Ford Focus LZ Sports Heater Core replacement

[charliedelta]

I have had a minor coolant leak on the 2015LZ. I replaced the coolant tank and cap.
Then a local mechanic indicated that the heater hoses were leaking and he changed them.

Now 1 year later I am getting this slow coolant leak again. Along with hearing the gurgling water noise like there is air in the system from behind the dash when starting. I did bleed/burp the coolant. The leak requires a top every couple of weeks depending on how many K's I do.

I am told that the heater core is a major job. I cant find moisture inside the car on the car on the floor nor can I see any leaks. I bought a pressure tester kit and when I pressure tested it it was static. When I put the car the ramps I can see coolant drip streaks on the underbody splash shield.

Anybody have further ideas that I can explore. Doing a heater core and hoses is beyond me.

Any suggestions?

Thanks

[marg99]

I would also check the water pump as they can leak from the shaft seal

[charliedelta]

Thanks I never thought about checking that.

Originally Posted by marg99

I would also check the water pump as they can leak from the shaft seal

[digbc]

The hose fitting that clips on to the heater core at the fire wall is leaking. The internal O ring is pinched or perished. Common fault. There is Youtube videos about it. My daughters car had the exact same thing. Feel the sound deadening behind the motor where the heater hoses are and I bet it is wet. It is a bit awkward to get to but can be disconnected and new Oring fitted without pulling 1/2 the car apart. O ring size is A115.

[charliedelta]

Thanks for that suggestion I will try that as well.

I was told by making inquiries that the "Coolant Water Outlet" is common failure point and causes a leak. Its cheap plastic bit mounted onto a hot engine that does fail. Its medium to big job to basically undo a lot of bits.

One thing is confusing me is this.

Say I top the coolant to maximum on the tank and then go for a ride with the heater running at max and I return and check the coolant level. The coolant level is down. If I let the car cool a bit to safe point to open the tank and I depressurise it. The water fills to the correct level. So once the tank is under vacuum even left over night, the water will never rise to the correct level until you open the coolant tank. Its a bit confusing.

Thanks for the reply.

Originally Posted by digbc

The hose fitting that clips on to the heater core at the fire wall is leaking. The internal O ring is pinched or perished. Common fault. There is Youtube videos about it. My daughters car had the exact same thing. Feel the sound deadening behind the motor where the heater hoses are and I bet it is wet. It is a bit awkward to get to but can be disconnected and new Oring fitted without pulling 1/2 the car apart. O ring size is A115.

[digbc]

Sounds like there is air still trapped in the system. The air compresses with pressure when hot and the level is lower, once you release the pressure (not vacuum) the level will rise.

[foxtrot3]

Hi. You tend to find with a heater core leak that the windscreen will fog up all the time and you will get a strong coolant smell. Cheers MD