Overheating 20v

[_matt]

hey guys, my 20v is having a few drama's at hte moment heating wise. im not sure if maybe the water pump has carked it or what. running the stock ac rad which seems to be a common radiator i see in most 20v's with a clutch-fan n shroud. problem is that when crusing in 4th or 5th at low revs its starts to get hot.. like 100+ but if i drop a gear and give it a punch, it cools back down to 70/80. but then will slowly climbs back up to 100+ unless i keep dropping gears and belting for a little. changed the thermostat and did a flush, but still no result.. collapsed baffles maybe? thought id ask u guys before i either opt for a new radiator or get a reco. thanks heaps guys!

[steroidchickens]

well over 20kms thermo fans dont do anything, so it cannot be that.
maybe the radiator is blocked and not flowing as much? or water pump? or belt? sounds like the more you rev, it the more it flows?

what about idle? does it overheat when idleing? does it have the same problem in any gear at low revs?

i diddnt really solve anything but thats what i would check.

[_matt]

yeah it seems the more i rev, the more it cools down.. yeah it gets hot idling at the lights. but when i take off in first with abit of punch it cools back down. it asif theres not enuff pressure to open the thermistat.. but it opens with temp not pressure. so im not sure. unless.. is there much diff with rwd to fwd water pump set ups? im running the rwd pump

[hillclimb86]

i ahd the same trouble with my toyota hilux few years ago flushed radiator, new termastat, new clucth fan two infact stiil overheated on freeways when cruising at low revs then got a new radiator not genuine though(to get a radiator reconditioned was about the same as new one) now no troubles ever good luck

[mattysshop]

try running a good brand radiator/cooling system flush.. providing all your thermostate etc is in working order.. this should give you some sort of good result, also make sure your using a good quality coolant.. NOT corrosion inhibitor, but a coolant that specifically says it raises the boiling point, and make sure you mix it between 30% - 50% coolant water mix..

try that after you have flushed it with the system flush properly.. and run plain water through it for a few mins..

[mattysshop]

at low revs/high speed... eg freeway/cruising it should actually be working much much better than high engine speed... as the water is getting much cooler staying in the radiator for longer.. and passing through a cooler running motor.. that isn't burning the most fuel it possibly can.. but driving sedatley, at high speed, but lower engine speed is how you get a car to cool down..

thats the best way i can put it at 11:10pm..

[spoon]

sounds like it could be your water pump, maybe not sealing the blades properly (broken) and not creating positive pressure until high revs. also blocked radiator - take it to a radiator place and get it flushed n pressure tested... even could be the thermostat temp sensor hose could be crimped stopping the thermostat opening untill enough pressure builds up to get past the crimp

[psychofox]

how have you set up the cooling system (I assume this is in RWD) Have you blocked the back of the head or are you running the water pipes from there to the rad? If you have't done this correctly, you may have introduced a big air pocket / restricted the flow such that there is not enough water flowing around when idleing (when the water pump is flowing the least) and at higher rpm it is pushing through the restriction. What orientation do you have the thermostat - if you have done custome water pipes you may have the thermostat in the water circuit the wrong way round - which may cause it to not open - the thermo must go in the bottom rad hose with the spring side towards the block.

Also as the AE86 has such an open engine bay, at highway speeds, the air coming up into thew engine bay helps cooling a lot - sometimes at highway speeds thermostats can be closed as the air is cooling the engine enough - this may be masking the problem (although unlikely as you say that revs cool the engine)

[rthy]

I agree with psychofox, how about posting some pics of your engine bay?

[_matt]

sum bay pics of the cooling setuip, thanks for ur input guys much appreciated. im narrrowing it down to water pump or the whole cooling setup all together