Stang70Fastback Posted December 22, 2013 Share Posted December 22, 2013 So I noticed a distinct sound from the car - particularly over 60 MPH, that I'm trying to pinpoint. It's a rather high-pitched sound, and at first I thought it might be a bad wheel bearing, but now I am wondering if it isn't the differential. As I said, it is much more noticeable at highway speed. It pretty much goes away entirely when I am coasting, but the more throttle I apply, the louder it gets. I checked the front differential fluid (god only knows the last time it was checked) and it appears the fluid level is exactly at the lower 'E' mark. One thing I did notice was a VERY strong odor as soon as I pulled the dipstick out (this after a short drive on the highway.) Perhaps diff fluid just has a very strong smell, but I was wondering if that alone might be a bad sign. The fluid was clear (brownish color, it seemed, though it's dark out so I didn't have much light) and it didn't seem to have a "burnt" smell, just kind of an unpleasant, sour smell. In any event, there isn't much I can do regardless at the moment, but I WAS thinking of adding fluid through the dipstick tube to bring it back up to the FULL line, since I'll be driving 450 miles tomorrow (today.) What kind of fluid does this take? I know I recently discovered that I shouldn't have been putting power steering fluid in the power steering pump, so I want to make certain I don't do something equally stupid. Link to comment Share on other sites More sharing options...
Baddog Posted December 22, 2013 Share Posted December 22, 2013 75-90W. Drain it and refill it. Takes 1.3 quarts. Link to comment Share on other sites More sharing options...
Stevo F Posted December 22, 2013 Share Posted December 22, 2013 It's gear oil so it will have a strong smell. I'd change it anyway if there's any doubts. Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 22, 2013 Author Share Posted December 22, 2013 I might just bring it somewhere in the near future and have them change the fluid in the front and rear diffs. I know it's a simple job, so it shouldn't cost too much. I'd do it myself but it's cold out and I remember a few years back I couldn't get the rear diff drain plug to budge. Link to comment Share on other sites More sharing options...
Bassnectar Posted December 22, 2013 Share Posted December 22, 2013 Breaker bars are your friends. I remember my first rear diff job witch a ratchet.... lmfao Sent from my SGH-I337M using Tapatalk Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 22, 2013 Author Share Posted December 22, 2013 Oh this was WITH a 3' breaker bar, which I admit isn't as big as it could be. Still it's just a pain in the assembly when you can't get the car very far off the ground, lol. Link to comment Share on other sites More sharing options...
cal71919 Posted December 23, 2013 Share Posted December 23, 2013 I didn't know the differential had a dipstick. What's recommended for fluid? Synthetic or conventional gear oil? Link to comment Share on other sites More sharing options...
spooln30 Posted December 24, 2013 Share Posted December 24, 2013 If your driving at a steady speed of 40 mph or higher and you slightly turn the wheel left and rigjt does the noise change pitch? The noise changing pitch would probably mean one of the wheel bearings if going. How to figure out which one, when your slightly turning left and the pitch increases it would be the right side and turning right with a pitch increase would be the left. It's a load thing. LOL. Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 28, 2013 Author Share Posted December 28, 2013 Yeah my dad was riding in the car and pointed out the sound was actually coming from the back (apparently where I sit it sounds like it's coming from the front.) In any event the car was in to Subaru this morning to change the fluid in both diffs and get an oil change. They confirmed the front was low, but said the rear was fine. However they said both were dirty. The car does feel smoother now (mostly due to the oil change) but in making a tight u-turn it did seem a lot smoother. We shall see if the whine is gone as I get to drive 450 miles later today. Link to comment Share on other sites More sharing options...
Stevo F Posted December 28, 2013 Share Posted December 28, 2013 I get a little bit of whine out of the rear differential at highway speeds. I did change the rear diff fluid (looked dirty) this year, but made no difference.Hardly noticeable and not on my list of concerns for the car (still am a bit unhappy with the cold engine tick/ piston slap and less than perfect idle) but it is a 16 year old car... Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 28, 2013 Author Share Posted December 28, 2013 Yeah the whine is still there. It's odd because it comes and goes, and it's only under acceleration. Oh well! Link to comment Share on other sites More sharing options...
Surbahar Posted December 28, 2013 Share Posted December 28, 2013 It's probably minor wear to the diff that's making the bit of sound under acceleration; nothing to worry about unless it gets louder, I'd assume. Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 29, 2013 Author Share Posted December 29, 2013 So I've got another question: How hot should the rear differential get after a long drive? Just out of curiosity I got under the car after my 450 mile trek today (ambient temp in the 40s) and if I pressed my hand against the diff casing (the rear part) it was burning hot and I couldn't keep my hand there more than 2 seconds. Is that normal? Link to comment Share on other sites More sharing options...
Ivant Posted December 29, 2013 Share Posted December 29, 2013 So I noticed a distinct sound from the car - particularly over 60 MPH, that I'm trying to pinpoint. It's a rather high-pitched sound, and at first I thought it might be a bad wheel bearing, but now I am wondering if it isn't the differential. As I said, it is much more noticeable at highway speed. It pretty much goes away entirely when I am coasting, but the more throttle I apply, the louder it gets. I checked the front differential fluid (god only knows the last time it was checked) and it appears the fluid level is exactly at the lower 'E' mark. One thing I did notice was a VERY strong odor as soon as I pulled the dipstick out (this after a short drive on the highway.) Perhaps diff fluid just has a very strong smell, but I was wondering if that alone might be a bad sign. The fluid was clear (brownish color, it seemed, though it's dark out so I didn't have much light) and it didn't seem to have a "burnt" smell, just kind of an unpleasant, sour smell. In any event, there isn't much I can do regardless at the moment, but I WAS thinking of adding fluid through the dipstick tube to bring it back up to the FULL line, since I'll be driving 450 miles tomorrow (today.) What kind of fluid does this take? I know I recently discovered that I shouldn't have been putting power steering fluid in the power steering pump, so I want to make certain I don't do something equally stupid. My manual says that the front diff should have it's gear oil replaced every 50.000ks or in your case 30.000mls. It would seem that some people I have talked to have never replaced it in the life of the car. Maybe it's time it was replaced. Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 29, 2013 Author Share Posted December 29, 2013 Yeah, I would have imagined it had SOME kind of service interval. I guess they are just so resilient that not enough problems occur for them to be something people generally think about. I'm more concerned about the heat in the unit than anything else at this point. I wouldn't have imagined they should get too hot. Link to comment Share on other sites More sharing options...
Casey Posted December 29, 2013 Share Posted December 29, 2013 I'm more concerned about the heat in the unit than anything else at this point. I wouldn't have imagined they should get too hot. They will get hot, especially after an extended drive. The gear lube not only lubricates the ring and pion gear and bearings, but also helps to transfer the heat to the cast iron housing. Cast iron is very good at retaining heat, so it'll take a while for the housing itself to cool off after a long drive. As long as you change the fluid at the recommended interval and keep it at the correct level, I wouldn't be concerned by the heat. Link to comment Share on other sites More sharing options...
Stang70Fastback Posted December 29, 2013 Author Share Posted December 29, 2013 Ok, that's good to know. Thanks for the help, guys! Link to comment Share on other sites More sharing options...
Nickup1 Posted January 1, 2014 Share Posted January 1, 2014 A shop near me wanted $100 for each diff. Screw that. Link to comment Share on other sites More sharing options...
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