4404mike

Hello Everyone, I’m new to the forum, but I have a 2011 Audi Q7 Prem. Plus 3.0L gas engine (140K) and the engine runs great. The vehicle is burning a lot of oil, about 1 ¼ quart per week (450 to 500 miles). I had the oil separator (PCV Valve) replaced ($813.32), now it burns about 1 quart of oil per week. The repair shop told me the piston rings need to be replaced. Since that job would cost over $3,500.00 to do, I will just keep adding oil each week before paying that amount, does anyone have any other items. Also, do you think adding high mileage oil stabilizer would help.

Thanks,

Mike

frqflyer

You need to have a leak down test done and not just let the mechanics throw money at it until they find the problem. Does it leak oil anywhere? Is there oil on the plate under the engine?

Rings are a likely culprit but I would think they would be really bad to allow that much oil through in a week. Have you made sure there is no water in your oil and vice versa? It could easily be valve seals and pulling a head and fixing that would be trivial compared to rebuilding the top end (never pulled heads on Audi so can't say how easy it is).

If you have any oil leaking it could just be a bad gasket.

A leak down test should help identify the culprit. Take it to a different shop for a second opinion and ask if you can be present while they do the test so you can hear/see for yourself what the issue is.

4404mike

The Audi dealership and an independent German auto shop both checked for oil leaks, none found. Also, there is no water in the oil or vice versa. I will be having a new EGR valve - right installed (Check Engine Code: P0410) next week; I will take it to another shop and have the leak down test done.

Thank you

frqflyer

Do you see any smoke come out of the exhaust when you start from cold or when you rev it after idling for a few minutes? If so there is a good chance it is seals.

On modern high mileage cars I've looked at the valve components are usually are worse than the rings or pistons.

Did this issue start suddenly or has it been getting worse over time? Was the car ever ran low on oil or didn't have a change for many many miles beyond the normal interval? If so it's quite possible rings are shot and possibly the pistons and even the cylinder walls.

But valve issues can result in a lot of oil being used also depending on the extent of the problem.

4404mike

No smoke at all, never. I purchased the vehicle used in February 2018, but I did not drive it very much (less than 100 miles per a week); February 2019 I started driving it everyday (highway and stop/go), 450 to 500 miles per week. The vehicle runs very strong, with no major issues. I did check with dealership where it was last serviced and they said that the previous owner never complained about high oil consumption issues. Also, since I've owned it never ran low on oil and always had oil change's done on time and the Carfax showed regular oil changes.

frqflyer

Btw, your EGR could be fouled up from burnt and unburnt oil going back to it. If it is gummed up and preventing gas from recirculating it could be causing you valves to get burnt. Personally I would try cleaning the EGR first and see if that gets rid of the error unless it is a cheap fix. Either way I would probably save that for after you diagnose where the oil is being drawn from because you may put a new EGR in and foul it up with the oil issue and have to replace or clean it again.

frqflyer

Have the mechanic pull the valve covers if it's not a major chore. It makes doing a leak down easier because you can verify you are TDC without using a probe and also inspect the seals at the same time and makes it a breeze to know if compression is being lost from the valves.

You could do a standard compression check to start instead leak down because if you are sure oil isn't leaking externally or into the coolant, if the compression is in spec I would imagine it has to be getting drawn in from the valves and it would be a bad seal (easy fix). If it's a bad valve (burnt or buildup valve or seat), stem or guide if will mean pulling the head in most cases and that is move involved but still nothing compared to rebuilding the top end.

4404mike

Hi frqflyer,

Thanks for all the information, i will be going over your ideas with shop later today, i'll keep you posted.

frqflyer

I looked at a pic of the 3.0T and it looks like removing the valve covers is fairly painless. Not much in the way to get them off from what I can see.

I would have them pull the covers, inspect the seals and do a leak down. Should be a pretty easy process and they can tell exactly where the oil is getting in. They can also inspect the valves for play because at 140k mi depending on how hard it was driven it might be time for more than just seals if the seals arent the culprit. Even if the seals are bad it doesn't mean that is the end of it. Sometimes the seals can go bad because of a bad seat, which usually also means a worn stem or guide, and that allows the hot gases to to make it up to the rubber seals and they break down.

I don't think you need to go to a German specialty shop for this type of basic diagnostic. Any reputable shop could probably do it just as well. Just do your best to let them know you know enough to not be a mark because some shops try to take people to the cleaners.

If you can be present during the leak down because with this much consumption you should be able to hear where the air is escaping even without a listening probe.

Up-it

Mate, before heading to any mechanic shop do this very simple test. This applied to both diesel and petrol engine vehicles. Firstly if it was worn valve guide seals. When you start your car first thing the morning have someone go around the rear of the car to see if blue/ white smoke is coming from the exhaust, also the smell is very present- this means your valve guide seels are worn as oil is allowed to escspe onto piston crown when sitting for a while and burns up on initial start up.

Secondly if it was worn piston rings and your lucky enough to still have good compression, the blue/ white smoke with the smell while be very present under all driving conditions, including reving the vechile/ driving etc.

Now your 3.0t is not a simple engine NOR is it an engine that should go to any standard mechanic for diagnosis. The upper valve train is very complex and the valves can not be checked for wear etc due to it been dual over head cam, these camshafts are also driven via a set of timing chains on the rear of the engine that can not be removed without removing the engine, story is camshafts stay in place.
if you have replaced your PCV recently as its very similar to the 4.2 they are quite inadequate for its job. If you take your car ti a shop or you do it youself, it would be best to remove your supercharger and see how much engine oil is actually being trapped inside it and this will determine if your are burning through your oil consumption via oil vapour mist in your intake. Its not enough to produce smoke but enough to show signs of high oil consumption. All FSI engines are victims of this and if no oil leaks are present anywhere on your engine then I suggest you google issues with Audi FSI engines with oil consumption faults so you cam understand what maybe going on internally.

see how you go.