I have a 2008 volvo S80 T6 (inline 6 with a turbo).
This week I noticed a rhythmic squeaking like a bad belt. I had also noticed a decrease in power and one instance of what sounded like a backfire during a quick acceleration. The vehicle computer has not thrown any warnings.
I brought it to the mechanic and he initially thought it was a belt too, but then wanted to “try something” and pulled out the dipstick. There was an audible hiss of air being sucked in and the squeaking immediately went away. When he replaced the dipstick, the squeak came back quickly. He could reproduce the same effect by loosening the oil cap, which also made a sucking sound and was very difficult to pull away from the top of the engine. He said there shouldn’t be that much vacuum in the dipstick/oil cap and that I should take it back to the dealer to have the vacuum system checked out (bought it used a few weeks back and still covered under the Massachusetts lemon law, so they’d have to fix it for free, otherwise I would have had it repaired right there and then). I went out and listened to the car running later and I could swear I heard a hiss but the mechanic didn’t mention it earlier and we were both standing there listening.
The mechanic suggested leaving the oil cap loose until I could get the vacuum problem fixed as that would make the squeak go away. He said something about the oil pan and vacuum but I didn’t quite catch it (or I just can’t remember it now). I left the oil cap loose like he said and there was an immediate and dramatic increase in power when driving and I can’t figure out whether the vehicle was that powerful before the problem.
Because of my job I both need to drive the car (at most 20 miles in a day and probably more like 4 miles) and cannot get the car to the dealer for a week.
Am I going to damage the car by driving it with a vacuum leak or whatever the heck is going on?
Thanks in advance!