Mr. Timewise

Ahh... Is the color more like clean motor oil then?

Mr. Timewise

I stopped by my mechanic this morning and we put the allroad on the lift to study the underside of the vehicle. The oil drip is, in fact, from the back of the transmission. It's the output shaft seal that is leaking...nice clean G 052 145 S2 (G052145S2) gear oil from the transfer case. This oil looks like fresh motor oil. (It does have a slightly sweet sulfur smell to it, by the way.)

So tomorrow the car will have the exhaust dropped, the drive shaft separated from the output of the transmission, the output shaft extracted, a new seal installed, and the gear oil topped up.

In regard to the red low oil pressure light on the DIS display it appears that the problem was as <b>frankinstyn</B> and <B>joshe8695</B> suggested. The oil viscosity was so low in the hot weather that the pump was unable to keep a head of pressure. The mechanic insists he used 4W50 (edit oops...5W40) synthetic (I forgot to ask which brand). I've now driven some 30 miles with my new oil and filter without the LOP warning indicator reappearing. Obviously I'll keep a eye on things, but the problem may have been solved with a simple oil change. And when the car is on the lift for the output shaft seal I'll take a serious look at what would be involved in replacing the oil pressure switch which is next to the oil filter and above the anti-sway bar.

My mechanic suggested that perhaps we should be using slightly heavier oil in the hot summer. This does sound reasonable. Anybody care to comment?

Just Me

40W (which i presume you meant to type) is certainly thick enough. I dont understand how it could be the source of your trouble. The 5W part is irrelevant at high temperatures.

hell, in my 2.7t (S4) i used 5W30 and ran it hard in hot weather.

Have you checked the sender unit? - they fail with some regularity.

G

Mr. Timewise

I'll pick up an oil pressure switch and swap out the one now on the car when the car is on the lift during the transmission seal replacement

Mr. Timewise

BTW...The cost for me to fix the leaky seal at the rear output flange for the 2002 allroad 2.7T Tip totaled $330, parts and labor. The parts included the new seal (01V-409-399-A; $50), new gasket (183-521-141-A; $10), new bolts (N-019-926-1; $7), and the hydraulic gear fluid (G-052-145-S2; $30). I did not replace the output flange (01V-409-809-A; $325) because the surface which the seal touches had no discernible wear.

scout2

I just went through a pressure sender myself, and people mentioned the pick up screen/filter getting clogged and showing this symptom. Mine turned out to be just a bad sender.

Mr. Timewise

I haven't replaced the LOP switch yet...it was too hard to reach without a significant labor charge by the indie. I'll do it on my own next week. At this moment we've got two fully operational and 100% available cars and I'd like to enjoy this rare moment for a week or so!

frankinstyn

Absolutely!

In some cars it isn't necessary. With some drivers it isn't necessary. If you drive hard however, the oil will thin out from the engine running harder and not having time to cool down as much.

In all cars you can read in the user's manual (thick booklet in the glove box) about the oil to use. That book will have a page (near the back I believe) with a chart that will tell you what oils are to be used with this engine. The 5w40 is thicker than the 5w30 and may very well be desirable in the summer.

The same reasoning can be reversed. Too high an oil pressure is also bad and that can happen from too thick an oil. If you drive conservatively and put in the thicker oil, the pump may have to work very hard to pump the thicker oil and you'll end up with extremely high oil pressure. In that case you would want to use the thinner oil.

I really wish these cars actually had an oil pressure gauge. I have a hard time trusting that the pressure switch is actually working.

SloopJohnB@mac.com

Keep in mind there is a procedure by ZF on filling auto trans oil. Temp is critical and trans has to be rowed through all the gears, etc.

If your mechanic has a vag-com he has to monitor auto trans temperature while fill is being done. Generally this means the trans has to sit overnight and cool down..if he does the output shaft seal and then does the trans oil change (trusting that his seal job won't leak with the new trans lube) you'll be ok.

Mr. Timewise

I used my own Vag-Com while changing the auto transmission oil. This was a separate procedure from the replacement of the rear output seal at the transmission transfer case (which has it's own hydraulic fluid - about 0.8 liters in a separate compartment at the back of the transmission).

While changing the 01V automatic transmission fluid in my allroad, I read the instructions that Bentley suggests, but actually followed the more detailed information provided by BlauParts (where I got 5 liters of fluid (G 052 162 A2) and new filter) as well as the great DIY from Jim Cappuccio in the Audiction.com site.

http://www.audiction.com/audi-mainte...-fluid-change/