Consolidated Operating Temperature Thread (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
May 7, 2003
Threads
62
Messages
3,163
After searching through all the threads of what tempurature the 80 series should run at when the cooling system is operating properly, as well as discussions of what people have observed with operating temps, I have decided we should have a consolidated thread. If you have done the Raventai mod or have a seperate temperature gauge, please post the following:

1) Year of truck and any mods to the engine,

2) What gauge you have and where the sensor is mounted (if not the raventai mod),

3) Any cooling system upgrades, replacement parts, etc (radiator, fan clutch, which ones).

4) Coolant used, mixture ratio, and any coolant additives.

5) Temperatures observed while driving around town, sitting idling (i.e. drivethrough), on the highway at highway speeds, and the air temperature when you recorded these temperatures. Was the A/C on?

6) Highest coolant temperature observed.

7) Thoughts on the highest safe operating temperature.


I'll start:

1) 1996 Stock engine 6 degrees of advance on the timing.

2) Raventai Mod.

3) Fan clutch (factory blue), thermostat and 1993-94 radiator replaced in the past week.

4) Toyota red coolant 50/50 with distilled water and 1/3 bottle of redline diesel water wetter (same as regular water wetter without the corrosion inhibitors).

6) Prior to cooling system replacement. Long uphill climb, 3/4 throttle, 3rd gear 2800 rpm, 215f before backing off in 75-80f weather. 210f in stop and go and idling at 85 f. 200f at 70mph heating to 210f at 80mph in 85f weather. All with A/C on.

Now: 17% grade 3/4 mile climb after exiting freeway (first gear climb) 205f in 92F weather (test previously aborted). Freeway 195f top at 80mph in 92f weather. Idling at drivethrough 200f. All with A/C running.

7) 215f before, 205f after new parts.

8) I would guess that 217f-220f would be a safe operating temp given that is where the A/C comes back on if the truck has gotten too hot. I remember most older cars had a 220-230f as a starting point for the red zone. I think it is reasonable to expect to see 200-205f on a regular basis in 80f+ weather.
 
Dont forget about the sun....

Driving to the lake 7:00 sun out 100+ 195* all the way. Driving home 8:00 sun down 100+ 180* all the way home. AC full blast both direction:D

Out here in the west the sun is a huge variable on running temps
 
1. 1997 - Please look to sig line for mods; there are a few fun ones! :D

2. Greddy Temp Gauge mounted on the upper radiator inlet hose.

3. New HG (original was PM'ed, not fully failed), new factory fan clutch (blue), new factory thermostat, new factory coolant (toyota red longlife changed at least annually).

4. Toyota Red, 60% H2O / 40% Coolant, NO repeat NO coolant additives especially after my frustrating findings with Redline Water Wetter (prior to HG replacement) Redline Water Wetter sucks with Toyota Red in my humble opinion and besides that made no major difference with recorded temps anyway.

5. Temps around town are almost always between 88 and 90 celsius, temps at idle are same, temps around the highways are almost always between 86 and 90, temps when really racing rig up gravely mountain roads with four wheels spinning and touching the redline from time to time are between 90 and 98 celsius. These are all the top temps experienced with hot summer sun.

6. Highest operating temp observed was 98 celsius while really racing rig. Highest temp observed otherwise was 94 celsius on super hot summer day with AC on and driving rig really gently.

7. Highest safe operating temperature for me is 100 celsius, yes thats conservative, yes im paranoid!

Hope that helps! :cheers:
 
Supercharged, Isspro gauge, sender in the upper water neck, OEM thermostat, 94 3.0 V6 fan blade, new clutch (16210-66020):

Cold weather, usually 180 to 185, sometimes 190 but not often.

Warm weather to hot weather:

This really swings wildly and I have spent a lot of time studying it. Moving down the road it usually runs 190 to 195 unless I am towing and pushing hard. I have seen 220 to 225 on occasion.

Idling in hot weather with the A/C on can swing wildly and I have seen 220+ if I do not kick-in the electric fan. Just today I came home and left it idling with the A/C on and the aux fan running and the temp held at 200-202 for about 15 minutes before I finally shut it down. If I do that same thing with the aux fan off the temp will creep well past 220.
 
Rememmber that ambient temps regularly exceed 90 plus (with a truck that might as well be black) and the blower blocks a good deal of airflow through the engine compartment in addition to being a big heat-sink. Also, the stock gauge remains "flat" at that temperature.
 
cruiserdan said:
Rememmber that ambient temps regularly exceed 90 plus (with a truck that might as well be black) and the blower blocks a good deal of airflow through the engine compartment in addition to being a big heat-sink. Also, the stock gauge remains "flat" at that temperature.


You have more experience with the truck than I do but I would consider that performance unexceptable.
 
i'm pretty sure mine would do the same as Dan's if i let it although it does generally stay cool at idle.

1) Year of truck and any mods to the engine,
1993 - had a head gasket/valve grind this year and everything freshened on the way in


2) What gauge you have and where the sensor is mounted (if not the raventai mod),
raventai's 1993 temp gauge mod

3) Any cooling system upgrades, replacement parts, etc (radiator, fan clutch, which ones).
new fan clutch and most hoses in april,

4) Coolant used, mixture ratio, and any coolant additives.

55/45 toyota red/h20

5) Temperatures observed while driving around town, sitting idling (i.e. drivethrough), on the highway at highway speeds, and the air temperature when you recorded these temperatures. Was the A/C on?

-idle generally same as on the flats - will usually hold a higher temp if it was alereayd there when it goes to idle.
-cool days on the flat = 190 or so
-hot days on the flats = 195 or so
-cool days on a gentle grade = 200
-hot days on a long gentle grade = up to 205
-cool days on a steep grade = up to 210-212
-hot days on a steep grade = up to 210-212
-add about 3-5 degrees with AC on (won't even try it on a long steep grade)
-add about 3-5 degrees with a 1000 lb trailer
-truck temp recovers very fast once you go level or downhill but even a slight continuing grade can hold the temp high


6) Highest coolant temperature observed.

-210-212 since h/g job
-saw it was in the red on a stock gauge for 10 seconds tops when i blew the head gasket

7) Thoughts on the highest safe operating temperature.

-i would run as high as 220 in an emergency
-i do not like regularly going over 200 in ordinary driving.
 
landtank said:
You have more experience with the truck than I do but I would consider that performance unexceptable.


I second that. A gauge with a flat spot is unacceptable and so are constant water temperatures in excess of 200 degrees.
 
Gauge said:
I second that. A gauge with a flat spot is unacceptable and so are constant water temperatures in excess of 200 degrees.


Not according to Gumby. Here is an exchange he and I had some months ago on this exact topic:

Gumby said:
I have had not a few engineers tell me the enigne is much happier at the temps it was designed for. In the case of the 1FZ-FE 195+. the engine will heat up faster to operating temp and stay there irregardless of driving conditions. tolerances will stay consistant. oil will flow at a consistant rate. fuel metering will be consistant.

look at it this way. Your coolant temp drops to 165 after a trip down the highway on a cool day. Your ECM enriches your fuel a little more at 165. Your engine really does not need the enriching, but it's programming says that it is not up to temps yet. It can't know that it is. it dumps more fuel. O2 might pull it back unless the programming says that closed loop does not occur until ECT is 190+. More fuel is not better than the right amount of fuel. It's way better than not enough, but not better than the right amount. You get carbon build up, ring wash out, oil thinning, poor fuel mileage and poor emissions.

A carb didn't know or care what the ECT was. It's vital to FI. it's also vital to FI that it gets the information it expects. Garbage in, garbage out.


cruiserdan said:
'K

195+.........+ how much before you get nervous?


Gumby said:
220-225

many factory electric cooling fans don't even turn on until 220.

cruiserdan said:
OK, thanks.

We know that the A/C konks out at 226 so that is getting warm and will not come back on til it drops to 217. So, can we then postulate that the 1FZ should run 195 to, say, 215 then?

Gumby said:
Sounds about right. i wish we had someone with Toyota connections. Maybe a guy who worked at a dealer that could get in touch with the Toyota tech center. ;)
 
guys, let's be reasonable here. As I said elsewhere, if the A/C is designed to cut off at 226F that hardly suggests that 210 or even 220 is an unacceptable temperature... Obviously the designers were intend on keeping the temp not too much higher than 226, but one would think that if 210 was unacceptable they would have set the A/C cutoff to much less than 226, no? When I slowly towed a trailer up a steep dirt road in 90 or 100F a few days ago, I was getting 220F with A/C on. Well, anal/paranoid/worrywort as I am, I didn't stop. That should tell you something...:)

Seems to me that the upper limit is a function of the allowable pressure in the cooling system to prevent boiling, not so much a function of the hardware materials in the system... So, figure out the rad pressure relief valve setting, that should tell you the max temp you should sustain.


this cooling paranoia of the last month or 2 is getting a bit out of hand, perchance? :)
 
e9999 said:
guys, let's be reasonable here. As I said elsewhere, if the A/C is designed to cut off at 226F that hardly suggests that 210 or even 220 is an unacceptable temperature...

this cooling paranoia of the last month or 2 is getting a bit out of hand, perchance? :)

That was one reason I started this thread. I don't think it is reasonable to expect that the cooling system will never go over 190-195f. I also wanted to try to get a baseline so people can tell when their cooling system isn't up to par so they know when they should start to worry.

It appears from the posts here and some past posts, that with heavy loads, when climbing on hot days, 220f has been seen with several members having trucks with cooling systems in good shape.
 
Unfortunately when my truck saw it's greatest tempuratures I didn't have my OBDII scanned with me. I did have my modded stock gauge and I think it hit around 218. This was towing uphill with the AC on. The outside tempurature was probably 75F or so.

Just a couple days ago I was driving when it was about 100 out and I had the scanner attached and read a tempurature of 212 going up a slight incline at 65mph. Normally my truck runs at about 195-200 and often times sees 205 on the freeway. I do have a high speed heat problem since my tempurature is usually 195-200 at slow speeds and idling, but will often go to 205-208 when traveling faster than 65mph.

This weekend I'm hoping to get some more readings since I'll be testing out some new resistor values in my stock gauge.
 
here are some stock switch and observed data stock temp gauge data points. They suggest the designers did not want it to run over 226 on a sustained basis but that the truck could run up to 245 for short periods with a possibility that 93-94s were expected to max out about 240. The designers, presumably, did not know how fragile the head gasket would turn out to be, but I think we can assume their parameters were safe for the rest of the engine.

226 = AC cut off
216 = AC cuts back on

factory gauge settings for a 95-97

222 = stock temp gauge begins to move from numb dead centre
228 = stock needle at 2/3
238 = stock needle at 3/4
244 = top of stock needle touches the bottom of red
250 = bottom of stock needle slips into red
254 = stock needle at centre of red zone
259 = top of stock needle touches top of red
266 = bottom of stock needle leaves red

For a 1993 stock gauge initial movement was roughly the same but you need to subtract 6 degrees from the red zone numbers. No idea if this is a design difference or a manufacturing tolerance issue as the two gauges have some slight cosmetic differences but appear to be electrically and mechanically identical.

a debate as to safe operating temperature occurred when raventai was deciding how to calibrate the temp gauge mod. in the end the resistors available drove the bus and we ended up with 216 at the bottom of red for the 95-97 gauge and 213 for the 93-94 gauge. I can vouch for the psychological effect of getting to red on a gauge even knowing it is an arbitrary number rather than a factory choice.

https://forum.ih8mud.com/showthread.php?t=53142&page=10&highlight=temperature+gauge+shut
 
Darwood said:
Unfortunately when my truck saw it's greatest tempuratures I didn't have my OBDII scanned with me. I did have my modded stock gauge and I think it hit around 218. This was towing uphill with the AC on. The outside tempurature was probably 75F or so.

Just a couple days ago I was driving when it was about 100 out and I had the scanner attached and read a tempurature of 212 going up a slight incline at 65mph. Normally my truck runs at about 195-200 and often times sees 205 on the freeway. I do have a high speed heat problem since my tempurature is usually 195-200 at slow speeds and idling, but will often go to 205-208 when traveling faster than 65mph.

This weekend I'm hoping to get some more readings since I'll be testing out some new resistor values in my stock gauge.


I have posted detailed temp measurements someplace else, and I have reached 220F under severe conditions, but I can safely say that on the freeway at 60 or so my temp goes back down to 185 or so (with ambience in the 70-80 range), which is likely with a partially open thermostat. I believe my cooling system to be in excellent condition, fan less obvious but clutch seems OK. That suggests that the rad is working very well to keep things cool on mine when relying on outside air speed, but less at low speeds where the fan is more critical. If you don't see that low temp at high speed, maybe your rad is indeed questionable?.
 
It is all a matter of perspective I suppose. Personally I think the AC cutoff is a failsafe designed by Toyota to prevent serious problems before things start breaking. I do not think it was designed to toggle on and off and leave passengers sweating to death while wondering, "Why the hell isn't my AC working?" - all while the idiot temp gauge doesn't move.

When I took a shop class, (this was many years ago mind you), I remember vividly that the most efficient operating temperature for an internal combustion engine was between 180 and 190 degrees. I believe the thermostat in the Land Cruiser fully opens in the 180 something temperature. I forget exactly. Someone help me here.

For me, 195 is my limit as a constant temperature. Anything more breaks down my oil unnecessarily. Also, this engine is made of dissimilar metals - a cast iron block and an aluminum head - which expand and contract at different rates and temperatures. Extra heat only exaggerates the problem of trying to keep these two metals sealed together and makes the head gasket more prone to failure.

Now, if my engine were equipped with a cast iron head, (like the earlier models), I would feel different. Uniform expansion of similar metals. I would still not like 200+ temperatures, but I would sure worry a lot less if I saw them.
 
Gauge said:
I believe the thermostat in the Land Cruiser fully opens in the 180 something temperature. I forget exactly. Someone help me here.

For me, 195 is my limit as a constant temperature. Anything more breaks down my oil unnecessarily

Actually the thermostat does not fully open until 195 or 205f, I can't remember which. Also, your oil (even mineral) will not experience any breakdown issues until temps exceed 230F for extended periods. Oil has come a long ways in the past 10+ years.
 
Gauge said:
I would still not like 200+ temperatures, but I would sure worry a lot less if I saw them.


Here is a chart provided by Gum in the thread that had our discussion:
temps.jpg
 
I do not have an aftermarket gauge in the Land Cruiser that gives exact temperatures, but I did install one in my Toyota Tacoma.

This much I can say for sure - Thermostat in the Tacoma opens at 185 degrees. Pushing it hard with the AC on, I have experienced temps up to 215 for short bursts. However, as a constant operating temperature I have never experienced more than 195. That to me seems normal.

Also, whenever I start my Tacoma I hear the loud roar of the clutch fan before it quiets down - something I do not hear in the Land Cruiser.

I'll be picking up my Hayden Clutch Fan today.
 

Users who are viewing this thread

Back
Top Bottom