Ok, so last week or 2 weeks ago I asked about a whining sound and I got responses saying to delete the c101 connector. I did that and it didn't eliminate the whining sound but I did notice the engine running a bit smoother. So now I realized after going through mass amounts of gas on a long trip that I went from 19mpg combined 6 months ago to about 13-14mpg all highway. Maybe the whining sound is related? So when I start the car it runs perfect and sounds perfect but after a minute of driving the whining starts and gets pretty loud and it sounds like it's from the actual engine, not the power steering or anything. It doesn't matter how warm the engine is, it runs perfect for a minute then the sound comes up. So it makes me think that some type of pressure builds up while the engine is running and causes the sound then the pressure drops when the engine is off. That is just my guess from trying to think with common sense. So if anyone has any suggestions as to what may be causing it or things to check it is greatly appreciated. Thanks.

P.s.- And if anyone tells me to get a compression check or thinks I should get one please tell me how in dummy form because I really don't have any clue how to do one or what the good readings are. Thanks again.

 

Does it sound like a vacuum leak? Does the sound change with engine speed? I'd try to locate the source of the noise. A length of rubber hose, one end held near your ear, is useful to locate such things.

 

no it's not a vacuum leak. Its really loud and it does change with rpm increase not necessarily speed. I cant decipher exactly where its from because it sounds like its from inside the engine.

 

Distributor bushings?

You MUST use something to narrow down the noise yourself. Radi had a good suggestion.

The noise may not be related to the MPG loss either. Could be coincidence.

 

It really helps to know about your XJ fill out your profile or at least a year in the title.