mystery of corolla differential runs dry

My father's 97 corolla with the 3 speed transmission recently develop a whine. Drove it to my usual mechanic where he suggested to try change both the oil in the tranny and the differential to see if it helps. (this transaxle has a seperate differential drain plug). The tranny was drained first and the fluid looked and smelled okay. Then he open up the drain plug of the differential - I could not believe my eyes that only a few drops drained out, it was almost dry !

My question to the group is : how can the differential run dry without my father noticing any leak ? I am very sure there is no stain on my father's drive way, where he park his car 99% of the time. Where would have the oil gone ? I was thinking of the drive axle oil seal but my mechanic said it looked okay.

Last time the car had the transmission and differential oil change was about one year ago at the same shop. I am thinking if my mechanic forgot to fill the differential during the last change, how could the unit went one year a few thousand miles without blowing up ? Actually according to my dad the whine only developed in the last few days.

Any suggestion about what could have caused the leak ?

Reply to
Jack
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What was the oil level in the transmission?

Reply to
Ray O

As far as the differential; most diffs are equipped with a vent, something that looks like the top of a pressure cooker, that opens when the pressure in the differential builds. These are known to rust and get stuck in the closed position. When this happens, the pressure in the diff can't vent, and pressure keeps building. So, what happens is that it starrs pushing the oile past the seals, but usually only when the car is moving. The pressure eventually drops and there may or may not be a leak shown on the driveway.

Reply to
SupraGenius

I think your right on and they forgot to refill the differential. As to how could it go for a few thousand miles without blowing up, that is easy. All oil does in the differential is to keep the metal surfaces from rubbing directly against each other and wearing. Once it is gone the metal surfaces simply get polished as they rub against each other, and start to wear out. The unfortunate part is that the gears in the differential right now are probably just about completely worn out.

It's no different than a kids bicycle chain that gets wet and never gets lubed.

If gearing immediately blew up when it ran dry, then lots of people would have axles blowing up in their cars as they drive around, because CV joint boots inevitably crack and fling all the lube out. What usually happens though is it keeps working for a long time, then eventually when it's very worn, it starts making a racket. Just exactly what happened to your dad.

Ted

Reply to
Ted Mittelstaedt

put the oem oil back in and drive it also it sounds like your tring to get the shop to replace your diff for free?

and if it blows well you know where the wine came from also find another shop and check your tranny

Reply to
tudysmuck

The oil level was normal in the tranny.

Reply to
Jack

I never knew of the vent that you mentioned. And this make me think of another possibility. Recently there had been a small scale flooding where my father lives. He told me he once drove through water as high as the top of the bumper. Would it be that some water got past the vent and enter the differential, push out some oil to the transmission ( I think the tranny and the differential has a pathway where oil can exchange). When the unit get hot the water got evaporate through the vent, leaving very little oil in the differential.

Is this possible ?

Reply to
Jack

well I am not trying to blame my mechanic, cause he is an honest guy that I trust. But since he is also human, he is still prone to making mistakes once in a while ..... my question is, my father's car runs normal after refilling the differential, should I ask for some sort of compensation from the mechanic ?

Reply to
Jack

I don't think a mechanic would 'forget' to fill the differential - at least on my 92 Geo Prism it required a lot of work, including moving some kind of rubber thing, to get at the plug. What is more likely is that this is the first time the thing has ever been checked. When I checked mine it was low (not necessarily dry); I filled it up and put everything back. It made little or no difference in operation of the car. So I don't think you have a problem but anything could happen!

Reply to
ep45guy

THere is the same rubber thing to be removed from my father's '97, not sure what that part is for but it is there. I tend to believe my mechanic since he has been a very competent and knowledgable guy ever since I started using him six years back, but still everyone can make mistakes.... if it is not him it would be difficult to find a reason for this mysterious oil loss..

snipped-for-privacy@yahoo.com wrote:

Reply to
Jack

back. It made little or no difference in operation of the

My shop said that the differential is automatically changed when you change the transmission fluid. Sounded weird, but is it true?

I have a 95 Corolla.

Reply to
stinkeroo

A 95 corolla can have either a four speed or three speed tranny. If it is a three speed unit like my dad's the differential has to be drained and filled seperately.

Reply to
Jack

Quite. Remember, fluids are not compressable, so if water leaked through any vent, it would raise the level of fluid and not leave much room if pressure builds. But if the vent were closed enough to keep the pressure in, I doubt it would let water in.

But you never know.

When I was working as a salesman at a used car dealer, we bought a bunch of cars that had come from a flood in PA. Most of them just needed to be drained, refilled, cleaned and dried. But every once in a while we would get one where someone tried to start the engine without draining the fluids and, BAM! Hydraulic lock, where the engine blows because it is filled with liquid. The same thing that keeps your car from starting if you put in too much oil.

Reply to
SupraGenius

Just yesterday I was flushing the bosses transmission (97 camery) and saw the second plug. Pulled it to drain the entire transmission and noticed the fluid wasn't as dark as the rest. Looked it up and discovered the final drive section.. Now what if I assumed that it was part of the transmission and thought that it was filled through the fill tube? Or an axle was removed and it dripped out there and the tech didn't know it was a separate fluid area?

my 2 cents.

Reply to
Steve H

The typical answer is that the diff wasn't filled through it's separate fill point, which is threaded into the flat, vertical, aluminum diff. plate on your A131E transaxle. Having driven it for a year without mass destruction of the differential section is improbable, but possible.

A less likely scenario would be that the fluid leaked through the internal case seals into the regular fluid reservoir. This would show as a higher than normal level on the dipstick, unless there is *also* a fluid leak present.

Don't think that 'mechanics' always remember to fill the separate diff reservoir. I have seen plenty of Jiffylose jobs come in on a hook just miles after a trans service with an dry diff full of metal shrapnel.

Reply to
Comboverfish

There is no rubber part related to draining your A131E transaxle. It has a pan drain plug, a diff drain plug, a diff fill plug, and a dipstick tube for filling the trans section. The pan gasket has rubber in it, but I doubt that is what you are refering to.

Toyota MDT in MO

Reply to
Comboverfish

"no rubber part related to draining your A131E transaxle."

It's weird because I saw my mechanic remove a black rubber thing before he could get to the differential fill plug.

Reply to
Jack

That would be the frame vibration damper. Not a part of the transaxle, but it gets in the way of the diff fill plug if you don't have the exact combo of tools to reach in there. It's absence does make plug removal easier.

Maybe the mechanic removed that plug and no fluid ran out, so he thought the diff was empty, or the translation of what he actually said got lost somehow. On a properly filled A131E, fluid will be right at the level of that plug hole when cold. It may run out a bit which is OK, but if it is significantly lower than the hole when checked with your pinkie, then the diff is low.

If you remove the drain plug on the *bottom* of the diff, aprox 1.4 Qts of ATF will drain from a properly filled unit.

Toyota MDT in MO

Reply to
Comboverfish

"Maybe the mechanic removed that plug and no fluid ran out, so he thought the diff was empty,"

Thanks for your response. I remember my mechanic drained the transmission first (I stood under the car with him), then the differential. The tranny drained okay but nothing but a few drops came out of the diff. I couldn't believe my eyes when I saw it.

Reply to
Jack

Does a 95 Corolla with overdrive have a separate transaxle oil thing than the transmission fluid?

I had them change the fluid and they said it was all one big thing, so it wasn't really possible to change the axle fluid or whatever it is.

Reply to
st-bum

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