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had a flat tire this moring,changed it to the dounut tire and drove about 10miles. started hearing a loud noise and vibration from the rear.honestly though it was the dounut tire. turned around and started home. when i was half way home started smelling the worst smell ive ever smelled from a car.when i got home looked under the rear and right beside the rear pumkin was smoking and looked as it might be leaking something, was very very hot even after 20min of sitting. what do u all think it could be????help!!! car is a 98 outback with about 200000miles 5speed with a 2.2liter.
 

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Lawn ornament XT
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Boiled or burnt CV joint grease will make a truly wicked smell. Burnt gear oil is a close second. Both live back there, where you're describing.

I wonder if you overheated the limited-slip pack in the differential?

+1 on WIBrewDude's question... how fast were you going? Supposed to be a 50mph max with the donut, and IMO even that is asking for trouble.
 

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My 97 manual says to pull out the fuse for the AWD when driving on the donut. Only had to do it once for about 10 miles going about 45 mph. No problems or smell other than Sacramento in the Summer.
 

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had a flat tire this moring,changed it to the dounut tire and drove about 10miles. started hearing a loud noise and vibration from the rear.honestly though it was the dounut tire. turned around and started home. when i was half way home started smelling the worst smell ive ever smelled from a car.when i got home looked under the rear and right beside the rear pumkin was smoking and looked as it might be leaking something, was very very hot even after 20min of sitting. what do u all think it could be????help!!! car is a 98 outback with about 200000miles 5speed with a 2.2liter.
Taco Bell does that :gasp:

Seriously, I have never and will never use a donut/mini spare on a drive tire.

It would be like driving in a circle at whatever speed you were going for however many miles you had driven, that cannot be good.
 

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My 97 manual says to pull out the fuse for the AWD when driving on the donut. . . .
Best double-check that. It should be that the fuse is to be installed in the AWD/FWD socket when using the donut spare. Installing the fuse disables the AWD (puts the car into FWD mode -- light should come on in the instrument panel), thereby avoiding potential damage to the AWD transfer system and drive trains due to the difference circumference tire.
 

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OP has a 5-speed. No fuse to deal with, AWD damage must be managed by limiting speed & limiting distance.
 

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2003 LL Bean Outback H6 and 2019 Outback Base
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Does this affect ALL subaru vehicles ?....... ALL years ?

Why wouldn't Subaru put a tire with same circumference ?

Seems to be some mixed results on how to go about this.......
 

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Does this affect ALL subaru vehicles ?....... ALL years ?

Why wouldn't Subaru put a tire with same circumference ?

Seems to be some mixed results on how to go about this.......
This is most directly related to the transmission type, so that's what you would pay attention to.

A full size tire costs & weighs more. Some buyers just won't buy a car unless it comes with a spare tire. Some buyers would never consider changing a tire themselves. If half of your customers demand a spare and the other half will just call AAA, a donut seems like a fair compromise. Tire technology is quite advanced and most drivers stay on clean roads, so flats aren't that common. There's no law saying they have to provide a spare at all, so lots of manufacturers give you a donut and a list of restrictions for operating on it.

Subaru gives out donuts, and when you need to use the donut that means you need to drop everything and limp directly to the nearest tire service shop to properly fix your situation. It is NOT so you can keep driving around normally until the weekend and then deal with it. If you require that capability, get a fullsize spare.

With the 4EAT transmission, you have the ability to lock out the rear wheels electrically by way of the AWD fuse. Again, it is meant as a limp-home mode, not a get-through-the-trip-then-deal-with-it mode. There seems to be less risk since the AWD is locked out, but the lockout itself will stress the AWD duty C solenoid somewhat, and this should be minimized.
 

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Best double-check that. It should be that the fuse is to be installed in the AWD/FWD socket when using the donut spare. Installing the fuse disables the AWD (puts the car into FWD mode -- light should come on in the instrument panel), thereby avoiding potential damage to the AWD transfer system and drive trains due to the difference circumference tire.
Sorry, I stand corrected. Sixteen years was too long to recall even though I was trying with all my brain. I do recall the light on the dash after following the instructions in the manual. Flats where you need to limp to a tire store are uncommon if I've only done it once in the life of this car. I did not know it was only for AT cars.
 

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2003 LL Bean Outback H6 and 2019 Outback Base
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You got it rasterman !!! What about putting in " fix a flat " ? That way all tires the SAME.
I have used this before.......A LONG time ago before I owned a subaru. It seems like the perfect solution to this issue.

What do you think ?
 

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I was driving about 40 to 45mph. there is no Awd fuse on manual outbacks for that year. was looking in my haynes repair manual and it says that the CV joint is a non serviceable item and that if it goes bad i gotta replace the whole drive axle.is it possible that i just burnt some grease in it? also forgot to say on the earlier post that when i pushed in the clutch it stopped making the noise, if that helps... thanks for all the info guys.
 

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You got it rasterman !!! What about putting in " fix a flat " ? That way all tires the SAME.
I have used this before.......A LONG time ago before I owned a subaru. It seems like the perfect solution to this issue.

What do you think ?
It's ok in a pinch... doesn't fix every flat, and you still need to take it to a tire service place to get the goop cleaned out (or suffer balance issues) and have a proper patch plug put in.

But it does solve the size issue nicely.
 

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Even with the AT and the use of the FWD fuse to disable the AWD (i.e., put car in FWD mode), there's still a risk. The differential is designed with the idea that the two output shafts (wheels) turn at the same speed (or very close) most of the time. That's why the spider (pinion) gears that transmit force from the ring gear to the side gears don't have any bearings. The spider gears are fitted on a fixed pinion shaft, and are metal-on-metal, isolated from each other only by a thin layer of gear oil, if that. (This is not unlike the engine crankshaft journals except that the journals are made of special metals and have oil pumped into the bearing area, whereas the differential gears do not.) When the differential side gears turn at different rates, the spider gears have to rotate on the pinion shaft. Typically, in a 90 degree turn, the spider gears rotate minimally and then stop -- it's a relatively slow, and temporary situation. But racing down the highway with two different tires can be something else. The spider gears are continuously rotating while transferring engine torque to the side gears and axles. That puts a lot of pressure on the mating surfaces. (Using the engine example, turn off the oil pump and have the crankshaft journals lubricated only by dipping into, or splashing of, the oil in the pan.) If the gear oil is unable to provide the necessary lubrication and cooling under this extreme condition, the mating surfaces of the gears and shaft can heat up, as will the oil. Differentials often fail when one wheel is allowed to spin wildly even for a very short time, such as when stuck on snow or ice. And typically, the mechanical failure is evident in the spider gears and/or the shaft they turn on.

I agree with rasterman -- even the limited distance and speed for use of the donut might be problematic.

But this is a digression. Was the smoke and apparent heat coming from the differential or from one of the side axle CV-type joints?
 

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" fix a flat" Is the way to go...................problem solved..........if no work......then plan B with fuse
 

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I bet the donut spare had very low tire pressure also. Just replaced brake pads on a family members Civic. Rotated the tires and the 60lb PSI donut was down to 29lbs. If the civic had the Subaru AWD it for sure would have caused the AWD some heart burn had it been needed.

Speaking of which after spotting that low PSI in the spare on the civic I have a sticky note on the fridge to go through our cars and make sure the spares are all proper PSI.
 

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Yeah, I did the annual trunk check/emergency gear refresh a couple of weeks ago and found my donut down to 15. Then I learned that my portable inflator was kaput. Then I learned that harbor freight had a much better one on sale for $19... solved a few problems that day.

Remarkably good for the money. Not fast, and it's weird having to start the pump before connecting it to the tire, but it's tiny, not loud and seems decently constructed.
 
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