1NZ overheating

[Yamidan]

Hi all, I've been lurking for a while but not posted anything.
I bought an NCP91 Yaris 1.5 about 6 months ago and I've been having a recurring overheating problem. Just after I first got it it overheated to the point where the red coolant light came on and the motor stalled. The dealer I bought it off sent a truck and a loaner car, then came back to me and said because it's been on the lot for so long the coolant was low and the water pump was bad.
They replaced the water pump and thermostat, refilled the coolant and sent it back to me.

In the last 2 months driving around with the heater off, it'll go for about 30 minutes before the coolant temp gets to 95C and then starts to climb fast. I turn the heater on and blast the fan then the temp comes down to mid 80s and sits there.

I've checked the coolant and it's not using much (if any at all) and it stays a good colour. The oil looks good too. No froth or milk.

My partner took it out the other day as her car was blocked in and it was pouring with rain. She drove for about 40 minutes without the heater on but did not realise the temp climbing so when she got home while idling in the driveway the red coolant light came on again. She got out of the car and noticed steaming coolant spewing out of the overflow like a running tap.

Has anyone had similar experiences? At this stage I am suspect of the new water pump not being new, new thermostat stuck shut, radiator being blocked or worst case scenario the head gasket going out. Any advice?

Cheers

[nortonfb]

Just a guess, the system needs bleeding. Most likely air bubble.
Bleed system, if that doesn't fix it pressure test for head gasket leak.

[ex-x-fire]

Maybe the radiator fins are clogged with dirt & bugs.

[tmontague]

I had a similar issue at the track and it was a bad aftermarket rad cap that went after about 3 years. My red coolant light never went on but my reservoir would be almost empty after a 45 min track session as the rad cap wasn't holding proper pressure so coolant would boil out. Put an oem cap on and never had an issue again despite track coolant temps at 222F

Also make sure no air is in the system, although driving around will typically take car of that in these cars

[B.B._07]

Is the radiator fan cycling on and off once you reach operating temperature? Is the fan running continuously once the coolant temp starts rising?

If you suspect the new water pump take off the serpentine belt and spin it by hand to see if it spins freely, and check if the weep hole is leaking. Might also want to borrow a radiator pressure tester from an auto parts store (if available). You can rule out a stuck closed thermostat by taking the car on a 10 minute drive and checking (by feel) the temperature of the upper and lower radiator hoses. They should be the same temperature if the thermostat is working properly.

[Yamidan]

Thanks for the replies crew,

Norton, I thought so too. I drained the coolant and refilled. Heater open, parked on an incline, running the engine for 20 minutes with the rad cap off and topping up as the level in the filler neck dropped.
The heater blows very hot when on max and it took a little over 3 litres so I assume there is no bubbles.

ex-x-fire, the rad, along with the rest of the engine bay is super clean. It could have a blockage internally restricting flow.

T-montague, I did suspect the rad cap, but it's the OEM unit and looks in a great condition. I bought a new unit anyway along with a new thermostat and water pump which I'll swap out on Saturday.

B.B._07, the rad fan turns on when the engine coolant temp sensor reads 90C. If the heater is off at that stage and I leave the engine running within 10 minutes there will be boiling coolant bubbling up in the reservoir. If I turn the heater on max then the temp drops quickly down to below 90c and the car has no more complaints. The water pump doesn't make any noises and seems to turn freely. The guy who replaced it says the propeller on the original unit had separated from the shaft. I suspect he glued it back on and refitted the unit calling it new.
The rad hoses is a tricky one. After 10 minutes the top hose still feels cool, and the bottom hose is barely warm. It gets hotter the closer I feel to the block. Could it be a breach in the head gasket through to the water jacket is pressurising the system and forcing the flow to stop or go in the wrong direction? I imagine that would damage the water pump quite quickly.

Thanks for all your replies, I appreciate the help.

[tmontague]

A head gasket is the last thing it would likely be on the Yaris unless it has a history of a severe over heat that warped the head.

You still have coolant flow going to the heater core so the question is why doesn't it seem to be flowing through the rad adequately?

Wp is a possibility, semi blocked/clogged rad is another.

Had the engine ever had one of those coolant dealers added to it?

[Yamidan]

I added the head gasket to the list because of the 2 overheat/ red light events that stalled the motor. I don't have much experience with the 1nz (but plenty of experience with other motors and Toyo A series motors) so it's reassuring to hear the head gasket is unlikely. In the event a HG is blown I would junk the motor and swap it for a junkyard salvage as here they're about the same price.

Not sure what you mean by "Had the engine ever had one of those coolant dealers added to it?"

I've had the car for several months and got it with about 130K kms on the clock. It did come with a fairly complete service history which looked good but at the end of the day you never truly know what happened to the car before I got it.

On Saturday I'll swap out the WP and thermostat and give it all a good flush, then if it still over heats I'll replace the rad. After that it'll be a replacement motor I guess. At least they're light and cheap.

[tmontague]

Sorry, it was supposed to say "coolant sealer" those liquid seal-a-leak things that are harmful long term for your engine and other parts

[Yamidan]

So, thermostat is good (tested out of the car), water pump seems good and turns freely and quietly by hand. Coolant level is good, no air bubbles seem present.
Driving between 70-100km/h after 10 minutes the coolant temp goes to 90c and starts climbing rapidly (1degree every 3-5 minutes). Then I turn the heater on full, cabin fan on full and the temp drops to 85-90c and sits there rock solid. The air is blowing “scorching desert wind” hot and after a 30 minute drive the top rad hose is still cold and soft to squeeze. Starting to smell like a blocked rad to me unless I’ve missed something?

[Yamidan]

Sorry, it was supposed to say "coolant sealer" those liquid seal-a-leak things that are harmful long term for your engine and other parts

You were right on. I got around to pulling the rad today and the top tank was almost fully sealed with a sparkly porridge like substance.
New rad went in and the car won’t go over 81c now with the AC on full and heater tap closed. Hopefully there’s not more of this crap in the galleries.

[thebarber]

**Edit: i just saw the last post saying you got a new rad**

I'd get a spill free funnel kit and burp the system properly.

Put funnel on and fill halfway. Start car and idle it for 10-15min and watch bubbles leave system. Even squish upper rad hose on occasion to get air out.

https://images-na.ssl-images-amazon.com/images/I/410gKy372TL._SL500_AC_SS350_.jpg

[tmontague]

You were right on. I got around to pulling the rad today and the top tank was almost fully sealed with a sparkly porridge like substance.
New rad went in and the car won’t go over 81c now with the AC on full and heater tap closed. Hopefully there’s not more of this crap in the galleries.

Glad to hear you got the problem sorted you should he good for the foreseen future, the rad tends to be the most narrow part of a cooling system so the block itself shouldn't be restricted due to that goop crap.

I have personally never found the 1nz to he hard to burn if you have the front jacked up, I just over fill the overflow reservoir when I'm re filling an empty system and after driving around a bit it will burp itself and pull from the overflow.

But as Barber stated, the funnel allows you to do it all in one shot in your driveway and is a convenient tool

[ojeysky]

Hello,

Can someone please help, when am on highway instead of my temperature staying below 90C it goes as far as 105C or more. I have changed gasket, coolant and rad cover.
However what I noticed is that whenever I am descending the temperature rapidly goes back to normal, is this a problem with breeze not getting to the radiator when moving on a flat surface?

I will appreciate all the help I can get here.

Thanks

[tmontague]

Have you changed the rad?

[ojeysky]

Have you changed the rad?

No I havn't changed the rad, its still the stock version.

[tmontague]

How fast are you going on flat surfaces and what are your rpm's? That coolant temp is high but depending on your engine speed and ambient temps that could be considered normal especially since the car cools down on descents.

I've seen temps that high before but that was at the track during 40 min sessions constantly above 4k rpm and with ambient temps around 30 degrees celsius

[ojeysky]

I hardly get past 4krpm(mostly 3krpm), but I notice that the temp does rise faster on flat surface once I get pass 80miles towards 100miles/hr but once i get back to less than 80miles the temp starts to come back down gradually. However this is not the case whenever I am descending, even if am over 100miles/hr, my temp keeps reducing.

If it will help, am heading back home from work and will share export of the log from my scanner once i get home.

Thanks

[ojeysky]

Attached is my scanner log, you will notice that my ambient temperature is 81C, while I could not get up to 100miles/HR on this drive, you will notice that my temperature did hit 98C even with the short trip.
Could the ambient temp be an indication of a problem?

[tmontague]

100mph is 160km/h and iirc would put the rpm fairly higher than 4k. Like I mentioned earlier depending on ambient temps this potentially could be normal. Descending puts virtually no load on an engine so it would make sense that temps come down

[ojeysky]

Even without getting above 4000rpm, staying within 120km/hr my temperature still get beyond 95C(look at the log I shared) and that doesn't seem normal. I also don't think my ambient temperature is normal as it reads 81C even though following a related thread [1] it seem my ambient temp sensor is not connected.
Regards
1. http://www.yarisworld.com/forums/showthread.php?t=31176

[ojeysky]

I really need help with this issue as I am out ideas

[tmontague]

How are you reading coolant temp? Potential faulty coolant temp sensor or a semi clogged rad.

Any reason why you went to the trouble to replace the head gasket?

[ojeysky]

Am reading the temp from my scanner (Blue driver), I once flushed the radiator before putting in a new coolant. How do I know if the temp sensor is bad? By temp sensor, do you mean the ambient temp because that one isn't even existing on the car? (May have pulled out without me knowing). Though I don't know where the scanner gets a reading of 81C from since the sensor wasn't existing.

On the gasket, I was driving on the highway and I suddenly saw the overheating light on the dash, thereafter I was told my gasket was bad because coolant gets thrown out if I start the engine with rad cap open.

After changing the gasket, my temp hasn't gotten beyond 110C but I think it's just because I now actively monitor the temperature as I think it may have overheated otherwise.

Thanks for helping out so far.

[dogsridewith]

Thread OP tried replacing/checking a number of things...then solved overheating by replacing clogged Yaris radiator

[ojeysky]

A new radiator is somewhat expensive in my country but if am going for that, I want to be almost certain that it is the fix to the problem. Is there a way I can verify this before proceeding to replace?

[ojeysky]

I decided to try bleeding the radiator this morning, am attaching the initial behaviour of the coolant as there were lots of foaming and bubbles, after leaving it for about 20 Idle, the foaming reduced, though I will note that whenever the fan kicks in the coolant pops and spills out from the radiator.

Does the above give any indication of what might be causing my temperature increase?

I have also attached screenshot of my bluedriver scanner during the bleeding.

From the screenshot you will notice my ambient still reads as 81C, should I be worried about that?

[tmontague]

That seems like a ridiculous amount of foaming and bubbles in coolant.

I'm surprised you to all the cost and trouble to do a head gasket without doing a leakdown test. Get a leakdown test and see what it shows. You could have a warped head which would make the new head gasket useless if that is the problem.

The coolant will spill over as the temp increases that is normal

[dogsridewith]

Am reading the temp from my scanner (Blue driver), I once flushed the radiator before putting in a new coolant. How do I know if the temp sensor is bad? By temp sensor, do you mean the ambient temp because that one isn't even existing on the car? (May have pulled out without me knowing). Though I don't know where the scanner gets a reading of 81C from since the sensor wasn't existing.

On the gasket, I was driving on the highway and I suddenly saw the overheating light on the dash, thereafter I was told my gasket was bad because coolant gets thrown out if I start the engine with rad cap open.

After changing the gasket, my temp hasn't gotten beyond 110C but I think it's just because I now actively monitor the temperature as I think it may have overheated otherwise.

Thanks for helping out so far.
maybe U the 2nd one this week killing a Yaris engine by driving along w/ over-temp lamp lit and broken serpentine belt? (or something else disabling the cooling system) but maybe not. maybe neither head gasket is bad and you're just seeing boiling coolant.

[ojeysky]

That seems like a ridiculous amount of foaming and bubbles in coolant.

I'm surprised you to all the cost and trouble to do a head gasket without doing a leakdown test. Get a leakdown test and see what it shows. You could have a warped head which would make the new head gasket useless if that is the problem.

The coolant will spill over as the temp increases that is normal

Unfortunately there is no automobile shop where I can do a leakdown test in my state, I will have to drive over 400 miles to get to another state (Lagos) where I can do such test. Is there any check I can do myself different from the leakdown?
Fyi, car drives very well, just the high temperature that remains a concern and by the way I seem to have high fuel consumption as well (11L/100km)

Thanks

[ojeysky]

maybe U the 2nd one this week killing a Yaris engine by driving along w/ over-temp lamp lit and broken serpentine belt? (or something else disabling the cooling system) but maybe not. maybe neither head gasket is bad and you're just seeing boiling coolant.

Nope, the gasket change happened earlier in the year, when I had overheating light and my belt is fine.

[B.B._07]

On the gasket, I was driving on the highway and I suddenly saw the overheating light on the dash, thereafter I was told my gasket was bad because coolant gets thrown out if I start the engine with rad cap open.

After changing the gasket, my temp hasn't gotten beyond 110C but I think it's just because I now actively monitor the temperature as I think it may have overheated otherwise.

Thanks for helping out so far.

When you had the head gasket changed did you have the root cause of the overheating addressed? If not changing the head gasket is kind of like treating the symptoms but not the disease.

Once the car reaches operating temp (once the cooling fan starts cycling on/off) you shouldn't see any bubbles or foaming at the top of the radiator.

Your long term fuel trim value of -13.3 indicates the car is running rich which seems to be validated by the poor fuel economy you're experiencing.

[ojeysky]

My mechanic who worked on it, informed me that the cause was fixed and I actually haven't experienced overheating since then. I got the car sometime last year with 100k+ miles without maintenance history.

Yes the bubbles stopped after the fan kicked in but it happened at the second kick in cycle of the fan.
What do I need to check on the poor fuel part? Here is what I have done:
Changed plugs, air filter, 02 sensor, and coolant.
I also started using recommend oil 5w30 full synthetic as my mechanic indicated that previous owner may not have used such oil and that it's one of the causes.

[ojeysky]

Update!

The feedback I got from my mechanic is that cylinder head is warped, hot cylinder compression are finding their way inside the cooling system.
I guess getting a new engine will be the next line of action. However I do not have the budget for now with kids resuming school next week.
Question is, car drives and idle very well for now, no smoke and performance seem good except fuel and temperature. What are things I can do on the car to minimise impact of the warped head pending when I get a replacement engine?
By the way my engine oil also reduces by a litre for every 700 miles and I wonder if changing to 10W40 semi synthetic will be okay. Weather condition is usually 30C above across the year

Thanks for your support so far.

[ojeysky]

Hello,

Has anyone tried this stuff before, is it safe to use?: https://images-na.ssl-images-amazon.com/images/I/81sQ%2B0h4UJL._SL1500_.jpg

[thebarber]

have you tried a new rad cap? you could be sucking in air if the rad cap no longer seals properly.

[ojeysky]

have you tried a new rad cap? you could be sucking in air if the rad cap no longer seals properly.

Yes I have done that.

[ojeysky]

My fan normally kicks off at 96C, is it possible to reduce that to say 86C? Perhaps having the fan blow earlier will reduce the impact until when I get to replace the engine. How do I get the temperature trigger point reduced?

[ojeysky]

Bump....! Anyone with an idea on this?

[B.B._07]

Bump....! Anyone with an idea on this?

The cooling fan is on a 2 speed circuit with the ECT sensor connected to the ECU which determines at which preset coolant temp the fan will engage at low or high speed. You can't modify the coolant temp values at which the ECU will turn the fan on at high or low. The only way you could change when the fan turns on would be to bypass the ECU control and install an aftermarket adjustable fan controller with a temperature probe. Hayden Automotive and Derale are two companies that make adjustable fan controllers.

https://www.amazon.com/Hayden-Automotive-3654-Adjustable-Thermostatic/dp/B0049EYE6O/ref=sr_1_4?ie=UTF8&qid=1539323762&sr=8-4&keywords=radiator+fan+controller

https://www.amazon.com/Derale-16759-Adjustable-Fan-Controller/dp/B000CN4XZI/ref=sr_1_3?ie=UTF8&qid=1539323762&sr=8-3&keywords=radiator+fan+controller

Installation and availability in Nigeria might be a challenge.

[ojeysky]

Thanks a lot for your response, you are right it might be difficult to get this in my country, but I will look around. I had thought one could adjust the temp from 96C to something lower easily.

Meanwhile I may need to check if my fan is indeed running at the low or high speed, at what temperature level are both triggered?

Thanks

[ArmstrongRacing]

Normally if you get all of the air out of the system with the funnel or running the engine with the cap on for a few minutes, let it cool down, then top off.....and you also replace the caps, the issue should be corrected.

However if there was sealer clogging the radiator it’s possible the head gasket passages and/or the heater core has some restriction now as well.

All of us with 1.8 swaps have never had overheat issues while racing or otherwise. My car doesn’t even have a heater anymore and still has the original radiator, and it’s never been above 210.

[ojeysky]

Just to update that everything is fine with my car now. It so happen that it's a radiator issue. I installed a brand new one and so far all seem good. I will take it on a long journey next week to really see how well it performs.

Am a happy man for now!

[rayfloyd170]

This happened to my Yaris as well last week, i have real-time monitor for my coolant temps and while in traffic at desert climate sometimes it goes beyond 97-98degC. also while in highspeed highway driving it randomly goes to 95C. It wasn't like this before. It used to hover at 86-88C on peak summer and even during idle for an hour it barely reaches to 90C. I was wondering since i just drain/fill with new coolant and burped the system. Also the fan is spinning high when AC is on.

I am really sure i drained a bright red/pink toyota super long life coolant and that was very clear to rule out sludge in the radiator. I also drain/fill every 2years since coolant is pretty cheap here.

In addition to that the AC is not blowing the usual cold air if it goes near to ~95degC.

Last thing on my mind was to clean the radiator with soap and rinse it with water. I went to a car wash shop to utilize the liquid bubbly soap and told the guy to lower down the water pressure and focus cleaning the radiator. In this way it can also clean the AC condenser.

Immediately after this, my coolant temp just hovers around 86-87C even on idle for long time in desert ambient temp of +45C.

Cleaning the radiator resolved my problem because there was no leak, rad cap was good and plainly it was just soiled over or the radiator/condenser accumulated dust in the desert.

Bonus, AC is now chilling cold too even at peak summer.