My '91 Legacy LSi (2WD auto) has recently developed a whine when I apply the gas. It's not from the engine, as when I do this in neutral, there's no louder whine when I apply the gas. When coasting, the whine is barely audible, but when the gas is applied and the engine/tranny is loaded (like on a hill) it can be loud enough to interfere with hearing the radio. The noise is like that of a jet engine if you get seats in the back of the aircraft. The pitch increases with speed. I commute 100 miles daily and don't want to get stuck if there's remedial action I can take now.

Any thoughts/suggestion?

Thx, Stephen

 

I'm beginning to think it's the differential.

The noise is related to road speed, not engine speed.

If I change gears and select 2nd or 3rd, the noise doesn't change with the engine revs.

The driveshafts were replaced about 8K ago, so I'm ruling them out.

The wheel hubs don't heat up, so I'm ruling out wheel bearings.

I'm ruling out the tranny as the noise dissappears when in neutral, and doesn't change with gear ratios.

I believe that only leaves the differential in the running gear.

Anyone have experience working on the front wheel drive differential that could lend some advice on how to proceed?

Thanks,

Stephen

 

No offense, but perhaps the lack of input on this issue has to do with the fact that you're complaining about driveline whine from a car which is 14+ years old. Few cars, aside from showcars that sit in a garage and are polished with diapers, survive 14 years of driving without substantial problems, especially in high-wear areas such as the driveline. My suspicion is that as soon as you crack the case on that differential or transmission, you're going to find dozens (if not hundreds) of things wrong in there, and will be told (with a serious face) by your mechanic that you need to start searching junkyards for a driveline swap from another car with hopefully less wear.

You are driving 100 miles a day(!) in a car that is over a decade old. You are either a very, very dedicated fan of that particular vehicle, or you need your head examined!

 

Well, I was hoping for some helpful diagnostic assitance, rather than a statement of the obvious. This has been a reliable and well-maintained car for the last 155K miles. This recent noise may be a showstopper, or it may be something I can remedy, and drive some more until the next issue crops up. It's a fine car for it's age and use, and still an enjoyable drive. If I can get another few thousand miles out of her then it may be worth the effort, depending on the degree of problem. A noise, with no operational problems, may or may not be that showstopper. I'd like to be able to determine that.

 

If you want an opinion on it, I would say 1) your differential diagnosis seems pretty solid; and 2) my wife's Civic had this problem (only FWD car we've had, ever) and it was the driveshaft itself, which had somehow become bent or warped and was out of balance. Since yours have been replaced, you might eliminate that, but it is possible they were installed badly or one of them damaged before install.

My brother drove his Loyale wagon past 220k with just minor problems; after all, it is a Subaru! But he faced the same dilemma that you are going to face, in that replacement parts are going to be very scarce and you'll have "cascade" problems where one thing going wrong means a series of failures in short order. Congratulations on wringing so much life out of the car; we'll see if I can get my wife's Legacy GL wagon to 100k without a 2nd head-gasket replacement (the dreaded 1997 engine!)...

 

A guy recently told me that he also had a whine from his Subaru automatic tranny under load and that his mechanic attributed this to the tranny oil pump on the way out.

Any opinions out there?

Stephen