Common issues for the B8 S5 4.2 V8

[Riker]

I have a friend who is in the market for a 4.2 S5, could anyone help me ascertain some of the potential horror stories with this particular engine platform if you are caught outside of warranty? Thank you in advance!

[boneyxy]

I've owned mine for 3 + years now, bought it when it had 50k miles on the clock and it now sits at 120k miles. Mine's a 09 6mt.

I had no idea about the reliability issues coming in, but I must say I've been pleasantly surprised with how reliable she's been, and I daily drive it too. Also I have never come across any owners who have complained about recurring issues due to design problems, or horror stories as you put it.

Besides the routine maintenance, brake and tire changes, which can be a bit on the pricey side there is only one really major repair that was REQUIRED! Carbon cleanup! These engines are infamous for carbon buildup due to the fuel injection system, and will need a carbon cleanup anywhere between 60 k- 100k miles. I had my first one done at 80k miles and this job can cost about a grand depending on the shop.

Other issue I had was a coolant leak because of the coolant expansion tank corroding. New tank, cheap fix!
These are the only 'issues' I would say I have had.

Other than this when my car hit the 70-80k mile mark, I replaced the control arms, and suspension. At 100k I put in new engine mounts and a clutch. Now I consider these items to be wear and tear with a car of that age, and when I did replace them, they still had plenty of life (nothing actually failed).

[BrianCramer]

Good to hear! I just purchased an 08 with 81k miles on it. I knew about the carbon cleaning going in. There isn’t a place close to me that does them. I may bite the bullet and do it myself.

[Riker]

I've owned mine for 3 + years now, bought it when it had 50k miles on the clock and it now sits at 120k miles. Mine's a 09 6mt.

I had no idea about the reliability issues coming in, but I must say I've been pleasantly surprised with how reliable she's been, and I daily drive it too. Also I have never come across any owners who have complained about recurring issues due to design problems, or horror stories as you put it.

Besides the routine maintenance, brake and tire changes, which can be a bit on the pricey side there is only one really major repair that was REQUIRED! Carbon cleanup! These engines are infamous for carbon buildup due to the fuel injection system, and will need a carbon cleanup anywhere between 60 k- 100k miles. I had my first one done at 80k miles and this job can cost about a grand depending on the shop.

Other issue I had was a coolant leak because of the coolant expansion tank corroding. New tank, cheap fix!
These are the only 'issues' I would say I have had.

Other than this when my car hit the 70-80k mile mark, I replaced the control arms, and suspension. At 100k I put in new engine mounts and a clutch. Now I consider these items to be wear and tear with a car of that age, and when I did replace them, they still had plenty of life (nothing actually failed).

Great to hear thanks for the feedback!

Good to hear! I just purchased an 08 with 81k miles on it. I knew about the carbon cleaning going in. There isn’t a place close to me that does them. I may bite the bullet and do it myself.

If it's feasible, definitely give it a shot yourself!

[boneyxy]

Good to hear! I just purchased an 08 with 81k miles on it. I knew about the carbon cleaning going in. There isn’t a place close to me that does them. I may bite the bullet and do it myself.

Honestly, if I had enough garage space back then I probably would've done it myself. And there are plenty of writeups and tutorials on the job.

[AWDfreak]

I have a friend who is in the market for a 4.2 S5, could anyone help me ascertain some of the potential horror stories with this particular engine platform if you are caught outside of warranty? Thank you in advance!

No horror stories for me, but some common issues seen on this forum...

Coolant leak (o-ring fitting rear of engine)*
Coolant expansion tank leak (cracks at the bottom)*
Oil filter housing leak
Thermostat failure*
Carbon buildup
Clutch issues (6sp)
Front-end suspension wear
Failed engine mounts
Timing chain guide wear (I think pre-2010, expensive!)

* has happened on mine (2012, 55k miles)

[Smac770]

I would have imagined speeding tickets was the most common issue for 4.2L owners.