Bluemoon
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| posted on 8/9/09 at 12:06 PM |
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small air leak? Try rad weld?
Hi all,
I seem to have a small air leak on the cooling system, no luck in finding it! I allways get an air lock in the top of the rad (polo). I guess I have a
small air leak that lets air in on cooling.
The on warming up the expansion tank tends to over flow. If I bleed the polo rad this tends to stop this..
Soo
Would people recommend Holt Radweld to attempt a fix? As I can't find the leak..
Dan
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Mr Whippy
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| posted on 8/9/09 at 12:11 PM |
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if you had a leak it would steam when hot plus there will be furry (antifreeze coloured) deposits round the area. If the head gasket is leaking
slightly it too can cause air locks and the expansion tank to overflow
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adithorp
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| posted on 8/9/09 at 12:17 PM |
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In all the years I've been repairing cars, I've never seen a cooling system leak air in.
The polo rad has a bleed pipe on it so it self bleeds anyway. Check your presure cap is holding pessure (simplest cause)then work from there. Just
adding RadWeld won't help. If anything it'll just make the system less efficient.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Bluemoon
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| posted on 8/9/09 at 12:31 PM |
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There is no room for a bleed on the rad (nose cone very tight) You might get a 90 deg elbow on if I could find one with a small enough OD (it's
a 6.5mm pipe on the bleed)... No luck so far..
Most others seem to not plumb in the bleed just block it as I have with a M5 screw...
Dan
[Edited on 8/9/09 by Bluemoon]
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adithorp
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| posted on 8/9/09 at 01:51 PM |
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Have a look at Rover K series engines in the scrappers. They have 90' bends on the bleed pipes.
Once bled it should remain that way, so you've still got something else going on. Get the cap checked, or just change it, as a starting
point.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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britishtrident
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| posted on 8/9/09 at 02:08 PM |
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You need to do cold pressure test on the system ----
Small cooling system leaks when hot just flash off into steam --- steam is invisible ---- so you need to pressuirse the system when cold.
You can do this the Locost way by using a pump up garden sprayer and a plastic Tee to coonect in to the small bore bleed pipe.
Put some coolant in the sprayer and pump up the pressure until the presure cap is ready to lift.
If you really really want to put a radiator leak sealer don't use Radweld or even worse Barrs Leaks they are not safe to use in modern engines
instead use K-Seal it is very fine and dosen't clog up the system.
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Bluemoon
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| posted on 8/9/09 at 02:22 PM |
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Don't think it's the cap as it once bleed it seems to behave.. Only once cooled down will the problem re-occur...
I will try a cold pressure test tonight if I get time (that way I get to check the cap to..)..
Dan
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tomprescott
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| posted on 8/9/09 at 04:44 PM |
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Good luck with it, just be glad its quite a simple system, I had a 106 and only knew of 3 of the 4 bleed valves (one was very well hidden) - was a
real head scratcher trying to workout what was going on!
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britishtrident
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| posted on 8/9/09 at 05:00 PM |
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I have often wondered car manufacturers don't just put a Schrader valve on the highest point in the cooling system that would make pressure
testing, vacuum filling and bleeding the system really easy.
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Bluemoon
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| posted on 9/9/09 at 11:03 AM |
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Fitted a Schrader valve to the bleed hose this is what has happened..
1) Pressurized system with air to 20psi, pressure cap opens (not sure what pressure it opened mind)..
Looked for leaks, couldn't find any, tightened a few hoses though... No deposits that I could see..
Pressure was vented for a long time...
2) After about 2 hrs pressure 15 psi, still leaking from preasure cap..
went to bed!
3) this morning (after ~10hrs or more) about 10psi in system preasure cap sealed.
Will check tonight to see if it's still holding at 10psi..
To me it looks pressure tight but I wonder if the pressure cap is working correctly as it vented very slowly and took a age to re-seat... Is this
normal?
Dan
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