Differential Howl still a problem with the 4th gen. Update: Differential officially cooked

My 2gen 2009 Tacoma 4cyl 2WD started with a pinion whine (I never thought of it as a howl but maybe) which started about 5-7k miles and gradually got worse. Originally only at about 55-70 when you were coasting or very light acceleration. If you took you foot off the gas and decelerated it stopped and with moderate acceleration it stopped. Took until about 39k after 3 tries I took the service manager for a ride and he heard. Said a problem with a clearance not right from the factory. They could have shimmed it if caught early but the ring gear was already worn. The replacement started making noise at about 56K and dealer could not hear it. Had my shop drain diff through a filter funnel after the dealer would not and bits of metal and gunk was found. Went back to dealer and he said I needed a left axle bearing which is a sealed bearing on the old 2wd. Had my shop change the bearing which was an expensive part with the ABS sensor, etc. He said that the metal and gunk was from the diff and not the axle bearing. Possible that when the original chuck was changed they did not flush the rear end tubes enough but likely that this diff was melting down also. Truck was totaled at 62K.

 

While aftermarket gearsets such as yukon or nitro do have a strict break in period, it's not needed on an oem differential. Toyota oem gears are lapped with the same pressure driving creates. They are already "broken in" at the factory. That being said, Toyota does recommend varying speeds and avoiding towing when the truck is brand new.

 

I wonder if the problem exists with Japan built Toyotas? The quality, fit and finish of bat Guano Mexico seems worse than Baja California Mexico built Tacomas. I had never heard of vehicles coming from the factory with low transmission and differential fluids before the shift to Mexico.

 

Even if that is the case the appearance of the oil when I did my first change at 1000 mile indicated that further break in was required than was done at the factory including the material that was now stuck to the magnetic drain plug.. For me that was worth the extra $40 and 1 hr of effort. But its my vehicle and my $40, your results may vary

And its not just factory gears that are lapped... From Nitro gear

Nitro gears are manufactured from 8620 steel gear forgings in the same manufacturing facilities as GM, Dodge, Ford and Toyota. They are precision machined using computer controlled processes, heat treated, CNC triple-lapped and Rockwell tested for hardness.

And Yukon.

Gear sets are lapped at the factory.

Fact 1: At 1000 mile the magnetic drain plug has collected metal
Fact 2: The oil has obvious very fine metallic particles floating in it as any picture of a OEM or aftermarket gear sets show at 500 miles.


And even for all this pre lapped gear sets they recommend 500 mile break in oil changes
Saying it wont benefit from a break in change is denying the facts.

 

When I do the 2nd oil change at 5K I think I will change the rear diff fluid and screen it. I'm thinking I should wait to change the front diff fluid since it has not had much use at all other than to engage now and then to keep it working? Only about 4k now and has not been used to tow yet as I was going to rent a camp trailer but ended up renting an RV because they had not figured out the recall on the axle yet.

 

No two cars are going to be the same. Diffs sound different from vehicle to vehicle and brand to brand. Sometimes you get what you get...it's just a little noise most of the time. Just saying, if it's going to bother you...then make the first 200 miles very, very easy. Driving off the lot with 3 or 4 miles on it and getting on the freeway (even if you're keeping it under 55) for an extended drive home is probably not going to help. Diffs get really hot in the first 100 miles. Even if they're lapped at the factory...the rear gears really need 100-200 miles of short trips...no hauling/towing...and keep it off the freeway if you can. Then you can beat the crap out of it all you want.

I am not at all easy on my vehicles...but I do baby them off the lot these days.

 

The only thing I've heard resembling a 'howl' is in 4L.

 

Those are exactly the results i found. I changed all the oil (both diffs and the TC at 1000 mile mostly because I had already bought enough to do them all.
The TC was supper clean and really didn't need it. And same for the front diff. When not in 4WD only the spider gears are spinning because of the ADD (and not the ring and pinion) . Even if i used 4WD 5% of the time the wear the front diff experiences would be 1/20 of the rear so maybe 100K would be a better interval there..

 

I've got a 2023 TRD OFF-ROAD with 7,600 miles and I started to pick up the howling noise in the Rear Diff after a few thousand miles. So, I took it into the dealer this week and they said my differential has issues. The shop ordered a bunch of parts and they will rebuild it once the parts arrive.