Overheating

james250 · July 3, 2014

On my IS250, last year In the hot summer days in July, a few times I experienced my temperature gauge going above the half way mark then coming back down. I thought it was down to the hot weather 31 or 32 degrees or so. but never had that issue in the previous 5 years of ownership even during the hot days. Anyway then in August last year on a hot day stuck in the city, then when eventually cleared and hit the open roads the temp gauge went rocketing high. Stopped and coolant was boiling through expansion bottle and I was losing coolant through the expansion bottle.

I took it to a garage who checked it after the car had been siting over the weekend and couldnt replicate the overheating on a road test. So they did a pressure test and diagnosed it to be a broken radiator pressure cap. This was replaced and approx 50% coolant changed.

The car was fine since. Few months ago, I did a complete coolant change and car has nicely been staying below the middle mark. However, today with the weather only 28 degrees or so outside, I was stuck in very slow moving traffic for about 30-40minutes. Just when I got to the end of the traffic I noticed temp gauge has gone higher than the middle mark (not red) but relatively higher than the middle mark. By this time I reached the end of the traffic so was now cruising on dual carriage at 50mph. I also turned AC off and put the inside heating up a bit with windows opened. The gauge settled back down to below the middle mark.

When i came closer to my destination, got stuck in a little bit of traffic for about 5 minutes but it was moving traffic. I put AC back on but temp didnt go up. Got to my destination and left the car idling for a while and temp was still ok. Held the revs a bit and noticed it went up a bit but back down.

Popped open the hood and coolant level is fine. No signs of any leaks whatsoever. My radiator cap is only 1 year old now.

Not sure if the overheating problem from last year has completely gone. I purchased a new thermostat to change as a preventative measure when I get some time but never got round to doing it.

Radiator Cap is ok as it's only one year old

Coolant Level OK

No Coolant Leaks

Waterpump Seems OK, no noise and no leaking residue next to water pump

Headgasket - there is no major signs of HG problems either

Thermostat - could it be a possible sticky thermostat?

This only happened today and problem is I probably wont be able to reproduce the problem tomorrow, so diagnosing it becomes a bit tricky.

Anyone have any suggestions or advice?

Thanks

steve2006 · July 3, 2014

Radiator cooling fan kicking in and out when engine goes over normal temperatue?

james250 · July 3, 2014

Sorry forgot to mention that Steve, yes radiator fan kicking in. It was on all the way when I was stuck in traffic

ChumpusRex · July 3, 2014

Thermostats usually fail open, or can leak a bit when coolant circulation is fast (I think this is why some people find that engine temperature goes down after the engine is revved hard).

However, I did have a thermostat fail closed on a previous toyota, which resulted in rapid overheating.

I'd change the thermostat, seeing as you've already got one to hand. Water pump is always possible, but it usually gives problems with overheating on the motorway or going up hills.

That said, if your radiator cap fell apart, and bits fell off into the coolant, then who knows what has happened to the bits. I could well imagine that one might have got stuck in the thermostat and is screwing with it.

james250 · July 3, 2014

Mark, when the radiator cap broke last year the garage took apart the hoses and removed the broken part inside. I dont think the thermostat is failed in a position because it's only happening at certain time, could it be sticky or intermittent thermostat issue? I am wondering if I should change waterpump too

When coolant is at operating temperature the thermostat will be open wouldnt it? so if the thermostat is open then the coolant should be circulating and hence thermostat shouldnt be the cause of overheat. But I am assuming a faulty thermostat may close and open even during hot coolant temp? in my case if it was thermostat that closed, then it must have opened again when I turned AC off and put heating on and picked up speed.

Also, can someone kindly explain why a broken/damaged radiator pressure cap would have cause overheating last year? from what I understand the purpose of the pressure cap is to pressurize the system to a certain psi, anything over that gets expelled into the overflow bottle. By it pressurizing the system it increases the boiling point. So a faulty cap will just cause coolant to boil but why would the temperature get effected?

james250 · July 4, 2014

An update, today was a degree or so hotter and I got stuck in just as bad traffic as yesterday. When stuck in traffic jams, i turned my AC and heating off and opened windows to allow inside of car to stay cool. The temp gauge stayed exactly where it should be. When I passed traffic jams and hit the dual carriageway, i started AC and closed windows. There was a moment when I was crusing at about 55mph with AC on, i noticed the temp gauge went from just below the middle mark (where it always sits) to the middle (maybe a bit over) So I turned off AC and heating and it went back down. After that I got stuck in slow moving traffic for about 25mins and kept AC off and temp gauge stayed where it should be.

When i was in stationary traffic with windows open, I could hear the fan kick in and turn off for a few seconds then turn back on.

So, I am wondering since it seems to be linked to AC, could it be the waterpump? as the AC and waterpump are both driven by the drivebelt and maybe having the AC on is effecting the waterpump which is probably not in good shape? Is there any other signs of a faulty waterpump?

ChumpusRex · July 4, 2014

Thermostats can get sticky or slow to respond, so unpredictable things could be related to that.

A radiator cap without pressure could cause overheating by allowing boiling to occur. If the coolant boils, you get gas bubbles forming - these are much bigger than the water that formed them, so the pressure rises, or the coolant gets forced out (in this case, into the bottle, where it might overflow and be lost, giving a low coolant level which won't cool). The bubbles could also cause problems with cooling circulation - if the water pump starts sucking in bubbles of steam, it won't be pumping any coolant.

Possibly it could be the water pump, or radiator. If the AC is on, then it will preheat the air going to the radiator - this means that the coolant in the radiator doesn't cool as much - and if there is a problem with coolant flow (failing water pump, sticky thermostat or clogged radiator) then this could be enough to cause overheating.

james250 · July 4, 2014

If it was the radiator, then when stuck in the hot traffic even with AC off, wouldnt it have overheated?

Next time it goes past the half way mark, is there any checks I can do to test the thermostat by pressing on the hoses?

C Mclean · July 5, 2014

Try checking the radiator for airflow through it. May be O.K. without the AC running, but once the AC starts up, it puts a lot of heat into the airflow in front of the radiator, hence the reason for the electric fan being required to kick in as soon as the AC comes on.

james250 · July 6, 2014

How do you check radiator for airflow?

I think I'll change the thermostat and waterpump as preventative measures anyway. Since the original stock one has covered almost 160k miles. If that doesnt help, then I am assuming next options would be radiator and fan?

C Mclean · July 6, 2014

How do you check radiator for airflow?

I think I'll change the thermostat and waterpump as preventative measures anyway. Since the original stock one has covered almost 160k miles. If that doesnt help, then I am assuming next options would be radiator and fan?

make sure that both the AC matrix and radiator core is not partly blocked with leaves, paper or any other muck. Try giving them a good wash, not a pressure wash, but using a hosepipe. Wash them out from both directions, thru the grille and from the engine side. Also, if you can disconnect the top and bottom hoses and then see how the water flows thru the radiator using the hose on max flow. Make sure you fill up with the proper antifreeze and bleed the system if it needs it.

uszokrepper · July 17, 2017

So, I have to tell a story.
I live in a mountain and i have a european modell IS 250(RWD). 2006, with 165.000km with full extra and full service book so everything must be fine. But...
It is in Italy, Meran. Hot summer days and yeah the road up to the mountain to my home is 13-14km from the city.
I have this car since 2016 summer and no problem with it.
I got this job in the mountain and since from the first time my car will every time overheating if i climb the mountain.
It is always different. Sometime it is only 110C but sometimes if outside is too hot than 130C or almost in the Red line.
I have to always turn on the heater core on full open(classic trick).
So read many many topics and videos. I checked the leaks or maybe a bad head gasket or something. But nothing...

- Changed the thermostat(the old was also fine, i have tested) - Nothing happend
- Changed the oil(i read somewhere it could be also a problem) - Nothing
- Changed the coolant - Nothing
Than i realized, the radiator cap was broken so i changed it but always yet - Nothing happend
Than i wrote a big comment in a topic somewhere and somebody said "get out the radiator and from outside or if its need than also inside wash it."
Okay, let's try...why not...
- I taked out the radiator and i got this what you see in the pictures!!
My good...i haven't seen like this before...
So, yeah 11 yeras old car, everything works fine in a normal road but on the mountain you become every little **** immediatelly.
Might be never was washed this radiator...
So i washed it. Put everything back and now works fine :)
36C is outside. I have found a way long road up to the mountain and nothing happens :) Max 96C and than the ventilators come on for 20 second and that's all :)

So i prefer for everybody to check this out If your car is overheated!!

And another featuer...Before i put it out i checked from the front bumper how it looks(really i must have it out or not...?) And from the front bumper it looks like clean! But not....
And another thing...the climate radiator is front of the normal radiator(picture) and the climate radiator has bigger holes than the normal one...thats why it looks clean and the thing is...it is clean!
So dont be tired. Get it out and **** off overheating :)

P.S.: The ventilator at working was so loud. Now are quiet :)

Farqui · July 17, 2017

Wow, that radiator core was REALLY clogged up. It looks like fur/hair, grass and dust?

No wonder the engine was struggling to keep cool.

Well done fixing the issue.

Malc · July 18, 2017

I was initially wondering if the air temperature was affecting it, rarified air etc up the mountain and having some odd effect BUT hey, the farmyard clutter of all that rubbish clogging it up just has to be the reason .............. I envy you driving up the mountain to work ....... I remember my Grand Tour of Italy in my now ancient Ls400 in 2015, driving up and around the Dolomites in early May, wow, stunning ....................... journey of a lifetime.

Malc

Texas · July 18, 2017

That is some serious Krap in there, what sort of state is/was the filters (Engine air intake and cabin air inlet ) on this car like?

paul m.

Britprius · July 18, 2017

I have mentioned this before in previous posts, but has the car ever had front end damage. If the two radiator fans get changed over they blow from the engine compartment, and out of the front grill. This means at higher speeds the air stops flowing through the radiator, and on a hot day causes overheating.

To check start the car and leave running till the fans come on. Stand in front of the car. Does the hot air from the engine compartment blow out through the front grill. If it does the fans have been interchanged.

Remove the fans from the motors leaving the motors where they are, and swap the fans over.

John

uszokrepper · July 18, 2017

14 hours ago, Farqui said:

Wow, that radiator core was REALLY clogged up. It looks like fur/hair, grass and dust?

No wonder the engine was stirggling to keep cool.

Well done fixing the issue.

Yeah something like that...11 years of dust :/ :)

uszokrepper · July 18, 2017

2 hours ago, Texas said:

That is some serious Krap in there, what sort of state is/was the filters (Engine air intake and cabin air inlet ) on this car like?

paul m.

Actually i checked everything...water pump, thermostat housing....everything and also the inside of the radiator. Nothing dust inside or aluminium dust or something NOTHING...so yeah that was the problem and nothing else thanks God :)
And i hope i understood your question but this is the radiator :D

uszokrepper · July 18, 2017

1 hour ago, Britprius said:

I have mentioned this before in previous posts, but has the car ever had front end damage. If the two radiator fans get changed over they blow from the engine compartment, and out of the front grill. This means at higher speeds the air stops flowing through the radiator, and on a hot day causes overheating.

To check start the car and leave running till the fans come on. Stand in front of the car. Does the hot air from the engine compartment blow out through the front grill. If it does the fans have been interchanged.

Remove the fans from the motors leaving the motors where they are, and swap the fans over.

John

No, with the fans is everything okay :) Works fine and how i know this car hasn't got ever front or any damage.