Motoring Discussion > Get rid of radweld? Miscellaneous
Thread Author: Skoda Replies: 28
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 Sat 2 Jul 11 21:27 
 Get rid of radweld? - Skoda
I think i already know the answer but just in case there's a trick somewhere, is it possible to get rid of radweld once it's been added to a coolant system?

I'm assuming it's rad weld or a similar idea - lots of grit in the coolant?

Does this stuff just break up after a while? Radiator gave up the ghost this week in the Golf, and when i dropped the coolant today (intending to reuse since it's not that old), the entire bottom of drain tray was completely covered with the stuff. I don't remember getting much grit when i drained the old coolant ~1 year ago when doing the thermostat.

Have flushed crazy amounts of water through the block & hoses with the garden hose, still getting small amounts of grit out.

Metal water pump, but i don't want to tempt fate with that junk still in there.
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 Sat 2 Jul 11 21:34 
 Get rid of radweld? - Zero
When did it get in there then? or more to the point, why? surprised you didn't notice it the last time you dropped the coolant.

AFAIK, flushing is the only way, there is no magic bullet.
Last edited by: Zero on Sat 2 Jul 11 at 21:34
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 Sat 2 Jul 11 22:00 
 Get rid of radweld? - Skoda
Must have been the previous owner. It's as if this stuff has all just let go en masse. Knowing my luck there will be a clump somewhere critical blocking flow.

Only thing google comes up with is running it up to temp with soda in the water, but it's an alloy head on the engine so can't do that.
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 Sat 2 Jul 11 22:11 
 Get rid of radweld? - Armel Coussine
I don't think flushing will get rid of Radweld or similar products. They coat and narrow the whole cooling system and may block any tight irregular pinch-point. That is what they are supposed to do after all. They weren't the best idea in old-tech cars, so it's a safe bet they will be even worse in modern ones.

Been there, done that, wasted the dozen filthed-up tee shirts.... ten bucks down the drain when twenty would have got a proper engineering solution.

Motorists in a hurry and a panic... don't you just admire their intellect?

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 Sat 2 Jul 11 22:37 
 Get rid of radweld? - Skoda
Aye, i don't think i'd have put it in myself but i can see the benefit if you're stuck somewhere.

picasaweb.google.com/106022899596357479599/GolfRadiator?authkey=Gv1sRgCITwld3_jLjGugE#5624871013144638594

Here's the old rad (its in the new rad box to go to the skip). On the left side there's signs of an old leak - i'm guessing that's what the radweld was for, and on the right at more or less the same point there's a fresh leak, the one i'd noticed dribbling on the driveway, with crystals of coolant visible.
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 Sat 2 Jul 11 22:53 
 Get rid of radweld? - -
I hate the muck, it ends up blocking your heater matrix, and believe you me that's not a job you want on a VW group car.

I have before now jerry connected a pressure washer to the hoses and flushed the system like that, that will fetch anything out.

Have you run the hose through the heater alone Skoda, is that running freely...if it is then you could disconnect the heater hoses (connect the inlet and outlet together) and put more pressure through the engine.

Might this grit you're seeing be rust, is it possible a previous owner ran water only causing considerable rusting inside the block?
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 Sat 2 Jul 11 22:57 
 Get rid of radweld? - Number_Cruncher
The old way of doing this was to remove the thermostat, and connect a flushing gun to the top hose. The flushing gun had connections for water, and for compressed air. The idea being that the bubbles would loosen carp which a steady stream of water wouldn't disturb.
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 Sat 2 Jul 11 23:19 
 Get rid of radweld? - Skoda
GB>> it ends up blocking your heater matrix, and believe you me that's not a job you want on a VW group car.

GB>> Might this grit you're seeing be rust

I might not be able to sleep now GB ;-)

If the heater matrix goes, i think i'd take it out the circuit like you mentioned for flushing. Rust i don't know for sure, but it seemed more like sand than anything else.


NC>> The flushing gun ... and for compressed air

I'm out of luck on both counts there. We've v. high mains pressure & strong flow here so i've given it a good shot.

I wouldn't mind as much but the water pump is driven via the cambelt, don't want grit interfering with the operation of that.
Last edited by: Skoda on Sat 2 Jul 11 at 23:21
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 Sat 2 Jul 11 23:27 
 Get rid of radweld? - R.P.
I bought some radiator stuff for an old hack we ran at one time, this was in the form of very fine (slightly larger than sand) type granules. Horrible stuff If you've got any left from today's flushing run a magnet across it to see if its magnetic. -
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 Sat 2 Jul 11 23:00 
 Get rid of radweld? - AnotherJohnH
I have a different, positive, experience:

F reg 1988 Peugeot 505 (2.1 petrol) from just outside warrantee had a slightly weeply head gasket, and not having the testicles to tackle the wet liners I gave it some radweld - it was still going happily something around the 10 year mark when the owners after us got rid, and they reckoned it was the best/most reliable car they had ever had: petrol/tyres/servicing only.

And, somewhere in the back of my head is a memory of Jaguar using the stuff at the manufacturing stage to plug the leaks up.... hmm, perhaps that's not such a strong recommendation given the Jag reputation from years ago.

Your mileage and experiences may vary..
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 Sat 2 Jul 11 23:10 
 Get rid of radweld? - Iffy
We used Barr's Leaks in the 1970s.

Customers who had little money were grateful for a cheap fix.

One I recall was a leaking heater matrix on a Jaguar XJ6, which is a dashboard out job to do properly.

The symptom was only a damp passenger footwell carpet, so Barr's Leaks was sensible solution.

It also came in handy doing breakdowns.

Last edited by: Iffy on Sat 2 Jul 11 at 23:10
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 Sun 3 Jul 11 03:42 
 Get rid of radweld? - VxFan
I've previously used Radweld and had no issues with it.

It fixed the leaking radiator on my Mk1 Astra. I never noticed any grit or other foreign matter when I drained the system a couple of years later. Leak never came back when I drained and flushed the system.

It also fixed a leaking core plug on my Mk3 Cavalier. Impossible to change it without having to remove the exhaust manifold first. Again, no grit, etc when drained, flushed and refilled.

You sure the 'grit' isn't just corrosion from the cooling system?
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 Sun 3 Jul 11 08:50 
 Get rid of radweld? - Cliff Pope
I've used either Radweld or Bars in the past, very successfully. As I recall it wasn't a gritty sludgy stuff at all, just a concentrated cloudy solution.
The theory was that it was innocuous until it came into contact with air, ie it found the leak, when it expanded and solidified. Once done, the remainder remained in solution, and could be drained out later on without affecting the repaired leak.
I don't think it was meant to be left in for years, because obviously eventually dissolved air would activate the whole lot.

Cornflour was the traditional trick, but again, flushed out after the job done.
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 Sun 3 Jul 11 09:29 
 Get rid of radweld? - Old Navy
Urban myth?

Or did BMC / British Leyland put a radweld type stuff in their coolant systems on the production line. Their dealers parts departments used to sell it in solid block form which was crumbled into the radiator like an OXO cube.
Last edited by: Old Navy on Sun 3 Jul 11 at 09:29
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 Sun 3 Jul 11 17:05 
 Get rid of radweld? - Victorbox
You could try this stuff: www.a1-motorstores.com/store_main.asp?int_product_id=3982
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 Sun 3 Jul 11 17:18 
 Get rid of radweld? - Zero
I would still be worried about the why. If its radweld why is it there, if its not radweld why is it there.

The why matters,
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 Sun 3 Jul 11 18:10 
 Get rid of radweld? - Lygonos
Probably alloy corrosion rather than radweld.

Wont be magnetic either.

Looks like white fine grit usually.

Maybe you dislodged a bunch by squeezing a rubber coolant hose? It can coat the inside and often feels 'crunchy' when you squeeze it.

What do you mean by "radiator gave up the ghost today"? May have some bearing on cause/effect of the white crud.
Last edited by: Lygonos on Sun 3 Jul 11 at 18:13
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 Sun 3 Jul 11 19:33 
 Get rid of radweld? - Zero
Mind you the title of this thread is starting to give me ideas.

Git Rid of Radweld? Radweld sounds like chief of some ancient Iceni tribe, or Wessex King

Radweld the Riotous.
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 Sun 3 Jul 11 19:50 
 Get rid of radweld? - R.P.
His Court would have been leak free...
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 Sun 3 Jul 11 19:51 
 Get rid of radweld? - R.P.
Ethelred of Radweld...?
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 Sun 3 Jul 11 20:05 
 Get rid of radweld? - Skoda
picasaweb.google.com/lh/photo/pq0CvNZHH0KOHoOoJZ_LlH8HNYQ7oRu_xRSpM6AmJOc?feat=directlink

Tried to do a photo of the sandy grit grains.

Yesterday I'd poured the coolant into an oil carrier for taking to the tip, so today i decanted it into the drain tray again but it's not come out well in the photo, just oily grains. Plus most of the larger grains just went straight back in the oil carrier...

It's not magnetic this stuff. It likes oil, all the grains are coated after being in the oil carrier overnight.


Lygonos>> Maybe you dislodged a bunch by squeezing a rubber coolant hose? It can coat the inside and often feels 'crunchy' when you squeeze it.

None of the hoses felt crunchy, they're all in surprisingly good condition. Had been squeezing them all before i dropped the coolant to see if any needed replacing at the same time. That might be the reason all this stuff has dislodged but i didn't feel it's presence through the rubber hoses.

Lygonos>> What do you mean by "radiator gave up the ghost today"?

Well maybe bad turn of phrase, it wasn't a catastrophic failure, more of a pin hole leak. Hadn't been that well developed either - coolant reservoir was still closer to the max line than the min.

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 Sun 3 Jul 11 23:08 
 Get rid of radweld? - Lygonos
Maybe that's what remains of much of the radiator core - the pin-point leak is where it has corroded through first?
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 Sun 3 Jul 11 23:21 
 Get rid of radweld? - Skoda
Good point lygonos. I feel an angle grinder session coming on tomorrow to see what the old rad looks like inside, just curiosity.
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 Mon 4 Jul 11 08:31 
 Get rid of radweld? - AnotherJohnH
make sure you don't need to return/px the old rad before you destroy it
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 Mon 4 Jul 11 09:15 
 Get rid of radweld? - madf
Sounds like aluminium oxide plus dirt: lack of proper anti freeze mix.. Plus metal to metal contact - aluminium /iron/steel via the coolant system..

Try Radflush which does work...but flush out cooling system several times.

PS: I would replace the water pump - time for it to go...

Last edited by: madf on Mon 4 Jul 11 at 09:15
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 Mon 4 Jul 11 09:57 
 Antifreeze tester - Skoda
See those anti freeze testers, can't remember the proper name, hygrometer or something. Do you need differently calibrated ones for different types of anti freeze?

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 Mon 4 Jul 11 10:28 
 Antifreeze tester - henry k
Hydrometers are available from £3/4 on Fleabay
IIRC these common ones are for old fashioned Ethylene Glycol anti freeze.
Not sure if there are others for the long life anti freeze.
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 Mon 4 Jul 11 10:19 
 Get rid of radweld? - henry k
>> make sure you don't need to return/px the old rad before you destroy it
>>
I thought most radiators were on an exchange basis. They resuse the top and bottoms.
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 Mon 4 Jul 11 10:58 
 Get rid of radweld? - bathtub tom
I think you'll find they're nearly all cross-flow nowadays, with the plastic sides crimped onto the ally core.
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