4a-c Ae82 Overheating Problem!!!

[WiLo]

if its in the middle of the guage like in pic i wouldnt worry too much, thats where my old 4ac rolla used to sit once i had the thermo replaced



before i had the thermo replaced it would sit just above cold after driving for just under an hour with a lot of downhill which ment accelerator wasnt used/compression braking, after thermo was replaced it would sit between 1/4-1/2 which was alright i think

[cambelt]

Ah you just confirmed it . The gauge is jap ND so it must be the VDO sender in the motor thats not quite exactly matched to the gauge.
d

[WiLo]

no worries, your lucky i remebered i had the guage sitting in my drawer and that i could be bothered installing the drivers for my IR USB

[nos4ag]

Hey Guys!!
The temp guage sits excatly on half way with the thermo fan on all the time, and never moves. As soon as I connect the thermo switch cable and drive the car without the thremo fan on all the time, it starts to creep up slowly. It doesnt go into the red at all on the guage though, but as we are selling the car soon, I want to make sure that everything is still allright. Thanks for those pics WilO, they are much appreciated.
I think I am just going to put in an aftermarket switch and sell the damn thing, its a great little car though, and apart from this hasnt given me any troubles.
Thanks again guys for your help
Regards, Ben.

[oldcorollas]

re: fan temp switch.

pull it out, chuck the end in boiling water and check it switches.

then, clean it well (ie get off all the sludge, and MAKE SURE the threads on it, and the hole it goes into, are clean.. corrosion on the alloy bit it goes into (where it bolts to the .. gearbox?) can also be an issue.
perhaps first, check there is continuity between the body of the sensor, and the battery negative (iem return path thru the engine etc..)

my mums AE82 had same issue of fan not coming on... was just toomuch scale bui8ldup on the end of the sensor and the threads.. cleaned it and has been fine since.. the motor has over 300,000km on it and same sensor so yours should be ok.

do you get the gurgling noise form th eheater core? heater always on when changing coolant? seems the AE82 has an issuie of trapping air in there.. maybe park uphill and try to get the air out..

as for sucking in the hoses on cooling, means the recovery system is not working.. ie, the radiator cap is not letting the radiator suck coolant back in from the recovery tank... perhaps it is the wrong radiator cap?

and new thermostats CAN fail.... you'd be surprised..

[nos4ag]

OldCorollas, where have you been all my life!!
Thanks heaps for the info, rep to you buddy!!
I have heard a bit of a gurgling sound from inside the car when I start it up, and I will take out the switch and clean it and see what that will do. If what you are saying is correct, then after I put a clean switch back in, there should be no problem with it turning on and off.
Ill keep in touch.
Regards, Ben.

[Gary]

ive got a similar problem with a mates car, AE82 seca - 4AC (carb)

Cooling system is aok, we've pulled it all apart:
- radiator is fine, chunky bits werent coming through at the time of flushing, just dirty water. flow seemed fine, i flushed it at a couple different angles using a garden hose
- pump replaced with a new one, the old one was fine (no play in the bearing, fins looked new)
- thermostat replaced with a new one, that was faulty, now we're not running a thermostat at all
- back coolant passage flushed while the thermostat and hoses were out, dirty water but no chunks, flow was fine (shot the hose in from both sides)
- new guage thermo sender (drivers side, near the top rad hose), thermo switch was working fine as the thermos were coming on and going off at the right times
- no bubbles/smoke/oil/compression problems to suggest BHG, the HG was replaced recently i hear anyway
- the guage seems to work fine, it read cold when we put the engine all together, guage moved as a guage would, themos come on when it reads the middle, etc.
- system doesnt leak at all, checked hoses, thermo housing, pump and radiator for signs, the coolant level doesnt drop i hear

as far as i can tell, thats all there is to this system, we've flushed it all and replaced coolant, system is pretty much bled of all air. but the guage is still creeping up to hot when we give it a good squirt, and mate uses the car to tow bikes sometimes (tows it fine, bikes are only a couple hundred kilos and trailer isnt much), but the heat creeps up to and past H when he tows, and if he goes up hills for a while, or if its a crazy hot day - otherwise it happily sits just before the H line

the only thing i can think of is the tune, i checked the existing plugs to find them showing quite decent signs of running lean, replaced the plugs while i was there. when we went for a spin to check the waterpump and thermo housing seals were good, we came back and checked plugs again to find the new ones were burnt as well (white). the timing is also out by quite a bit

can the above two factors contribute to overheating? i understand the concept of running lean, but as far as i knew, in engines like this it couldnt quite heat things up to the point at which it became a problem - i sorta thought it was only a major drama for high compression engines
this bit is a bit far fetched, so bear with me. i noticed these heads are reverse-flow, meaning the exhaust manifold is quite close to the coolant passage. i thought perhaps the increased cylinder temps (affecting water jackets largely), and the increased exhaust temps (affecting the back coolant passage mostly) together would be a cause for temps getting quite high?

i cant think of it being anything else, mates getting the car looked at by a mechanic buddy who had similar ideas to us, ive told him to tell his mate to fix timing and look at carby tuning (i think most of its auto but i dunno carbies) to try and stop it running lean and see if that solves the problem

anyone got any thoughts? more than happy to hear em

[Cuzzo]

If you think your radiator is at all possibly blocked.

go one of these
ebay link

farkin cheap. i bought and run one on my twinky.

[RobertoX]

Just going on your thoughts of running lean. Try replacing the fuel filter (in case it's blocking flow) and then give the carby a good squirt with carby cleaner (jets blocked). Should be pretty cheap...
Also to rule it out see if your mechanic mate has a wideband O2 sensor to stick in the exhaust pipe.

[sexybackra28]

i had the same problem in my dads ae82 exact same problem. he changed everything he could cost him about 2k? and all he had to do was change the lead where the fan is. i wasnt sure what it was exactly but it was something to do with the lead where the fan is was fked up and that supposely gets the fan going if tis getting to a certain temperature. dad replaced it and now it struggles to get to half way. not sure it its the same with you or if i made any sense but im sure you'll work it out. ill ask him when he gets home from the cup

[Gary]

thanks fellas

when we removed the radiator the wiring to the fans looked fine not a bad thought though

hopefully his/our mechanic mate can get it running properly (ie not lean), see if that sorts it. cuzzo they're heaps cheap hey.. might suggest he get one of those anyway

[cambelt]

A 4ac will overheat if you take the thermostat out , put a new one and drill the bleed hole to 4 mm.
Dave

[Gary]

err... really? how so?