1j overheating

[yann]

My engine is overheating badly despite the thick aftermarket radiator and good quality twin thermofans I have installed.
My first thought is that the thermostat is broke,how do you check if its working or not?
Is it a big job to replace,is it in the coolant tube that bolts to the side of the head?
Thanks for any help

[lexsmaz]

Certainly the thermostat is the first port of call, its located in the fitting that goes onto the back of the water pump, ie; follow the bottom hose up to the metal inlet housing, & there are 2 bolts you need to undo & the thermostat is in there ...
Also when did the problem occur, have you done some changes, ie; thick after market radiator or did it just happen. if its after some changes you might have to re-look at what you have done or fittted ...
To test the thermostat, visually look to see that the bracket etc holding the guts of it is not broken, if it looks ok you will need to immerse it in water & start to heat the water up, use your kitchen hotplate, you will need to put a thermometer in the water & keep an eye on the thermostat when it starts to open up, should start to open at the temp stamped on the thermostat, & open quite wide very soon after, if it looks sus buy a geniune one from toyota & even compare the two together in the water ...

[SL666]

when does it overheat? in traffic? or on the hyway etc?

[Dale]

Are you sure it's not something as simple as an air lock if you've just replaced the radiator?

Thermostat is just below the front turbo

[lojik]

Check that the thermofans actually spinning.
I had overheating issues, it turned out to be a burnt out relay that was supposed to be switching the fans on n off.

[EldarO]

could be anything from BHG to thermostat.

start checking stuff one by one, but you need to give a discription about under what conditions it heats up...

sitting in traffic? on the highway? temp drops when you rev it? etc.

[SL666]

could be anything from BHG to thermostat.

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[Admiral coFF33]

Easiest thing to do in order is :

1. Start car , and leave it running for a good 5 mins with radiator cap off to ensure all airlocks are let out.

2. once you have completed 1 , replace radiator cap and run car again for 5 mins and look for ANYYYYYYYYYYYYYY drips (best to test with some Techaloy as its fluro green) even the slightest pressure leak can cause overheating

3. check thermostat and rubber seal on radiator cap

4. TK test for BHG

also you need to tell us wether it overheats whilst idle (at traffic lights) and if it doesnt start to go back to ~75 ->85 whilst driving at a constat 60kph or more...

[yann]

thanks heaps for all the advice,ive checked all the basics like leaks,air pockets and the fans switching on so im gona take the thermostat out and see if it works.
it over heats bad in traffic but it still runs hot even on the highway

[EldarO]

SL666, neg rep applied, keep stupid shit to yourself.

are you losing coolant at all? or is it just heating up too much?

if the latter, id suggest either blocked radiator or thermostat.

[SL666]

EldarO: I could have said the same to you. It was either post the pic or neg rep you for the BHG suggestion - Only reason i didn't was because of the Dave Chappelle ref, but i might go back and do it anyway, i am yet to decide.

Yann: taking out the thermostat isn't the best idea, its in there to regulate (slow it down) even when its fully open, and *trying hard to remember* i'm not sure the housing will seal without the thermostat? (but i could be thinking of a mitsu thing)

Before f*cking with that, idle it up, wait for the thermo's to kick in, make sure they blow the right way - ciggie smoke, lit piece of paper etc is a really good way to tell. Its really easy to wire them backwards when you have had engines in&out etc.

if the fans are ok -
Get a thermostat, chuck it in, don't just remove one. cheap and easy.

until you get around to it, just crank up the heater when she gets warm.

BTW how do you know she's getting warm?

[EldarO]

BHG? whats wrong with that suggestion? its a valid reason to have a car overheat.

[Admiral coFF33]

SL666 is right.
Try that.
The likelyness of fucking up thermo fan install is slim though as generally u can only put them on 1 way.

But before taking the thermostat out and draining the system and having to make a new seal around the thermostat housing and all that shit which will take a whole day.

get a TK test done to assure you DONT have a blowen head gasket.
Takes 5 mins if u know a mate with a tester , or alternativly your local radiator shop will charge u $50 and will take 15 mins if they aint mega busy.

Will save u time/anger

[SL666]

pretty sure it's not.

a BHG can be caused by overheating (and subsequent head warpage) but if your headgasket has blown, it will not usually present itself as overheating.

The headgasket can only blow in a few ways.. the only ones that will effect the coolant in any way are.

coolant passage to oil passage - oil contamination in the water, and water contamination in the oil, if you have lost enough water though this into the sump to be causing overheating, you probably would have noticed the oil level raising by a couple of litres..

coolant passage to combustion chamber - the combustion gasses pushing coolant out the overflow, and then the water filling the combustion chamber once the engine is off. Again, would have to be pretty severe to cause overheating, and if its that severe, overheating is not going to be the first symptom you are likely to notice.

coolant passage to outside of block - if you have lost a couple of litres of coolant down the side of the block, you would probably notice it.. if not by the sheer volume of water you would have lost, by the coolant stains etc.

[SL666]

coFF33: AFAIK a TK test should usually be done on coolant thats pretty new? there is always some contamination of coolant with combustion gasses over time - its really something you check as a last resort IMOHO in my limited experience you will see lots of little bubbles in your coolant at idle if there is a bad leak.