So... After having my heater fixed 6 months ago because it had a broken core, I gave my car a bit only to have the pleasant smell of coolant coming out of my air conditioner and steam coming out of my dash vents.

After taking it back where I had the core replaced, it was diagnosed that there is a electrolysis effect eating away at my aluminium heater core.

Causes could be a stray earth or a highly conductive coolant or just a faulty connection somewhere. When it was tested my coolant was reading .5V between the overflow tank and -ve terminal. its meant to be 0.1V.

Has anybody had any experience with this. I have a electrical background and was thinking of electrically isolating the core next time. Is this possible?

My car has done 140000km and had the coolant last flushed with my last service which was 20000km's ago.

ive never had this problem myself but a mate did and it ended up being a bad earth on the fan but ive heard a lot of bad earths on starter motors are known to cause this

have a read of this web page it a good start for you anyway and good luck

Electrolysis Stray Current Worms - Caravan and Motorhome Books

cheers trev

Interesting.. Ill have a look around the car in the morning... I just hope it isnt a small little thing which is impossible to find.

Would adding an inhibitor to the coolant make any difference?

im not to sure id be giving the system a good flush

as once this starts happing it pretty much turns your cooling system in a battery and then your really f*cked

flush it really well then put some good coolant in the car then start testing for bad earths that's how id do it

cheers trev

sorry to hi jack your thread, but I too am getting steam coming in from the vents when the AC is on. I thought that was normal, but do think that is a sign the heater core is on its way out? I am not loosing any coolant but I do get a funny smell coming in every now and then.

firstly im no ac tech

but this would be my guess

is it steam or mist ?

mist can sometimes be caused by moisture condenseing on the evaporator (the part that cools the air ) during dehumidifying the air this is normal everynow and then but if it happens more often maybe check to see if you drain plug is blocked if its a dirty air smell do you have water on the drivers side on the floor everynow and then ive had this and my drain plug was fine but the bottom of the aircon catch tray was full of crap causing the it to leak the air filters in these cars inside your glove box area are a joke

my whole fan area was full of leaves and crap that all gets push further down into the system and its a major pain the ass to remove as well dash out job

or you heater is leaking but surely you can smell or taste the coolant in the air if this is the case

cheers trev

If its steam coming from the dash vents you will defiantly know its coolant by the smell.. secondly if its coolant coming from the vents then more than likely its pooling on the floor in the cabin too. I had about 200ml's on mine. I found my AC was smelling spicy before the heater went again. I thought it was just a look heater hose seeping into the firewall and causing the smell then the hoses were tightened and continued to have the smell, till I disconnected the heater when the core went, now there is no smell at all.

Im not that fussed about fixing the heater yet.. I just want to get the voltage down to normal levels or its going to be a bit of a waste putting a new core in.

thnaks for the info guys. Yeah definitely no coolant smell when the steam/mist was coming thru the vents. must of been all the humidity and moiture in the air

Hi mate,

You will find that the voltage you measure should be no more that 300mv.. I would certainly be checking any additional electrical devices that you may have fitted to the vehicle, then check your earths (pain in the ass, no easy way around it..) Two things to consider as well: The quality of your coolant.. Genuine isnt a bad option at less than $40

Quality of the heater core you fitted previously (There are alot of Chineese Ones on Ebay..)

It also pays to check the quality of your battery terminals (clean and refit) and main earths..

Good luck dude!

I had my battery die about 3 months ago and there was a really bad earth to on the terminal. lots of corrosion on the terminal. That bad the car would barely kick over. I cleaned that out and put a maintenance free battery in. The core is a genuine ford cored and I guess the coolant isnt as fresh as it was 6 months ago when the core was installed. I have had a couple of hose leaks from clips not being tightened all the way and ive just topped it up with water and glycol additive.

Ill wait till I flush the coolant before I go hunting for the earths.

My car does not have any aftermarket electrical additions that I nor the previous owner have installed

how hard would it be to electrically isolate the core from the chassis?