What's a good coolant temperature?

Toyotafanboi · 19-06-2015 01:53PM #1

I know, i know. me again, coolant again. at my wits end. let me be brief.

car: 02 celica vvtl-i UK model.

- temperature gauge never got to half way, ever.
- asked on a celica owners club, done a poll, every member voted that their gauge went to half way within 5-10 minutes of driving.
- long story very short, changed thermostat to see would that rectify things, soon after discovered head gasket failure.

- long story really short, fitted a new engine, same engine but from a 1999 japanese import celica.

- just picked it up, drives like a dream, sounds and drives a lot nicer than my old engine. temperature gauge doesn't go to half way!!!!

- checked with OBD scanner and the engine temp while driving is a steady 69-71 degrees celcius, creeping into the low 80's if stuck in traffic or parked. pretty much the same as the old car.

- if left idling it will get to 96 degrees, then the fans will come on, cool it down to 90-91 and switch back off.

- my gauge never goes past position two

anyone who has anything even remotely constructive, please help. is 69-71 degrees an ok operating temperature? i would be semi-ok with the gauge reading low if i knew the temperature was ok to work with.

jimgoose · 19-06-2015 02:24PM

71C sounds a tad cool to me for a modern-ish yoke, but not madly so. If it's happy and steady there, well...

Could that gauge be a bit tired at this stage?

19-06-2015 02:29PM

did you reuse a temp sensor? Completely different car but my previous golf did that and it was the temp sensor, also caused it to run a bit rough on start up.

Toyotafanboi · 19-06-2015 02:33PM

yeah, i just worry that the cool running of the old engine is what caused the head gasket failure (just an uneducated theory) and really want to avoid this again. can't understand this.

the only thing in it's favour is that this new engine will idle up from a cold start to 95 degrees in 10 ish minutes. the old engine could be idling literally for over an hour and would struggle to make 80 degrees.

the gauge seems ok imo, once the car gets over 80 degrees it rises to the normal position. but once the car is in motion it cools right down and stays steady @ 69-71 degrees.

i didn't carry out the swap, but from talking to my mechanic he said that he he lifted the complete engine out of the old celica and placed it into mine and just plugged my loom etc in, there was no exchanging of parts between engines, so i assume (dangerous thing to do) that it's not the old temp sensor being reused.

pain in the ****ing arse.

jimgoose · 19-06-2015 02:34PM

Toyotafanboi wrote: »

...the gauge seems ok imo, once the car gets over 80 degrees it rises to the normal position. but once the car is in motion it cools right down and stays steady @ 69-71 degrees...

Have you made any modifications to the nose of the car? Spoilers, intake mesh, any of this kind of thing?

Toyotafanboi · 19-06-2015 02:45PM

jimgoose wrote: »

Have you made any modifications to the nose of the car? Spoilers, intake mesh, any of this kind of thing?

totally stock.

interestingly, the aircon rad is the front most rad in this car and shields around 75% of the coolant rad.

it's looking like donedeal or a bonfire for this celica. i literally don't ever remember feeling this frustrated over anything.

Atlantic Dawn · 19-06-2015 02:53PM

On the petrol Toyotas I have driven including one with vvtli engine the temperature gauge always went around the 50% mark after around 10 minutes or so. Around here...

jimgoose · 19-06-2015 02:55PM

Toyotafanboi wrote: »

totally stock.

interestingly, the aircon rad is the front most rad in this car and shields around 75% of the coolant rad.

it's looking like donedeal or a bonfire for this celica. i literally don't ever remember feeling this frustrated over anything.

There's the oil/water differential theory of head-gasket failure. What sort of oil exactly are you running in it?

Toyotafanboi · 19-06-2015 03:01PM

Atlantic Dawn wrote: »

On the petrol Toyotas I have driven including one with vvtli engine the temperature gauge always went around the 50% mark after around 10 minutes or so. Around here...

http://i.ytimg.com/vi/yfUwerMi2Uw/maxresdefault.jpg

that's where all my other 1.4 and 1.6 vvti's have always sat.

jimgoose wrote: »

There's the oil/water differential theory of head-gasket failure. What sort of oil exactly are you running in it?

i'm using 5w30 fully synt...

jimgoose · 19-06-2015 03:01PM

Toyotafanboi wrote: »

...i'm using 5w30 fully synt...

Mmm. Doesn't get much better.

Toyotafanboi · 19-06-2015 03:05PM

jimgoose wrote: »

Mmm. Doesn't get much better.

would a ****ter oil retain more heat, thus somehow keeping the engine warmer.

epically clutching at straws i know!

jimgoose · 19-06-2015 03:08PM

Toyotafanboi wrote: »

would a ****ter oil retain more heat, thus somehow keeping the engine warmer.

epically clutching at straws i know!

There is a theory knocking about that engine heads are cooled more by coolant, while the block tends to be cooled more by the oil. Therefore, there are times when there will be a difference in temperature between the two, and the greater the temperature difference the more "shear" on the HG due to expansion. Also largely theoretically, this could be at least partially counteracted by using a hideously expensive full-synth oil, even a grade lighter than recommended to improve flow.

Pov06 · 19-06-2015 03:09PM

My 1.0 Yaris goes up to 85 degrees Celsius in about 10 minutes and pretty much stays there.

nd · 19-06-2015 03:15PM

hmmm given that if idling it gets up to above half and enough for the fans to kick on, it seems like that when on the move the rad just does a very good job of cooling it down. But if other people's same version celica is going to half way, I can see how it'd be head wrecking.

Does the heater get hot fairly quickly and stay hot when on the move?

Interslice · 19-06-2015 03:27PM

The temp guage in the alfa like yours sits just above 70 and slowly goes to just below 90 if you stop. OBD follows suit. Apparently normal in these. most other cars just sit in the one position to stop panic and threads like this all over the internet

. Thought when I first got the car I had a thermostat stuck open. Was that poll on your exact model and engine?

Tea 1000 · 19-06-2015 03:30PM

You might have a problem with the heater system maybe?

Toyotafanboi · 19-06-2015 03:33PM

Interslice wrote: »

The temp guage in the alfa like yours sits just above 70 and slowly goes to just below 90 if you stop. OBD follows suit. Apparently normal in these. most other cars just sit in the one position to stop panic and threads like this all over the internet . Thought when I first got the car I had a thermostat stuck open. Was that poll on your exact model and engine?

yes, the poll was on my exact car and engine. i'm aware that in real life, the temperature is fluctuating and that most gauges rest at half way reading 90°C when really they could be +/- 15°C or whatever, i just thought that a constant 70 was particularly cool?

i had a punto before too where the gauge was pretty active too, would drop a little while driving and only be half way in traffic, it's just annoying me because all other celicas seem to make half way and stay there.

Interslice · 19-06-2015 03:37PM

Toyotafanboi wrote: »

yes, the poll was on my exact car and engine. i'm aware that in real life, the temperature is fluctuating and that most gauges rest at half way reading 90°C when really they could be +/- 15°C or whatever, i just thought that a constant 70 was particularly cool?

i had a punto before too where the gauge was pretty active too, would drop a little while driving and only be half way in traffic, it's just annoying me because all other celicas seem to make half way and stay there.

Could you ask someone to log their temps on the obd? I logged mine with torque and they do exactly as yours plus/minus a few degrees

Tea 1000 · 19-06-2015 05:36PM

Atlantic Dawn wrote: »

On the petrol Toyotas I have driven including one with vvtli engine the temperature gauge always went around the 50% mark after around 10 minutes or so. Around here...

7,000 rpm, eh?

That'll warm her up alright!

toastedpickles · 19-06-2015 06:16PM

Complete opposite end of things here, I had that problem with my 900, so i changed, the coolant temp sensor, and repositioned the thermostat as there was a little valve on it, which had to line up with a bleeder valve or something, done this and it works like a charm now, it's over in the build thread somewhere i think! Could actually be a faulty gauge?

Toyotafanboi · 19-06-2015 06:21PM

Thanks everyone. I'm inclined to think the gauge is ok as it has risen to around a quarter by the time it's around 70 degrees and it's perfectly in the half way position when the car does get to 80 degrees +.

Really really stumped.

I can't even bring myself to say it but does this sound like a faulty thermostat and should i change this one too :P

Atlantic Dawn · 19-06-2015 06:23PM

Tea 1000 wrote: »

7,000 rpm, eh? That'll warm her up alright!

That's where the vvtli magic happens

nd · 19-06-2015 06:41PM

might it be that there is a circuit or w/e that normally stabilizes the needle in the middle like interslice was saying. If it is within a specific temp range. And that that part of your gauge is not working.

Teddington Cuddlesworth · 19-06-2015 07:05PM

Sounds like the thermostat isn't closing to me.

For the cost of a new thermostat its worth trying. Ensure the cooling system is properly bled after replacing it.

Special Circumstances · 19-06-2015 08:21PM

Teddington Cuddlesworth wrote: »

Sounds like the thermostat isn't closing to me.

For the cost of a new thermostat its worth trying. Ensure the cooling system is properly bled after replacing it.

It does sound low (to me, caution not a mechanic) during driving, and it also seems to me as if the thermostat is open for longer than it should be.... But iirc the stat was done recently.

19-06-2015 08:34PM

Toyotafanboi wrote: »

.....

the only thing in it's favour is that this new engine will idle up from a cold start to 95 degrees in 10 ish minutes. the old engine could be idling literally for over an hour and would struggle to make 80 degrees.

the gauge seems ok imo, once the car gets over 80 degrees it rises to the normal position. but once the car is in motion it cools right down and stays steady @ 69-71 degrees.

....

pain in the ****ing arse.

Classics stat symptoms

nd · 19-06-2015 08:50PM

In the morning when the engine is cold, how long approx after it's running does it take for the internal car heating to get warm? If a long time imo the thermostat is probably stuck open/not closing properly. If it gets warm after 5 mins imo it not stuck open.

Toyotafanboi · 19-06-2015 08:53PM

Special Circumstances wrote: »

It does sound low (to me, caution not a mechanic) during driving, and it also seems to me as if the thermostat is open for longer than it should be.... But iirc the stat was done recently.

Yeah you see, with my original engine that was problem i had. But i drove it on like that for like 6k miles or more like a jackass and pretty soon after i fitted a new thermostat the head gasket gave in.

Now i've had a replacement engine fitted, just picked the car up today and same story. Runs great and i assume if the mechanic only ran it at idle it would have went to half way on the gauge and looked fine but on a run it sits at a quarter.

I'd hardly be so unlucky as for the thermostat to be goosed in the new engine too :pac: but it does seem that way.

Augeo wrote: »

Classics stat symptoms

See above,but yeah, i'm coming around to that way of thinking. Luckily i have an array of thermostats here to suit the car. Next time i have 4 hours free i'l pop one in :P

Be ok to drive it a few miles to work over the weekend before i change it?

I get heat a minute or two after cold start, and it stays good and hot.

nd · 19-06-2015 09:23PM

You'd be grand to drive it even with no thermostat. It'd just mean heating would be slow to warm up. It's if it's stuck closed that'll cause it to overheat.

dieselbug · 19-06-2015 09:30PM

"See above,but yeah, i'm coming around to that way of thinking. Luckily i have an array of thermostats here to suit the car. Next time i have 4 hours free i'l pop one in :P

Be ok to drive it a few miles to work over the weekend before i change it?

I get heat a minute or two after cold start, and it stays good and hot."[/QUOTE]

Surely you dont intend fitting a used thermostat.

It would be good practice, standard practice really to fit a new stat when changeing the engine, just like you would fit a new timing belt or new filters etc.

Fit a new genuine one from Toyota and flush the system first if it's dirty.

Toyotafanboi · 19-06-2015 09:38PM

No, i have 3 new thermostats here for that engine, 2 gates and one Mr.T used for around 150 miles. Long story :pac:

A lot of new parts were fitted during the engine swap, clutch kit, water pump, lot of new seals etc, it's a chain driven engine. The thermostat was overlooked, but not to worry.

What's a good coolant temperature?

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