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Beyond pissed at Hyundai

I have a 2005 Hyundai Elantra. One day I opened the hood to find coolant residue on the engine, but no holes in the hose. Infact, The coolant had blown out through the return. Problem is that there was no problem. Not According to the Temp Guage any way. So I changed out the hoses and the thermostat, or rather had them done. Fast forward 10,000 miles. Second verse same as the first. So I topped the coolant burped the system and still I have high temp on the Radiator-engine return and an ice cold engine-radiator return. So I called the dealer and get this. Its probably the thermostat its common. and…wait for it… It won’t show up on the temperature guage. So this means any Tom Dick or Harry can overheat the engine do to low coolant or insufficient coolant flow ( actually zero if the thermostat is closed) and never know about it until the engine just dies. I am glad I caught it while I still have an engine to talk about but I just thought others may want to know. The elantra is poorly designed in this way and should be avoided.

oops… reverse the hoses. the Engine-radiator is hot and the radiator-engine is cold. The rest is right

The hose to the radiator is hot, and the hose from the radiator is cold? This seems to be a plugged radiator, to me.

Help me understand it, hellokit. It seems like the engine warms the coolant and the radiator cools it when things are working right. 'Enery the 8th’s Elantra must have some other problem; possibly the thermostat, as he mentioned.

The time versus money favors the dealer on this one. I am really hoping its a Warranty issue but I am not holding my breath.

Did you buy this vehicle used or new? If you bought it used, did you have it inspected by your mechanic before you bought it? Did you buy it “as is” or with a warranty?

On day one, when you found coolant residue on the engine, I would have taken it straight to the shop and had the cooling system pressure-tested. In fact, doing that right now might not be a bad idea.

The “cooled” coolant would still be hot to touch. If the hose is cold, it must not be getting any flow.

Sounds like a stuck thermostat to me and yes, it’s entirely possible to have an engine running hotter than normal without it showing up on the gauge. This is usually true of engines that have the gauge temperature senders mounted up high.

The car is 5 years old and I don’t consider it a design flaw at all although granted, my preference would be that the sender be mounted down lower.
How often do you check the coolant level anyway; e.g., between the first time and the second go-around?

And if you’ve run the engine to the point where it’s hot enough to die then your engine does have some problems. The only question is the degree.

Thanks, Whitey.

I agree with what everyone is saying. Remember that you want the engine running at operating temperature, and not cold. The coolant reentering the engine should have had disspated from it enough heat to keep the engine running at operating temp, not enough to make the coolant cold. The actual function of the T-stat is to restrict flow sufficiently to allow the engine to maintain operating temperature. The engine would cool fine without a T-stat, but would never warm up.

There are four common cause of inadequate flow: a thermostat stuck closed, a clogged radiator, a water pump with eroded imellars, and a hose with a collapsed inner lining. All of these can be tested for.

By the way, whenever you have an undiagnosed cooling problem like yours it’s good practice to also check the function of the fan. Your overheating could be happening when you’re stopped.

Sincere best.

***There are four common cause of inadequate flow: a thermostat stuck closed, a clogged radiator, a water pump with eroded imellars, and a hose with a collapsed inner lining. All of these can be tested for. ***

Maybe five – the fifth being a air bubble under the thermostat. Put a thermostat into an old Mazda once and it simply would not open although it worked fine when heated in boiling water on the stove. Finally gave up and replaced it with a different brand which worked properly. The difference? The brand that worked had a small hole that allowed a small amount of air-fluid exchange even with the thermostat closed. Air bubble was the only theory I could come up with.

I had an overheating problem with my K-car, and the thermostat was the culprit. It was a 5 or 10 dollar part and easy to replace, and it was an easy fix. Are you sure that “the elantra is poorly designed in this way” or did you just miss an obvious cheap fix?

I am kinda dense tonight but still interested, may I summarize? The issue here is an engine that runs hot but the overheat condition is not relayed to the temp gague?

Dealer says that the thermostat is probably the faulty component causing the overheat, but what reason is being assigned too the “no indicated overheat” condition?

I think we all know a sending unit that is not immersed in coolant will send an incorrect value, is this what we are dealing with here?

Oldschool. That’s What I Get Out Of It.

Now it sounds like we’re dealing with a head gasket or another reason there’s air in the cooling system.


In rereading the thread, I agree. Nice catch oldschool.