Differential oil for a 1976 Corolla?

[OceanRuns]

I picked up a 1976 Corolla cheap (I'll try to get a pic up later). It runs and drives, but has issues (hence the price). One is that the rear differential whines when you take your foot off the gas, but not while applying throttle. Any thoughts as to what that may indicate?

I can see it's leaking. Which fluid would you use? Is synthetic worth a shot?

Thanks.

 

[old1]

Sounds to me like the gears are not mating right, probably caused by loose bearings. Maybe real thick grease might help, but probably only a temporary patch to get it through till it can be repaired at best. When I had a GM 10 bolt that did that, and not very bad at that, when I took it apart the bearings literally fell apart they were so worn.

 

[eljefino]

Yup could be the pinion bearing. Haven't these all been turned into drift cars?

 

[HangFire]

Synthetic only makes a difference if you are towing, or running in extremely cold or hot weather. If it costs the same as conventional, sure, why not.

Check the fluid level immediately and have it checked out as soon as possible. Cheaper repairs like bearings can turn into rebuilds or replacements very quickly. Pumpkin noises should not be ignored. Ask around to find a good rear end shop. Often the local 4x4 shop is a good place to start. They make so much money at upgrades they won't bother trying a milk a repair job.

 

[OceanRuns]

What should I put in to keep the level full until it's repaired?

 

[Tegger]

Originally Posted By: OceanRuns
I picked up a 1976 Corolla cheap (I'll try to get a pic up later).

I had a '75, and '81 and an '82. Nice cars, but the '75 was not well-designed at all for north-eastern winters.

Originally Posted By: OceanRuns
It runs and drives, but has issues (hence the price). One is that the rear differential whines when you take your foot off the gas, but not while applying throttle. Any thoughts as to what that may indicate?

Does it whine in all gears? If all gears, then the diff is probably worn.

If this car has a 5-speed, those T50 5-speeds were notorious for getting whiny as the miles piled up. The noise was in 5th only, though.

Originally Posted By: OceanRuns
I can see it's leaking. Which fluid would you use? Is synthetic worth a shot?

If the diff is whining, new oil likely won't solve that. It probably needs a rebuild.

The manual calls for a monograde 90wt EP oil. You can use a more-modern 75W-90 EP oil. It doesn't matter whether the oil is syn or not.

 

[A_Harman]

Rear end whine on trailing throttle means that the pinion depth mating with the ring gear is wrong. Not an easy thing to fix. Can you buy a professionally rebuilt rear end for it? It would be a lot faster just to change the whole thing out than trying to rebuild it.

 

[Tegger]

Originally Posted By: A_Harman
Rear end whine on trailing throttle means that the pinion depth mating with the ring gear is wrong.

And that's most likely due to wear resulting from low-fluid.

It was common for these diffs to leak at the seal at the front of the housing. Oil would then get slung all over the transmission tunnel.

 

[6starprez]

Don't know what the noise could be but IIRC, I put 75W-140 in the old '78 Corolla I had in the mid-'90's. Never had a problem with that car. The body forced it to the junkyard as it rusted away.

 

[Rhymingmechanic]

For a 1980 (the oldest search possible), Amsoil lists 80W-90, 75W-90, or 75W-110. That tells me you can keep it topped off with plain old 80w-90 until it gets repaired.

Check the fluid level and rearend out ASAP, though. It's probably not a common failure, but I had a Chevy Caprice rear that started making noise and leaking. It turned out that the pinion nut had loosened, letting the pinion take out the seal.

 

[asand1]

You will likely need a new ring and pinion with your bearings. Toyota likes 3rd member rear ends, and another one could probably be picked up at a wrecking yard. I believe many are interchangeable (pickups incuded) as long as you stick to the same ring gear diameter.

 

[OceanRuns]

Ok, I changed the fluid. The noise is still present.

It was a bit of an adventure, as the fill bolt took some effort (pounding with a hammer, lots of penetrating fluid, and multiple attempts with muscle and an impact gun). I also had to purchase a 24mm socket. But, it finally came off.

I drained 350 ML. So, it was obviously low. I added some 80w-90. I had one pump hose blow off and spew oil all over. LOL. Luckily, I was on my side driveway, which already has oil spots and isn't front and center. The drain bolt has a number of a small metal shavings on it.

I took it for a drive, and there is definitely a substantial leak. In a short time at the gas station, there were already drips. I have a clean tray under it now, and I'll try to pin it down more.

This is the first time I've ever changed differential fluid. So, it was fun to do something new.

More car specs: automatic (3 speed), 2TC engine. Aside from this issue, it starts on first or second crank, and shifts ok. The speedometer seems like it may be off. I do see RTV sealant around the bell-housing. So, I wonder if at some point someone changed internal components (as taking it apart isn't necessary for drain/fill), and may have done so improperly.

 

[OceanRuns]

Here is a photo. It is basically rust free (underside pretty clean). Current reg, clean title. It appears to basically be in stock form.

 

[MolaKule]

Nice looking '76.

Quote:
I took it for a drive, and there is definitely a substantial leak. In a short time at the gas station, there were already drips. I have a clean tray under it now, and I'll try to pin it down more.


If it isn't coming from a gasket it may well be coming from the drive pinion seal.

 

[gold01ca]

Nice looking old car, I'm an old Toyota fan.

 

[72te27]

Hey, OceanRuns, believe it or not, there's a following for these cars. I'm partial to the '71 through '74 Te27 chassis myself, as I have a 1972. Completely different car than yours, same family though. Mine has the same bulletproof 2TC motor as yours with a few differences, mostly cylinder head port size and fewer emissions controls.
For info, check out 3tcgarage.com
The 3tc is the later, longer stroke version of our engine, but the info is basically the same.

As far as your diff, there is a gasket between the carrier flange and the housing. As Tegger pointed out, they leak there.
Contact patch alignment between a ring and pinion is a science, and can have everything to do with the noise from your diff. Have a shop check it. It's not necessarily worn out. Your car should have the 6.7 inch ring gear, btw.

 

[mjoekingz28]

Originally Posted By: OceanRuns
Ok, I changed the fluid. The noise is still present.

It was a bit of an adventure, as the fill bolt took some effort (pounding with a hammer, lots of penetrating fluid, and multiple attempts with muscle and an impact gun). I also had to purchase a 24mm socket. But, it finally came off.

I drained 350 ML. So, it was obviously low. I added some 80w-90. I had one pump hose blow off and spew oil all over. LOL. Luckily, I was on my side driveway, which already has oil spots and isn't front and center. The drain bolt has a number of a small metal shavings on it.

I took it for a drive, and there is definitely a substantial leak. In a short time at the gas station, there were already drips. I have a clean tray under it now, and I'll try to pin it down more.

This is the first time I've ever changed differential fluid. So, it was fun to do something new.

More car specs: automatic (3 speed), 2TC engine. Aside from this issue, it starts on first or second crank, and shifts ok. The speedometer seems like it may be off. I do see RTV sealant around the bell-housing. So, I wonder if at some point someone changed internal components (as taking it apart isn't necessary for drain/fill), and may have done so improperly.




How you like that GL-5 smell?

I hated it for years but now it piques my interest.

 

[CharBaby]

Walmart has the cheapest gallon of 80W90 gear oil at $12.**/gal.
This is what I am using for the Lexus RX in my signature as it has a leaky rear diff seal(cold temps only). The leak isn't bad in the summer months but, I have to keep it topped off ~ every 2 wks in the winter(SUCKS!)

Rhymingmechanic said it first!
Until you decide what you're going to do with the differential, just keep it topped off with any of the gear lubes as others have mentioned.

 

[Tegger]

Originally Posted By: OceanRuns

That looks EXACTLY like my 1975 1600, right down to the color, the grille, and the little vent on the hood!!! Lovely! The wheels should have chrome trim-rings on them, and are probably from an SR5.

As I said, your diff leak is most likely the pinion seal, which was common on these cars. Get underneath and see if there's oil slung all over the transmission tunnel where the driveshaft bolts on to the diff nose housing.

Better check the steering box as well; those also leaked.

 

[CharBaby]

My sister had a '72 Corona MKII and a '79 Corolla ST that she ran the life out of back in the day. They both looked similar...to the best of my recollection.(I got that from The Watergate Hearings). I watched them live on TV back in '73