Okay - I know nothing about cars except that I love to drive, so each time I go in to have maintenance done, I worry that I’m being taken advantage of, being a woman and all. So - last year I took my 2003 Audi TT to an independent car repair shop. She was running great but needed an oil change. The people were very nice and after a few hours called to tell me my car was ready and all it needed was the oil change. I drove it off their lot and right away, she started to stall, back fired and blew black smoke - the fuel wasn’t getting to the engine. What the heck? She was running fine when I brought her in so what happened? They put her back on the computer and told that nothing was ‘shouting’ at them - so I left the car. Two days later she was ready again - to the tune of almost $1000. They told me 'the air mass meter and load were reading way too high…and found fuel pressure about 5 PSI too high under all conditions. There was more oil present in intake tube than normal…and they found the spark plugs fouled from poor running condition". So they replaced the spark plugs, the “crankcase vent valve at air inlet for turbo as it is allowing too much oil through”. Now - it’s time for her yearly maintenance again and I’m afraid to take her to the same shop, for fear that they were less than honest. But here’s my quandary - maybe it was just a coincidence, but why, then, was she running great prior to dropping her off and then BOOM! She basically fell apart? These are nice people and I don’t want to judge them unfairly but until now didn’t know where to turn with my concerns. She has 35,000 miles and I’ve had since she was new.
It sounds suspicious to me. The car has only 35,000 miles, and suddenly after an oil change it starts to smoke and stall?
It sounds like oil got sucked into the air intake somehow and caused smoke, stalling, and plug fouling. I don’t know what they did to cause that, but all the stuff about the mass airflow meter reading high and the fuel pressure being too high sounds like BS.
The stuff about “more oil present in the intake tube” and the “vent valve allowing too much oil through” sounds closer to the root of the problem…maybe oil got sucked through the PCV (positive crankcase ventilation) valve and into the intake…or maybe there’s another way for oil to get sucked in through the turbo…
I don’t know how they would have caused that…overfilling the oil sump? Pouring oil somewhere it shouldn’t have been poured? Someone more familiar with your engine may have a better idea how oil got somewhere it shouldn’t have.
I think they screwed up, somehow caused oil to be sucked into the cylinders, and then charged you an arm and a leg to fix their mistake. Did they replace anything besides the spark plugs and the “crankcase vent valve?” Because $1000 to poke around and then replace spark plugs and a PCV valve is highway robbery.
Don’t go back there. Check the Mechanics Files section of this website for a recommended European car specialist near you, or check Yelp reviews.
I think I agree with jesmed. Something doesn’t sound right with only 33K on it, shouldn’t need that much work. I suspect they messed something up or disconnected something by “mistake” and then started just thowing parts at it trying to figure it out, or worse. Maybe just onces take it in to a dealer to have the oil changed and a second opinion. Nice people can be thieves too.
You’re not judging them unfairly. You’re simply making a decision based on your past experience. Even if it was a coincidence (and I seriously doubt that it was), there is absolutely no reason to go there again. Why treat yourself to an anxiety attack if you don’t have to?
Find another shop. Ask everyone you know, and see if a common name pops up.
Huh, so would over filling do that? Interesting. So they maybe forgot to drain the oil and just dumped in four more quarts, then took them $1000 to figure it out?
I too had a trusted shop that I went to for years and the owner goes to our church, but three times and you’re out and don’t go there anymore except for tire service. Applied voltage to my 4th gear solenoid and blew it out after I told them that wasn’t the problem. Failed to see a broken in half crank sensor that only made it 30 miles the next day and cost me a day and a tow. Screwed up an alignment and failed to see the front engine cradle was falling off. And a few others like fuel pumps, etc. I just quietly found another shop.
I think that the OP has gotten some very good responses so far, but nobody has asked the “elephant in the room” question, namely…What can you tell us specifically about the maintenance of this vehicle that is driven only ~3k miles per year?
I am asking because all-too-many people focus solely on the odometer mileage factor for car maintenance w/o considering the equally-important elapsed time factor for maintenance. If the OP is changing oil & doing other maintenance only on the basis of odometer mileage, then the vehicle has not been maintained properly.
@Nervous Nellie–How many times per year do you have the oil changed?
If the car has an automatic transmission, how often has the trans fluid been changed?
What about the brake fluid?
When was the PCV valve replaced previously?
What about the spark plugs?
While I agree that this mechanic sounds less than competent, the possibility that he was being honest about fouled spark plugs and about problems with the PCV valve has me wondering if this car is really being maintained properly.
@VDCdriver makes a good point about maintenance, especially the brake fluid. The spark plugs , not so much. The maintenance schedule in the service manual (Bentley) calls for plug replacement at 35 or 40 thousand miles depending on chassis number, so they were not overdue. But I change the oil on my wife’s car every six months with not much more mileage per year. Anything less would make me uncomfortable
A much bigger problem is the timing belt, which if original as I suspect, would be at least 11 years old on an interference engine.
I urge the OP to have it replaced ASAP if such is the case. It will not be cheap.
Thanks for the “hat tip” @the_same_mountainbike, but @jesmed mentioned that possibility before I did. I also had come across this in the service manual: WARNING- Do not overfill…If engine oil level is above maximum mark, catalytic converter can be damaged.
I don’t see how that could happen without the oil getting into the combustion chambers.
Good ideas above. It would be great if we lived in a world where you could take your car for an oil change and the work would always be done correctly. Unfortunately that isn’t always the case. There’s lots of ways to make a mistake on oil changes, and pretty much every one has occurred at some point or another. I suggest you be proactive and monitor the quality of the work being done for you.
It’s not possible to say for certain based on your postings, but under or more likely overfilling could be a cause of this problem. For future oil changes, ask a friend to show you how to check the oil level using the dipstick. Then whenever you have an oil change done, before leaving the shop pop the hood and double-check the shop’s work yourself by inspecting the dipstick. The oil level should be clean and right at the mark, but not over. Check it again when you get to your next destination. Then again the next AM before starting the car.
Lewis, the way it gets into the combustion chambers is through the space under the valve covers. That space is openly connected to the oilpan via the drain channels through which oil drains from the valvetrain to the pan. Overfilling can result in the crankshaft whipping the oil into a frappe, and it can make its way up the drain channels, under the valve cover, and get drawn in through the PCV valve.
This actually happens because the crankcase is pressurized by blowby, and the space under the valvecover is at a relative low pressure from being drawn on by the passage through the PCV valve. Whip the oil into a froth, create a higher pressure in the crankcase than under the valvecover, and you have a recipe for oil ingestion into the engine.
It should also help in understanding it to note that the PCV valve allows passage into the intake. It blocks passage in the other direction. Its actual function is to prevent any backfire from igniting volatile fumes under the valvecover. Remember that oil IS a hydrocarbon. Vaporized and hot, it can ignite.
I believe the theory is spot-on. Oil ingestion can cause all of the problems you described, and overfilling can cause oil ingestion. I’d bet lunch that they added the specified number of quarts of new oil but never drained the old oil.
TSB, Thanks for the detailed explanation. I knew oil aeration was a problem from a lubrication point of view, now thanks to you I understand how it can cause oil ingestion also.
Thank you all so much for your comments! In answer to those who asked if I have regular maintenance performed, the answer is an emphatic YES! I have the oil (synthetic) replaced once a year and at the same time have a general ‘check up’…like a ‘well car’ exam. She has manual transmission and I am definitely aware that the time is approaching to have the timing belt replaced - the Audi manual states ‘around’ 40,000 miles. I take better care of my car than I do myself. Just wish I had come to the ‘community’ earlier instead of worrying about this for the past year.
“I am definitely aware that the time is approaching to have the timing belt replaced - the Audi manual states ‘around’ 40,000 miles”
Are you sure about that?
The repair manual that I consulted states, “75,000 miles or 60 months, whichever comes first”.
60 months=5 years, so your timing belt is overdue for replacement by ~5 years, which should make you very nervous, as major damage to the engine will occur when that belt snaps–with no warning whatsoever.
Rubber, which is the main component of the belt, dries out & deteriorates just from sitting, even if an engine is not used, so you REALLY need to get this done a.s.a.p. You should have the water pump, serpentine belt, and all belt tensioners replaced at the same time.