS6 Blue, 1998 D2 S8 Black, 2000 D2 4.2 QS/S8 Ming Blue, 2003 D3 4.2 Ming Blue, 2005 B7 S4 Blue, 2006 D3 3.0 Tdi Black, 1999 D2 4.2 Silver, 2003 D3 4.2 LPG Crystal Blue, 2000 D2 S8 Silver, 2007 3.0 Tdi Q7 Black, 2009 B8 S4 Black, 1998 D2 S8 Agate Grey, 2006 D3 4.2 Tdi Blue, 2006 D3 S8, 2007 Q7 3.0 Tdi, 2006 C6 S6, The Second 20 Audis: 2011 A7 Sline, 2001 A2 1.4 Tdi Black, 2002 A2 1.4 Tdi Silver, 2006 A8 4.2 Tdi Blue, 2007 4.2 Tdi Q7, 2006 S4 Cab Silver, 2010 RS6 Saloon Black  , 2007 TT Roadster, 2010 A8 D4 4.2 Silver, 2006 C6 A6 2.7 Tdi Quattro, 2000 D2 4.2 QS/S8 Ming Blue (again), 2008 Q7 4.2 Black, 2009 C6 RS6 Saloon Daytona Grey, 2001 Fully Loaded A2 Tdi, 2006 Avant S6 Black, 2007 VW Caravelle Exec Black (almost an Audi) 2009 TT Roadster Daytona, 2015 Q7 4.2 tdi lava grey, 2002 GmbH D2 demonstrator, 2006 D3 A8 LWB 4.2 Tdi Black Most Recent Audis: 2001 A2 1.4 Tdi Black, 2007 4.2 FSi Q7 ABT Blue, 2016 S5 Coupe Launch model, 2004 S4 B6 Cabriolet, 2016 Q7 Sline White, 2006 Q7 4.2 FSi Black, 2012 Q7 Sline+ 4.2Tdi White, 2008 Blue Audi S8 Everything Else 1989 Subaru Justy, 1986 Vauxhall Cartlton 2.0 GL, 1985 Vauxhall Carlton 2.2 CDi, 1987 Ford Sierra XR4x4, 1983 Vauxhall Senator, 1985 Vauxhall Senator 3.0i, 1997 Polo Saloon, 1997 Peugeot 306 1.9 TDi, Ford Sierra Sapphire 2000E, 1990 Subaru Justy, 2000 Subaru Impreza, 2000 Subaru Impreza RB5, 1993 Range Rover LSE, 2005 VW Bora, 2003 Skoda Superb, 2003 VW Passat V6 4 Motion, 1996 Peugeot 106, 2000 Range Rover 4.0, 2019 Tesla Model 3 Performance
|
|
#9
6th April 2009, 12:54 PM
|
|||
|
|||
|
both temp switches have been replaced which i purchased form yourself 2 weeks ago!! i have been checking the temp via vag com it is showing 4-5 degrees lower then what the guage is showing, but i have noticed and checking the bottom rad hose frequently and notice it is cold at all times! this leads me to believe the thermostat is buggered?
|
|
#10
7th April 2009, 01:18 PM
|
|||
|
|||
|
might be adding to the confusion, but the a/c fan will only run when the climate is on (and ECON is not selected) just checked mine, and the air con compressor clutch pulls in followed by a/c fan spin up, as soon as the climate is switched off or ECON selected, the clutch drops out and a/c fan stops.
I'm a bit confused about what you mean 'heater' do you mean the climate? W
__________________
-- 8 - 4.2 - 2002 - LWB 4 - 2.5 - 2004 - CVT - B6
|
|
|
|
Linear Mode
