overheating again

hi all any help plz ive had increasing overheating probs with my mode 54 plate started overheating on long runs now all the time after about 15 mins ive taken it to 3 garages they have checked viscous fan, water pump, thermostate, all seem to be working ok ive even had a dye test to see if its a cracked block head gasket ect nothing coming up at all ive even bought evans water free cooland that stoped it boiling out but nothing else ive dropped that out now and put water back in having a dye test again tomorrow and a cilinder pressure test the only thing i can say thats relivent is when car overheates if i put heaters on it cooles back down to normal ? any ideas guys cos other than changing engine dont know were to go this is very very frustrating

Whats the condition of the rad

Has the rad cap been tested

May have an air lock

when you say about the rad do you mean any obvious signs of wear ? cos can you check it ??

If the Core is blocked not easy to diagnose but with the money you have already spent mite not be a bad shout to replace the rad before doing anything radical like changing the engine.
You can however check are all the fins there does it look as i descibe moth eaten




If you remove the hoses and pour water in the top inlet does it flow freely through the radiator ???
When running does the radiator have cold spots and hot spots

everything your explaining happened to mine, even the dye test, came down to the headgasket was gone, new gasket and skim and all is well

I had the same symptoms, had the thermostat changed by local garage and the the rad changed and the fan changed (by main stealer) a few weeks later. They road tested it each time and it was fine. Few weeks later it blew big style - new gasket and head skin then went down the logical route everytime, swopping those most likely to fail first, but it was definately the head gasket in the end

. When it finally went, the temp gauge was fine until about 2 miles before, then when going round corners it would soar, before returning to the level. Then it blew the rad pipe and that was it. AA man did their tests at the side of the road and he said he didnt think it was the head as the pressure was fine and that it could have been an iffy water pump, exactly what the garage that sorted it said, until they road tested it and the temp started to soar, then the stripped it and did the head gasket and skimmed it.