2014 Toyota Sienna Transfer Case
About this episode
Bernie looks at a high-mileage 2014 Toyota Sienna with growling, humming noises that increase with speed and traces the problem to worn transfer case bearings. He explains that the repair is unusually labor-intensive because the engine cradle has to be dropped and the engine and transmission separated before the transfer case can come out. To keep costs down, the shop chose a used replacement unit, and he also notes that regular transfer case fluid changes can help prevent trouble.
2014 Toyota Sienna
"It's a 2014 Toyota Sienna van. What was going on with this particular vehicle?"
They’re working on a 2014 Toyota Sienna minivan. This one had drivetrain noises, and the shop traces the problem to the parts that help the van send power to all wheels.
This episode focuses on a 2014 Toyota Sienna van. The Sienna is a minivan, and in this case it’s equipped with an all-wheel-drive system that includes a transfer case—so drivetrain noises can point to that specific component.
drivetrain noises
"So this van came in for some drivetrain noises. We did some diagnostics on it. Road test to verify the customer's complaint."
They’re describing unusual sounds coming from the car’s power system. Those noises can come from parts that transfer power to the wheels, and the type of sound can help the shop figure out which part is worn.
“Drivetrain noises” refers to sounds coming from the power-transfer path—things like the transmission, driveshafts, differential(s), and transfer case. Because these parts work together, a specific noise pattern (growling/humming under acceleration) can help narrow down which component is failing.
hoist
"Put the vehicle on the hoist. Being all-wheel drive was excellent because you can run the vehicle on the hoist."
A hoist is the car lift in a garage. It raises the vehicle so the mechanics can access and test parts underneath more easily.
A hoist is a lift used in a repair shop to raise the vehicle off the ground. Running an AWD vehicle on a hoist can let technicians listen to drivetrain components more directly and safely while the wheels/axles are turning.
all-wheel drive
"Being all-wheel drive was excellent because you can run the vehicle on the hoist. We can listen to the various drivetrain components with a stethoscope and found that the right rear wheel bearing was noisy, which we talked about in a different podcast."
All-wheel drive means the car can send power to all four wheels. Here, it helps the mechanics test the drivetrain while the car is lifted so they can pinpoint where the noise is coming from.
All-wheel drive (AWD) sends power to more than just the rear wheels, typically both front and rear. In a shop setting, AWD can make diagnosis easier because the vehicle can be safely run on a hoist while listening for noises from different drivetrain components.
right rear wheel bearing
"We can listen to the various drivetrain components with a stethoscope and found that the right rear wheel bearing was noisy, which we talked about in a different podcast. But this particular one, we also found the transfer case was very loud."
A wheel bearing helps the wheel spin smoothly. When it wears out, it can make a loud growling or humming noise, and mechanics have to identify it before replacing other parts.
A wheel bearing is a set of bearings that allows the wheel to rotate smoothly while supporting the vehicle’s weight. A noisy wheel bearing often produces a growling or humming sound that can change with speed and may be mistaken for other drivetrain noises until inspected.
transfer case
"But this particular one, we also found the transfer case was very loud. There's a lot of noise coming from the transfer case bearings. And that's what this podcast we talk about replacing the transfer case."
The transfer case is a component in AWD vehicles that sends power to the wheels. If its internal bearings wear out, it can make loud grinding or humming noises, which is what they’re diagnosing here.
A transfer case is the gearbox that splits engine power between the front and rear axles on an all-wheel-drive (AWD) vehicle. When its bearings or internal parts wear out, it can create loud whining/growling noises, especially under acceleration or load.
transverse mounted engine
"And this is a transverse mounted engine. So it has to actually change the rotation from side to side. Am I thinking right? Transverse to longitudinal."
A transverse mounted engine means the engine sits sideways in the car. That layout changes how the drivetrain parts fit together, especially the parts that send power to the wheels.
A transverse mounted engine is installed sideways in the engine bay, with the crankshaft running left-to-right. This layout is common in many front-wheel-drive and some AWD vehicles, and it affects how the drivetrain is packaged and how power is routed to the wheels.
transverse to longitudinal
"Am I thinking right? Transverse to longitudinal. There's some gears inside there and Volvo, they called an angle gear unit, which is probably a good description."
This phrase means the car has to redirect power because the engine is mounted sideways, but the drive system needs to send power front-to-back. Gears inside the drivetrain handle that change.
“Transverse to longitudinal” describes changing the direction of power flow between a sideways (transverse) engine layout and a front-to-back (longitudinal) drivetrain layout. In practice, it requires drivetrain components (like gear sets) to re-orient rotation so it can drive the correct axle(s).
angle gear unit
"There's some gears inside there and Volvo, they called an angle gear unit, which is probably a good description. We ended up going with a used unit."
An angle gear unit is a set of gears that “turns” the direction of power. It helps the car send power from the engine to the rear wheels even when the engine is mounted sideways.
An angle gear unit is a gearbox section used to change the direction of rotation between drivetrain components. In this context, it helps connect a transverse engine setup to a drivetrain that drives the rear axle by re-orienting power flow using internal gears.
used unit
"We ended up going with a used unit. It was a much cheaper option than a new one. And there's plenty of low mileage used units out there that will last a long time."
A used unit means they replaced the broken part with one that came from another car instead of buying brand-new. It can save money, especially if it’s low mileage and in good condition.
A “used unit” refers to replacing a failed or removed component with a previously owned part rather than a brand-new one. For drivetrain parts like a transfer case, this can be a cost-effective approach if the donor vehicle and mileage are known and the unit is properly inspected.
engine cradle
"Why are we looking at an engine sitting on a cradle? So this is how you get the transfer case out. There is no easy way to remove the transfer case on this."
An engine cradle is the heavy metal frame that holds the engine in place. On some cars, you have to lower it to get enough space to remove drivetrain parts.
An engine cradle is a structural subframe that supports the engine and often connects to the transmission and other drivetrain mounts. Some vehicles require lowering or dropping the cradle to access and remove components like the transfer case.
engine transmission assembly
"Basically, the engine cradle needs to be dropped with the engine transmission assembly all in one. Then the engine has to be lifted off and separated from the transmission"
That phrase means the engine and transmission are treated as a single mounted unit during the job. They’re moved together to make room and to avoid disconnecting things that would be too difficult to separate.
The engine-transmission assembly refers to the combined mounted unit of the engine and transmission as a package. In some repairs, the cradle must be dropped with this assembly together because separating the transfer case without removing major mounting points isn’t practical.
drive shaft
"That's where the drive shaft to the rear goes. Yeah, we have a rubber glove on there just to keep oil from pouring out."
A drive shaft is a spinning metal shaft that carries power from the transmission/transfer case to the rear wheels. If it’s damaged or out of balance, you can get shaking or vibration.
A drive shaft (prop shaft) is the rotating shaft that transfers torque from one drivetrain component to another—commonly from the transfer case to the rear differential/axle. It must be balanced and aligned to avoid vibration.
catalytic converters
"What we're looking at above that arrow is one of the catalytic converters. And then the steering rack sits right above the green arrow."
Catalytic converters are parts in the exhaust system that help clean up engine exhaust. They can be located near other underbody parts, so mechanics sometimes have to work around them.
Catalytic converters are emissions-control devices that reduce harmful exhaust gases by converting them into less harmful substances. They’re typically mounted under the vehicle and can be physically close to drivetrain components, which affects service access.
steering rack
"And then the steering rack sits right above the green arrow. I believe that stays in place on its mount."
The steering rack is the mechanism that turns your steering wheel into the motion that actually steers the wheels. It’s a mounted part under the car, so it can be in the way when working on nearby components.
The steering rack is the core component that converts the steering wheel’s rotation into left/right movement of the tie rods. It’s mounted to the vehicle and can sit close to other underbody parts, so it may need to stay in place or be protected during drivetrain work.
differential
"So this changes side to side motion down the vehicle to power the rear wheels. So then there's also, when part of this, there's a differential in the front and a differential in the back."
A differential is what lets the two wheels on the same axle spin at different speeds, especially when you’re turning. Without it, the drivetrain would bind up.
A differential allows the left and right wheels on an axle to rotate at different speeds, which is necessary when turning. In AWD/4WD vehicles, there can be a differential at the front and another at the rear to manage power distribution.
trans axle
"Exactly, yeah. And the front differential is part of the transmission. So it's a trans axle."
A transaxle is when the transmission and the differential are packaged together in one unit. It helps simplify the drivetrain layout, especially on certain drivetrains.
A transaxle is an integrated unit that combines the transmission and the differential (or transaxle gearbox) into one assembly, commonly on front-wheel-drive layouts. The speaker is noting that the front differential is part of the transmission assembly in this configuration.
bearings
"So eventually they do go bad. There's bearings inside that wear out. And that's what causes the noises."
Bearings are the small internal parts that help moving components spin smoothly. When they wear out, they can start making noise and may lead to bigger problems.
Bearings are precision components that allow rotating parts inside the transfer case to spin with low friction. When bearings wear out, they can create grinding or whining noises and eventually contribute to transfer case failure.
fluid change
"Maybe a fluid change or two over the history of the vehicle might have made a difference. We don't know the history of the vehicle, but changing the fluid every 100,000 kilometers is a good thing to do."
A fluid change is when you drain out old, dirty fluid and put in new fluid. In a transfer case, clean fluid helps the internal parts last longer.
A fluid change means replacing the lubricant in a component (here, the transfer case) to remove contaminants and restore proper lubrication. For transfer cases, fresh fluid helps reduce wear on gears and bearings.
100,000 kilometers
"We don't know the history of the vehicle, but changing the fluid every 100,000 kilometers is a good thing to do. OK, there's a question."
They’re suggesting you change the transfer case fluid about every 100,000 kilometers. Doing it on schedule helps keep the internal parts lubricated and reduces wear.
“100,000 kilometers” is the service interval being recommended for transfer case fluid changes in this discussion. Regular intervals matter because transfer case fluid degrades and picks up wear particles over time.
fill plug
"The fluid drains out and then there's a fill plug on the side. It's fiddly to get to. And there are some transfer cases and some differentials are very difficult to change fluids in that some cars"
A fill plug is a screw/bolt you remove to add fluid. It also helps determine the correct fluid level, so the vehicle needs to be positioned correctly while you service it.
A fill plug is the access point used to add the correct amount of fluid to a component like a transfer case or differential. Because the fill level is often set by the plug’s position, getting the car level matters for an accurate fluid level.
Pawlik Automotive
"If you're having issues with your transfer case or your Toyota Sienna, the people to see in Vancouver, BC, Canada are Pawlik Automotive. You can book your appointment at pawlikautomotive.com."
Pawlik Automotive is the repair shop the hosts suggest you contact. They’re described as having lots of experience working on different kinds of cars and repairs.
Pawlik Automotive is the shop the hosts recommend for diagnosing and repairing drivetrain-related issues like transfer-case problems. They’re presented as a local service provider in Vancouver, BC, with experience across many vehicle types.
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