gabriel_koehler1
Supra Low Coolant Issue
Summary of the thread
A 2002 Toyota SupraIV owner experienced a check engine light due to a low coolant level, despite not noticing any leaks. Possible causes discussed included a faulty radiator cap, cooling fan issues, or a water pump problem. A suggestion was made to check for milky residue under the oil cap, indicating a potential head gasket issue. Ultimately, the problem was resolved by replacing a faulty coolant reservoir cap, which had caused slow evaporation.
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4 comment(s)
gabriel_koehler1 (community.author)
Thanks for the suggestions. I will check the radiator cap and cooling fan. How would I go about checking the water pump? And what does milky residue indicate, head gasket failure?
wernersturm48
The water pump is a pain to check properly without taking things apart, you're mainly looking for leaks around the pump housing. Some people listen for unusual noises, too, but that's not reliable. Yes, milky residue is a sign of coolant mixing with oil, which is often a head gasket issue. Given the error code and low coolant, I'd honestly suggest taking it to a workshop. They can pressure test the system and properly diagnose it. Could be a simple fix, or something more involved. Better safe than sorry!
gabriel_koehler1 (community.author)
Okay, thanks for the advice. I appreciate the help. I took the Supra to a workshop as you suggested. Turns out it was just a faulty coolant reservoir cap, causing slow evaporation over time. Replaced it for 52€. Everything seems fine now.
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TOYOTA
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SUPRAIV
wernersturm48
Low coolant in a Supra? Hmm. I had a similar issue with my old Volvo V70, but the symptoms were more dramatic - overheating and steam! First, check the radiator cap. If it's not sealing correctly, coolant can evaporate. Also, give your cooling fan a look; make sure it's kicking on when the engine gets hot. Ever checked the water pump? Any milky residue under the oil cap?