john hardy

help with cooling system

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hi there, im needing some help please with cooling system issues on my lexus is 200 sport t reg , 99 model , i ve had car around 3 months everthing was running fine until recently , was travelling in car when temp gauge was going to high , loss of coolant , pulled over straight away,let car cool down, topped up and had heater fans on full all way home,got back ok, when we started looking into what was wrong this is what we found, coolant leaking running down back on both sides of black plasic electric fan casings, top of coolant black plastic expansion tank has lifted in two places one at either end , has little clips , think theyve perished  , is there any quality bonding agent for plastics which would seal this , anyone else had this issue, my dad thinks leaking from here, want to seal then test it, we took out radiator and all back casing with expansion coolant tank on , the temp sender for the electric fans on bottom of radiator broke off , ive found some after market ones on e bay cheap enough , was quoted £80 + by lexus main dealers, is this a part where you should be using a genuine part are or these after market ones reliable enough, anyone with experience on these, does anyone know what temp electric fans cut in at, not sure if there working properly want to test ,  anyone know which colour wires live for temp sender for electric fans, putting in new japspeed radiator got of e bay, old one not leaking but matrix starting to perish, its genuine toyota radiator whats come off, anyone know how long these usually go far if serviced right, anyone know if you can find out if its original radiator on car from new with codes whats on radiator , was thinking of getting it reconditioned if there really good, prior to this there was no visable loss of coolant on ground or major loss in expansion coolant tank, checked this weekly since bought car , when put back on going to put some white card down on top of plastic cover in bottom of engine bay, see if anything else shows up, when , i rung up lexus the guy there said there was a bypass pipe near thermostat housing with 2 o rings where there are known to go, anyone know anything about this or anything else i should be checking which could be causing or contributing, any help and advice will be greatly appriciated as havent got a service manual yet, cheers john


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Hi mate,

I've recently had issues with my cooling system too, the rad went and needed replacing. I also replaced the temp sensor, this was £15 from SC Motor Factors and works like a charm. The fans are supposed to cut in at 98 degrees C. You can bypass the fans by putting a piece of wire in the connector, bridging the connections, this will bring the fan on all the time to test if the fans are working. Although this should not be a fix for a faulty sensor. Watch out as SC's sold me one listed for my car and was too small, there are two sizes for the rad and you want the larger size sensor. Not sure which colours are which but this can be identified with a multimeter once the sensor has been bypassed. My radiator i just replaced had done 147,000 miles. If your replacing the sensor and rad, you might as well replace the thermostat too at the same time, two 10mm bolts and just pops out.

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