RADIATOR FLUID GOING DOWN SLOWLY

  • Tiny
  • houssarinit
  • 1992 Toyota Tarago
  • 300,000 miles

I have a 1992 Toyota Tarago GLX that loses its radiator fluid every 2-3 weeks. I have had the car pressure tested, had a new radiator put in, hoses and clamps tightened and tested, a new radiator cap size 0.9 put on - still with no luck. Does it need a tighter cap? Any ideas where the fluid is going

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Wednesday, August 8th, 2012 AT 6:09 AM

24 Replies

  • Tiny
  • caradiodoc
  • Expert
  • 25,437 posts

Most likely cause is a leaking head gasket. Add a small bottle of dark purple dye to the coolant, drive it for a week, then search with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If you find it inside the tail pipe, the head gasket must be replaced.

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Wednesday, August 8th, 2012 AT 6:39 AM
  • Tiny
  • KHLow2008
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  • 41,997 posts

Have you checked the heater core?

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Wednesday, August 8th, 2012 AT 2:41 PM
  • Tiny
  • houssarinit
  • Member

Thanks for your quick replies. I haven't had the heater core checked yet. My mechanic has assured me it is not the head gasket. He has had it under pressure test now fow 2-3 days and he still can't find any leaks. Can it still be the head gasket? I am praying to just go for a tighter radiator cap for $15 instead of a new head gasket for bigger money. I'll change the head gasket at last resort. Could be anything else other than the head gasket?

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Thursday, August 9th, 2012 AT 1:58 AM
  • Tiny
  • caradiodoc
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  • 25,437 posts

Since we know coolant is being lost, add a bottle of dye to see exactly where it's going.

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Thursday, August 9th, 2012 AT 2:03 AM
  • Tiny
  • houssarinit
  • Member

Do I buy the purple dye from an auto shop?

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Tuesday, August 28th, 2012 AT 6:37 AM
  • Tiny
  • KHLow2008
  • Expert
  • 41,997 posts

Auto shops should be able to tell you which type to use.

Coolant depleting from recovery tank with no losses from radiator itself is never a head gasket problem.

The most common causes of minutes leaks are hose joints. Check all joints for signs of coolant. When leaks are minute, they sometimes do not leak when engine is hot and at times is the other way round, leaks occurs only when hot.

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Tuesday, August 28th, 2012 AT 6:42 AM
  • Tiny
  • houssarinit
  • Member

Will a tighter radiator cap fix the problem or make it worse. Mechanic has had the car under pressure overnight, to find no leaks in the morning, and no drop in pressure. He has found leaks at hoses and the radiator that he has fixed, but the fluid still goes down slowly. I can smell fluid when I stop the car

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Tuesday, August 28th, 2012 AT 6:46 AM
  • Tiny
  • caradiodoc
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  • 25,437 posts

Auto parts stores have the dye. They will ask what you're using it for so they give you the right stuff. It will say right on the bottle which fluids it can be added to. The bottles are only about an inch in diameter and two inches tall. Many auto parts stores also rent or borrow tools and they will have the black light used for searching for the leak. The dark purple dye will show up as a bright yellow stain under the black light. Follow that stain back to the source. Don't forget to check at the inside of the tail pipe.

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Tuesday, August 28th, 2012 AT 6:48 AM
  • Tiny
  • houssarinit
  • Member

Hello Mate. I have the dye for the radiator, but I can't access the radiator directly. Can I pour the dye into the overflow bottle? Do I let the bottle run down to empty and then put the dye in? Thanks

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Wednesday, September 5th, 2012 AT 3:41 AM
  • Tiny
  • caradiodoc
  • Expert
  • 25,437 posts

Yup, you can pour it in anywhere as long as it will mix with the coolant. I guess I'd wait until the engine had been running and is still warm. The pressure will be gone in 10 to 15 minutes but the reservoir will still be full. Within an hour the coolant will begin to cool down and contract. That will draw some back into the radiator along with the dye. It could take a few warmup cool down cycles but with each one more of the dye will go into the system.

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Wednesday, September 5th, 2012 AT 4:53 AM

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