AC not working, bad compressor? / Leaking engine oil

[enzomoscoso]

Hello Audi people! Just joined the Audizine forum and the Audi family with my 2008 S4 B7 with 88k miles that I got a month ago. I've never done in depth mechanic work, just a bit of small fixes here and there.

The AC currently blows warm air. I'm the third owner and the previous owner got the car taken to a reputable mechanic that diagnosed the issue as a bad compressor. After filling the system with refrigerant (not with a vacuum, just a can from Autozone) everything leaks out after an hour or so. I injected UV dye into the system and looked for any obvious leaks without removing any major parts of the car. Didn't find anything obvious. Then I removed bumper and slam panel and checked with the UV light and didn't see any obvious AC leaks. I looked around the pressure switch but I didn't remove it to check it thoroughly.

















I figured since I've gone this far and the compressor is likely bad, I ordered a Nissens compressor, Accumulator, and O-ring set from FCP Euro.

Audi VW A/C Compressor - Nissens 4F0260805AH
Audi A/C Receiver Drier - Nissens 8E0820193F
A/C System Retrofit Kit - Santech 559807901

I'm really hoping it's not a leak near the evaporator core which you have to remove a lot of the interior for.

I did notice a lot of oil and gunk around the front of the engine. Are there any areas of common leaks that I should look into in that area? The previous owner said there's a leak where the oil filter housing meets the engine, but that's at the back of the engine so I don't think it's the source for all that gunk in the front. Any pointers/advice for the AC and oil leak would be appreciated. Sorry for any oversights this is all very new for me!

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[enzomoscoso]

Forgot to include the pictures sorry. The lighting is not ideal.

[All_Black_A4]

The previous owner was correct. Even though the OFH is at the back of the engine, the angle the engine sits causes any leaking oil to flow towards the front of the car. Once it hits the crank pulley its gets thrown everywhere. Other known leak issues are the valve cover gaskets, oil cooler O-rings and the O-ring that seals the water pump drive shaft can also leak. Leak points on the back are the cam shaft seals. The good news is since you've already got the front end off, it's all accessible now. Most parts vendors sell the Oil check valve kit that includes the OFH O-ring, so it good preventative maintenance to do while you're at it.

[enzomoscoso]

The previous owner was correct. Even though the OFH is at the back of the engine, the angle the engine sits causes any leaking oil to flow towards the front of the car. Once it hits the crank pulley its gets thrown everywhere. Other known leak issues are the valve cover gaskets, oil cooler O-rings and the O-ring that seals the water pump drive shaft can also leak. Leak points on the back are the cam shaft seals. The good news is since you've already got the front end off, it's all accessible now. Most parts vendors sell the Oil check valve kit that includes the OFH O-ring, so it good preventative maintenance to do while you're at it.

This is all very good info, thanks. Are there any DIYs you would recommend? I have the erWin and I've found some videos online but I'm not sure if they are the best.

I found the Audi Oil Check Valve Service Kit - Elring 079103161DKT, Audi Valve Cover Gasket Kit - Elring 079103483LKT, Audi VW Engine Oil Cooler O-Ring - Reinz 079103121AD, and VW Audi Camshaft Seal - CRP 079109293C on FCP Euro. I'm about confused about which O-ring is for the water pump drive shaft. Is it this one: Audi Engine Water Pump Seal - Genuine VW Audi N91008902, #4 on the image?

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[VinnysS4]

#4 is the seal for the water pump to block /shaft seal

Front leak:
You'll need the 2 new oil filter housing seals and you'll want to do the valley pan seal along with the oil check/spray valves while you're in there. Just remove the intake and you'll find a puddle of oil
The oil cooler seals like to leak as well. Since you have the front end off, remove the alternator and its bracket and the hoses from the oil cooler and you can pull that off.
Only other leaker down low is the front main seal or upper oil pan gasket

As far as the AC goes, if it has a leak, I'd try to find it before replacing everything. I just fixed a wrx AC. All it needed was an oring on the high pressure hose.

Sent from my SM-N960U1 using Tapatalk

[WileyBrill]

Since you are a self-proclaimed "new" Owner - take it from a, (coming up on 18 yr. Owner) - 06 B7 Avant:
1. What do the service records show as per "oil & filter change intervals" - screw the Audi book/guide lines. OEM Oil is Castrol SynTech (full synthetic), 5w40 and use OEM filter @ 5K intervals.
If has been serviced at 10K, (Audi book) - IMMEDIATELY, change out the oil & filter and change again at 3K intervals, until the dip is so clean you have a hard time seeing the level on the stick!
Use an "evacuator", down the dipstick shaft, and suck it dry!, then refill, pouring the first qt into the filter cylinder - SLOWLY, filter out, then quickly as it runs down to 1/3 full, put in the filter and quckly close the top - 6NM - NOT TO EXCEED - it's Plastic...
2. At 88K, when you get to 90K - change out every fluid in it ! USE Audi OEM Genuine new fluid - but, NOT G13 for collant (Audi admits it "separates") " use G12.

3. If you hear the "death rattle" - before you get into "chain Work" - search out in Audizine the "oil pressure valve replacements" !

4. New/Clean/OEM Spec engine oil and filter cartridge - are the "lifeblood" of the S4 B7 Engine!

WB

[enzomoscoso]

Since you are a self-proclaimed "new" Owner - take it from a, (coming up on 18 yr. Owner) - 06 B7 Avant:
1. What do the service records show as per "oil & filter change intervals" - screw the Audi book/guide lines. OEM Oil is Castrol SynTech (full synthetic), 5w40 and use OEM filter @ 5K intervals.
If has been serviced at 10K, (Audi book) - IMMEDIATELY, change out the oil & filter and change again at 3K intervals, until the dip is so clean you have a hard time seeing the level on the stick!
Use an "evacuator", down the dipstick shaft, and suck it dry!, then refill, pouring the first qt into the filter cylinder - SLOWLY, filter out, then quickly as it runs down to 1/3 full, put in the filter and quckly close the top - 6NM - NOT TO EXCEED - it's Plastic...
2. At 88K, when you get to 90K - change out every fluid in it ! USE Audi OEM Genuine new fluid - but, NOT G13 for collant (Audi admits it "separates") " use G12.

3. If you hear the "death rattle" - before you get into "chain Work" - search out in Audizine the "oil pressure valve replacements" !

4. New/Clean/OEM Spec engine oil and filter cartridge - are the "lifeblood" of the S4 B7 Engine!

WB

Previous owner did not have many records, the only thing I have is an invoice from the shop where it was manual swapped. The only other service I have from the previous owner is that the ignition coils, spark plugs, and rear sway bar end link (s)? were done at 85k by a shop.

- A different shop did an oil change + new oil filter at 88k. They used Liqui Moly 10W60 Synthoil Race Tech GT1 Engine Oil, which is higher viscosity than you and others recommend. Not sure why they went went this oil, this was before I had the car. They also did the serpentine belt.

As of now I have:

- Replaced the AC compressor (Audi VW A/C Compressor - Nissens 4F0260805AH) and accumulator (Audi A/C Receiver Drier - Nissens 8E0820193F) . Changed O rings on the AC lines for whatever fittings I pulled out to do that job. Did a vacuum test and recharged with 520g of r134a (500g +- 20g). The AC now blows cold.

- Replaced the oil cooler O rings (Audi VW Engine Oil Cooler O-Ring - Reinz 079103121AD)

- Replaced the Audi Engine Water Pump SealVAG-N91008902

- Replaced the brittle vacuum lines that shattered when I touched them with 4mm ID vacuum lines and 4mm OD male to male fittings.

- Replaced the valley pan gasket, OFH gasket, OFH O ring, Oil spray valve, and Coolant (G40). (Audi Oil Check Valve Service Kit - Elring 079103161DKT)

- Replaced the suction pump elbow off the intake manifold since that cracked when I pulled it out. (Suction Pump Elbow 079133382C, 079 133 382 C )

- Replaced the front driver's side inner and outer CV boot since it was leaking. (Audi VW CV Joint Boot Kit - GKN 4E0498201 , Audi CV Boot Kit - GKN 8E0498203C )

- Wired in the reverse light switch because it wasn't done at the shop where it was swapped. Now I have to do the Clutch Vent Valve to ECU for cruise control.

- Diff fluid change: Valvoline SYN GEAR OIL 75W90 (GL5)

- MT fluid change: Motul Gear 300 75W90 Synthetic Gear Oil - Motul 105777

- PS fluid change: CHF 11S Hydraulic System Fluid - Pentosin 1405116

- Coolant change: Audi Mercedes Porsche VW Engine Coolant / Antifreeze - Zerex 861526

Should I change the oil again and use Castrol SynTech (full synthetic) 5w40? Not inclined to do this since I spent $160 in oil for the oil change and to refill after repairs. The other fluids are not what you recommended (not OEM) but just what I found browsing Audizine, and the coolant came with the check valve service kit from FCP Euro. The 3rd gear synchro has been grinding on fast shifts since it was swapped. When I changed the MT fluid only 2.5 liters came out. With the car level I filled it to 3.3 L and checked that the fluid level was within 1-2mm of the fill hole. The transmission noticeably shifts better into 3rd gear now, after changing the fluid. On every 5-10 cold starts the chains rattle the slightest bit for a second. No rattle on idle or on warm starts. Based on what I've seen I'm not too concerned about this. Eventually if I own the car long enough or it gets worse I'll do the guides and other maintenance items when/if the engine is out. I also raised the car 10mm in the front since the previous owner has it lowered on H&Rs and it was scraping.

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[WileyBrill]

enzo, Just a bit of background: I'm an OEM Guy, no mods, most times Audi Genuine, but always OE manfr. Here's the rub on the 10w60 oil, my opinion, (you know what the "w" means = "Winter").
So, 10 is higher viscousity than 5 = thicker, equals harder to "push" thru the cold engine and ALL those tiny passages to keep oil where it needs be, not metal on metal.
I special ordered/had built, my Avant - I'm the only one who drives it - miles, (146K), are nearly all highway - never even gets started, unless can "run" for min. 30 min.!
In the last two (2) years, I went to suction to remove engine oil - it is simple, and "magic" - the hose has a 45 degree cut on the tip, so it doesn't bottom-out on the flat/ccokie sheet oil pan.
Speaking of which - dead flat for engine oil level check is a Must! When sucking out the oil, due to placement of the dip-stick pipe, an ever so slight lift of the right-rear - puts the oil flow, right on target to collect every bit possible. (first time we did it - we did a test - cracking the drain plug/off - Zero Drop of engine oil presented!)
The suction tool cost me $60 tops - MyteVac 7 qt cap. - so you have to empty midway.
I use Hengst Oil cartridges - Mann Air filters @ 10K intervals.

As for engine Coolant - VW Audi Genuine G-12, (G-13 proven, by VW to "seperate" - perish the thought) MT fluid, VW Audi Genuine, refill to just below filler hole level.

Since using the fluid evacuator for engine oil changes - even my 147K mi. engine, shows so clean on the first/follow up level checks - seriously, it is difficult to see the oil level - it is that clean!
Castrol Syntech 5w40 - what came from the factory... That is my motto - go with what it came from Audi with...
(Walmart has the best $ on the Castrol) - now, didn't used to be that way!

NGK sparkplugs four (4) prong, true platinum/iridum - no counterfits, the NGK Factory guy in MI, is the source - 10K since change over - I agree. My Avant came with NGK "nickel" - no good, I learned the hard way - (I'm on my third set of VW/Audi Genuine cats - due to plug failures...) $5k a pop + labor...

Only - use Shell or Chevron Premium - I think Shell is best, (the nitrogen add). But, I add Chevron Techron every qtr. year, (3 months).

I used GKN for the CV boots too. (OE Mfr)

I'm NOT an Expert - I just have a Lot of years and miles with my Avant, learned a Lot from "others" mistakes, even dealership, piss poor brain techs, (who claimed to be Audi Master Mechs.)!
Others here have their opines - Zolli is an A/C Whisperer... I just know what works/has worked/not worked for me... And, nearly 18 years in - still smiling, evertime I drive "her".

Oh, and yes, I have "The Bently Manuals"...

WB

[Zolli]

Well done with the A/C repairs and oil check valve / gasket repair. Nothing to add except that it would have been a good time to change out the orifice tube as well.

Hopefully you also changed out your snub mount. I know some of them don't react well to the oil slung around by the crank pulley.

Personally, I would recommend changing the oil to the proper spec. These engines are fussy. I've run Castrol, Mobil 1, Motul, and Liqui-Moly. Liqui-Moly is the one that my engine seems to like the best - smooth smooth smooth.

I also highly recommend Liqui-Moly's Ceratek additive and their Engine Flush. In case it's not super clear in their directions, those additives replace the same volume of oil that would be there otherwise; they are not "in addition to." I only bring it up because it gave me pause way back when.

[enzomoscoso]

enzo, Just a bit of background: I'm an OEM Guy, no mods, most times Audi Genuine, but always OE manfr. Here's the rub on the 10w60 oil, my opinion, (you know what the "w" means = "Winter").
So, 10 is higher viscousity than 5 = thicker, equals harder to "push" thru the cold engine and ALL those tiny passages to keep oil where it needs be, not metal on metal.
I special ordered/had built, my Avant - I'm the only one who drives it - miles, (146K), are nearly all highway - never even gets started, unless can "run" for min. 30 min.!
In the last two (2) years, I went to suction to remove engine oil - it is simple, and "magic" - the hose has a 45 degree cut on the tip, so it doesn't bottom-out on the flat/ccokie sheet oil pan.
Speaking of which - dead flat for engine oil level check is a Must! When sucking out the oil, due to placement of the dip-stick pipe, an ever so slight lift of the right-rear - puts the oil flow, right on target to collect every bit possible. (first time we did it - we did a test - cracking the drain plug/off - Zero Drop of engine oil presented!)
The suction tool cost me $60 tops - MyteVac 7 qt cap. - so you have to empty midway.
I use Hengst Oil cartridges - Mann Air filters @ 10K intervals.

As for engine Coolant - VW Audi Genuine G-12, (G-13 proven, by VW to "seperate" - perish the thought) MT fluid, VW Audi Genuine, refill to just below filler hole level.

Since using the fluid evacuator for engine oil changes - even my 147K mi. engine, shows so clean on the first/follow up level checks - seriously, it is difficult to see the oil level - it is that clean!
Castrol Syntech 5w40 - what came from the factory... That is my motto - go with what it came from Audi with...
(Walmart has the best $ on the Castrol) - now, didn't used to be that way!

NGK sparkplugs four (4) prong, true platinum/iridum - no counterfits, the NGK Factory guy in MI, is the source - 10K since change over - I agree. My Avant came with NGK "nickel" - no good, I learned the hard way - (I'm on my third set of VW/Audi Genuine cats - due to plug failures...) $5k a pop + labor...

Only - use Shell or Chevron Premium - I think Shell is best, (the nitrogen add). But, I add Chevron Techron every qtr. year, (3 months).

I used GKN for the CV boots too. (OE Mfr)

I'm NOT an Expert - I just have a Lot of years and miles with my Avant, learned a Lot from "others" mistakes, even dealership, piss poor brain techs, (who claimed to be Audi Master Mechs.)!
Others here have their opines - Zolli is an A/C Whisperer... I just know what works/has worked/not worked for me... And, nearly 18 years in - still smiling, evertime I drive "her".

Oh, and yes, I have "The Bently Manuals"...

WB

Thank for this info I really appreciate it! I always let the car warm up before any spirited driving and I baby it while it's cold but I'm not as careful as you haha. Trying to take care of the car and fix as much as I have the time and knowledge for. This is my first car and I've never worked on cars before, really threw myself into it with the mechanical work.

Well done with the A/C repairs and oil check valve / gasket repair. Nothing to add except that it would have been a good time to change out the orifice tube as well.

Hopefully you also changed out your snub mount. I know some of them don't react well to the oil slung around by the crank pulley.

Personally, I would recommend changing the oil to the proper spec. These engines are fussy. I've run Castrol, Mobil 1, Motul, and Liqui-Moly. Liqui-Moly is the one that my engine seems to like the best - smooth smooth smooth.

I also highly recommend Liqui-Moly's Ceratek additive and their Engine Flush. In case it's not super clear in their directions, those additives replace the same volume of oil that would be there otherwise; they are not "in addition to." I only bring it up because it gave me pause way back when.

I will change out the engine oil, probably will run it for a bit until I have time to change it, not more than a thousand miles or two. I'll look into that additive and engine flush. Is there a manual trans fluid additive you guys would recommend? The previous owner heard of something that might help with my synchros (or delay the inevitable synchro/trans rebuild or swap).

Finally got the cruise control working, the shop that swapped the car had connected one side of the clutch switch to pin 39 on the ECU but forgot to connect the other side to switch 12v. Easy fix.

[WileyBrill]

enzo, zolli is right on the oil visc = get that 10w-60 shit out of there! Second thing and I just learned this, yesterday - the hard way. DENSO is the Original A/C Condenser and Compressor on my 0ct 05 build S4 Avant - NOT Nissens... The "OE" is a red-herring - the Denso has the proper - solid aluminum, threaded blocks, press-fitted into the top/bot channels - NOT the cheap-shit steel "clips that Nissens, bolts in the channel. See: "Let's be prefectly Clear" thread I posted, yesterday !
carry on...
WB