3.2 BFH New heater matrix airlock - bending my sanity!

Discussion in 'VR5, VR6 & Wx' started by G60Dub, Dec 12, 2017.

  1. G60Dub

    G60Dub Forum Member

    Joined:
    Oct 23, 2003
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    Location:
    Angus
    Okay here goes...

    Old heater matrix developed the smallest of leaks a few months back - only very slight such that the windscreen would only start to scum up after a few days.

    Anyway car went into the bodyshop at the beginning of October for some much needed TLC and picked it up at the beginning on November. The following week I decided to replace the heater matrix before the weather got any worse as couldn't be hooped with wiping down scummy greasy windows over the winter. Anyway the physical part went smoothly given the studious amount of disassembly that's involved in just getting to the darn thing.

    Anyway topped up with coolant (50/50 mix with distilled water as always) and 'bled' it - poor heat to say the least but assumed an air lock and as I was dropping the coolant and replacing the water pump and thermo housing etc. the following weekend didn't overly bother given the matrix outlet hose was nice and toasty hot.

    Roll on the following week and new water pump in, old one was fine apart from a bit of play in the shaft but its been in for 76K and was an unknown quantity so decided to replace it to be safe. Replaced the thermo housing, stat and CTS at the same time more so has I had a full spare set left over from when I was planing to do the chains and cams. Prior to replacing the cams, chains DMF etc the thermostat failed when I was away from home so had to buy a full new extra set. lol

    Anyway full drain this time - lower rad hose off, including the oil cooler hoses when replacing the waterpump and a nice slow and easy fill up with 50/50 mix. So this is really starting to wind me up as I'm hardly using the car because, in short the matrix refuses to bleed properly. On a low blower setting I get nice hot burn your hands toasty hot air but a soon as I ramp up the blower speed the temp drops to hot/lukewarm given I'm assuming the air is removing more heat than can be replaced due to poor coolant flow.

    Innards of the old matrix were completely free and as clean as a whistle as is the rest of the cooling system as I always replace the coolant every two years or sooner if the PH of the coolant mix starts to drop.

    So diagnosis...

    Get a very low flow on the coolant return line back to the expansion tank and a decent jet as soon as I rev it so new water pump is a good as the old one.
    Tried the usual- cap off, burping hoses, 3 mins at 2000 RPM, expansion tank unfastened and lifted as high as possible all on a pretty steep slope outside work all to no avail.
    Even pulled the matrix hoses shoved some PU hose on both the inlet and outlet and blew it through it backwards to check it wasn't physically blocked - re bled afterwards and a little better but not much.

    Now considering disconnecting the expansion tank overflow line, capping its inlet on the expansion tank, pinching the bleed line from the upper rad hose and also pinching downstream of the filler line on the heater out to thermo block hose and then somehow got to figure out how to blow into the header tank lol to try and back flush any air in the matrix out the bleed line on the matrix inlet hose through to the disconnected overflow line.

    Beginning to think the actual damn things blocked but surely cant be as its a new matrix; never had such an issue so anyone any constructive suggestions that don't involve petrol and matches? lol
     
  2. Savagesam

    Savagesam Moderator Staff Member Moderator

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    My car was an absolute ballache to bleed the system, I ended up driving down the road at 6k with the cap off to get the airlock out, and now it's perfect.
     
  3. Tristan

    Tristan Paid Member Paid Member

    Joined:
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    Location:
    Southern IRELAND
    On one mk2, I had to fill the matrix with coolant, then reconnect the hoses, no matter what I did it wouldn't purge the air lock.
     

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