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Coolant draining, no leak detected

8K views 30 replies 12 participants last post by  Red Raspberry 
#1 ·
I have a 2012 Hyundai Sonata with 95,000 miles. My coolant is obviously draining somewhere. Every 5 - 7 days the coolant lowers from the full line to low line. The Hyundai dealership completed a diagnostic/pressure test but could not detect a leak anywhere. Any advice or ideas?
 
#3 ·
No white smoke. About 6 months ago, the place I took the car to for an oil change also did a coolant flush. They forgot to attach the hose and coolant coated my engine. Needless to say, it always has a hint of coolant smell. Not overpowering though now, so I don’t think there is any new coolant burning. I will keep an eye and nose out for both things you noted however. Thanks!
 
#6 ·
Does the heater inside work? Does the engine temp seem normal or running higher? Also, are you adding it to the expansion tank OR directly into the radiator?

Unless it's now going into your engine our still dripping out, it sounds like they didn't bleed the system of all air (especially after they messed up).

If you're able to, park car on incline, let cool down, open radiator cap, add coolant, start car and let ildle while squeezing upper rad hoses. Keep adding coolant as it goes down and air is displaced. When bubbles mostly stopped, close radiator cap and fill expansion tank.

You may need to repeat this once or twice. Reason your expansion tank drains is back half of your system that's opened and closed by tstat stays closed until engine warms up. At that point, coolant from rad flows in and displaces some of the air. Now that rad is low, expansion tank fills radiator. And the whole thing repeats... 7 times.

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#7 ·
Actually, scratch all of the above. The shop that did the job should really deal with this; not you. Unless you don't trust them to check it out again, I'd take it right back and describe the issue before you touch it some more and they claim you caused the issue.

Your money, their work, their problem.

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#9 ·
I would strongly suggest you also have them (or a trusted dealer) do a pressure test (while warm) to ensure you don't have a gasket leak (at the heads, etc.) into the engine which can cause all manner of bad news!
 
#10 ·
Tiny cracks in the head gasket ( I have had this issue) would only appear in cold weather when the engine cooled at night the gasket would contract and the coolant would be sucked into the cylinders and be burned at start up in the AM,. No coolant leaks could be found, pressure test when warm was also fine, no coolant in oil etc. . No problem in the summer months but every winter the coolant level would drop consistently and I would add a sealer to get me through the winter and all would be fine again. My son currently has the same issue with his Altima. Just saying, a possible scenario but not sure where the original member lives, is it cold enough in the winter for the cracks in the gasket to contract and open up etc.
 
#11 ·
I did not know that about the need to test when it is stone cold. Thanks for the tip!
 
#13 ·
Need to know which hose they took off / or how they did so called flush...

Only real leak concerns I have seen with the 2.4 / 2.0T is the heat hose at fittings on back of head,, they like to seep when re-install and factory spring clamps re-used,, even when setting clamps back in original location via impressions on hose...

Some times you have to just do a good visual and find the stains, as coolant at very slow seep will evaporate and not have chance to make it to floor on a hot engine.. look for green-white chalk stains.. finger around ends of hoses at fitting for seepage.
 
#14 ·
When DIY for that location, do you recommend replacing factory clamps with worm gear clamps or something else (better)?
 
#22 ·
It's beyond me what exactly you mean..."you can't stand backwards on stairs...". Why not? I think I can!
 
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