Oil Sending unit leaking right side of engine

[Dougohio2003]

I just purchased an RS6. Daytona with ebony interior out of NH. It's a bucket list car for me. I had an 01 A6 4.2 and drove that up to 197K miles before it had to go. I just picked up this car a few weeks ago. 83K miles, rebuilt transmission. However, I noticed a fairly significant leak by the front right of the engine. I looked today while it was up on a lift and it looks like a leak by an oil sending unit. The oil sending unit looks like a rectangular aluminum block right above the right side engine mount off the engine block. I can see a hard oil line coming off of it going back to what I assume is the right side turbo. My friend owns his own shop, but he's never worked on an RS6 so he asked me to check and see what I could find. Any suggestions or anyone had this issue before? Thanks.

[bethridg]

I haven't heard of the oil pressure sensor being the source of a leak before. Are you sure that's where it's coming from? Valve cover leaks are common but easy to identify. Loose oil filter, adapter or oil cooler lines? The OEM motor mounts are filled with a black hydraulic fluid that leak when torn.

Anyway, besides the oil pressure sensor there are crush washers used on that banjo bolt attaching the sensor block to the oil cooler.

Pics of the general area while my engine was out below.

[lswing]

Oil/coolant exchange pipe. It's a common failure, search Bufkin Pipe, it's the metal replacement piece. Very tough with engine "in place", 8-10 hours. The extras section of my website has some PDFs that show it better.

Welcome! Use "site:rs6.com Bufkin pipe" in Google, the search on here is fairly weak. Go back then forward with your browser if crap shows up from the Google link.

[hahnmgh63]

Bethridg has great pics there for you. Let me know if you need anymore as I have my engine sitting on a stand right now almost ready to go back in the car...6spd conversion. Never seen a leak from there but someone may have had it loose at one time or another. You can probably get to it if that's it without pulling the engine but if you do then as lswing said, definitely do the plastic Coolant pipe as he mentioned with the Aluminum replacement.

[Dougohio2003]

Thanks for the great tips. I'm already talking with my mechanic about your suggestions. This car had it engine out in July of last year. I'm thinking maybe this was overlooked when it was installed back in the car. Couple questions? Where do I pick up the Aluminum coolant pipe replacement? lswing, I could not get your website to work for some reason. Off subject, but I looked a the Eurocharged Tune and the MTM TCU tune, you guys look like you've done tunes. Thanks again. Glad to have found this forum.

[lswing]

Ah crap, I'll fix the site Monday. Search James Bufkin on eBay, he makes the pipe, $25.

Tune for ECU and TCU makes a big difference, roughly 50hp and 75tq easy. Just be careful, the extra torque can tear the trans up if driven hard, see current threads on this.

[Bigglezworth]

I just purchased an RS6. Daytona with ebony interior out of NH. It's a bucket list car for me. I had an 01 A6 4.2 and drove that up to 197K miles before it had to go. I just picked up this car a few weeks ago. 83K miles, rebuilt transmission. However, I noticed a fairly significant leak by the front right of the engine. I looked today while it was up on a lift and it looks like a leak by an oil sending unit. The oil sending unit looks like a rectangular aluminum block right above the right side engine mount off the engine block. I can see a hard oil line coming off of it going back to what I assume is the right side turbo. My friend owns his own shop, but he's never worked on an RS6 so he asked me to check and see what I could find. Any suggestions or anyone had this issue before? Thanks.

What color is the fluid? Is it oil or is it coolant. Coolant is likely the plastic coolant pipe that runs from the block to the side mount cooler. Oil could be a couple of things. The oil lines that run to the front oil cooler have a take off point in front of the oil filter. They can and do leak if not tightened properly. Check to ensure the oil filter is on tight. Also, you can have a leak on the front oil cooler that treks back and drops down below the alternator. Engine mounts can fail and the fluid can leak from them also. That fluid is dark and has similar appearance to oil.

[Dougohio2003]

The fluid is definitely oil. We ran the car for 5-10 minutes while it was up on the rack. After cleaning the area, we eventually saw the oil coming from the hard line/aluminum block area and dripping down. There is a new grade 8 bolt holding the aluminum block to the oil cooler. When I take the car back, we are going to see if that is loose, then check the washer on the hard line. I'm going to replace the sensor too just in case. Any other suggestions?

Also, where do you buy the MTM TCU upgrade?

[bethridg]

There is a new grade 8 bolt holding the aluminum block to the oil cooler.

I sure hope you mean banjo bolt instead of a standard bolt. Otherwise your turbos are probably starved if not toast.

[lswing]

Also, where do you buy the MTM TCU upgrade?

MTM is basically not available new anymore. The last retailer was in Canada. A few other tuners have done the programming though, and 034 Motorsports seems to be the main company offering it these days. There are a few other indy shops and tuners offering also. This is a solder in chip that is pre-flashed by the tuner. Most cases you will need to send you TCU in to be done. Just a word of caution, I did get a chip from MTM in the mail years ago, my experienced mechanic soldered it in and it didn't work, and during the removal process the TCU was burnt, out $500. So be careful or have a warrantied shop do the solder in place. Very nice minor upgrade with quicker shifts and higher shift points.