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The mkiv Supra Owners Club

Thermostat ?


Jake

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My car is overheating, badly.

Most of the way home work the Water Temp gauge was pointing straight up but every now and again it'd go back to the normal mid way position for a couple of mins.

I've bought a new thermostat on my way home and I'm waiting for the car to cool down before I try and fit it.

Anything I need to beware of before tackling this?

 

Where is the Thermostat located anyway? I couldn't see it when I had a quick look just now.

 

 

Thanks

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Thanks for all the replies so far ! :tongue:

 

OK so the thermostat isn't on the top side of the rad so it's got to be underneath. I've just been and borrowed a couple of trolly jacks and will attempt to change the thermostat in the morning, it's pouring with rain at the moment.

 

Does anyone know if this is a do-able job for me at home on my drive with just your average 'spanners and sockets' tools? Am I going to have to remove other stuff apart from the engine undertray thing to get at the thermostat housing?

Somebody one here must know.

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Originally posted by Matt Harwood

I'm sure you would have noticed, but I'll say it anyway... The oly time my car has overheated, the front bumper opening was full of leaves. That was on the motorway on a windy day though.

 

Just a thought. :)

 

Matt only noticed when the roots came up over the bonnet !!!:cool:

 

Dude:flame Dev

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Thanks for the replies guys.

 

I've bee searching and found a thread which sounded very similar to my problem. It never actually comes to any conclusion what the problem is though :conf:

 

I've a least found out that the stat is at the bottom hose engine end but I'm still none the wiser as to whether it's a job I should tackle myself.

 

The car has had a siezed viscous fan coupling as long as I've owned (over a year) but I don't think that is causing this problem.

I'm prepared to attempt replacing the 'stat but I do not fancy changing the water pump. I'll be down Halfords/Toyota/Motor Factors tommow AM trying get a new rad cap too.

 

Oh and the really good news is that I'm pretty sure the rad is cracked as well now! There was steam coming out under pressure from the (plastic?) top of the rad, between the core and the filler cap.

Oh joy.

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Originally posted by dude

Does the heater still work ????

It does eventually, I've noticed recently that it's taking a very long time before I can get any hot air out of it. Seems that the Temp gauge has usually been at Normal for ages before I can get any warm air from the heater.

What makes you ask that? Are you perhaps thinking "air lock"? Or (please God no) "heater matrix"?

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Originally posted by Jake

It does eventually, I've noticed recently that it's taking a very long time before I can get any hot air out of it. Seems that the Temp gauge has usually been at Normal for ages before I can get any warm air from the heater.

What makes you ask that? Are you perhaps thinking "air lock"? Or (please God no) "heater matrix"?

 

No im thinking that the fan has F***ed the water pump , it was vibrating badly !!!! and the WP is not circulating the water as it should , to change pump is timing belt and a bit more !!!!

 

Dude:flame Dev

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3 coolant probs I see regularly now, in order of "commonest".

 

Rad cap knackered

 

Water pump leaking, water often evaporates before it hits the ground, and they stsrt by leaking only when the engine is hot, and not by dripping when engine is off, unlike most other WP's.

 

Rad leaking, core rotted out.

 

 

Get a coolant system pressure check done (I can do this, and fix whatever is causing the prob).

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Originally posted by dude

No im thinking that the fan has F***ed the water pump , it was vibrating badly !!!! and the WP is not circulating the water as it should , to change pump is timing belt and a bit more !!!!

I can't see a static (non-viscous) fan causing water pump failure. Surely a properly operating one is locked up solid when the engine is hot anyway, right? OK so it probably doesn't aid a smooth tickover but that's about all isn't it?

Anyway, if it's the water pump then it is, no point me crying about it now. I'll try the easier/cheaper possibilities first though.

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Originally posted by Chris Wilson

3 coolant probs I see regularly now, in order of "commonest".

 

Rad cap knackered

 

Water pump leaking, water often evaporates before it hits the ground, and they stsrt by leaking only when the engine is hot, and not by dripping when engine is off, unlike most other WP's.

 

Rad leaking, core rotted out..

The Rad cap looks pretty new but I'll change it anyway. It's never lost water before today, I've never had to top it up once in over of ownership. I'll have a butchers around the pump in morning and see if I can spot any leaks.

 

The Rad core doesn't look in bad condition from what I can see so far.

 

I wish you were nearer to me Chris!

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Most of the pumps ive changed have had a plastic Impeller the replacements from Toyota have had Metal ones , if the Impeller has lost a couple of blades that would account for the car getting hot and poor heater , the tanks on the rad can crack for absolutley no reason its due to the type of plastic used and that fan should never be fully locked like yours has been so yes its quite possible that it could destroy the pump , i cant believe it hasnt flown off and gone thru the rad by now , you wont believe how many viscous seized fans ive seen do that , you may find the stat easier to change if you remove the allternator .:thumbs:

 

Dude:flame Dev

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Originally posted by Ian C

Alex's overheating problem was cured by replacing the radiator. It had died of old age. If the rad is cracked as well it really should be replaced. Sounds like you need the viscous coupling and pump doing too, £££

Yeah the rad if definitely cracked. Obviously I'll need to get that fixed or replaced ASAFP but I'm wondering if that could be the cause of the problem or whether it's a result of it overheating. I don't really understand the mechanics of how a faulty red cap could have be a suspect for this problem but I guess a crack in the Rad would have a very similar effect, right?

 

All things considered, I think I'd rather change the Rad than the waterpump.

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The cooling system is pressurised, which raises the boiling point of the water in the system. If the rad cap is leaking out pressure the water pressure drops and the boiling point drops. Eventually it goes below the normal running temperature of the cooling system and boils up.

 

Your rad may have been cracked by excessive heat OR the actual crack is depressurising the system as noted above and causing the overheat.

 

I'd start by replacing the rad. If it still overheats, you've not "lost" anything as the rad needed doing anyway... You're highly unlikely to crack a new rad by overheating a bit once on the shakedown.

 

-Ian

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Well I filled the rad back up and took the car for a long drive and it's working fine. I'm thinking that the crack in the plastic top tank of the rad might have been there for a while and it has slooowly let the water leak out until it got to the point where it started overheating.

Anyway, I've got the rad out of the car now, after a bit of a struggle and one "How Do I" phone call to Dude (Thanks John!) and I've been quoted £80 by Serck Marston to fit a replacement top tank and another £80 if I want it re-cored. The core itself looks pretty good though.

I'll be over the moon if I get away with this for £80!

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Well, you would need to overheat the car a lot, badly, and constantly, and even then something else would go before the radiator cracked due to overheating. So you won't crack it by the car overheating a bit on the shakedown run after fitting it.

 

What I'm saying is you won't wreck the new radiator if that wasn't the cause of the overheating so it's OK to fit just that to start with :)

 

-Ian

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Another thing, I'm suprised the Rad was doing any cooling at all : there were hundreds of leaves blocking the majority of the cooling fins. They were all stuck between the front of the rad and the back of that other thing that looks like a rad.

 

What is that thing anyway? Seems like it's only about an inch or less thick but as wide and high as the radiator. I can't see any pipes going in or out of it but I suppose there must be somewhere.

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Originally posted by Ian C

What I'm saying is you won't wreck the new radiator if that wasn't the cause of the overheating so it's OK to fit just that to start with

Ah! I understand now.

http://www.mpaconsultancy.co.uk/iamstupid.gif

 

Thanks mate

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Originally posted by Jake

Another thing, I'm suprised the Rad was doing any cooling at all : there were hundreds of leaves blocking the majority of the cooling fins. They were all stuck between the front of the rad and the back of that other thing that looks like a rad.

 

What is that thing anyway? Seems like it's only about an inch or less thick but as wide and high as the radiator. I can't see any pipes going in or out of it but I suppose there must be somewhere.

 

Air con radiator?

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