5000 Radiator Overflow Tube Broken

[Ameer Antar]

Ya, audi cooling systems are way different than american radiators....but I
would NOT even attempt running w/o the line to the overflow box. The reason
is b/c w/o it you have no radiator cap. in american cars, the radiator cap
is on the radiator itself, but on the type44 it's remote. Caps are the only
thing that really can regulate pressure in the system and prevent too much
pressure. You need to limit the pressure, but it also needs to be a certain
amount, b/c w/ more pressure, more heat gets transferred from the block/head
to the coolant. W/ the overflow tube closed, you may run into a problem of
too much pressure, unless you leave the top 1/4 of the radiator tank empty,
since coolant expands a great deal under higher temp. In the old days, eg.
on my '65 MGB, they just had an overflow tube that dumped on the ground, but
that's really bad for the environment and can kill pets. But even w/ their
design, the radiator cap was still in the system before the overflow tube,
so that cap controlled what goes to the ground. By leaving out the overflow
box, that's all gone....I think the best in this case is just a repair or if
you have some good epoxy, I bet you could drill a fitting into the endtank
seal w/ the epoxy. Don't know if PVC pipe would handle up to 250 deg., but
obviously aluminum, brass, copper will all work as fittings. good luck.

-ameer

----- Original Message -----
> Message: 11
> Date: Mon, 14 Jan 2002 16:18:22 -0800
> To: quattro at audifans.com
> From: Brian Devlin <bdevlin at stanford.edu>
> Subject: Re: 5000 Radiator Overflow Tube Broken
>
> That's not an overflow tube in the way an American car would have
> one. It really lets bubbles get out of the radiator and into the
> tank. It is pressurized along with the rest of the system, so you
> lose some boilover protection by having it disconnected. Plug both
> ends and it should cool just fine. But you will want to use the plug
> in the radiator as a purge valve next time you refill the system.
> -Brian
>
> >Hi,
> >
> >I broke the overflow return on the radiator end.
> >I've plugged the hole with a machine screw.  Has
> >anyone
> >had experience with this blocked?  Are there
> >overheating problems?
> >
> >Any recommendations/BTDT for fixing.  Has anyone
> >drilled the tube out the radiator and epoxied in a
> >tube?
> >
> >thanks,
> >Matt
> >
> >
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