A bright red trail under the car
Automatic transmission cooling hoses can split and leave a bright red trail of fluid under the car. RAA's advice is not to drive it until it's been inspected, because a gearbox that runs low on fluid can be badly damaged. If the gearbox slips or won't select a gear while you're driving, pull over somewhere safe and switch off.
What Adelaide asks of a gearbox
Towing up the freeway
Heading east to the Hills or Melbourne, the South Eastern Freeway climbs out of Glen Osmond, and it's a long pull with a caravan or a boat behind. RACT says transmission faults on the road are more common when towing. Have the fluid and any leaks checked before the trip, not after the first hot climb.
South Road's stop-start
The North-South Motorway is being built to bypass the traffic lights on South Road, but the River Torrens to Darlington section is still under construction. Until it opens, many cross-town drives are a string of take-offs and stops, and summer heat makes that harder work for an automatic's fluid.
The long run north
Port Augusta is about 310 km up the highway, and the outback tracks start well beyond it. A long, hot run with a load on is when a tired transmission gives itself away. On a 4WD, the transfer case and differentials have their own oil, and they're worth checking at the same time.
Automatic, manual or CVT?
Automatics slip, flare between gears or take a moment to engage when the fluid is low or worn, and sometimes when the pump or clutches inside are wearing. The fluid check comes first.
CVTs use pulleys and a metal belt instead of gears. They're sealed, so they shouldn't need topping up, and a low level points to a leak. A worn CVT makes a noise that gets louder over time, or shudders at low speed, and driving on regardless risks more damage.
Manuals that crunch going into a gear often have worn synchros (the rings that match gear speeds), though a dragging clutch can feel the same. Clutch repairs covers that side. Whatever the gearbox, RAC WA's advice is to stop fully before changing between drive and reverse.
What the mechanic should do first
- Read any stored transmission codes.
- Check the fluid level and condition, and say what that tells them.
- Look for leaks at the seals, the sump and the cooler lines.
- Road test the car, cold and warm, to feel when the fault happens.
- Tell you in writing whether it's a service, a repair or a rebuild, before any of it starts.
Where we'd start
We'd have the fluid level and condition checked before anything else, because it's the simplest answer and sometimes the whole one. If it turns out to be more, we'd want the diagnosis and the options in writing before agreeing to a rebuild or a replacement gearbox.