Hyundai i40 coolant issue

BlakeS94

I've been having persistent issues with my coolant for the past few months. Originally it was leaking slightly, my mechanic noticed the water pump was shot so changed that, a few weeks later there was another leak which turned out to be damage to the front of the radiator, shortly afterwards yet another slow leak, which was the bottom rad hose clip was not clamping properly so it was replaced, all been okay since recently I was driving and it overheated. Got it into the garage and the system was bled and refilled. It's very irritating at this stage, been in the garage maybe 4/5 times. It needs to go back to the garage tomorrow because I was driving home from work and the coolant reservoir emptied itself and there was coolant under the bottom rad hose again so I presume the hose itself needs changing. I've tried bleeding the system myself also but it won't take any more coolant. The radiator coolant bubbles constantly with the cap off but I've ruled out head gasket as there's no white smoke from the exhaust, no residue on the oil filler cap. No coolant in oil and vice Versa, unless there can still be a cracked cylinder head or gasket without any of these symptoms. Anyone have a clue what can cause all this? Other than this issue the car has been A1 and while it's no German executive saloon, I quite enjoy owning it.

John.G

I don't see any mention of the thermostat being changed.

BlakeS94

John.G wrote: »

I don't see any mention of the thermostat being changed.

I've inspected the thermostat housing myself and saw no leaks, the only leak seems to be directly underneath where the bottom radiator hose meets the water pump, also while it has overheated on a couple occasions, when it hasn't overheated the temperature is at operating and there's no big spikes or anything erratic, I've also noticed a sloshing liquid/sucking sound from behind the dash, I don't know very much about modern Cars cooling systems but I think this is an indication of air in the system still?

John.G

Engine overheat, assuming pump and thermostat OK will never happen with the car in motion and will normally only happen while idling if the cooling fan doesn't cut in.
Overheating in any case should not result in any leaks as the coolant tank cap pressure relief valve should lift.

The sloshing sound is certainly not normal and any air in the system should be removed in the coolant tank which is called a degassing tank in the USA, if you just slacken the cap and release any air while the coolant is hot then it most certainly should not return.

Hellrazer

https://www.boards.ie/vbulletin//showpost.php?p=112032191&postcount=15

https://www.boards.ie/vbulletin//showthread.php?t=2058038598

There was TSB was for coolant leaking.
The head bolts were too long for the block (or the block wasnt threaded deep enough for the head bolts) and caused cracks in the block.
Id be going to Hyundai and asking was it included in that TSB by getting them to check the VIN

Manufacturer fault all the way. You might get somewhere.

Dirty Nails

BlakeS94 wrote: »

The radiator coolant bubbles constantly with the cap off but I've ruled out head gasket as there's no white smoke from the exhaust, no residue on the oil filler cap. No coolant in oil and vice Versa, unless there can still be a cracked cylinder head or gasket without any of these symptoms. Anyone have a clue what can cause all this? Other than this issue the car has been A1 and while it's no German executive saloon, I quite enjoy owning it.

Just because it's not mixing oil means absolutely nothing. Bubbles in the expansion tank is most likely a compression leak in to the cooling system.
Fill the bottle to the brim with the cap off & engine running - watch the bubbles to see if there is a smokey appearance to them. I think some i40s suffered from a porus block.

BlakeS94

There was TSB was for coolant leaking.
The head bolts were too long for the block (or the block wasnt threaded deep enough for the head bolts) and caused cracks in the block.
Id be going to Hyundai and asking was it included in that TSB by getting them to check the VIN

Manufacturer fault all the way. You might get somewhere.[/quote]

Very helpful,thank you I'll look into it

BlakeS94

Dirty Nails wrote: »

Just because it's not mixing oil means absolutely nothing. Bubbles in the expansion tank is most likely a compression leak in to the cooling system.
Fill the bottle to the brim with the cap off & engine running - watch the bubbles to see if there is a smokey appearance to them. I think some i40s suffered from a porus block.

I have bled air from the radiator before, reservoir bottle was near the full mark, radiator didn't take much more coolant but as I've said there was a steady stream of bubbles that never stopped, no smokey appearance and no bubbling in the reservoir either.

Dirty Nails

BlakeS94 wrote: »

I have bled air from the radiator before, reservoir bottle was near the full mark, radiator didn't take much more coolant but as I've said there was a steady stream of bubbles that never stopped, no smokey appearance and no bubbling in the reservoir either.

Maybe I misunderstood when you said " The radiator coolant bubbles constantly with the cap off "

Regardless, air in the cooling system is coming from somewhere.You shouldn't ever need to do that.

BlakeS94

Dirty Nails wrote: »

Maybe I misunderstood when you said " The radiator coolant bubbles constantly with the cap off "

Regardless, air in the cooling system is coming from somewhere.You shouldn't ever need to do that.

I meant when I've bled air from the system through the radiator cap it just continues to bubble even when I've gotten as much air out as I can, Yeah it's just been going on a long time and no proper fix to date. If there's coolant coming out around the bottom radiator hose area there must also be air getting in?

Dirty Nails

BlakeS94 wrote: »

If there's coolant coming out around the bottom radiator hose area there must also be air getting in?

In theory it should empty the expansion bottle instead of sucking in air.

BlakeS94

Dirty Nails wrote: »

In theory it should empty the expansion bottle instead of sucking in air.

It also emptied the expansion bottle 😩

BlakeS94

BlakeS94 wrote: »

It also emptied the expansion bottle 😩

Just got the car back from my mechanic, pressure test wasn't great and he noticed coolant coming from bottom radiator hose, turned out to be the clamp connection between the hose and radiator, it looked to be tight but it wasn't, new clamp put on and pressure test came back good, couldn't have went better I had nightmares about head gasket repair costs.