Over-Heating/leaking Radiator Corolla 2002

[kcoralla86]

Yes they are very fiddly to do because of the lack of space. As said above id get a haynes mannual for the car as it will explain everything in a step by step tutorial if you dont know where to start :)

I would change the gasket/seal on the thermostat housing at the same time. Generally these come with the new thermostat so check at the time of buying ;)

When filling up coolant i always put one litre of coolant in one litre of water untill topped up to make sure you keep a 50/50 ratio of coolant and water. If you live in a hard water area i would buy some de ionised water to fill it rather than the tap stuff.

The heaters need to be on hot and the system filled up preferably with the rear of the car at a lower height than the front, this avoids airlocks. Run the car with the expansion cap off for a few minutes then replace to aid bleeding the coolant system. You should get hot air through the heaters on the car once warm (tho its a comon prob on corollas to only get luke warm air) but it shouldnt be cold. This confirms the system is bled correctly.

All this is explained in the haynes mannual in great detail if you decided to purchase one :)

I just had a quote from Toyota to replace the Thermostat - £108.91 plus VAT. Thermostat was £25 plus VAT... but I can get it for £8 online.

I think I am going to take your advice to get the Haynes Manual, and do it all myself hopefully all within about £40 I reckon. Just seeing if the thermostat I am buying comes with the Housing Gasket or not. Otherwise will need this from Toyota for £9

[kcoralla86]

Yes they are very fiddly to do because of the lack of space. As said above id get a haynes mannual for the car as it will explain everything in a step by step tutorial if you dont know where to start :)

I would change the gasket/seal on the thermostat housing at the same time. Generally these come with the new thermostat so check at the time of buying ;)

When filling up coolant i always put one litre of coolant in one litre of water untill topped up to make sure you keep a 50/50 ratio of coolant and water. If you live in a hard water area i would buy some de ionised water to fill it rather than the tap stuff.

The heaters need to be on hot and the system filled up preferably with the rear of the car at a lower height than the front, this avoids airlocks. Run the car with the expansion cap off for a few minutes then replace to aid bleeding the coolant system. You should get hot air through the heaters on the car once warm (tho its a comon prob on corollas to only get luke warm air) but it shouldnt be cold. This confirms the system is bled correctly.

All this is explained in the haynes mannual in great detail if you decided to purchase one :)

Right I have my stat & gasket & the Haynes book. But reading the book I am a little confused or unsure now about the problem being the Stat.

The book says: "If the engine runs hot, use your hand to check the temperature of the radiator top hose. If the top hose is not hot, but the engine is hot, then the thermostat is probably stuck in the closed position, preventing the coolant inside the engine travelling through the radiator. However if the top hose is hot, it means that the coolant is flowing and the thermostat is open."

Now my top hose does get hot suggesting that the coolant is flowing and the thermostat is open. But the book doesn't say anything about the bottom pipe being hot or cold (in my case cold).

Am I right in thinking that my thermostat is stuck open, and therefore it's constantly letting water/coolant flow through the engine, and as the engine is getting hot, its boiling it away?

OR could it be as simple as an air locking problem. I'll keep reading to ensure I haven't missed anything about the bottom pipe, but at the moment, I have read any reference to it.

What do you think?

[Steven252]

The top hose will get hot wether its stuck open or closed as the heat from the engine transfers to it even if the water is not flowing. The bottom hose will always be colder than the top hose but on a boiling engine it will be still pritty warm.

If your thermostat was stuck open then the engine would never overheat and would take ages to warm up. Plus when traveling at 50-60mph the engine tenp would drop on the gauge all the way to cold as it would be over cooling.

It could be a simple airlock as i said before but i would change the thermostat just to eliminate it as being a problem.

An easier question i should have asked is, does the top of the radiator get hot?

[kcoralla86]

The top hose will get hot wether its stuck open or closed as the heat from the engine transfers to it even if the water is not flowing. The bottom hose will always be colder than the top hose but on a boiling engine it will be still pritty warm.

If your thermostat was stuck open then the engine would never overheat and would take ages to warm up. Plus when traveling at 50-60mph the engine tenp would drop on the gauge all the way to cold as it would be over cooling.

It could be a simple airlock as i said before but i would change the thermostat just to eliminate it as being a problem.

An easier question i should have asked is, does the top of the radiator get hot?

Thanks for the prompt response. To answer your question, when I checked the top of the radiator was not getting hot at all. I could touch the top of the radiator with my hand and not feel any warmth... this was even after the gauge had gone right up to hot.

Am I right in thinking that any airlocks should come out when I replace the thermostat as I am flushing the coolant, and refilling?

[Steven252]

If the radiators cold its deffo a stuck closed thermostat or a failed waterpump (unlikely as they generally leak when the fail)

Follow the haynes mannual to change the thermostat with the tips i gave for bleeding and youll be fine :)

[kcoralla86]

If the radiators cold its deffo a stuck closed thermostat or a failed waterpump (unlikely as they generally leak when the fail)

Follow the haynes mannual to change the thermostat with the tips i gave for bleeding and youll be fine :)

OK Thanks for the advice... Will hopefully get to do this over the next couple of days. Then will let you know what happens.

[kcoralla86]

I've just tried to have a go at changing the thermo... and seems harder than I first thought. Firstly the thermo doesn't seem to be where I thought it would be. I saw a video on Youtube that shows you how to locate the stat in any car which was to follow the top hose from the radiator, and at the other end is the stat. Well on the Corolla this leads to the right side of the engine.

However, the alternator is at the front left of the engine and beneath it is the end of the bottom hose that leads to the radiator. So am I right that the video I saw in this case was wrong, and the stat is actually at the end of the bottom hose from the radiator not the top?

It's started raining now, so I can't do it today. I will try to have another go at it, but the Haynes book was saying to take the alternator, and drive belt out which seems like a lot of work (for me anyway as I'm no mechanic).

[Steven252]

the stat will be at the top hose ;) itll never be on the bottom one.

[kcoralla86]

the stat will be at the top hose ;) itll never be on the bottom one.

So why would I need to remove the alternator which is on the other side of the engine?

[Steven252]

Double post

[Steven252]

the stat will be at the top hose ;) itll never be on the bottom one.

So why would I need to remove the alternator which is on the other side of the engine?

Does the top hose even go there? On my E11 it goes straight to the right hand side of the inlet. Im unsure on the E12? Can you post a pic?

Edit: here you can see where the top hose of my E11 goes to the block (themo is by there iirc but ill check in the light)

On the E12 on google i cant see where is goes??

????

[kcoralla86]

the stat will be at the top hose ;) itll never be on the bottom one.

So why would I need to remove the alternator which is on the other side of the engine?

Does the top hose even go there? On my E11 it goes straight to the right hand side of the inlet. Im unsure on the E12? Can you post a pic?

Edit: here you can see where the top hose of my E11 goes to the block

On the E12 on google i cant see where is goes??

????

Ok based on the 2 pics... mine is the E12 engine (pic of mine attached) You can see that the top hose (on the right of the radiator) goes in to the right side of the engine underneath the Engine Oil Cap. It's very difficult to see as when you take the engine cover off as I have done there are some many wires and pipes. The top radiator hose is underneath these. However the Alternator looks to be in the bottom left of the engine by the Oil Dipstick.

file://localhost/Users/Ketan/Pictures/PhotoSync/Ketan%20Panchal's%20iPhone/Camera%20Roll/IMG_1432.JPG

[kcoralla86]

OK how do you add a picture?

[Steven252]

Upload to photobucket them copy and past the img code

[kcoralla86]

Upload to photobucket them copy and past the img code

Here is the picture of my engine.. The top radiator hose ends just below the engine oil cap beneath all the wires and other pipes. While the Alternator is the silver block at the bottom left of the pic nearer to the Oil Dipstick... so not sure why I need to remove the Alternator which is nowhere near the Top radiator pipe. The bottom radiator pipe definitely ends behind the alternator. I don't know if this is correct but maybe Toyota designed it slightly different in this model?

[Steven252]

Ye it does seem so!

Follow the top hose from the radiator (the big chunky one) to where it goes into the block - i cant see it in the photos. Whete it enters the block the thermostat housing will be there

[kcoralla86]

Ye it does seem so!

Follow the top hose from the radiator (the big chunky one) to where it goes into the block - i cant see it in the photos. Whete it enters the block the thermostat housing will be there

So I've had the thermostat changed. Had a friends friend do it. And yes the stat is at the end of the bottom hose by the alternator, and not at the end of the top hose as we expected. I also still have a over heating car, so the guy is replacing the water pump for me tomorrow, which should hopefully solve it. We don't think it is the head gasket because we can't see any kind of white substance on the oil dipstick, there is no other water leaking, and there is no water coming from the exhaust pipe, so it really should not be the head gasket.

Will give you an update once the water pump is replaced... I managed to get a ADL Blueprint one for £35 which wasn't bad I thought.

[Steven252]

Tats the first time ive ever heard of a thermostat being in a bottom hose and i used to be a mechanic :o

Hopefully the water pump sorts the overheating out, the zz engines are really tough so fingers crossed for the headgasket :)

[oldcodger]

Tats the first time ive ever heard of a thermostat being in a bottom hose and i used to be a mechanic :o

Hi,

Seems the wrong way round but it is right.

Just checked the hoses as the car came up to temp and the top hose does get fully hot before the stat opens in the bottom hose inlet.

Kcorolla86 and there is no water coming from the exhaust pipe,

Water often comes out of the exhaust, partic when warming up, so don't let that mislead you.

[Steven252]

Unless the corolla waterpump flows the opposite way to every other engine ive come accross then it being in the bottom hose is a plain stupid idea by toyota!

[kcoralla86]

Unless the corolla waterpump flows the opposite way to every other engine ive come accross then it being in the bottom hose is a plain stupid idea by toyota!

Well when my mechanic was looking at the water pump, he said if we have to take that out then we will also need to replace the timing belt, but then when he looked at it he noticed the water pump was driven by the timing belt... which he said was different and not usual. SO then he said because of the way it is done, the timing belt won't need to be changed. But he found it interesting that the water pump was designed differently.

He is working on it in the morning, so hopefully by lunch I'll know whether the new pump has fixed it... fingers crossed!!

[Steven252]

The vvti engine is chain driven so there is no cambelt ;)

[kcoralla86]

RIght so I've had the water pump replaced... and this still hasn't cured the problem. So that must mean the head gasket is gone. Or is there anything else that might have caused this? Do you know how much I am looking at to fix the head gasket?

The mechanic told me earlier that if it was the head gasket then it would be more than the value of the car probably.

[oldcodger]

Hi,

I wonder why the garages / mechanics you are taking the car to do not offer what would seem very obvious advice, and that you are having to use the forum to locate the problem ?

I'm only a diyer and sure a professional like Steven 252 will correct me, but surely your garage / mechanics should be advising you to have a cooling system pressure test and now a cylinder block pressure test to identify the cause of the problem ?

[Steven252]

Hi,

I wonder why the garages / mechanics you are taking the car to do not offer what would seem very obvious advice, and that you are having to use the forum to locate the problem ?

I'm only a diyer and sure a professional like Steven 252 will correct me, but surely your garage / mechanics should be advising you to have a cooling system pressure test and now a cylinder block pressure test to identify the cause of the problem ?

Spot on :)

Id have the coolant system pressure checked and "sniff" tested to see if exhaust gasses are present in the coolant system. The engine then needs to be compression tested to see if coolant is getting into the cylinders. Is it losing water?

Another thing that has not been checked is wether you are getting water flow, it is possible that one of the pipes has blocked and therefore stopping the water from traveling around. When it overheats are the pipes going rock solid so that you can not "squish" them? Also after the car has gone cold when you release the radiator cap do you get alot of pressure? (there will be some but not alot at cold)

Is your mechanic confident that the cooling system has been bleed correctly. Even with a new rad/thermo/waterpump with a airlock present the car will still overheat.

The unfortunate thing is, if a car is constantly over heated then the likely hood of the head gasket failing is greatly increased.