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The mkiv Supra Owners Club

Urgent help bleeding coolant system.


Kaan W

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The stat will only open at 82 degrees mate. If the stat isn't opening, that's why the bottom hose is cold. Check the dash temp gauge, stat should open with the gauge at half way. Failing that take the stat out and drop it in a pan of boiling water and it should pop open (i think). Once the stat opens, the water level in the stat will start to drop

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The stat will only open at 82 degrees mate. If the stat isn't opening, that's why the bottom hose is cold. Check the dash temp gauge, stat should open with the gauge at half way. Failing that take the stat out and drop it in a pan of boiling water and it should pop open (i think). Once the stat opens, the water level in the stat will start to drop

 

Ok i'll try this sounds like it could work. Do I need to replace any gaskets?

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You may do, I'm not over sure, depends on the state of the old one I suppose. A stat isn't a lot of money from Toyota

 

Yeah I was just thinking if I test it and it pops open then it still can work. But I meant if I get a new stat do they usually come with gaskets?

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The one that I bought didn't have gaskets, they are separate. The part number is 90916-03093 for a stat. I've just dropped a spare one that I had in boiling water and it opens approx 10mm. if it works, when you put it back in, there is a "jiggle pin" that is in the ring bit of the stat, that should sit at the top when you reseat the stat.

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The one that I bought didn't have gaskets, they are separate. The part number is 90916-03093 for a stat. I've just dropped a spare one that I had in boiling water and it opens approx 10mm. if it works, when you put it back in, there is a "jiggle pin" that is in the ring bit of the stat, that should sit at the top when you reseat the stat.

 

Ok mate thanks for your help much appreciated. I will test the stat tomorrow and have another ago at filling the system.

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Ive been thinking that if coolants not getting to the thermostat then its not going to open to let the coolant through the rest of the engine. Is it possible to take one of the heater hoses off and poor water in from the top to enable it to come into contact with the thermostat?

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That's sort of the point of the thermostat. Take the stat out and test it. Sometimes overthinking stuff can make things more difficult. Go back to basics, test the stat and flush the system out to ensure there's no blockages. Once you've done that, see where you're at mate.

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Yes. If there's an air lock in the block, the stat won't open. Get the basics out of the way to begin with and then you know everything's right. If everything's working, then it can only be an air lock or headgasket failure.

 

Thats what I need to get my head around tho, getting coolant to the stat! it shouldnt be anything else as car was working fine and all ive done is put a new radiator on. I just cant get the coolant to the stat :confused:

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What I do is remove the top hose from the radiator, fill the engine from top hose until the rad is full, refit, run.

Just do this. Leave the rad cap off and the odd bubble will come through - keep topping it up with coolant whenever the level drops a bit.

 

Bear in mind it takes ages for a car to warm up enough for the thermostat to open, if you're just idelling it rather than driving it. It'll be 5-10 mins until the thermostat opens, and if you're doing all of this without checking to see if the temp gauge has moved at all, then you're half blind to what is going on (I say half blind as the temp gauge is a big fat lying machine, but at least when it shows half way the coolant is roughly at the right temp).

 

Once the car IS up to temp and the thermostat opens (hopefully) the coolant will come gushing out of the rad so slap the cap on quick if you haven't already. Switch off the engine, let it cool down for a few hours, top up the coolant, drive the car for 15~20 mins - watching the gauge just in case it gets too hot - let it cool down again, top-up if necessary, repeat if necessary.

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I thought the heater hoses are all part of the main water system?

It is, but it's effectively a separate circuit. You decide if you want coolant to flow through that circuit via your selection on the heater control knob in the cabin. The thermostat 'decides' whether coolant needs to be sent via the car radiator (i.e. to start cooling the coolant, once the engine is hot enough). The two systems don't run in series, they couldn't. They are parallel and - bar the fact they share the same coolant fluid - separate systems. i.e. What the thermostat is/isn't doing makes no different to the heater matrix in the cabin.

 

- - - Updated - - -

 

Will the rad fill up tho if the stats shut?

Yes, because you're filling both 'sides' of it.

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Just do this. Leave the rad cap off and the odd bubble will come through - keep topping it up with coolant whenever the level drops a bit.

 

Bear in mind it takes ages for a car to warm up enough for the thermostat to open, if you're just idelling it rather than driving it. It'll be 5-10 mins until the thermostat opens, and if you're doing all of this without checking to see if the temp gauge has moved at all, then you're half blind to what is going on (I say half blind as the temp gauge is a big fat lying machine, but at least when it shows half way the coolant is roughly at the right temp).

 

Once the car IS up to temp and the thermostat opens (hopefully) the coolant will come gushing out of the rad so slap the cap on quick if you haven't already. Switch off the engine, let it cool down for a few hours, top up the coolant, drive the car for 15~20 mins - watching the gauge just in case it gets too hot - let it cool down again, top-up if necessary, repeat if necessary.

 

That sounds like it makes sense i'll try this tomorrow and let you know. Before when I tried I switched the engine off after a few minutes everytime steam started coming out the rad cap opening so i'll let it warm up for 10 minutes hoping the stat opens.

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That sounds like it makes sense i'll try this tomorrow and let you know. Before when I tried I switched the engine off after a few minutes everytime steam started coming out the rad cap opening so i'll let it warm up for 10 minutes hoping the stat opens.

Steam will come out of the radiator opening when the coolant gets hot and the cap isn't in place to stop it. That's what hot water does - steams. :)

Sorry if that sounds facetious but I'm not sure I understand what you mean here.

 

I think you car and thermostat are probably 100% fine and working correctly and you are worrying over nothing, but it's difficult to tell without being certain what is happening. That's not a criticism BTW, everyone who knows what they are doing went though the 'oh god what is happening, I've ruined something!' stage at some point. ;)

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Steam will come out of the radiator opening when the coolant gets hot and the cap isn't in place to stop it. That's what hot water does - steams. :)

Sorry if that sounds facetious but I'm not sure I understand what you mean here.

 

I think you car and thermostat are probably 100% fine and working correctly and you are worrying over nothing, but it's difficult to tell without being certain what is happening. That's not a criticism BTW, everyone who knows what they are doing went though the 'oh god what is happening, I've ruined something!' stage at some point. ;)

 

I know mate dont worry I dont think that, the advice you have given makes perfect sense :) I probably am just worrying over nothing lol.

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Also I forgot but I removed the electrical plug from the small aux fan as its constantly on for some reason. That shouldnt effect the stat should it?

 

The electric fan runs all the time as soon as you disconnect the sensor at the bottom of the original radiator. The sensor has normally closed contacts. That means the sensor has continuity until the coolant gets to the rated temp of the sensor, when the contacts then open, a relay will then be de-energised and the fan comes on. I guess they did it this way to provide a bit of protection if the sensor was to fail, so rather than no fan ever you have fan all the time. There is also a NC sensor in the AC that is in series with the sensor in the rad that will also have the same effect. Could it be that you have put the rad sensor back and connected it and then left the sensor in the AC kit disconnected? If so that would bring the fan in. The relay fo the fan is down by the passenger side headlight.

Edited by Shane (see edit history)
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