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Driving without an air filter

I would like to know what driving for 5,000 miles or more without an air filter can possibly do to an engine. I have a 2007 Prius. I bought it certified used from a Toyota dealership. It had approximately 8,900 miles when I bought it. I took it in for the 5,000 mile oil change and check and the mechanic came out showing me an empty gasket. I am interested in knowing what someone knows about such a thing. Thanks so much, Prius 2007

Without an air filter, the engine will suck in all sorts of dirt, dust, pollen, and other nasty things which can severely decrease engine life. How much is hard to quantify, but I would bet some scoring of the cylinder walls has occurred, which can result in increased oil consumption, and, again, decreased engine life.

That said, being a hybrid, and depending on your driving style, the engine may not have been running for many of those 5000 miles. Still, I would bet on some damage. How much, and how serious, is hard to tell accurately without actually opening up the engine.

In all likelihood, it’ll mean the engine will last only 290,000 miles instead of 300,000.

Hopefully you weren’t following close behind a truck on a dusty gravel road or driving through a sand storm. I’d certainly get something in writing from the mechanic regarding the missing filter and then I’d sit down with a Toyota rep to discuss a longer warranty period. Toyota will likely downplay the potential for problems, but (as was mentioned previously) whatever goodies that were sucked into the cylinders did them no good.

I’d sure like to know how the filter came to be missing in the first place. At 8,900 miles, no one should ever have touched it. I’ll bet the filter replacement interval on this car is over 20,000 miles. Probably 30K. Why would anyone have changed it, and why was the gasket still there?

I’m starting to think this was a scam to sell you a filter you didn’t need (which is really sad, because air filters are not that expensive). There’s no reason for anyone to have ever touched the original air filter. I think there WAS a filter all along, and they ripped it out and showed you an empty gasket. If the gasket was empty, where did the filter go? This is really starting to REEK. I think you should consider another place to have your Prius serviced.

I have NEVER heard of an air filter missing but the gasket remaining in place. This is really BOGUS! If you had said there was no filter, fine, but the GASKET is the give-away. The gasket and filter are basically one piece. There’s NO WAY the filter part can separate from the gasket during normal vehicle operation.

I think there’s NOTHING wrong with your car. Your Toyota dealer is another matter.

About all you can do now (besides making sure to use a filter in the future) is to obtain a used oil analysis at the next engine oil change. May even want to do that one ahead of schedule. It should not be high in silicon, even though the ‘no-filter’ oil may well have been. If the wear metals are not elevated (and there is quite a bit of Prius data to compare with), you can conclude that no little rocks got in there and scratched the shiny parts. Are you up for this additional $30 expense?


My sentiments exactly. It makes no sense at all that someone would have removed the air filter.

Was this a quick-lube place by any chance?

“I’m starting to think this was a scam to sell you a filter you didn’t need (which is really sad, because air filters are not that expensive).”

At the Quicky Lube (which I do use for oil changes only) things like air filters and wiper blades are WAY more expensive than at chain parts stores. Probably a high-profit line for them.

Great idea, DAS.

On a normal car…for every gallon of gas the car uses…it will use 10,000 gallons of air. Personally I’d want that filtered.

Not having an air filter can let all kinds of tiny objects blast the filament in the MAF (Mass Air Flow) sensor. If the MAF becomes damaged, it will send erroneous airflow data to the engine computer. The engine could run too rich, or too lean. MAFs are very expensive…hundred$.

Just out of curiosity, are you sure it’s the ENGINE air filter that’s missing? I ask because the cabin air filter is usually on the Quick Oil-Change place’s check list, but on most Toyota models it’s a option, so it’ll be missing from a lot of cars. Every time I get the oil changed on the company xB, they always come back saying the “air filter” is missing. Sometimes the word “cabin” gets in there, but sometimes it’s dropped somewhere between the service bay and the waiting room.

Actually this isn’t a scam. I took the car to a reputable Toyota Dealer close to home. They have no reason to take a part out of my car and make only $25.00 for that part. The original dealer, the one I bought the car from said that they looked back at the mechanics notes and said at the time of sale and while doing the 160 point certified check the mechanic removed the air filter to clean it but did not replace it. Hmmm. I am still pursuing this issue with the dealer. They are unwilling to do anything at this time and pretty much say, everyone makes mistakes - you have a warranty to cover any problem. I feel they are not taking responsibility. Oh well. Thanks for your input.

what seems very strange to me is that the 1.5 VVT-I engine from toyota wich is the same the toyota echo and prius use , doesnt work without and air filter if you remove it and try to start the car without it the car will just not make it .it doesnt start at all the check engine light come one and the car drowns by the amount of air coming into it.
so i dont believe you could drive even a mile without a air filter

The mechanic wrote “took out air filter to clean but didnt feel like putting it back in”? You must mean he felt it did not need replacing in the “it was very dirty sense” But I put the old one back in. Just a terminology thing. Or are you saying because there is a mechanics note about the filter you have a clue?