Deceleration Noise

[hungtaoc]

I used to have a 98 Outback (automatic) and I have recently purchased a 01 5 speed outback. The car makes a deceleration noise after 4th gear after I get up above 45mph. When I let off the gas (in 4th or 5th gear), I can hear a sort of metallic clicking sound. The speed of the clicking sound slows down as I slow the car down and it does not go away even if I switch into neutral and coast to a stop. The sound just slows down until I come to a complete stop.

This does not happen when I am in 1st, 2nd, or 3rd gear. Is it more likely that it is transmission related or differential related? I think the noise is coming from the front end but I am not sure.

Thoughts?

[subiesailor]

Originally Posted by hungtaoc

I used to have a 98 Outback (automatic) and I have recently purchased a 01 5 speed outback. The car makes a deceleration noise after 4th gear after I get up above 45mph. When I let off the gas (in 4th or 5th gear), I can hear a sort of metallic clicking sound. The speed of the clicking sound slows down as I slow the car down and it does not go away even if I switch into neutral and coast to a stop. The sound just slows down until I come to a complete stop.

This does not happen when I am in 1st, 2nd, or 3rd gear. Is it more likely that it is transmission related or differential related? I think the noise is coming from the front end but I am not sure.

Thoughts?

Change the gear oil in the transmission - the MT shares the fluid with the front diff - rear diff may also need servicing. Start there

[tdelker]

Make sure to get the oil specified in your manual. There are issues with some gear oils (some synthetics) damaging the manual syncros.

[hungtaoc]

I will try this and get back with you guys. The clutch was replaced by the previous owner 30K miles ago and so it is probably a good idea to drain the fluid. I did check the fluid level of the front diff/transmission. The fluid is full and has a clean light yellow appearance.

[subiesailor]

Originally Posted by hungtaoc

I will try this and get back with you guys. The clutch was replaced by the previous owner 30K miles ago and so it is probably a good idea to drain the fluid. I did check the fluid level of the front diff/transmission. The fluid is full and has a clean light yellow appearance.

Hmm?

Any idea if the prior owner had the release bearing and the plate replaced when they did the clutch? Not uncommon for people to cheap out on the clutch job and for those two things to cause issues shortly down the road.

[hungtaoc]

That's a good question. I don't know if the owner replaced those because the receipt of the repair only says "clutch replacement". I guess I will start with the fluid.

By the way, I am thinking about draining the tranny and rear diff with Subaru's Extra-S 75w90. There are too many opinions about what brand is best so I figure I will just go with Subaru's. Any idea how much I would need if I am only doing a drain and fill (for both front and rear differential)?

[1 Lucky Texan]

look in the manual but, I THINK it's a little less than 4qts in the tranny, and a little less than 1qt in the rear diff (actually amounts you can drain).

be sure to remove the rear diff's FILL plug first.

fred beans and maybe one other on-line dealer has quart bottles for sale. Some folks say they can get it from local dealer if they take their own jug in. Otherwise, you have to buy some huge tub of it.

[1 Lucky Texan]

Manual Transmission, FWD..........7 pints
Manual Transmission, 4WD..........7.4 pints
Differential, Rear..........1.7 pints [3]

[hungtaoc]

Alright, I just want to update you guys on what I have done. I have had the car for 2 months now and I have encountered the following problems:

CEL on, deceleration noise, engine old is overfilled and a year old (but not more than 3000 miles since last oil change since it was never driven).

Here are the things that I have done so far:

1) Changed both O2 sensor with Denso O2 sensor, Genuine Subaru knock senor
-CEL resolved.

2) Did an oil change. The engine runs a lot smoother.

3) Changed air filter, PCV, fuel filter.

4) I changed the transmission/front diff oil. I did not notice any broken pieces in the oil but the oil looks really bad. It looks like a greenish milkshake. I am guessing that the previous owner put some type of off-brand fluid in the tranny. I changed the oil with Subaru Extra-S 75w90. By the way, I got the Extra-S from a seller on Ebay and 5L bundle is $75 (including shipping and tax). The manual says that the front diff takes 3.8 quarts of fluid (3.6 L) but I only put in about 3.2L. I guess not all of the oil fluid was drained out.
- Deceleration noise persists even though shifting has improved.

Currently I still cannot get the rear differential screws to budge. I am going to take it to a mechanics buddy either this weekend or the next and try to get the plug loose.

I did a search on the various Subaru forums and the deceleration noise seems like a common problem on the 5 speed. The unfortunate thing is that for those who were skill enough to tear apart their transmission, they found an array of causes. Others have reported that they kept on driving and the transmission hasn't died after 30K.

I think that since the noise is within tolerable level, I will just live with it for now. If it gets too bad I will have to get the transmission rebuilt. I have a faint suspicion that the strange gear oil put in by the previous owner messed up the synchro but I am not sure.

Thoughts, anyone?

[subiesailor]

The description of the differential sounds like contaminated gear oil water and probably topped off or had the wrong type of oil put in it.