Hi guys I'm in a bit of a pickle, I can't understand why my car over heats when traveling long distance e.g. Motorway driving i would have to let off the throttle but is fine driving around town e.g. Start- stop driving it doesn't overheat then. Any ideas! Cheers
toyboy3,
Jun 30, 5:52pm
blocked radiator
jasongroves,
Jun 30, 5:55pm
Are you sure its actually overheating and not a faulty gauge! Would be a good idea to test the cooling system for faults though. Radiator specialist would be able to do a few basic tests for next to nothing. Check the thermostat is opening at the correct temp and that the fans are operating. It is strange that it doesn't happen around town though.
foneguy1987,
Jun 30, 5:57pm
O I forgot to mention the radiator is brand new just had it replaced. The issue was happening before when my old radiator was leaking but still same issue after putting in new radiator thanks
berg,
Jun 30, 6:02pm
Have you got spot lights or mesh in the air inlet. Another cause we found was some aftermarket front bumpers/spoilers had either smaller air inlets or bled the air off before it went through the radiator.
fordcrzy,
Jun 30, 6:31pm
replace the thermostat and while you are there get the little "T" piece that comes of the tstat housing replaced. that little T can get blocked up and the thermostat doesnt work properly. the small hose off the housing draws water through past the t stat element. if it gets blocked the stat doesnt open properly. the t piece also often breaks off causing sudden loss of coolant
fordcrzy,
Jun 30, 6:51pm
also from memory the temp sender is at the back of the head. the only coolant flow that the back of the head gets is that which flows through the heater core. if your heater core gets blocked then the flow at the back of the head is less and you will get a hot spot on #4 cylinder causing the gauge to go high. if you trace the heater hoses from the fire wall to the back of the head you will see the sender.pull it out and make sure it isnt caked in scale
foneguy1987,
Jun 30, 9:30pm
Hey huge thanks to all who replied. I doubt it is the thermostat! If the thermo stat was stuck opened wouldn't the the engine take ages to warm up! I have noticed though that the both fans never turn on even after going for a drive! Unless of purse I turn on AC if it's because of the fans not working Is this the item I need to replace! Trademe: 386025381
bitsy_boffin,
Jul 1, 12:48am
1 fan is switched only with the AC, but the other should of course come on with temperature.
foneguy1987,
Jul 1, 7:32am
Oh sorry guys another piece of info i forgot to mention is that when highway driving it seems to happen more often when my engine hasn't warmed up yet.
The temp needle would go a little past midway before I get scared and let go of the throttle. Which then after a few seconds or so the needle would drop back down to just below midway point. not sure what woulsnhave happened if I kept my foot on the accelerator, didn't want to risk anything.
Never had this problem during start stop-driving! Car would just warm up like normal and temp needle would stay just under midway point.
fordcrzy,
Jul 1, 4:19pm
you need to take notice of what i said about water flow.
the mx5 head has a very strange water flow path around it.if that T piece or your heater core gets blocked you are going to have issues. i think your heater core is blocked and its affecting the temp sensor for your gauge
if the fan wasnt working you'd be overheating around town not on the open road.
fordcrzy,
Jul 1, 6:36pm
theres two issues thatwill cause the issues you are having. the t off the t stat housing blocks and there no water flow past the thermo stat which is off on the extension housing at the front of the engine as the engine heats up it gets too hot as it takes a while for the t stat to see the water temp with no flow through the t piece, 2) your heater is blocked causing a localised hot spot in the back of the head. stop start driving causes the water in the block to move around but a constant rpm will cause a localised hotspot in the back of the head where the sensor is.
foneguy1987,
Jul 2, 10:07am
Ok thank you guys but I think I have given up there are so many suggestions I can't do all of them especially the one about the heater hose etc I can't even fit my hand in the rear of the engine haha total noob at this. I know how to change thermostat no problem but the suggestions from fordcry seem a bit out of my mechanical capabilities.
Whom can I take this problem to get it checked or sorted out! Any wof place! Radiator speciIst!
fordcrzy,
Aug 20, 4:02am
just replace the thermostat.easy job.while you are doing that just check that the T piece isnt blocked by sticking something down it. if that doesnt work then you need toget the coolant system checked and the heater checked for flow.if your radiator was clogged up then theres a good chance the heater is too
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