[flat4]

Hello to all Hyundai owners! I'm new to the forum. Luka from Slovenia. We own a i30 1,6 CRDi.
I was just searching for coolant overflowing problems with i30 and found this topic, so I joined the forum in hope to get some advice.
@Phil: I hope you don't mind me jumping in and taking the opportunity: Last week we noticed the expansion tank was almost empty and it was rusty colored. I filled it between L and F and it overflew the next day. We took the car to a dealer and they said it needed cleaning. But a week after it came back from service, I think the coolant level in the expansion tank is lower again. And it is rusty colored. Do you have any idea what it could be? Also, when the problem first occured, heating was poor. Now it works, but I noticed today that the right side of the dashboard vents are blowing cooler air than the left side, when the heating is turned all the way to the max.
Any help would be much appreciated.

Best, Luka

[Phil №❶]

@Luka, you're very welcome and welcome to the forum too. It's tricky to give advice, as there are alternatives.

1- You could take the car to a radiator specialist. It sounds like there is a build up of sediment in your cooling system. The only proper way to remove it is a power flush, with the correct equipment.
The heater in the cabin is a small heat exchanger, this would need to be flushed also, however, care must be taken not to blow the seams of the heat exchanger, or you will have a leak inside your car. Hard to get at usually and expensive to repair. Even with this, the sediment will gradually return. Once it is there it is very difficult to remove.

Special care would be needed to ensure that the replacement coolant is of good quality and suitable for your car.

2- Go to Hyundai and have them do the job, it will cost plenty.

I'm not sure if you're still in warranty or not. If so, you should use option 2, otherwise option 1.

The concerning factor is, how did the coolant get dirty.

Causes are, (1) Air in the cooling system, caused by a slow leak and low reservoir fluid level, which allows rust to occur. (2) Plain water used as coolant for an extended period. (3) Incompatible coolant or mixes of different coolants used.

Good luck.

[Dazzler]

Welcome flat4

Phil has pretty much covered it.

Sounds like the least you need is a coolant flush and replacement with new. (ASAP)

[Doggie 1]

Welcome to the forum, flat4. 

[flat4]

Phil and Dazzler, thank you for the replies. We drove the car to an authorised dealer exactly a week ago, explaining that the coolant was overflowing. Since the car is just out of 3 year warranty, we asked to be informed of the costs of repair before anything is done. They said they have checked the car and the system needed to be flushed and refilled with fresh coolant. They charged us 107 € for that, so yes, I get the expensive part I checked the coolant level in the expansion tank again yesterday, and it is below L line again. So, what to do next? Could the flaw be in the expansion tank cap? I remember hearing that it could be the cause of quite some coolant problems... Also, fearing the worst: What are the symptoms of blown head gasket? If this is the case, it should be covered under the 5 year motor warranty, right?

p.s. I would also like to say, that the car was only serviced by authorised dealers, since it was under factory warranty up until the last regular service.

Cheers, Luka

edit: Thank you all for the warm welcome!

[Shambles]

Hi Luka, and welcome aboard.

Sorry to hear of the problem you're having - what a shame your warranty period is up

Anyway, as TBird1 hasn't been back to us yet with an update to his issue I'll break your post away to create your own brand new thread.

No, no, I insist - and there's no charge for your first thread

[flat4]

Thank you Shambles.

Cheers, Luka

[The Gonz]

All good advice. Does anyone else think it is odd that the temperature would be different between sides? I assumed there's just one heater core and that this might indicate a problem in the ducting or its valving.

[flat4]

I have to say I suspect a blown head gasket causes pressure build up as the expansion tank keeps making quirky "teapot" whistling noise after a run on the highway. Unless this is normal?

[The Gonz]

The coolant should never boil. Two ways of avoiding boiling are 1) don't go over boiling temperature (a bit higher than 100 degs for mixture such as coolant) and 2) maintain higher than atmospheric pressure.

You may have one or both of these problems without it being a blown head or gasket. It may even be a faulty (premature) expansion valve - as in thermostat.

[flat4]

Thanks Gonz. I am always monitoring the temperature gauge on my dash and it never goes over 90 degrees. So, to eliminate the faulty expansion valve cap, I should replace it and see what happens?

[The Gonz]

Thanks Gonz. I am always monitoring the temperature gauge on my dash and it never goes over 90 degrees. So, to eliminate the faulty expansion valve cap, I should replace it and see what happens?

I haven't looked at prices but it sounds like either a very cheap potential solution or spare cap.

[Phil №❶]

You must ensure that when the engine has stopped that the fluid level in the expansion tank is at least at the F mark. As the engine cools, fluid is drawn back into the radiator from the tank. If it's not high enough, then air will be drawn in and that is bad. Air contains oxygen, oxidised iron, Fe O₂ is rust.

[eye30]

Can dye be put in the system and them check to see if there are any signs of leakage.

[Phil №❶]

BTW, blown head gaskets produce a distinct ticking sound, under load. Once that is heard, the engine stops soon after. Also, there is commonly water present in the exhaust pipe, well after the car has warmed up. In severe cases, you can actually hydraulic the motor, which will prevent the engine from cranking at all. All these symptoms are to be avoided at all costs.

[flat4]

I dropped by my friend who is a mechanic. We ran the car through it's paces and did we figured out that a blown head gasked would have built up more pressure. We both agreed that faulty tank cap valve is the main suspect here, as slight breathing through the cap can be heard even with a gentle squeze of the radiator hose.  Will order a new cap at the dealer tomorrow (8,60 € + 10 day delivery...) and then I'll keep you posted.

p.s. Heating is okay today...

[eye30]

Will order a new cap at the dealer tomorrow (8,60 € + 10 day delivery...) and then I'll keep you posted.

Better/cheaper option than other suggested.   

[flat4]

Hey. I replaced the faulty expansion tank cap and the coolant overflowing has stopped. But since the cap was faulty, the coolant has been boiling in the system, so the dealer told me the cabin heater unit has to be replaced because is totally clogged...

Man, I am really starting to feel frustrated arround this car. Does anyone here have some advice on the cabin heater?
I appreciate the help, Luka

[Phil №❶]

That's bad news Luka.

The heater core can not be responsible for your coolant overheating problem. You need to see a professional to find out where your blockage is. The engine thermostat may not be opening or the radiator and or engine cooling pathways in the engine block may also be clogged. These need to be cleared to cool the engine. This is my opinion, sorry.

[Just Rick]

flat4 I haven't anything else to offer from what has already been offered,my biggest question would be why the heck do you have rusty looking coolant in a relitively young car,if the car has been regularly serviced as per the book from new,I couldn't see why you'd have rusty looking coolant,anyhow hope you get it sorted,cooling system problems are the pits.

[Twempie]

Had same symptoms as Luca (low rusty coloured coolant and air heard escaping through the radiator cap when lightly pressing the top hose while the engine was still warm).  In addition ther was no heat coming through the heater. The dealer tried an engine flush and replaced the coolant but this didn't fix the loss of coolant problem. They then replaced the heater matrix under warranty (which turned out to be clogged) and fitted a new radiator cap which I suspected was the source of the problem. So far there has been no more coolant loss although the coolant is looks brown (probably needs a good flush through with water).

One difficulty however is that the coolant resevoir bottle is dirty and I have to remove the radiator cap to check the levels as the fluid is no longer visible through the plastic. Read somewhere that it can be cleaned with abrasive material like coffee grounds but I don't fancy taking the hoses off in case I can't get them on again!
Cheers

[Phil №❶]

Even if you did clean the reservoir bottle, as the "brown" stuff is all throughout your engine, it would simply return quickly. Fluid under normal conditions, flows from the motor on heating then returns to the motor on cooling, so you see it's a two way path. It's a closed system with supposedly, no air, so no rust. Unfortunately, yoou have had air in yours, and the coolant has not been able to stop rust from developing.

There are several problems here.

The rust is in suspension in the coolant and is as fine as clay, so it will eventually, over time, settle back in the heater core and the core of the radiator.

A thorough professional flush and clean may resolve the rust issue, but I can't see Hy being interested in that. As your repair was a warranty job, you can't take the vehicle for proper flushing toi another company, without the approval of Hy.