C5 issue solved.
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Thread: C5 issue solved.

  1. #1
    1000+ Posts George 1/8th's Avatar
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    Dec 2003
    Melbourne, Victoria.

    Default C5 issue solved.

    I have noticed this year that the coolant overflow reservoir needs topping up every month or so, but never needed this before ( not in the first 2 years I've had the car). Then I saw a small water patch under the car, passenger side , just inside of the front wheel. Not where the aircon normally drops condensation, which is more central. I traced it to the RHS heater matrix hose where it has a plastic sphere midway between the matrix at the firewall and the engine block. I've been watching it for months, a very small yet annoying leak in the system. Only the lower half of this “degassing” sphere seems to be getting wet, so I determined it might be starting to split around it's centre join /seam. There was no visible split or degeneration in the hoses. It was looking like I would have to replace this sphere in the heater hose. I looked for replacement heater hoses for a C5 V6 series one, someone said it was no longer available. Not on ebay, even from England. All the C5s I've seen in the wreckers lately have been 2 litre diesels, none of which have this part. I thought I could pull it out and see if I could replace it with brass fittings screwed into a brass 3 way union. The hoses are 3/4, and though you can get BSP fittings for that size hose, there is nothing available to screw these into. Maybe I'd have to engineer something. Then I found plastic hose fittings and adapters of all sizes, and cheap at the hardware store, with a better range. I ended up with a ĺ Tee piece, and one ĺ to Ĺ adapter. I could make up a replacement part with these fittings and some Heater Hose, simple enough. I then found some rubber stoppers and plugs so I could block off the hoses when I pull out the little degassing thingy. I spilled almost no coolant as I removed it. I had a good look at it and it seemed to be pretty well perfect, no sign of stress or wear. I went ahead and set about replacing it anyway, with my assortment of plastic hose parts and I realised the hose from the block to the tee would now need to be longer. I cut a piece of heater hose the required length, then went to remove the older , shorter one from the block. It didn't want to budge. I ended up cutting it off to loosen it.
    That's when I found the cause of the entire episode. The end of the metal pipe was corroding under the hose clamp, and the corrosion was expanding , which was causing the leak. The water was then running along the bottom of the rubber hose, and flowing over the OUTSIDE of the degassing sphere.
    So, I removed the corrosion with coarse sandpaper, covered it with Black mastic, and cut a replacement hose. All done. I'll be keeping an eye on this from now on.
    I needed this solved before the warm weather comes.
    This could happen to any make or model of car, so be aware.

    The third image was supposed to be the first one. It shows the wet lower half of the degass sphere. The second one, with the red hose cap should be the second one, showing the corrosion. The fourth image should be third, it shows most of the corrosion removed. The fifth shows the end of the pipe with mastic to seal the surface. The sixth image shows the new hose in place, and the first image is the final one with the clamps fitted correctly.
    Far out, this page edit thing is difficult to navigate. But there you go.


    Cheers... George !/8th.
    Series 1 C5, V6 Petrol .
    Attached Thumbnails Attached Thumbnails C5 issue solved.-correctly-clamped.jpg   C5 issue solved.-culprit.jpg   C5 issue solved.-bottom-half-wet.jpg   C5 issue solved.-corrosion-almost-removed.jpg   C5 issue solved.-sealed-mastic.jpg   C5 issue solved.-new-hose-place.jpg  

    Last edited by George 1/8th; 10th August 2017 at 12:08 PM.
    JohnW, FIVEDOOR, BallinaOB and 1 others like this.

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