Coolant loss

BlakeS94

My car has had an issue with losing coolant for quite a while now it's been going on for many months maybe even a year, almost every component of the cooling system has been replaced, water pump, thermostat, radiator, and the head gasket has been replaced and head re-machined and hoses have been checked.

Brought it to main dealer at one stage and they said heater core is leaking? But there's no sign of leakage under dash or anywhere on the footwell of passenger or driver side. And I have heat from the vents, But it's still losing coolant, currently back in with my mechanic.

The head had a slight crack in the margin between the valves but that was sorted with the skimming, engine block was inspected and is in good shape, car always drove fine and still does other than the losing coolant issue. The level in expansion bottles drops an inch or so after each drive. Has anyone got advice on what else could be at fault?

I'm not looking for someone to tell me trade it in because that's not an option if there's another issue and I have to spend a little more money I'll do that, to me that's better than taking out a 5 figure loan for another car.

So any input on what the issue could be is greatly appreciated. Car is 2013 Hyundai i40 and yes I'm aware of the issue and TSB about cylinder head bolts, my car doesn't seem to have been affected by that.

greasepalm

Surprised nothing has shown up with the joys of cars and issues.

So not getting a strange burnt smell under bonnet when hot and a taste in your mouth saying a leak?

Petrol or diesel as if it was petrol pressure test cooling system with spark plugs removed and scope all cylinders for coolant and assuming it starts ok and no white smoke out rear?

Internal leak inside would leave rainbow smears on screen assuming vent is pointed to screen.

BlakeS94

greasepalm wrote: »

Surprised nothing has shown up with the joys of cars and issues.

So not getting a strange burnt smell under bonnet when hot and a taste in your mouth saying a leak?

Petrol or diesel as if it was petrol pressure test cooling system with spark plugs removed and scope all cylinders for coolant and assuming it starts ok and no white smoke out rear?

Internal leak inside would leave rainbow smears on screen assuming vent is pointed to screen.

No burning smells, its 1.7 diesel and was pressure tested by main dealer all they found was thermostat stuck closed and they replaced. No internal leak as would have been discovered when doing head gasket job, no smoke from exhaust whatsoever, it's a strange one, car is driving well absolutely no signs of anything wrong besides the coolant level dropping, I've removed the belly pan in the past, cleaned it off and re installed and there was no new spills on it after running the engine, system has been bled of air also

greasepalm

Is there an expansion tank on yours as remembering fords had issues with cracks and caps on bottle but stains would be seen on inside valance when that happened.

With pan removed after a run leave a sheet of cardboard underneath in a spot where it is dry and check after a day or so for stains noting any position of them. When car is hot system is under pressure and more likely to weep in the cooling down but might need time to see results.

BlakeS94

greasepalm wrote: »

Is there an expansion tank on yours as remembering fords had issues with cracks and caps on bottle but stains would be seen on inside valance when that happened.

With pan removed after a run leave a sheet of cardboard underneath in a spot where it is dry and check after a day or so for stains noting any position of them. When car is hot system is under pressure and more likely to weep in the cooling down but might need time to see results.

There is yes, I've taken it off and inspected it myself there isnt any cracks on it. That's exactly when the level is dropping after I drive it and when it cools down the level in expansion bottle is lower, car overheated on one occasion and I turned engine off immediately, that was prior to head gasket repair and I've checked the level after every drive and kept topping it off so temp gauge has been in the middle all the time never above.

greasepalm

Water expands in the bottle when hot and contracts/drops when cold is why there is a max line to not overfill it.

BlakeS94

greasepalm wrote: »

Water expands in the bottle when hot and contracts/drops when cold is why there is a max line to not overfill it.

I know that, I only top it up to the max line when engine is cold.

David Geary

Possible causes of leakage could be.

Slight crack in the cylinder head. It will need to be pressure tested

Also heater matrix is a possibility.

Use a pressure tester is used to pressurize the coolant system. Leave it pressurized overnight then physically examine the heater matrix. A certain amount of dismantling is required to get access to it.

David.

BlakeS94

David Geary wrote: »

Possible causes of leakage could be.

Slight crack in the cylinder head. It will need to be pressure tested

Also heater matrix is a possibility.

Use a pressure tester is used to pressurize the coolant system. Leave it pressurized overnight then physically examine the heater matrix. A certain amount of dismantling is required to get access to it.

David.

If you read my original post I said the head has been done so thats not the issue, it was pressure tested overnight when the head was done and was all good. I have the car back now they pressure tested it again and there was a tiny slit in the top radiator hose where it connects to the engine, sorted now level has been good for last few drives. Going to get heater matrix replaced anyway as main dealer said it was leaking but doesn't seem to be leaking enough to see inside car under dashboard

XLR 8

BlakeS94 wrote: »

If you read my original post I said the head has been done so thats not the issue, it was pressure tested overnight when the head was done and was all good. I have the car back now they pressure tested it again and there was a tiny slit in the top radiator hose where it connects to the engine, sorted now level has been good for last few drives. Going to get heater matrix replaced anyway as main dealer said it was leaking but doesn't seem to be leaking enough to see inside car under dashboard

Had a similar issue with a VW it went back and forth to dealers and they could never find the issue. It was tracked down to a tiny leak in the coolant tank. When driving pressure would build up and the leak would emerge and spray directly onto the hot exhaust system leaving not a drop. As soon as the car was turned off the pressure would drop and no evidence remains. IIRC it was along a seal where the tank was moulded and was thicker compared to the rest of the tank and would never have failed totally. I became anal and was continually topping it up to the max mark. I just kept an eye on it and rather than keep filling it I just kept it on minimum and it remained there. Hole must have been between Min & Max mark.

BlakeS94

XLR 8 wrote: »

Had a similar issue with a VW it went back and forth to dealers and they could never find the issue. It was tracked down to a tiny leak in the coolant tank. When driving pressure would build up and the leak would emerge and spray directly onto the hot exhaust system leaving not a drop. As soon as the car was turned off the pressure would drop and no evidence remains. IIRC it was along a seal where the tank was moulded and was thicker compared to the rest of the tank and would never have failed totally. I became anal and was continually topping it up to the max mark. I just kept an eye on it and rather than keep filling it I just kept it on minimum and it remained there. Hole must have been between Min & Max mark.

Yes a similar issue with my car as the coolant was spraying downwards when under pressure towards hot engine and there was little to no sign of a leak as it was burned off. I also became anal checking the level after every single drive and topping off, but I've taken it for a couple spins now and put the foot down and the level hasn't changed bar the expansion tank level rising due to expansion of hot coolant, but returns to same level when cold. Hopefully this is the end of it

John.G

If the cooling system is tight then there should be a slight pressure in the exp tank if the filling cap is removed even after been parked overnight.