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Thread: Very slight coolant loss at heater matrix entry/exit

  1. #1
    Join Date
    Jul 2010
    Location
    Rugby UK
    Posts
    348

    Default Very slight coolant loss at heater matrix entry/exit

    I would be very pleased to receive suggestions on the following.

    I went under the trim on the front passenger footwell (RHD) to remove the pollen/cabin filter and discovered a coolant stain and weeping on the plastic cover of the heater matrix where the fixing bracket with torx screws is situated - just in front of the interior heater lines aluminum tubes that run from the side of the heater core and then pass through the firewall to connect to the rubber heater hoses in the engine compartment.

    Should I: 1/assume that the heater matrix is failing or 2/ that the 'O' ring seals need replacing? Can the latter be replaced in situ after coolant drained. I presume a fair amount of coolant remains in the lines despite draining it down.

    How big a job is replacing the matrix? Is it really a dashboard out job? If so does Vida cover the procedure. Has anyone done this successfully?

    Re cabin filters. There seems to be room to fit two. One at the back nearest the firewall which is thick (about 38mm) with activated carbon and a thinner one at the front which is half that thickness. I see filters listed by Bosh and Mann. Has anyone fitted two at the same time and did you use Mann or Bosh?

  2. #2
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    475

    Default

    On the cabin filters, my understanding is that it's an either/or regarding whether you go with thicker active carbon or thinner regular. I think I came across a post which said if you put BOTH in at the same time, the interior blower motor has to work extra hard to draw air and you run the risk of burning it up. I don't remember what brand I used when I replaced my filter but I think I went with the cheaper option.

    Not sure if it's related, but my '02 had the AUTO option on the CCM button for air re-circulation and it had the thicker filter. My '07 only has the manual ON/OFF button for air re-circulation and it came with a thin filter.

    My '02 had a slight leak from one of the O-ring seals and I could see the coolant was wet around the aluminum tube union with the heater core. It only leaked slightly in the winter with the heat going. Replacing the seals is difficult. Apparently, you have to line things up just right and/or use significant force to get the tubes to seat in the heater core with the new seals. All this while you're lying on the carpet in the foot well with your back twisted up. I played with it a while and gave up, afraid I was going to break something with the force I was applying. There are threads on the subject of people who have successfully replaced the heater core and seals.

    Good luck!
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  3. #3
    Join Date
    Jul 2010
    Location
    Rugby UK
    Posts
    348

    Default

    Xfingers Thank you so much for the adice. Re filters it makes a lot of sence. I looked at Vida regarding heat exchanger removal R.H.D 2001 and it frightened me off saying drain both coolant and refridgerant and remove ECC climate unit from the car. Mine also seems to be only leaking in the winter if I use heating so for now I will monitor the situation and re read all the posts on this useful site. I am small enough to on my back in the footwell but there is very little room to remove the heat exchanger and it is only too easy to break things.

  4. #4
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,070

    Default

    I did the heater core twice. First one was 1.5 days, second - less than 2 hours. The only part that goes out (besides the core itself) is the brake pedal switch.

    Replace the core, it is relatively cheap (Behr makes them for Volvo), and they all leak in 10-12 years.
    2002 V70 (sold)
    2005 XC70 (Telos Road took it. Did a chassis swap)
    2016 XC60

  5. #5
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    475

    Default

    As vtl says, the heater core isn't hard to access for LHD cars. Removing the climate unit wasn't required. Does anyone know if the heater core setup is different for a Right-Hand-Drive vehicle in the UK?
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

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