Changing the coolant flushing the heater core.

polomints

The coolant in my car is looking pretty nasty and I'm quite sure the heater core is quite clogged, is it OK to back flush it with a hose, also how should go about flushing the rest of my Coolant, I can't seem to find a drain plug on my radiator or it's probably just hard to get to it's a 2000 (mkIV) Fiesta 1.25 Zetec. Are kits available to help me do this?

forgotmyname

Kits available = a hose pipe..

Undo the bottom hose and let all the coolant drain from there. Undo the supply and return hose to the heater and put the hosepipe into the return and flush it out of supply pipe.

Swap it around and repeat several times.

Fill the system from the bottom hose and flush it out several times also.

Make sure you use the correct type of antifreeze and correct strength.

What is the coolant contaminated with though?

londonTiger

polomints wrote: »

The coolant in my car is looking pretty nasty and I'm quite sure the heater core is quite clogged, is it OK to back flush it with a hose, also how should go about flushing the rest of my Coolant, I can't seem to find a drain plug on my radiator or it's probably just hard to get to it's a 2000 (mkIV) Fiesta 1.25 Zetec. Are kits available to help me do this?

heater core shouldn't be clogged. It's high up in the system - even if it is just draining the water out isn't going to fix it.

I presume you mean radiator and not heater core - heater core is the bit that heats the cabin air.

Deposits tend to settle at the bottom of the radiator which is the lowest point in the system so it gets washed down and trapped there.

polomints

Rusty crud mainly, no oil.

Richard53

Rusty crud = it's been run without antifreeze/coolant at some point.


There's no harm in removing as many hoses as you like and flushing through in both directions until the water runs clear. Most modern cars don't have radiator drain plugs, and the usual method is removal of the bottom hose, as said above. Just use normal tap pressure, not a power washer. There may be drain plugs on the engine block which would give you more opportunity to flush out the difficult bits - a workshop or Haynes manual would show you where they were.


If the rad is really clogged, there is really no alternative to taking it off the car completely and flushing it thoroughly where you can turn it upside down and get into every corner.


Fill with the correct anti-freeze mix, and top up with the same, not tap water, to maintain the freezing and corrosion protection.

polomints

I'm pretty sure the heater core is clogged with crap, it's really inefficient and got worse recently after I put radweld in it to stop a leak (which it did). It'll mostly blow cold air except when my foot goes down, then it will blow warm briefly then go cold again.

afzaal1988

polomints wrote: »

I'm pretty sure the heater core is clogged with crap, it's really inefficient and got worse recently after I put radweld in it to stop a leak (which it did). It'll mostly blow cold air except when my foot goes down, then it will blow warm briefly then go cold again.

That use to happen to me when coolant level was very low. It could also happen like you yourself said when heater core is blocked.

But do check for air block also since you had a leak.

Strider590

I'd say most likely was the thermostat has jammed open, meaning your coolant never quite reached full temperature OR the actual heater valve has gone (extremely common in Fords).

polomints

I have a replacement thermostat, where does it go?

polomints

Ok, so I poured a bottle of Holts Radflush into the tank and ran the engine for 10 minutes, let it cool down then opened the radiator bleeder valve. First thing to come out was come gunk then I took off the expansion tank lid and it started to pour out for a while, I took of the tank cleaned that out and places it back on, I poured water into the the tank until the water comming out the radiator ran clear, I also ran a hose through my heater core. Anyway, now the heater is properly not working at all. I can feel heat in the hoses, but the valve won't open at all now. Third one to go since I go the car a year ago.

mcjordi

the drain plug is on the bottom of the rad on the passenger side. you need a 50p coin to undo it its plastic so be careful

thermostat on the 1.25 i believe is behind the alternator.