Normal for 4.0T to run "hot"? Big concern
08-10-2016, 04:37 PM
#1
Normal for 4.0T to run "hot"? Big concern
I have had my '13 CPO A8L 4.0T since the end of April. I traded in an '05 for this. I love it, but I noticed immediately when parking in my garage a slight burning smell. Not strong, but it's there. I also notice it inside the car. I thought the previous owner smoked so I totally treated the interior and the smell went away, but I still smell it a bit after going for a drive. This happens even after a brief, general drive, not even beating on it. The temp gauge is always in the middle, but the car just smells "hot" to me when I get out.
The other day it was raining and when I pulled the car in I noticed a sizzling sound from what I assume was the water running over the exhaust. Again, this was after a normal 20 minute drive, not pushing it. I have attached two YouTube videos of me attempting to stick my iPhone under near where I heard the sound.
Video 1: solid sizzle sound as soon as I got out of the car.
Video 2: this is one minute later, you can hear the brief sizzle after every drop of water.
I just hit 40k miles and have the original warranty. My dealer is an hour away so I was hoping to have an idea for them. Because of this great board I gave them the 1k and 3k downpipe issue and they replaced them, probably wouldn't have been so easy without your help.
The other day it was raining and when I pulled the car in I noticed a sizzling sound from what I assume was the water running over the exhaust. Again, this was after a normal 20 minute drive, not pushing it. I have attached two YouTube videos of me attempting to stick my iPhone under near where I heard the sound.
Video 1: solid sizzle sound as soon as I got out of the car.
Video 2: this is one minute later, you can hear the brief sizzle after every drop of water.
I just hit 40k miles and have the original warranty. My dealer is an hour away so I was hoping to have an idea for them. Because of this great board I gave them the 1k and 3k downpipe issue and they replaced them, probably wouldn't have been so easy without your help.
Last edited by theanimala; 08-11-2016 at 05:40 AM.
08-10-2016, 07:46 PM
#2
AudiWorld Super User
Doesn't matter if you drive it hard or not the exhaust, especially the cats, will get very hot. Optimal temperature for catalytic converters is somewhere in the neighborhood of 800 degrees. That is of course internal temp but outside temp will still be very hot and will stay that way for quite a while after you shut it off.
I've only driven mine for 4 days so I can't comment on the hot smell.
I've only driven mine for 4 days so I can't comment on the hot smell.
08-11-2016, 04:43 AM
#3
Your car is still in warranty, take it to a dealer and let them drive it and look at it, especially underneath and in the engine compartment, there shouldn't be any burning smell.
08-11-2016, 07:56 AM
#4
AudiWorld Super User
Forget the rain stuff. Water on hot exhaust, nothing new.
Smell: Should be none of course. If there is, suspect fluid leak and get inspected by dealer or otherwise. Might also be something different than you are suspecting at first, for example somewhat clogged HVAC drains letting stale water accumulate, or plenum drains with rotting leaf crap, or ten other scenarios.
With 10K to go on full 4/50 warranty more or less FWIW, if it were my car sometime in the next six months or whatever time you have left on the four years, I would have every cover off under there and inspect it front to back. Even one missed leak or torn seal or whatever will be a likely minimum 5-10x what it would cost even to pay a mechanic to inspect it all. CPO may cover later--though watch out on things like CV boots they don't cover, apparently not air shock units, and various other things. Having BTDT on my D3, I give the car a thorough top to bottom--both every switch and function and underneath a thorough visual--before each of 4/50 and CPO expire. Let them do the work on their dime, instead of finding some issue that started as a vague smell or whatever only post warranty when it has turned into some larger full blown problem.
Finally, yes they run warm, but underhood I would say no more so than my D3 W12 did. Smaller motor here, but turbo's in a V are never going to be remotely cold even after brief driving. The after run fans maybe exaggerate that sense too. But glad it clears some hot air under there for a while from the way long term plastics got heat soaked on my W12 over ten years.
Smell: Should be none of course. If there is, suspect fluid leak and get inspected by dealer or otherwise. Might also be something different than you are suspecting at first, for example somewhat clogged HVAC drains letting stale water accumulate, or plenum drains with rotting leaf crap, or ten other scenarios.
With 10K to go on full 4/50 warranty more or less FWIW, if it were my car sometime in the next six months or whatever time you have left on the four years, I would have every cover off under there and inspect it front to back. Even one missed leak or torn seal or whatever will be a likely minimum 5-10x what it would cost even to pay a mechanic to inspect it all. CPO may cover later--though watch out on things like CV boots they don't cover, apparently not air shock units, and various other things. Having BTDT on my D3, I give the car a thorough top to bottom--both every switch and function and underneath a thorough visual--before each of 4/50 and CPO expire. Let them do the work on their dime, instead of finding some issue that started as a vague smell or whatever only post warranty when it has turned into some larger full blown problem.
Finally, yes they run warm, but underhood I would say no more so than my D3 W12 did. Smaller motor here, but turbo's in a V are never going to be remotely cold even after brief driving. The after run fans maybe exaggerate that sense too. But glad it clears some hot air under there for a while from the way long term plastics got heat soaked on my W12 over ten years.
Last edited by MP4.2+6.0; 08-11-2016 at 08:05 AM.
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Golan Remi (07-18-2022)
08-11-2016, 11:14 AM
#7
AudiWorld Member
Mine run right away after shutting off engine and stay on quite a while. Feels like a blast furnace in my garage when I stand next to the engine compartment.
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Golan Remi (07-18-2022)
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08-11-2016, 04:57 PM
#10
AudiWorld Super User
My S8 kicks on right away. After most drives, though not all--colder day, shorter drive, etc. I notice the responses with identifying info are several S8's. I can't confirm what an A8 4.0T does since I haven't owned one or had it as a loaner.