Green98LegacyGT Posted November 14, 2017 Share Posted November 14, 2017 So I recently started getting a propeller noise on my car whenever I put the car into 5th gear and accelerate on the highway. The car shifts without problem and doesn't make any noise while on the gas in any other gear, just in 5th. Sounds like a grinding/propeller sound. It seems to be coming from the front passenger side. I have ruled out wheel bearing as it doesn't make the noise in high speed in 4th gear and there is no play on the wheel when lifted on a jack. My 5th gear used to whine a bit when I would accelerate driving at freeway speeds and now the propeller noise is driving me crazy. I changed the transmission/gear oil with subaru 75w90 a few months back and didn't see any metal scraps in the oil drained. I check the levels and it was a bit over. Could this cause noise or damage? I've been researching online and narrowed it down to transmission, front diff, center diff, shaft, shaft bearing, or transmission mount. Would hate for it to be a tranny problem as it is most expensive to fix. Looking for some wisdom here as I can not seem to fi d anyone else on the internet with the same problem. By the way, my shifter linkage is worn out and the stick shift has some play (side to side) when in gear. Don't know if that could cause it but thought I would throw it out there. I love this car and just bought some springs and shocks for it. Changed the timing belt, clutch, and brakes recently too. Hate to give this car up as I do enjoy it. Hoping the noise is just a loose screw or somethi g easy to fix. Thanks in advance. Link to comment Share on other sites More sharing options...
Brighton96 Posted November 15, 2017 Share Posted November 15, 2017 Change the diff and trans-fluid with high quality stuff and see if anything changes. May be fluid break down at higher speeds or lack of protection at higher speeds Link to comment Share on other sites More sharing options...
doublechaz Posted November 15, 2017 Share Posted November 15, 2017 After ruling out wheel bearings and brakes... Sounds only in acceleration or engine braking are usually gear alignment problems in a diff. That could be caused by a bearing allowing the gears to move or by gear wear. Sounds in all gears that aren't load based are often bearings inside the trans. I'd say a sound only in one gear would be from a synchromesh. I had a very faint sound in a synchro that I messed up. It was ok for about 8 years of daily. Then it slowly started to get louder. It didn't make it to 11 years. I just dropped in a working pull trans that I bought from somewhere. Good ever since. Link to comment Share on other sites More sharing options...
Green98LegacyGT Posted November 15, 2017 Author Share Posted November 15, 2017 Thanks for the suggestions everyone. Was just curious Doublechaz if it is the front differential you are talking about or the center diff? I have been reading around that the front diff is part of the tranny and if there are problems, the whole tranny would have to be replaced or rebuilt since the front diff is inside the tranny? Is the front diff inside a manual tranny or auto tranny? Guess I'll have to try to change the tranny fluid again. I wasn't able to find any off the S stuff by Subaru anywhere. Only the regular gear oil. I'll keep you all posted on my findings. Thanks! Link to comment Share on other sites More sharing options...
Setnev Posted November 15, 2017 Share Posted November 15, 2017 It's rare for the front diff to break. The are encapsulated in the front part of the transmission. Being it's a 5MT, the whole transmission needs to be cracked open to replace it, unlike the 4EAT being segregated inside the tranny. That aside, the center diff is much more common to fail. Subaru claims it's a sealed, non-servicable design, but it's far from it. They have a metal snap ring that holds the differential together. Unfortunately that snap ring is junk and will come apart in the tailshaft and make skittles of your transfer gears and bearings. I have personally seen 2 5MT failures of that center diff, one on my 99 Legacy L and the other on my 02 Forester. On my Forester, I went the cheap route and tried to fix it by JB welding the snap ring to the diff housing, but within 150 miles it came back out. It's my backup car, so I'm just going to drive it until the transmission dies whilst on the lookout for an affordable replacement transmission. Link to comment Share on other sites More sharing options...
Green98LegacyGT Posted November 16, 2017 Author Share Posted November 16, 2017 Good to hear that the front diff on the 5MT rarely breaks, that gives me some comfort. I'll have to check the inspect the center diff. From what I have seen on youtube, I guess you can take it off after removing the shaft? Also what sort of noises or symptoms foes a busted center diff exhibit before it craps out? Thanks again for your knowledge. Link to comment Share on other sites More sharing options...
Setnev Posted November 16, 2017 Share Posted November 16, 2017 Simple way to test it. Put the whole car on jack stands. Get one of those selfie sticks and mount your phone to it and start recording video. Have someone get in the drivers seat and start off slow and start going through the gears. Using your phone mounted to the selfie stick, probe in areas you hear the noise. If the noise is coming from the tail end of the transmission, prepare to remove the tailshaft. I did my repair in about 6 hours of wrench time. Drop the exhaust from the catback to tail pipe, remove the heat shield, remove the midshaft, unbolt the shifter assembly and assorted brackets and remove the shifter knuckle, 8 bolts on the tail shaft and knock it off with a rubber mallet. Make sure you have a pan to catch fluid. When you pull off the tail shaft look for stripped gears. Here's what mine looked like The gears shear off when the circlip on the center diff fails and gets caught up in the gears. When the center diff fails, its usually due to the circlip coming off and the viscous plates can no longer maintain the pressure needed to do its job. You'll get various sounds that range from marbles in your transmission, whirring, clacking, or helicopter noise during load, depending on how bad the transmission has progressed in its failure the noise can be felt in the gear shifter. Before I replaced the gears, I was getting a whirring and clacking that sounded like marbles. The bearing on my differential was bad, my gears were stripped, and the circlip came out of the differential. Link to comment Share on other sites More sharing options...
Green98LegacyGT Posted November 17, 2017 Author Share Posted November 17, 2017 Excellent advice! That all makes sense to me. Guess I'll have to get wrenching in the morning. Thanks for your help. Oh lastly, if the circlip breaks and causes the gears in the center diff to break, how can that damage my transmission? I only ask cause I have been driving my car to work and have been taking the streets instead of the freeway. If I continue to drive but not put it into 5th gear, can I cause damage to the tranny or just the differential? Many thanks again Setnev! Link to comment Share on other sites More sharing options...
Setnev Posted November 17, 2017 Share Posted November 17, 2017 Since the transfer housing shares fluid with the rest of the transmission, it is very possible that metal material got into the synchros and gears, especially if you can't put it into 5th gear. You also mentioned play in the shifter. That is due to that knuckle on the back of the transmission. It is very possible that it no longer has enough flex to put it into 5th gear, especially if it's hard to find and engage reverse. Best to replace the knuckle, part number 35047AC030 Link to comment Share on other sites More sharing options...
Green98LegacyGT Posted December 21, 2017 Author Share Posted December 21, 2017 So I changed my transmission gear oil once again and it came out pretty clean. No metallic shiny shavings in the drained gear oil. Did notice there was some very fine metal stuff on the magnetic drain plug, but nothing out of the ordinary. Once refilled, drove onto the freeway and shifted in 5th gear and it is still exhibiting the same noise problem and so I quickly shifted back into 4th and got off the freeway. While underneath the car, I checked the drive shaft for looseness or "play" and it was firm. Wondering if I should take off my differential and have a look at the syncros? Again, thanks for the advice and tips. This problem has got me looking for a older BMW 330i but I really want to keep my Subaru :/ Link to comment Share on other sites More sharing options...
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