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BACKYARD MECHANIC: CVT transmissions need good fluid loving


2017 Mazda 3 4dr Sdn Auto SE for $23,402

2017 Mazda 3 4dr Sdn Auto SE

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QUESTION: I had a new 2005 Ford 500 LTD with all-wheel drive. The owner's manual recommends changing "transaxle fluid and high-pressure filter on vehicles equipped with CVT transmissions" at 100,000 km. The Ford dealer did this job on another Ford 500 and told me that they had a very hard time in doing this and had to replace some parts.

I debated whether to go ahead with this, but finally came to the conclusion (because Ford recommends it) that I would have it done. Fortunately, they had no apparent problems with my vehicle.

Sometime later I had a fluid leak under the car and lost all power. I had it checked out and found that the "O" rings had not been properly installed -- they were twisted.

I now have another (used) 2005 Ford 500 LTD (because I really like the car) with 130,000 km and am trying to decide whether to have the transaxle fluid and high-pressure filter replaced on this car. I've obviously been putting it off for a while.

What is your recommendation regarding this service? Is it absolutely necessary to have this done?

ANSWER: I would have the fluid changed at the recommended mileage intervals on any CVT transmission. These transmissions use a steel belt that runs between two pulleys to move the vehicle. By varying the width of the pulley sheaves with the computer controls and hydraulics, the belt can ride further up or down on the pulley sheaves. This varies the gear ratio of the transmission.

Unlike a snowmobile CVT rubber belt, which is pulled by the engine, the steel belt in automobile CVT gearboxes is "pushed." The belt locks into a rigid position when it is pushed, yet can release and bend around the pulley when the tension is released. This seems impossible at first but it works.

The special CVT oil used in these transmissions is critical to belt and pulley life, and to the steel belt being able to grip onto the steel pulley sheaves. The oil has a lot of work to do, so it does need to be changed.

As for previous service problems, oil changes are often assigned to a junior staff member in the repair shop and a lack of experience may have caused the repair issues. You could check with the service department to see if this work can be done by someone with experience in servicing the CVT.

QUESTION: I am having this very frustrating problem using my iPod in my wife's Mazda2. There is no USB input so my only option is via a 3.5mm AUX jack which is part of the Mazda2 stereo system. I also use an iPod cable to a USB connector that fits into a Belkin cigarette lighter plug to charge the iPod.

When I turn on the iPod and radio there is an audible static hum in the background of the music. If I turn off the car motor the hum is reduced to a minimal amount. If I unplug the iPod power connection, I get music with no vocals, as if there wasn't enough power in the iPod to push the vocals through the car stereo system.

I asked the Mazda dealership if they knew of any problems or issues. They said no. I had their mechanic connect my setup to another car, a new Mazda3, and the same thing happened. It doesn't happen in my Acura. Any suggestions?

ANSWER: There may be a grounding problem that is causing the noise. Mazda states in the owner's manual that "noise may occur depending on the product connected to the auxiliary jack. With regard to connecting a portable audio or similar device to a power source, use the battery for the device, not the accessory socket."

This type of "electronic" noise is found in all vehicle power wiring and is difficult to eliminate. Computer, audio and other module-control and communications wiring is usually routed away from main power cables for this reason.

You could listen to your iPod using the Bluetooth connection if your car and device are equipped with them. Another option would be to have the optional dealer-installed iPod adapter installed at your local shop. This will charge the device and connect it to the audio system.

Jim Kerr is an experienced mechanic, instructor of automotive technology, freelance journalist and member of the Automobile Journalists' Association of Canada.