80 series HZJ80 1HZ Overheating

Member - Nick (TAS) replied:

Any black smoke??
Could be the fuel system over fuelling.
Radiator cap?
Get a test done for Co2 in the coolant.Could be a cracked head. Thumbs UpThanks 0

Malleerv replied:

Could be a slipping impeller in you water pump but it sounds more like a blown head gasket or cracked head to me.
Start it with the radiator cap off and watch it as it heats up idling or just above idle. Look for continuous bubbles of froth forming in the filler neck of the radiator.
If you see either its time to pull the head off.

Cheers Matt Thumbs UpThanks 0

Joe n Mel replied:

sounds a lot like mine, started heading up from Katanning, fine down low speeds and slowly worse as the days went by, started to get hot at 110 in cold RAIN ..............
1st did thermostat in perth, it was not opening fully, better but still getting hot.. (June)
2nd fitted sh radiator from wreckers in Perth, helped heaps, made it to Tom Price... Got hotter at Broome .....
Long story cut short.. Broome, Darwin, Alice Springs and halfway up the Tanimi for 3 months, was summer by then and all started getting hot again...soooo..
Got brand new radiator and fitted, new thermostat (again) and complete set of hoses and belts and re-oiled up the fan clutch and fitted watch-dog.... went heaps better but could not handle the REALLY hot days with A/c ....
Travelled back up to Darwin and back down to Booraloola and got a brand new fan clutch and it is as cool as a cucumber now, loaded, ac, 3 kids and camper ....
So from my experiance and all other posts i have read..... get a brand new radiator (exactly the same "original"), new t/stat, new hoses, new belts, new coolant, and finally buy a NEW and TOYOTA original fan hub, dont touch it just install as is and providing you dont have a cracked head you will have no further problems, if the head is cracked you will still need to do all above anyway if you want it to last....
Cheers matey and good luck...... Thumbs UpThanks 0

Member - Phil G (SA) replied:

#1 You need the radiator place to remove the top tank and have the radiator "rodded" - flushing usually doesn't do much. This is still the most common cause of overheating, and from what you say, it hasn't been done.

#2 have you cleaned out the air cond condensor in front of the radiator?

I'd also be fitting a digital temp gauge/alarm, like the TM2. Toyota temp gauges are poorly calibrated - they don't rise until the temp gets above 95 degrees. Thumbs UpThanks 0

Member - Serendipity(WA) replied:

After checking the usual cuprits for over heating - and it looks like you are onto these ones - the motor can over heat for a number of reasons already listed.

Usual cuprits are the radiator flow, colapsed hoses, poor water pump, blocked water jackets on motor. But usually there are tell tale signs of these and they build up with regular overheating problems.

Yours sounds much like an issue I had with my HJ75. Ran fine until one day a cop pulled me over and said I was blowing white smoke after taking off at the lights. This I had never noticed before and had no explanation at the time. Motor seemed to run alright.

That weekend we packed up the camper for a weekend away. Barely got 3 km down the freeway and the car over heated. Strange. Pulled over and let it cool off a bit at idle and took off again at 100km/h and bingo -over heated again.

Result - Mechanic found I had blown the rings in one piston. $5000 later I had a complete rebuilt motor. Very hard to deal with that cost at the time but with a blown motor a car is really worthless.

Looking back now I had the option of putting a turbo diesel motor in rather than the rebuild for a cost of $11 000 fitted. Should have done that but just struggled with that kind of money outlay.

Years later I spent $8000 and put the turbo diesel in - and what a difference. Just a world of difference and wished I had spent the money all those years earlier and had been driving around at real speed with better economy. So for 10 years drove with naturally aspirated and then 5 years with turbo in same car. Hind sight is a fickle thing.

David

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Member - Amy G (QLD) replied:

I second the radiator rodding- the fins fill up with muck over time and flushing it out doesn't remove it. My HZJ80 overheated under load when I bought it and this fixed it up (along with a new thermostat, which you've already done). It's not much money so definitely worth a go. Thumbs UpThanks 0

Hairs & Fysh replied:

Hi,
Stat with replacing the Silicone grease in the fan clutch, You can buy this from you local Toyota dealer, about $70 I think, It is a common problem with the early 80's.
You mentioned symptoms of a head gasket? Is your coolant system pressurizing more than normal?
Is there fine bubbles in the top tank of the radiator with the cap off? are you losing coolant? Because these are the usual signs of a warped head or head gasket problem.
I'd try the fan clutch first.
Hope you find it.


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Member No 1 replied:

I'm with Amy and Phil above

I had a radiator problem on an old 100 series just out of warranty
....found the core blocked with crap...err like a allot scale.....replaced and all ok

the coolant was supposedly replaced at its prescribed time ...what actually was this...they (the mob with a goanna as their logo) replaced coolant with a different type, without correctly flushing old stuff out which when combined reacted attacking alloy radiator...god only knows what it did to the engine side of it....it is a common problem going by the mob who replaced the radiator...i took up the issue, got some info from them but they then went very quiet and refused to talk when they realised where I was going

anyway check the PH of your coolant Thumbs UpThanks 0

Therifleman replied:

Good Day,some years ago my 80 series was overheating according to the temp. gauge when all else was in order.My mechanic put a temporary,properly calibrated gauge on it & took it for a good run(Mt.Colah to Gosford),all was good on the temporary gauge but the vehicle one was still showing it was overheating.Well there is a problem with the 80 series temp. gauge & the fuel gauge.It can only be rectified by replacing the fuel gauge,this was done & no more troubles.It may seem far fetched but if you talk to a GOOD!! auto.electrician he may be able to put you on the right track.
Regards,Mick. Thumbs UpThanks 0

Member - Pat (VIC) replied:

Hi.
when was the last time the shims done on the valves, as they wear the gap gets smaller restricting the flow of the gasses causing the engine to run hotter.
I know you say it still drivers the same i thought the same until i got mine done.
Worth a try if all else fails.
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fisho64 replied:

1st step-pressure test the cooling system and then you should see if there is a blown gasket, cracked head. Also as said-CO2 test.

But maybe if your not sure what to look for get a mechanic to at least diagnose it, probably save you mucho folding? Thumbs UpThanks 0