Replacement cost 4.2 vs 2.7T?

[COB6]

Maybe I've stressed myself out from reading the 4.2 problem threads, but my B6 has 128k on it..some rattle at startup (lasts about a second or less, does not sound metallic), burns little to zero oil, and runs like a bat outta hell. From what I've gleaned from aforementioned threads, my car is up.there in miles, and it's making me start to plan ahead.

Worst case scenario, let's say my motor jumps timing... would it be cheaper for me to find a 4.2, replace all timing components, pistons and basic hard-to-reach wear parts, or to swap over a 2.7T? Let's say I do the work myself (capable of it), but have no Audi-specific tools aside from the standard torx and triple square sockets. Since I aM making payments, there would be no upgrades aside from parts known for premature failure.. approximately what would each cost me? I am a carpenter, I don't make a shit ton of money but I can start saving up..

[demonmk2]

just do a timing chain/guide job on it..that motor has a lot more miles to go.

[COB6]

Thanks! From what I can tell, maybe I got a good one.. once that rattle starts to worsen, I will plan acordingly. Minus cost of engine lift, I can do this for around or less than 2k?

[demonmk2]

maybe. search the forums there's a kit for around 900 I think. get the jhm cam adjuster rebuild kit. since the motor is going to be out get a new throw out bearing and pilot bearing. shop for the best deals on gaskets too.

[moyenecorniche]

Warm or cold rattle is usually due to the 3 oil valves below your valley pan not operating. Also with a higher mileage you need to compensate with oil specs.. Dparm loaded a specific thread on this... Sure it is about this time that a precautionary motor pull and chain tensioner replacements is due. But then you need to make a list and see what else you should attend to while the motor is out....

[emilio]

why do people think swapping in a 2.7T is going to give them fewer problems? the 2.7T was one of the least reliable engines Audi ever produced - and that's stock. the only advantages they have is that there's a lot of parts and knowledge about them, otherwise... stock up on head gaskets. and turbos. and maybe some valves, just to be safe.

- emilio

[p3u]

why do people think swapping in a 2.7T is going to give them fewer problems? the 2.7T was one of the least reliable engines Audi ever produced - and that's stock. the only advantages they have is that there's a lot of parts and knowledge about them, otherwise... stock up on head gaskets. and turbos. and maybe some valves, just to be safe.

- emilio

Wrong wrong wrong...the 2.7t is a stout motor. Its all the ancillary items that tend to go bad.


Honestly, I wish one of the tuner companies would come out with a 2.7t swap kit for the B6/7 platform. For me personally I probably would do it, but I think there is an untapped market for this.

[demonmk2]

easier to work on maybe...more available parts and less expensive.

[RedS4avant]

why do people think swapping in a 2.7T is going to give them fewer problems? the 2.7T was one of the least reliable engines Audi ever produced - and that's stock. the only advantages they have is that there's a lot of parts and knowledge about them, otherwise... stock up on head gaskets. and turbos. and maybe some valves, just to be safe.

- emilio

My thoughts exactly

Sent from my Nexus 5 using Tapatalk

[emilio]

"ancillary items" like turbos and head gaskets on totally stock engines? maybe we've been hearing different stories about the 2.7Ts, because i would nevertouch one unless i had a dedicated track car and a lot of money to spend on it. the B5 S4s are great, they were my first Audi love, but there's a reason i bought a B7.

i'll take the BHF's oil and gas consumption any day. the timing chain components need such irregular service that all you regularly need to worry about are the typical high-performance car issues caused by too much heat in too little space: burst hoses, cracked fittings, and failing gaskets - all things 2.7Ts deal with, too.

- emilio

[S4NIK8]

I've owned a dozen 2.7t cars and have never seen a head gasket failure on one. The stock turbos? Yeah those can go bad after you flash the car in a tight engine bay where they tend to get hot anyway. A K04 2.7t isn't exactly a 'money pit' but different strokes for different folks, each setup (4.2 and 2.7) have their own ups and downs.

I sure wouldn't take out the 4.2 for a stock 2.7t or even a flashed stock turbo one

[LINDW4LL]

I've never heard of head gaskets being a problem on the 2.7. The stock turbos are the weak point, and would (should) be upgraded if one was thinking of putting a 2.7T in their B6/B7. With a basic turbo upgrade, you are in the 500hp+ range with no major engine flaws to deal with.

My 2.7T A6 had over 200k miles when I sold it, and was still on the original turbos. It was problem-free for the most part. They're quite reliable when maintenance is kept up with, IMO.

[p3u]

Never heard of head gaskets being a problem...nor from personal experience on a 600+ bhp have I ever had any.

I've also had a C5 A6 with 140k miles on stock K03s that were fine.

The K03s are the biggest thing to go if you start upping the boost and drive hard without proper cool down. K04 or other options take care of that.

[emilio]

i've definitely heard of plenty of turbo issues, both personally and online. the head gaskets were from a couple folks that had repeated issues with them, so those may have been faulty blocks, bad mechanics, etc.

i feel there's no advantage to reliability in aging performance turbos. an old Volvo or turbo-diesel will run for ages, sure, but more high-strung and aggressively-driven engines always seem to come with the stipulation "...as long as you replace the turbos." that's not making anything simpler in my book, that's just doing different work.

if it were a car that originally had a turbo then, absolutely, do whatever it takes to keep it running if it makes you happy. if your 4.2 completely craps out then, sure, look at engineering an engine swap (because that's what it takes). but if your engine is running well then a 2.7T might not make anything cheaper in the long run, and it certainly won't be easier.

- emilio

[p3u]

Love it when a persons experience is based off what they don't or never owned...

[Ob3R]

I agree, pu3.
You cant go off of online. You need to own a b5 to really know these cars. 175k miles on original turbos. Been running 19psi for the last 25k. Turbos are not really that much of a problem on 2.7tt especially if you know proper cool down/maintaince. Never had any problems on my b5 that were engine or tranny related. Although some problems with aux items. The motor especially is fantastic built just all the supporting things arent.
I own both a b5 and b6. I rather have the 2.7tt over the 4.2 any and every day. ive owned 1 b5 so far, i ve gone through 3 b6 s4's specicially because of crap engines that i didnt want to bother to switch out because of oil consumption. Ive done 2 timing jobs on the 4.2 s4's but when it starts eating oil like no other, then its pretty much a time bomb to when to replace it.

Sent from my Forever Check Engine Light B5 S4

[moyenecorniche]

i've definitely heard of plenty of turbo issues, both personally and online. the head gaskets were from a couple folks that had repeated issues with them, so those may have been faulty blocks, bad mechanics, etc.

i feel there's no advantage to reliability in aging performance turbos. an old Volvo or turbo-diesel will run for ages, sure, but more high-strung and aggressively-driven engines always seem to come with the stipulation "...as long as you replace the turbos." that's not making anything simpler in my book, that's just doing different work.

if it were a car that originally had a turbo then, absolutely, do whatever it takes to keep it running if it makes you happy. if your 4.2 completely craps out then, sure, look at engineering an engine swap (because that's what it takes). but if your engine is running well then a 2.7T might not make anything cheaper in the long run, and it certainly won't be easier.

- emilio

.... Do you even own an Audi ?? Your responses seem based on hearsay. On urban legends derived from people who never understood the cars they may have had experience with. If even they owned a 2.7T or a 4.2 V8... As far as " If It Were A Car That Originally Had A Turbo " Didn't see where the OP was thinking of installing turbo's to the 4.2... ( The RS6 twin turbo V8 would be nice ).

The question is ... Stay with the 4.2 and replace the chain tensioners or swap to a 2.7T .... The latter will require a harness reinstall plus multiple changes in mounts and hardware that was never designed for this particular B6 A4 / S4 platform...
The former ( chain tensioners replacement ) is a full motor pull which then would allow the OP to replace all the gaskets ( Heads, valley pan ) as well as other impossible to reach parts that may need upgrading..

Either way it is not without expense and time. Both depend on OP's skills but playing with timing components in a motor as complex as the 4.2 isn't for anyone who has not dived into a motor before.. The 2.7T swap isn't plug n play...

Both motors are quite reliable ... With One Caveat ... Steadfast attention to servicing and maintenance schedules. That means anticipating when parts are reaching their end of life and replacing before signs of failure. Turbo wise that also demands oil / filter replacements every 3-5,000 miles, totally dependent on region and driving conditions.

I do know this, my 1st B6 A4 1.8T had 208,000 miles ( original turbo ) the 05 Allroad 2.7T I've just bought has 92,000 miles original T's. My B6 03.5 S4 has 163,000 miles and motor was replaced at 11,000 miles ( previous owner ).
I would say over the years I do spend a lot of time in maintaining and wrenching my cars but in 12 years of rolling an Audi I have only been stranded 3 times, one of those from a blowout ... Its all about what you are willing to invest in these VAG's..

[melomandn]

I've owned a dozen 2.7t cars and have never seen a head gasket failure on one. The stock turbos? Yeah those can go bad after you flash the car in a tight engine bay where they tend to get hot anyway. A K04 2.7t isn't exactly a 'money pit' but different strokes for different folks, each setup (4.2 and 2.7) have their own ups and downs.

I sure wouldn't take out the 4.2 for a stock 2.7t or even a flashed stock turbo one

Nailed it.

And as ob3r said, proper warm up and cool down is huge. Too many people beat on their cars cold and put them away hot.

[LINDW4LL]

i feel there's no advantage to reliability in aging performance turbos. an old Volvo or turbo-diesel will run for ages, sure, but more high-strung and aggressively-driven engines always seem to come with the stipulation "...as long as you replace the turbos." that's not making anything simpler in my book, that's just doing different work.

Putting a 2.7T with stock turbos into a B6/B7 S4 that came stock with 340hp would be kind of pointless IMO. Sure, a tuned 2.7T will make more power than a stock V8, but it doesn't warrant the extra work of an engine swap when you could do a few small upgrades (turbos, clutch, fueling, MAF housing) and be at 400+whp reliably.

[demonmk2]

I guess the question could also be, source a low miles engine or timing chain/guides job or 2.7t engine swap. which is the lest expensive. which would depend on the knowledge of the individual wanting the work done.

I think that is the point OP is trying to make.