Need to repair a cracked header tank

Joe_Horner

BeenThroughItAll wrote: »

[...]

When I backflushed the heater matrix I found... guess what? It was full of tiny shiny particles looking a lot like copper filings.

That does suggest a fairly major overdose of the stuff which isn't really the chemical's fault. Think how much is in a bottle (about 150ml iirc), then distribute that all the way through the cooling system of maybe 4 - 6 litres. Nowhere is going to be "full of" it if the right amount is used.

My 405 has it because of a heater matrix leak about 3 years ago. Changing the matrix was NOT an option (full dashboard removal, which requires screen out as well) so it was either bypass the heater (also not an option - it gets cold round here) or seal it. Single bottle dose, as per instructions.

3 years / one routine coolant change / about 25k miles later and it's still sealed, the heater's toasty, and it hasn't affected the cooling ability in any way at all. If it had on those 405 TD's you'd know it because they're very marginal in the first place!

=rizla=

ferry wrote: »

Until my replacement comes I need to repair a tiny crack in my header tank.
Luckily its near the top so its only an issue when hot but can anyone suggest a product or weld that will seal will for a week or so?

thanks as usual

I;ve used some 5 minute epoxy on cooling systems before and it seemed to work well.

custardy

EdGasket wrote: »

You don't use 'gloop' for this type of problem. You need to clean the exterior of the header tank where the leak is; roughen the area with coarse sandpaper; apply a couple of coats of fibre-glass and resin and let harden (only a few minutes). Job done; you probably won't even need a new header tank after this repair.

Agreed,glass or even araldite would likely hold.

forgotmyname

It will cost you more attempting to fix it than just replacing it.

custardy

forgotmyname wrote: »

It will cost you more attempting to fix it than just replacing it.

What does it cost to read their post?

knightstyle

I had a small hole in the top of a radiator so jammed in a piece of wood cut to the same shape as the hole, then smothered with epoxy, lasted 2 years till I sold the car.

Joe_Horner

EdGasket wrote: »

You don't use 'gloop' for this type of problem. You need to clean the exterior of the header tank where the leak is; roughen the area with coarse sandpaper; apply a couple of coats of fibre-glass and resin and let harden (only a few minutes). Job done; you probably won't even need a new header tank after this repair.

If you're replacing the tank anyway then gloop is a perfectly good, and quick, stop-gap. If you're keeping the the tank (through necessity or otherwise) then working out the suitable solvent and solvent welding it is a better permanent repair than epoxy.

Once you know what to use, just run a little of the solvent along the length of the crack and let it do its stuff. It gets drawn into the crack by capilliary action, the polymer chains unwind as they dissolve then, as it dries, they all curl up again effectively knitting the edges back into an unbroken piece of plastic.

Acetone or MEK are good ones to try to start with for most plastics on cars but try on an inconspicuous (and doesn't matter if it melts completely!) bit first.

forgotmyname

custardy wrote: »

What does it cost to read their post?

I did read their post? And my quote is correct. Why mess around trying to fix it and spend as much as a replacement costs when they could get one much sooner.

No need to wait a week, use the extra money saved on not having to botch it on getting the new tank.

EdGasket

Joe_Horner wrote: »

If you're replacing the tank anyway then gloop is a perfectly good, and quick, stop-gap.

No No, you risk gumming things up unecessarily. It's a simple repair; no need for gloop or even a new tank.

Joe_Horner

EdGasket wrote: »

No No, you risk gumming things up unecessarily. It's a simple repair; no need for gloop or even a new tank.

That's the thing, for all the warnings I can honestly say I've never seen a rad sealer "gum things up" when used in the suggested dose.

On the other hand, personally if I had a tank on the way anyway, I'd probably just be topping up as needed in the meantime if the crack's above the cold level.