From: xenolith@optusnet.com.au   
      
   On 14/6/20 12:33 am, Scott Dorsey wrote:   
   >    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.   
      
   Any radiator that is 10+ years old should be replaced pre-emptively   
   because the plastic top and bottom tanks, which get brittle with age and   
   heat cycling, are likely to crack and develop a massive leak.   
   >   
   > 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   
   >   
   Most modern cars I've seen no longer have a heater valve as such. They   
   were always a point of failure - sticking, blocking, leaking, etc. The   
   trend now is to run hot water through the heater core all the time and   
   use *air flow control* to regulate the car's internal temperature. For   
   this purpose they use a *blend door/flap* in the heater/AC to achieve a   
   much more rapid temperature change - necessary with climate control.   
      
   --   
      
   Xeno   
      
      
   Nothing astonishes Noddy so much as common sense and plain dealing.   
          (with apologies to Ralph Waldo Emerson)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)