40 replies to this topic

[Bad_dude]

My 99 Corolla has been having this problem since the new year. I have taken the car back 3 times. First, about 8 months before the new year, the same transmission shop replace the driver's axle. It was a re-manufacture one. Then 8 months later, I notice the gear lube leaking out of the seal area. Took the car in for repair and a transmission fluid service. This place is a good and honest place and this is the first time we are having the problem. They replaced the seal 3 times and finally the owner decided to replace the seal again but this time he also replace the axle with a brand new one instead of the re-manufacture one. The leak stopped until today. Each week I checked for leak and it didn't leak again until I saw it this morning. This time, the leak is smaller and the gear oil does not leak on the floor. The owner gave a few scenarios:
1) Bad engine mounts causing the vibration to damage the seal.
2) Bad transmission bearing where the inner axle is meeting the transmission.
3) Bad tire balancing which is not a problem as the car drives smooth at high speed. Also the tires are pretty new, under 10,000 miles on them.

Please give me some ideas what could be wrong with the car or what the mechanic might be doing wrong.
Worse come to worst, could I just check on the fluid every now and just drive it like that? How long before the fluid all leak out? I am worry that the differential will get damaged. How often would I have to check it if I just leave it?

Thanks.

Edited by Bad_dude, 12 April 2012 - 07:08 PM.

[fishexpo101]

Bad engine mount, especially one that moves the powertrain enough to damage axle seals, should be pretty easy to see. Rev the engine in gear and see how much the engine rocks back and forth. A little motion is OK - excessive motion will be obvious.

Since you've had this leak for so long, problem gets fixed temporarily and then comes back - sure points to a bad differential oil seal or possible bad bearing in the transaxle. The differential oil seal is not too bad of a repair - assuming that the shop already investigated that option. The bearing on the other hand is a different matter. Not a really expensive part, but the labor is pretty intensive.

As long as you keep up on the fluid levels - should be OK temporarily. To avoid any issues, check everything before you drive the car. You can "guesstimate" the fluid level from the transaxle dipstick before you start the car - it will look overfull. Just mark it on the dipstick now, when it is full, and check and see how much the level drops. I did this to a older GMC 4x4 truck I had some time ago. Did it until we replaced the vehicle, so it was for a temporary fix. But we got another 100K miles out of it before the truck died.

[Bad_dude]

Bad engine mount, especially one that moves the powertrain enough to damage axle seals, should be pretty easy to see. Rev the engine in gear and see how much the engine rocks back and forth. A little motion is OK - excessive motion will be obvious.

Since you've had this leak for so long, problem gets fixed temporarily and then comes back - sure points to a bad differential oil seal or possible bad bearing in the transaxle. The differential oil seal is not too bad of a repair - assuming that the shop already investigated that option. The bearing on the other hand is a different matter. Not a really expensive part, but the labor is pretty intensive.

As long as you keep up on the fluid levels - should be OK temporarily. To avoid any issues, check everything before you drive the car. You can "guesstimate" the fluid level from the transaxle dipstick before you start the car - it will look overfull. Just mark it on the dipstick now, when it is full, and check and see how much the level drops. I did this to a older GMC 4x4 truck I had some time ago. Did it until we replaced the vehicle, so it was for a temporary fix. But we got another 100K miles out of it before the truck died.

Thanks Fish. I have a few more questions:
1) Is the differential oil seal the same as the axle seal? If yes then the shop has replaced it 4 times already. The first 3 times it held for a week. The 4th time it held for 2 months but he also replace the reman axle with a brand new one. The transaxle bearing, what would have cause it to go bad? Age of the car?
2) The engine mount in question, where is it located? Is it hard to replace?
3) The transaxle dipstick, where is it located? I think this car you can only check by removing the differential refill bolt. I only know of the oil and the transmission dipstick. Your GMC truck, how fast did the differential fluid goes down?

Thanks.

Edited by Bad_dude, 13 April 2012 - 11:58 AM.

[fishexpo101]

Yeah, differential seal/axle seals are used interchangeably.

As for the bearing, lots of things can cause it to go bad - plain old wear and tear, bad or wrong formulation of transmission fluid, excessive contaminants in fluid, excessive transaxle pressure/temperatures.

Motor mounts - there are 4. Two right under the engine - front and rear, the front one you can see pretty easily, sits right under the intake manifold, easiest to replace. The rear one, right above the cross member - little tough to see, even harder to get to. Then the two on the sides - one on the right, close to the serpentine belt area - the other by the transaxle. Both are a little more complicated to replace, but easier to get to than the rear mount. Usually the two under the engine wear out first (front and rear) - but you really need to look at all of them to be sure. Sometimes a mount will look good until you remove it - then find out the rubber insert is completely broken free of the metal mount.

As for the transaxle/differential fluid levels - if it is a 4-speed, just use the dipstick, single reservoir for both. In cases of 3-speed autos - you are correct, you'll have to pop the fill plug and check levels. Major PITA in that case. On my truck - it lost enough to put a couple of spots on the piece of cardboard I slid under it each night. Probably 2oz every day - 1/16 of a quart - go through a quart every other week - commute round trip was about 40 miles a day. Stayed pretty steady for the most part - but this was also a 4x4, so the parts under there are pretty beefy to start with. No telling how the Corolla will do - just have to check levels as often as you can.

[Bad_dude]

ok. You want the good or the bad news. You guessed it, I'll tell you both.
1) The axle seal wasn't leaking. They jacked the car up and showed it to me. So that's good. They check all fluid levels and all good.
2) The bad news, that P0420 is back on my way down to the shop. It's so weird that both times the code popped up when it's me who is taking the car to the same shop. The same shop pulled the codes. This time, the mechanic who pulled the codes said it was two codes but both codes are P0420. So I don't get it, 2 codes but both are the same, what could that be?
I guess the cat replacement is a must. Smog check for this car is toward the end of the year. The mechanic told me that some times replacing the O2 sensors fix the code but not always. Well the car is getting good mileage so I am debating with the O2 sensors, at least the one on bank one.
How hard is it to replace that cat? Dude, the OEM one is $1200. Holy cow.

Thanks.

Edited by Bad_dude, 13 April 2012 - 03:24 PM.

[fishexpo101]

Probably got two codes. One P0420 that was set and saved and one P0420 code that is pending.

I'm leaning toward the mechanic. If you haven't doubled checked the downstream O2 sensor - give that a look before you replace the cat. More times than not - with a P0420, the catalytic converter is working perfectly. It is usually found to be a faulty downstream (post-cat) O2 sensor or exhaust leak causing that code to come back. The upstream one is used for air/fuel feedback, so your mileage been decent, means that this sensor is working just fine. The downstream sensor reading is compared to the upstream one, if they "look" then same or if the downstream one is completely dead - you get a P0420 flagged.

[Bad_dude]

What's the best and easiest way to test to make sure it's the O2 sensor. If it checks out then the cat is the problem. Exhaust leak could be a pain to test thoroughly as I don't have access to a lift. I hate being under when it's hot to test the entire system. How accurate is the soapy water test?
Thanks.

[fishexpo101]

Soapy water test isn't 100% fool-proof. Add in a hot exhaust system, makes it tough to even check. Testing when cold only checks for leaks before the systems comes to temp - the trick is to see if that leak is still there once it warms up.

O2 sensor - best way to check is to backprobe the sensor and verify the waveform with a scope. Not everyone has the equipment available to test - in that case, might be able to pull the waveform from the OBD-II system via a datalogging scanner. There, you are limited by the sampling rate of the OBD-II system, so it may or may not be clear if there is an issue.

[Bad_dude]

Hello guys,
I know it's an old thread but I see no point in creating a new one when my problem still remains. My axle seal has been leaking again and it's not pouring out but I am a little concern. I have brought it back to the mechanic more than 6 times and each time it will last no more than a month. Both the mechanic and the owner said it takes at least 6 months to a year for the differential box to dry out and by then I would service the tranny again and they would also service the differential. I would like to know anyone has experience as to how long the fluid last in the differential box with this tiny leak. I can see a drop to 3 drops on the floor after the car has been driven. It does not leak over night like an oil pan leak. The fluid is clear and not like any tranny or engine oil color. So I know it's gear oil. The owner has offer to check and refill the fluid every 3-4 months. The problem is the shop is far out and my wife is being stupid some time and won't take the car by for 10 minutes to check the level when she goes that way to visit her mother each week. She feels that since I am unemployed, I should take it. I think it cost too much on gas and time to drive and come back only when she will take the car and go that way on the same day. I hate to drive 1.5 hours both ways just to check the level. A bottle of gear oil is almost $20 and I am unemployed for almost 2 years now so money is tight.

What are the possible causes for the seal to keep leaking like this?

Thanks.

[dom]

The sealing surface where the seal lip sits on the replacement axle shaft may not be smooth enough for a good seal. I've had the same problem on my previous car with an aftermarket axle shaft. When I realized what the cause was, I smoothed and polished the sealing surface on the shaft with wet fine emery cloth, then with metal polishing compound by hand. No more leaking afterwards.

If it's a manual tranny, you can easily check if your gear lube is low, by removing the fill plug in front to see if level is still close to the edge of fill hole, as it should. You can stick your small finger in, but gear lube really stinks... Fill and drain plugs take a 24 mm (15/16") socket, and are torqued to 29 ft-lbs. You can access fill plug from on top under the hood, with car parked on level ground. Total capacity is 2 quarts.

See photo in post #10: http://www.toyotanat...eferrerid=39715

Edited by dom, 10 October 2012 - 05:35 PM.

[Bad_dude]

The sealing surface where the seal lip sits on the replacement axle shaft may not be smooth enough for a good seal. I've had the same problem on my previous car with an aftermarket axle shaft. When I realized what the cause was, I smoothed and polished the sealing surface on the shaft with wet fine emery cloth, then with metal polishing compound by hand. No more leaking afterwards.

You can easily check if your gear lube is low, by removing the fill plug in front to see if level is still close to the edge of fill hole, as it should. You can stick your small finger in, but gear lube really stinks... Fill and drain plugs take a 24 mm (15/16") socket, and are torqued to 29 ft-lbs. You can access fill plug from on top under the hood, with car parked on level ground. Total capacity is 2 quarts.

See photo in post #10: http://www.toyotanat...eferrerid=39715

Thanks Dom.
It's been about 4 months since I notice the leak again. Since the capacity is 2 quarts, how low could it go down before the damage starts? I think 2 quart is full when you fill right? I just take my time this next weekend to take it in and have it check. This way I can measure how long it takes for the leak to go down. He replaced the remanufacture one with a brand new axle. The mechanic did all of the work so I can't see the surface of the axle. These guys have been good with us in the past. They are tranny experts that do just transmission.
Thanks.

[dom]

For a manual tranny, it takes 2 quarts to have it at proper level to edge of fill hole after it's drained... How low can it go is hard to say. You'll see how long it takes for it to go down by about 1/4". Check once it's completely cooled down. You can overfill it slightly if front end is jacked up a couple inches, with front tires still on the ground. I use a small funnel taped to a (3/8" ID?) clear hose that's about 2 feet long.

Edited by dom, 10 October 2012 - 05:35 PM.

[Bad_dude]

It takes 2 quarts to have it at proper level to edge of fill hole after it's drained... How low can it go is hard to say. You'll see how long it takes for it to go down by about 1/4". Check once it's completely cooled down. You can overfill it slightly if front end is jacked up a couple inches, with front tires still on the ground. I use a small funnel taped to a (3/8" ID?) clear hose that's about 2 feet long.

Hey Dom,
The fill hole for the differential box is facing the firewall about 3/4 in depth down from the top of the engine bay. I am not sure what size the bolt is. But you said it was 24mm? That's an odd size. I thought it would be like 19mm or something.
Thanks.

[dom]

It's actually on front of manual transmission, and is facing the back of the radiator.

It's 24 mm, but you can use a 15/16" (23.8125 mm) socket.

What you call a 'brand new' axle may be a low quality unit made in China, instead of Toyota's superior OEM axle shaft... There are many good used ones available.

http://www.car-part.com/

Edited by dom, 10 October 2012 - 05:35 PM.

[Bad_dude]

It's actually on front of transmission, and is facing the back of the radiator.

It's 24 mm, but you can use a 15/16" (23.8125 mm) socket.

What you call a 'brand new' axle may be a low quality unit made in China, instead of Toyota's superior OEM axle shaft... There are many good used ones available.

http://www.car-part.com/

He bought a new one from Toyota I think. I saw the plain white box with a Toyota simple on it. But that is beside the point. Are you certain that it is in the front? I watched the guy refill it and it's in the rear and facing the fire wall. I'll have to check to make sure again. I have an auto 3 speed.
Thanks.

Edited by Bad_dude, 10 October 2012 - 10:33 AM.