2000 Chevrolet Lumina transmission

Tiny
MARKYOES
  • MEMBER
  • 2000 CHEVROLET LUMINA
  • 3.1L
  • FWD
  • AUTOMATIC
  • 111,000 MILES
Losing transmission fluid but it is not leaking on the ground where could it be going and what would cause this
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Saturday, October 11th, 2014 AT 5:06 PM

5 Replies

Tiny
CARADIODOC
  • EXPERT
The most likely suspect is the radiator. Some cars have external oil coolers for the transmission fluid, but most have those coolers built into one tank of the radiator. Transmission fluid pressure while the engine is running can push the fluid through a leak into the coolant, which is bad. Cooling system pressure right after a hot engine is stopped can push coolant into the transmission cooler lines, which is real bad. Petroleum products in the coolant will rot rubber hoses from the inside, but that takes time. Water and antifreeze in the transmission don't lubricate moving and sealing parts like transmission fluid does.

If I'm right, you'll find an oily mud floating in the coolant reservoir.
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Saturday, October 11th, 2014 AT 9:30 PM
Tiny
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Ok I checked the coolant reservoir and I could see tranny fluid in it. So the onlu way to fix it would be getting a new radiator. Correct.
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Saturday, October 11th, 2014 AT 10:03 PM
Tiny
CARADIODOC
  • EXPERT
Yup. Have the transmission flushed right away, and have the cooling system flushed soon. If you still have the red Dex-Cool, (Dex-mud) antifreeze, most mechanics will want to get that stuff out of there. Be sure to replace the coolant every two years, not every three years like it says on the stickers on your car, and don't consider it to be "lifetime" coolant like GM advertised. Water pump lubricant and corrosion inhibitor additives wear out in about two years, and acids form that corrode metal parts. This is real comm on GM cars but it usually causes leaks in the heater core first.
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Saturday, October 11th, 2014 AT 10:26 PM
Tiny
MARKYOES
  • MEMBER
Thank you for the info. I'll get started on it in the morning. I had this problem once before on a 75 chevy 4x4, but it was the vacuum module and it was sucking the tranny straight into the manifold and into the engine oil.
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Saturday, October 11th, 2014 AT 10:46 PM
Tiny
CARADIODOC
  • EXPERT
That shouldn't have gone into the engine oil. It will get sucked into the cylinders and burned. There will be real black exhaust smoke. That's not so serious because nothing gets sucked into the transmission fluid. This was pretty common on Fords too. Only Chrysler never used a vacuum modulator.
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Saturday, October 11th, 2014 AT 11:09 PM

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