Rad weld - good idea or bad?

Tom W

Tom W

Active Member
Hi all.

The radiator on my p6 had sprung a leak. I've drained the system removed the rad and soldered where I think the leaks coming from, which seemed to cure things when it was refilled. However, now I've run the car up to temperature it's still leaking slightly. Not much, just a drip every couple of seconds. I could try more solder, but access to the leak isn't great and i dont think I can improve the joint. Does anyone have any experience of Rad-Weld type products? I've always avoided that kind of thing for fear it will clog up things it's not supposed to. I know the proper answer is to get the rad re-cored, but that's an expense I could do without. I'm really just looking for a quick fix with a view to getting the rad fixed properly in the future, but don't want to add anything that's going to cause any long term problems!

Cheers, Tom
 
In my experiance short term fixes end up costing so much more than doing it properly in the first place, I know it's not what you want to hear-............. I have used k-seal before and I paid for it :roll: loads :cry:
Not in my p6 thankfully
 
I have used K seal in my Audi. If you think there are a lot of awkward to access hoses on a P6, try an Audi V6 engine :shock:

I was losing about 1/2 litre a week and was looking at £100s to fix it. I put some K seal in and it fixed it for about 9 months, then it started leaking again. So I put some more in.

I wouldn't use it on the P6 though 8)
 
I would say i would like to work towards being a perfectionist , but sometimes " if needs must " it'll keep you going until a better time ! When a system flush and a recore of the rad is within budget :?
 
I had an alloy radiator on an Alfa with a bad leak once...right where the plastic tank met with the alloy...various "expensive" stop leak products were tried.
All failed miserably.
The best solution was...black pepper.
Leaked totally stopped...for a week...then another bottle of black pepper (the fine ground stuff).
I managed to do this for about 8 weeks until I located a NEW aluminium rad for $239...as opposed to the $600 Alfa wanted.
Just put the whole bottle in... :)
 
Mmmmm Black pepper, never heard of that one :!:

edit- is that before or after you put the egg in :LOL:
 
I'm going to have another go at locating the leak and soldering it. I think it's from one of the joints where the core mounts into the end tanks. It's difficult to locate properly though, as the water drips into the frame beneath the rad and all makes it's way out through the lower mounting bolt. The leak is so small it only leaks when the engine's running and there's pressure in there. When I remove the rad to get a better look, I can't get enough pressure from just filling the it to get it to leak. :roll:

I think you've all confirmed what I was thinking about rad weld. Since I've already spent ages de-sludging the engine and replacing the side plates, I don't want to add anything that will clog it up again. Also, the heater works well currently, so don't want to block that either.

If I can't solder it successfully, I'll have to do the job properly and get the rad re-cored.

Tom
 
Take the rad out, lay it face down with the pipes facing up and the cap on. Fill it with water then find an old bicycle inner tube. Cut through it on the opposite side to the valve then fit each open end over a rad pipe and secure with a hose clamp. Pump it up with a bike pump (or compressor) to 10 psi or so and voila: pressurised radiator! You should be able to spot the leak then. :D
 
I like your idea Kiwi Rover. I have a refinement on it though. Most of an inner tube's ability to take pressure comes from the tire around it. However if you go out a buy a thorn resistant mountain bike tire, then it will be able to take more pressure, as it has a much thicker cross section. They come in sizes up to 2 inches diameter, so they will slide over the outlets real easy. I think that if you had an old perished inner tube, it might not take 10 psi to well.

Unless your motor is already on it way out, I would not use pepper or chemi-weld on the radiator. It blocks up holes, including the ones you need for the coolant to flow through in the motor.

What sort of P6 is this for. If its for a 2000 with horizontal flow radiator, then there is a direct drop in replacement you might want to consider. It is a Chevy/ GM style radiator 22 x 19 ".

http://www.jegs.com/i/JEGS/555/52005/10002/-1
 
Hi, something I have used in the past is Araldite. The trick is to warm the rad up with a
space heater or hot air gun, mix the Araldite and spread over the area. The heat makes
the Araldite flow around and into the hole, Keep the heat on and it speeds up the curing.
I did this on one occasion years ago after damaging the rad by accident mid afternoon
just before wanting to go away for the weekend. Still there a couple of years later.

Colin
 
They are not bodges, they are well considered temporary repairs. The trick is knowing
where and when to do it, In otherwords we 'wing it'. :wink:

Colin
 
Good ideas about the inner tube and bike tyre. I'll try that.

The rads for a 2200tc, so I think that's the same type as the cross flow 2000 rad. It's a manual, so doesn't have the built in oil cooler. Is the Chevy/GM rad likely to be readily available in the UK?

Cheers, Tom
 
K seal is the weapon of choice in the trade and is 9 quid retail, so you only have that to lose IMO :)

Never heard anything bad about it but the old rad welds and Bars Leaks types do clog your system as they leave sediment.
K Seal stays liquid till it meets air at the leak.
Obviously a rebuilt rad is the 'Right' thing to do but it all depends on your wallet this week :wink:
 
K seal might be worth a shot then. I don't mind the £9 or so to try it even if it doesn't work. The main worry is adding something that clogs up other parts of the system. If I get a chance tomorrow, I'll see if I find out better where the leaks coming from and make a reassessment then. Not had much chance to do anything on it in the last week. The GM radiator looks interesting, especially as its aluminium so should be more efficient than the stock one.
 
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