> wrote:
>A friend put in stop leak and now the heater core is blocked. Unfortunately
>it is much harder to replace than radiator or thermostat (which seem to be
>okay anyway). He put some detergent in the coolant and reversed the hoses,
>which achieved nothing.

It does that. Replace the heater core. Don't just remove it and try to clean
it either. Likely there is enough stop leak in the radiator that if it comes
out, it will clog the heater core up again, so it may be worth replacing
the radiator pre-emptively as well. At the very least try to do a reverse
flush on the radiator.

The first question: where was the leak that he was trying to stop? If it
was in the radiator, the radiator has to go anyway. Worry first about
fixing that leak because fixing it may free up more stop leak to clog the
heater up.

Also.... make sure it is the heater that is clogged and not the valve.
The valve may be comparatively easy to replace, rebuild or clean. Either
way, it's something to clean before touching the heater core.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."