4AC AE92 Overheating, but head gasket is fine?

[jimmmayyy]

gas in coolant but clear of oil=cracked head

TK test will confirm.

[mattysshop]

regarding the thermostate, just go and buy one! i paid $11.50 for a new thermostat, and seal, seriously it's the cheapest thing you can do which might solve the problem..

my ae92 wouldn't actually get to temperature, it would only stay about 1/3 on the gauge... i figured it wasn't the worst thing that could happen (aside from slight increase in fuel economy)... the simple 8 min job to replace the thermostat and seal revealed that the original one was stuck 'just open'

[stradlater]

Cracked head hey....

Could do without that, but what can you do.

Anyone got a spare 4afc?

[88MKIII 1G-GTE]

My 4AFE currently overheats. Fans work, thermostat works (NEW). There seems to be a fair amount of water movement in the radiator, but sometimes you hear this weird sound, like possibly air going through the water pump. Car boils itself, and overheats, even after removing thermostat. Sometimes car will be hold high temp, like near red, then you go up a hill, temp drops, go through a round-a-bout, temp drops, floor it.... temp drops. Sometimes it holds temp fine, never seems to hit red with water in the system, but it just boils and evaporates until it overheats again. System has been fully flushed...

I guess I should check the sensors, then the pump?

[senn]

When it's COLD, with the rad cap off, and the heater set to hot, run it up to temp and make sure it's not got any air locks in it....

Also make sure all the hoses going to the expansion tank are clear. Also make sure you try a Toyota genuine rad cap. Some of the knock off's i've found don't fit/work correctly.

[stradlater]

Interesting, that is similar behaviour to mine.

I'm thinking I might have cracked the head in the heat the last few days. But we'll see - the car has now cacked itself again, could be the timing belt or the ignition coil - will find out tonight.

Can't seem to win with this thing, In fairness I probably should have put a new coil in it last time rather than a second hand one.

Sounds like your problem has something to do with a water pump mate?

[The Last Streetfighter]

With my 4A, I never got overheating problems when the pump went, UNTIL you could see some coolant leaking out through the pump shaft seal telltale.

[88MKIII 1G-GTE]

I think I'm going to remove said pump this saturday and get to the bottom of it... I hope the head is cracked, then I may be able to justify replacing motor. When I bought the car it was perfect, pulled as hard as my mates 4age, now it's slow, makes noises, oveheats, it has now started to idle high aswell, and it feels like the engine mounts are gone, but they aren't, so I guess gearbox mount or the clutch is wigging out, as it doesn't like taking off.

[JP]

is it using water?

Has the cooling system been burped?

[stradlater]

I'm actually starting to think that it's a cracked head.

Stupid thing is 'pinging' just off idle, and when it gets hot is pings rather badly.

The coil died again (though it was second hand) so I"m going to replace that with a new one and then take it for a spin again to see what's what.

Anyone got a spare 4afc or a spare 4afc head?

[88MKIII 1G-GTE]

Ok. Took my car to a mechanic on Thursday. Apart from paying him to do sweet fuck all and not find the problem, it did make me think of a new solution to our similar problems (if they are the same).

BTW: All mechanics are fucking useless unless you know them personally, or have used them that many times they remember you on a first name basis. When the mechanic gave me back my car telling me there's nothing wrong but the water level is a bit low, I could have knocked him out. The water is constantly low, that's what's wrong with the car, that's what I asked you to fix. He also said he took it for a drive around the block and it didn't overheat... You tell me a 4a with a new thermostat and full radiator that will overheat going "around the block." Fucking pawns. Sorry. Now onto my solution.

In my car, when you fill the radiator using a bottle or such to extend past the top of the radiator, when the car is up to temp and the coolant has expanded, no leaks. The water level doesn't drop. When you rev the car, you can see air escape for a bit until all you get it tiny minute bubbles(but lots of them, big bubbles constantly indicates something wrong), which tells me, there is flow.

The coolant boils out throught the overflow tank, even when the car isn't running after several minutes, it will still be steaming from here, which is linked via the pressure only sensitive cap. So my theory is, the only remaining thing neither of us mentioned that could contribute is the cap not holding pressure, allowing air into the system and vice versa.

Your problem may not be the same as mine, but I'm definately buying a new cap before writing of my head.

If I didn't just spend my last money paying said fwit, I would have a new cap right now, and could inform you if my theory is correct.

[CELICASUPRA7M]

sqeeze the rad hoses and see if theres pressure?

[88MKIII 1G-GTE]

I know there is pressure, when you take the cap off after drving for 30 -45min is shoots water everywhere and the pressure lock from the steam really attacks you. The point was actually to see if it holds consistent pressure. Anyway just bought as new cap. Shall see what happens

[88MKIII 1G-GTE]

Upon inspection the old cap has been replaced very recently, I bought another and swapped it anyway.

Something new has happened, the water pump has completely packed it, and is now visibly leaking around a drop per second with the cap off.. So I guess I'll replace the water pump....

FML...

[stradlater]

Well, FWIW - My problem is a cracked head up one of the valve pathways - that's why I have a good static peak compression but still shit everything else.