Overheating issues

[CyFi6]

I had problems with this last summer, but now its starting to act up again now that its getting hot out. My problem is at low speeds, specifically idle. With my AC on, idling in traffic on 105+ degree weather (in the sun, at night when its 100+ i don't seem to have issues), my temp seems to climb. I have an aftermarket gauge so i can monitor temperatures more precisely.

Sitting idle after exiting the freeway is when the problem seems to get the worst, temp slowly climbs from ~180 up to 210+. Here is everything about the car in list form.

Non turbo, stock
Fan shroud in place
Brand new fan clutch from Toyota
10 blade Turbo fan
Brand new Radiator
New head gasket last summer (NO signs of BHG at all.)
All heat shields, under engine covers shrouds everything in place
All fins on condenser AND radiator are strait and unobstructed.
Toyota Red coolant, 50/50
New OEM Toyota Thermostat
New upper hose+Toyota clamps
Cooling system recently flushed
No leaks
New belts
All hood seals in place, hood heat shielding fiberglass stuff in place
No coolant loss

When i take off from the stop i can hear the fan roaring, which tells me it is in fact engaging properly, and soon cools off. Also, if i sit there idling and heating up, if i pop the hood open all the way, the temp quickly drops to normal.

Any ideas would be great.

 

[Doward]

Considering you'd not even notice the temps moving on the stock gauge, I'd say you're fine. I mean, how much over 210 does it go?

 

[CyFi6]

Problem is usually by the time i start driving off, i havent gone much over 210, but i will do a test next time i see issues. As far as i knew, 210+ was considered "overheating"

 

[tbcmorris]

flamesuit on......i woild consider 190 to 210 op temp

 

[crisp]

flamesuit on......i woild consider 190 to 210 op temp

^^^ Ditto at face value...


105+ SUNNY weather running accessories and you are ONLY gaining a dozen or two degrees in TRAFFIC... hmmm... not sure that's a problem at 210 and under.




-crisp

 

[jdub]

flamesuit on......i woild consider 190 to 210 op temp

Close...the ECU looks for 176 to 212 deg F for normal injector ops and timing.

Phoenix in the summer is one of the few times I would use a 180 deg F T-stat...helps the coolant system get ahead of the high OAT.

Make sure the aux and condensor fans are operating properly.

 

[tbcmorris]

damn...i was useing gas 4 sroke engines as a whole....not just ours. im glad my advice was accurate. i wasnt sure if because of the 7ms cooling and oiling issue if it would be consider dangerous at 310.

 

[CyFi6]

Ok well its a year later and im am running into issues once again. I love my supra and its great that it is my daily driver, but it kills me that i have to closely watch my temp gauge at all times. It isn't this way from the factory, so why is it this way now with all new factory parts? I have no idea.

Today it was about ~109 F outside and i was cruising on the freeway for about 20 mins with the ac on high, engine temp was about 201 deg f, not too hot.

I got off the freeway and drove about 5 mins at around 35mph, coolant temps stayed about the same, rose slightly.

After this i pulled into a lot and parked the car, let it idle. Within not too much time the temp was rising and it was hitting almost 220deg f which is when i shut the car off.

I turned the ac off and started the car about 3-4 mins later and drove it less than a mile at low speeds before stopping again, temps were coming down around 210 now. After i stopped again and let it idle with the ac off the temps started rising again, got around 217, this is when i started driving again at like 35mph and the temps started coming down slowly again.

Got back on the highway and it went back to about 201 degrees.

There are however changes since the last time i posted so i will list them here

Now a rebuilt 7mgte
-1mm oversize bore, probe pistons
-Stock bottom end
-Stock head
-Everything machined properly, head gasket is sealed perfect.
Fan shroud in place, engine under cover in place
New fan clutch from Toyota
10 blade Turbo fan
Brand new Koyo all aluminum Radiator
Cometic .066" MHG
All heat shields, under engine covers shrouds everything in place
All fins on condenser AND radiator are strait and unobstructed.
GO5 premixed coolant
New OEM Toyota Thermostat
New OEM Water Pump
New upper hose+Toyota clamps
Cooling system recently flushed
No leaks
New belts
All hood seals in place, hood heat shielding fiberglass stuff in place
No coolant loss
Heater core bypassed
Turbo coolant lines bypassed
Throttle body/ISC coolant lines bypassed
R134a AC system
Electric aux fans upgraded to the turbo style dual fans (they work)
Gauge sensor is placed at the thermostat housing.

Basically the entire cooling system has been rebuilt with OEM parts yet the damn car still runs hot. Please let me know of anything you guys can think of to help me with this problem. I hate the fact that i have to be careful about my engine temperature during normal driving.

 

[modmonster2008]

have you replaced your radiator cap? maybe your coolant goes into overflow bottle and causes the temp to spike up you should check on that if yu meant no coolant loss as in system or in the radiator im not sure. also since u rebuilt your 7mgte with a few performance parts maybe you should have looked into getting a larger radiator perhaps, as well as timing could affect temp i think, keep us posted

 

[CyFi6]

I mentioned in the above post that it now has a dual core all aluminum Koyo radiator, though i forgot to mention the cap is less than 2 years old, and i tested it with a pressure tester and it is perfect(13 psi). Also forgot to mention that timing is set at 10 deg BTDC

Also, driving around on a cooler day (80's-90's) or with the A/C off the temperature usually stays around 190 deg unless i idle for long periods where it might rise to around 200

 

[Zumtizzle]

G05 premixed?

Where did you manage to find it premixed?

Oil cooler?

90916-03078 = Stock 88°C
90916-03079 = Cooler 82°C (179.6°F)

toss in the lower t-stat.

 

[CyFi6]

I got the premixed G05 at Napa because they were all out of the concentrated stuff.

Oil system is completely stock besides a shimmed oil pump relief spring, and im running GC 0w30

I figure by 210 deg the thermostat should be fully open so doesn't that mean im out of cooling capacity? On a cooler day or driving without AC the system is usually pretty damn stable at 190 deg so if i switch to a 180 its going to run at 180 under most conditions which is too cool for my liking.

 

[Zumtizzle]

Okay.

Try Switching the Mix from 50:50 to 75:25.

 

[jetjock]

I figure by 210 deg the thermostat should be fully open so doesn't that mean im out of cooling capacity?

No, it doesn't.

On a cooler day or driving without AC the system is usually pretty damn stable at 190 deg so if i switch to a 180 its going to run at 180 under most conditions which is too cool for my liking.

Huh?

 

[CyFi6]

My 190 degree OEM thermostat regulates my temperature to exactly 190 on a cooler day or when im not using my ac, so it only makes sense that a 180 degree thermostat would keep me running at 180 degrees most of the time (when its cooler, or im not using my AC), and i don't want my engine to run that cool considering the system is made to run at 190 and 180 is close to warm up enrichment. What are you saying "No, it doesn't" to? The fact that its fully open at 210 or the fact that if my thermostat is fully open and overheating im out of cooling capacity?

I wouldn't mind switching to a different mix but a brand new supra off the showroom floor wouldn't overheat this easily so why should mine, is the way i see it.

 

[jdub]

My 190 degree OEM thermostat regulates my temperature to exactly 190 on a cooler day or when im not using my ac, so it only makes sense that a 180 degree thermostat would keep me running at 180 degrees most of the time (when its cooler, or im not using my AC), and i don't want my engine to run that cool considering the system is made to run at 190 and 180 is close to warm up enrichment. What are you saying "No, it doesn't" to? The fact that its fully open at 210 or the fact that if my thermostat is fully open and overheating im out of cooling capacity?

I wouldn't mind switching to a different mix but a brand new supra off the showroom floor wouldn't overheat this easily so why should mine, is the way i see it.

Looks like you've got it all figured out then - after all assumptions about when the T-stat is fully open provides all you need to know. Same goes for the 180 deg stat - funny I'm in Phoenix and run a 180 deg stat here (per my previous post in this thread).

I understand though - what do me and JJ know about the 7M coolant system

 

[CyFi6]

No i don't fully understand which is why i updated the thread with all the new info. Im not one to take a persons idea and go with it without understanding the principle behind it, whether it be from one of you knowledgeable members or any other members. If any of you would like to share the information as to why i should run a 180 degree stat instead of a 190 it would be great.

The thinking im doing is that at 215+ the thermostat should be fully open (unless im mistaken, which is why i asked about what JJ was commenting on) and if temps continue to climb with a fully open stat it would mean im out of cooling capacity. So whether its a 180 or a 190 stat, once its fully open they perform the same. I know jdub mentioned it helps "get ahead" of the OAT, which i assume means it will be fully open sooner, but if at fully open my system cant cool the engine anyways i don't understand how it would help. I am also not aware of Toyota installing a different thermostat for different areas of the country from the factory but i could be wrong on that as well. Considering my engine is almost completely stock i expect it to perform as such, but there is obviously a weak point somewhere and i need some ideas on how to find it.

I think you guys take it as a stubborn attitude when in reality all im trying to do is get the information out of you all.

 

[jetjock]

Rather than go off on a tangent about how cooling systems work I'll point out a couple of things:

1) You have a history of over "anal-yzing" stuff, to your own detriment. Even when something is understood that's a bad approach but analysis on any level without knowledge to back it up leads to little more than flailing around as one gets forced into a long and (usually) painful process of elimination. It differs little from the guess-and-by-golly method typically seen here.

2) To the critical eye there's nothing obvious about your engine's "weak point" eg; there's no substantial evidence it's really overheating.

Maybe you should simply try driving the car. Put some tape over that gage if it makes you feel better or put the stock one back in...it was designed for folks like you.

 

[crisp]

Maybe you should simply try driving the car. Put some tape over that gage if it makes you feel better or put the stock one back in...it was designed for folks like you.

Interestingly, I have noticed for all the subtle "wandering" of the Autometer gage I put in, the stock one has never HINTED of an issue, which helped me understand that there is a pretty broad "window" of normal operating temperature from season to season and condition to condition in my case. I found JJ's post useful and actually applicable in MANY of my past behaviors which were overly sensitive to symptoms of performance which I really just didn't (and in many cases STILL DON'T) fully understand!


(NOTE: I'm not trying to project on the OP here, just noticing this at work for me, and continuing to learn as I monitor the dialogue of others such as this.)



-crisp

 

[jdub]

I think you guys take it as a stubborn attitude when in reality all im trying to do is get the information out of you all.

That is exactly how it comes across and continues even when provided the background info as to how something works. This is precisely why you don't see me replying to your threads.

You have a history of over "anal-yzing" stuff, to your own detriment. Even when something is understood that's a bad approach but analysis on any level without knowledge to back it up leads to little more than flailing around as one gets forced into a long and (usually) painful process of elimination. It differs little from the guess-and-by-golly method typically seen here.

This is exactly why your posts come across per above.

I agree with JJ, this seems to be nothing more that a normal thermal "bloom" in coolant temp due to reduced air flow at low speed...this is especially true for a car like the Supra with a small frontal area for air flow to the rad. Considering the very high OAT in Phoenix (especially lately), the efficiency of ANY coolant system is going to degrade...the decreased temp delta between OAT and coolant temps is going to guarantee it.

A couple things about "assumptions":
1) How do you know the T-stat is fully opening? Did you put it in a pan of water, heat it up and take readings with a candy thermometer as it opened? I can't tell you how many brand new T-stats (including Toyota) I've taken back because they did not open properly.
2) What temps are the aux fans coming on? How about the AC condenser fan?
3) Any cold spots on the radiator by using an IR temp gun? (Just because it is relatively new does not mean it doesn't have blocked tubes)

I could go on, but I've made my point. Instead of over thinking something, when one of the guys that actually know what they are doing gives you advice, it might be good to take it. There are a few guys here that base what they say on facts and writing essays on the subject might just take up a bit too much of their time.