What are your coolant temps?

[95ToyCruiser]

Thanks guys, just checking to see if mine is around what the typical 80 is running at.

I have flushed my coolant/replaced with Toyota red and new t stat, but it will go up to around 198-200 while idling sometimes, thinking of doing the fan clutch fluid change too.

Or replace all together with electric fan? Why don't more people do this for gas mileage and more consistant temps?

 

[Brian894X4]

I think the best way to know what the true stock normal engine temp is, is to measure a normal running 80 with a brand spanking new cooling system using all OEM parts. I have done that. And my conclusion is that 181 degrees is normal operating temp. Anything higher, except for extreme conditions and there’s a problem.

I believe the stock thermostat is 180 degrees. If the engine ever runs hotter than that, then the cooling system is being overtaxed. The stock 80 cooling system has extreme capacity and a perfectly healthy cooling system should rarely be overtaxed on a North American highway.

This system is designed to cool an 80 used in extreme desert conditions of Africa, Australia, Asia, running at low speed in the dirt. That means cool a stock 80 to 181 degrees in those conditions.

Most of us added things like lifts, larger tires, even block the radiator with bumpers and lights and winches, which affect stock airflow and add weight and load. The cooling system could be overtaxed simply because of restrictions in airflow. Although my experience is that you can restrict airflow pretty good and still run normal temps of 181 degrees under normal conditions.

I believe the most common problem people have is a plugged radiators due to the mystery sludge and they don’t even know it. Flushing does not work on this kind of sludge and you will not see it near the radiator cap in the one area you can actually look, so you’ll never know it’s there. Feeling around in a low pressure area with a long instrument of some kind through the radiator fill cap, might reveal a sample of sludge.
If the radiator has even just a little bit of sludge blocking a certain percentage of the tubes, the stock cooling capacity has simply been reduced, which means t-stat will have to fully open much sooner than normal and excess heat cannot be carried away, thus the higher than normal engine temps.

This means a lot of posters in this thread likely have problems with their cooling systems and dont' even know it, especially if they are running in the 190s+ this time of year based on their scan gauges.

 

[jeffro109]

So if we have the following new Toyota parts--radiator, t stat, water pump, hoses, system was flushed and then all the parts put in and new red coolant.

That seems to leave the fan, which is original or some mystery sludge back in the game. I am going with the fan...just cause it is easier!!

I also think that the truck should not be in the mid to upper 190s just street driving when it is 75 F outside. It might be perfectly OK at that temp, but I think it should be lower.

 

[Flank]

I think the best way to know what the true stock normal engine temp is, is to measure a normal running 80 with a brand spanking new cooling system using all OEM parts. I have done that. And my conclusion is that 181 degrees is normal operating temp. Anything higher, except for extreme conditions and there’s a problem.

I believe the stock thermostat is 180 degrees. If the engine ever runs hotter than that, then the cooling system is being overtaxed. The stock 80 cooling system has extreme capacity and a perfectly healthy cooling system should rarely be overtaxed on a North American highway.

This system is designed to cool an 80 used in extreme desert conditions of Africa, Australia, Asia, running at low speed in the dirt. That means cool a stock 80 to 181 degrees in those conditions.

Most of us added things like lifts, larger tires, even block the radiator with bumpers and lights and winches, which affect stock airflow and add weight and load. The cooling system could be overtaxed simply because of restrictions in airflow. Although my experience is that you can restrict airflow pretty good and still run normal temps of 181 degrees under normal conditions.

I believe the most common problem people have is a plugged radiators due to the mystery sludge and they don’t even know it. Flushing does not work on this kind of sludge and you will not see it near the radiator cap in the one area you can actually look, so you’ll never know it’s there. Feeling around in a low pressure area with a long instrument of some kind through the radiator fill cap, might reveal a sample of sludge.
If the radiator has even just a little bit of sludge blocking a certain percentage of the tubes, the stock cooling capacity has simply been reduced, which means t-stat will have to fully open much sooner than normal and excess heat cannot be carried away, thus the higher than normal engine temps.

This means a lot of posters in this thread likely have problems with their cooling systems and dont' even know it, especially if they are running in the 190s+ this time of year based on their scan gauges.

I have several problems with your statements, not the least of which is that you have some vague generalizations and complete falsehoods.
What is too hot ambient temp? What is too much engine load? Is too hot a 100 deg LA day, or a 115 deg Vegas day, or a 120 degree day in Africa? The purpose of the thermostat is not to regulate the engine to 180 deg and keep it there, it is to isolate the engine cooling system until it gets to operating temperature to avoid engine damage from running too cool and allow it to do so quicker.

When you say that a 1fz should not exceed 181 degrees, where are you getting this from? This is BS. Show me the spec. We have had a LOT of discussion about engine temps on this forum, and I have never heard or seen evidence of this. Please refrain unless you have proof, as this will make the newer guys scared that they are about to blow an engine when they get to 190 degrees which is not the case.

Mr T designed the engine and cooling system for extreme conditions, it's true. And safeguards to keep it working, such as the AC cutoff at around 218 deg. If Toyota had been worried about the engine running hotter than 181, this cutoff of a non-essential system would have been set MUCH lower.

Can you keep your engine temps lower by doing proper PM on the system - YES. Is it a problem indicator if your engine temp runs hotter than 181 - NO. If it is a nice fall day and you are running at 200 deg, you may have cause for concern, if it is 112 deg out like we get here in Vegas and you are running at 215 in stop and go traffic, you may not have cause for concern.

People, you have to maintain a relative sense of reason here, and not be so alarmist. The OP's question was whether or not he was running too cool. In answer to that, no he is not running on the cooler side.

 

[HooDoo]

Thanks Flank, I freaked out last summer when I saw 213 on my scangauge while climbing a steep dirt road. My air intake temp was also high, 140(?). Looking at normal driving temps I'm thinking my stock fan clutch may need some attention. I think a lot of these discussions have arisen because so many of us now have scangauges, or other gauges, that show these 10-20 degree temp fluctuations that don't show on the POS stock gauge.

 

[94SRUNNER]

Very well stated Flank. Most of the folks posting in this thread are seeing normal operating temps.

 

[Tools R Us]

... the AC cutoff at around 218 deg. ...

Agree, nice posting, ‘cept, IIRC this number is 226F?

... I have done that. And my conclusion is that 181 degrees is normal operating temp. Anything higher, except for extreme conditions and there’s a problem. ...

Disagree, like most newer motors the 1FZ is designed to run slightly warmer for better efficiency, all that I have experience with settle in at 190F ish, when steady state cruising. A bunch of locals have Ultra/Scan gauges, often caravan, the radio temp comparison calls often happen and the result is always within a couple of degrees. When steady state highway cruising in cool (for us) weather all are close to 190F ish. All have cooling systems easily capable of handling AZ desert triple digit plus temps and stout (likely stronger than needed) fan clutches.

... I believe the stock thermostat is 180 degrees. If the engine ever runs hotter than that, then the cooling system is being overtaxed. ...

Disagree. The test temp of the thermostat is first opening at 176-183F, fully open at 203F. From that one could assume that 180 is the number, but that would be incorrect. The temp sender is in the upper neck, measures coolant output temp. The thermostat is a lower design, lives in the lower water neck. When the motor is cool, the thermostat sees, acts on, bypass coolant flow, when warm it sees a mix of bypass and radiator output, when hot sees radiator output. The thermostat regulates coolant intake temp, the coolant then travels through the motor picking up heat and temp is read at output, so the motor runs at a higher temp than thermostat.

Some may believe this is bad, but it is not. In the “old days” motors were designed to run in the 170-180F range, this was mainly because of “life issues” mostly related to fluids, like motor oil breaking down at higher temps. All internal combustion motors become more efficient as temps go up, making more HP per cubic inch and gallon of gas. Motor design changes and fluid improvements have allowed designers to take advantage of more efficient/higher temps. As long as it can be kept in control, it is a good thing.

... This system is designed to cool an 80 used in extreme desert conditions of Africa, Australia, Asia, running at low speed in the dirt. ...

Agree that the ‘80 has a robust cooling system. But don’t need to travel to faraway fantasy locations to test it, some places in the good old USA are within a few degrees of the hottest places on earth.

 

[Flank]

Agree, nice posting, ‘cept, IIRC this number is 226F?

I'll defer, Kevin, to your knowledge. It only illustrates my (your) point further.

 

[Tools R Us]

... but it will go up to around 198-200 while idling sometimes,

The correct answer to this is; how long is a piece of string? There is no way of us knowing, comparing that number to anything, far too many variables, like; was the cabin climate control cycling, what was the ambient, was it in full sun, etc, etc, etc. IMHO, 200F is well within the operating range and is nothing to even note, if we were talking +220F, now it is time to pay attention, maybe.

... thinking of doing the fan clutch fluid change too.

IMHO, good idea, a strong clutch is a good thing.

... Or replace all together with electric fan? Why don't more people do this for gas mileage and more consistant temps?

Because there is little/nothing to gain, mainly only losses. Electric fans are less efficient, the process of converting mechanical energy to electric (belt to alt), controlling it (relays, wire connections, etc), then converting it back to mechanical (motor to fan) has significant losses. Any gains are from careful control and most aftermarket systems don’t have the sophistication needed for any significant gain.

The factory fan can be very powerful, in a wheeling rig a powerful fan is a good thing. To make an electric as powerful is going to take a bunch of $$$, if even possible.

In a wheeling rig reliability is king, the cooling system is one that most would agree is critical and there is nothing more reliable that a fan driven by a belt, period. Instant, quick failure is very rare, most common is clutch bearing locking, this leaves the fan full on, the rig drivable. With a complicated, electric system there are a ton of failure points, most all leave the fan dead, so rig useless.

 

[Flank]

Brian, I read your post that was deleted, and one thing is clear. You (Rightfully so) have different expectations out of a cooling system than the average or even above average driver of a 15+ year old truck. (by the way, I don't think you should have deleted it.)

If I dependent on the truck as a business tool, as you do, to safely take me hundreds of miles from anywhere and back with clients, that would warrant a few thousand dollars to make sure my cooling system is in AS NEW order. I have visited your site many times (I like it, and your truck as well).

But the fact is that the temps we have been discussing are not going to be catastrophic or even a big concern for the average or harder than average driver, and barring further giving into the obsession to make our trucks new again, we don't necessarily need to do rad replacements just because we run 190-200 temps in certain conditions.

Were I doing expedition work, I would certainly be anal about my cooling system and radiator. Frankly, I wish I had the excuse. My point is that we need not frighten the average guy with the fact that damage will be done if they run in the 190s and 200s, the engines will take it. As your mileage gets higher, it is prudent so pay more attention to the temps to avoid HG issues, which are a crapshoot at best. 212,000 on the clock, with original HG, so wish me luck.

 

[FirstToy]

My AC cutoff is about 218F (from where the Scangauge is reading it)

Running too cold is bad too. More wear, less efficient, etc.
Tstat fully opens at 190 or so, I believe.
That would assume a fully operating cooling system and motor is most efficient at 190+F.

I have read many times that a gas engine is most efficient @ 200F. That is a sweeping generalization, but I think a nugget of reason in there as Tools elaborated.

Instead of thinking lower is always better, if you think of 190-200F as "most efficient" and declining efficiency on either side of that scale, maybe it will ease the mind.

Obviously, 'too cold' does not have the consequences of 'too hot' (since the motor always will cycle thru the 'too cold' zone with every use). But cycling within the parameters of the stock gauge, I don't think is a problem.
Maybe Toyota was smarter than all of us when designing that gauge?? Ignorance is bliss, maybe too much info just causes a lot of unneccesary worry?

As you can see, i've gone thru the entire cycle - worry, panic, problem solving, frustration, giving up, logic and acceptance.

 

[Flank]

Maybe Toyota was smarter than all of us when designing that gauge?? Ignorance is bliss, maybe too much info just causes a lot of unneccesary worry?

As you can see, i've gone thru the entire cycle - worry, panic, problem solving, frustration, giving up, logic and acceptance.

Amen to that, Brother from another mother.

 

[Tools R Us]

... My point is that we need not frighten the average guy with the fact that damage will be done if they run in the 190s and 200s, the engines will take it. ...

That is the normal design operating range. I don't even worry about briefly seeing 220F. Two examples: When idling relatively long term, say 20-30min, in full sun, at 110F+, A/C on full bore. When used in short stop mode with hot conditions, drive till fully warm, turn it off briefly, 5-15min and it will be ~220F at each restart. When driving is resumed, the temp rapidly drops back into the 190F's range, no issue as long as recovery is quick.

The "idle mode" is one of the things we discovered when we started playing with fan clutches. Loaded idle is where the fan output temp is the highest, so is where the clutch should be full on. If the valve is adjusted cooler, the idle mode is used for loaded cruise, with no stronger opening for idle. If the valve is left at the stock setting or slightly hotter and much thicker fluid is used, the idle temps fall, idle A/C performance is better and recovery is much quicker.

If you want to make the motor run cooler, it is easy, simply run the cooler S/C thermostat. IMHO this is counterproductive. A cooler running motor is less efficient in all modes. It can't burn/evaporate off contaminates in the crankcase as efficiently, so is more prone to sludge buildup. Will make less H/P per cubic inch and less H/P per gallon of gas.

 

[80BajaBound]

cause for concern?

First off let me tell you what I'm working with... 97 FZJ80 206k 3x locked, 4.88's, OME J's with front spacers, bumpers front and rear, sliders and BF AT 305/75/16's, new radiator and water pump, the PHH hasn't been replaced. Yesterday in North County SD it was 60-65 degrees out at 3 pm. I was driving up a pretty incline that is no longer than 1/4 mile (Elfin Forest rd for anyone that is local). Randomly I looked at my Scangauge and it read 219*!! I pulled over in a parking lot to let her cool down. She recovered quickly (190's), so I headed back down the hill. The rest of my drive home (10 miles) it was in the 200's with relatively flat roads and consequently was getting almost 19 mpg!

So my questions are -
Is there any cause for concern here? ( I read earlier in this post that "if you are in the 200s on a nice fall day there might be cause for concern")

What steps should I take to resolve this cause for concern?

 

[94SRUNNER]

80BajaBound, Have you done anything with your fan clutch? I didnt see it mentioned in your description. How about the rest of you cooling system?

Before this instance...what temps were you regularly seeing?

 

[CJF]

x2 on fan clutch.

 

[80BajaBound]

Nothing with the fan clutch, I'm assuming that's my next course of action. Previously, I'd been experiencing temps in the 190's but never over 200, even on longer higher speed inclines on the 15.

 

[Brian894X4]

The fact that it recovered quickly sitting at idle leads me to believe that the fan clutch is working as it should. If the fan clutch had issues, it would either stay hot or get hotter, since you have zero or very little airflow through the radiator sitting still.

I'm not saying it's not the fan clutch. Maybe its worn to the point that it can't move enough air at the low speed, high engine load condition of running up an incline, but can move enough air to cool it at idle.

 

[ripple]

I've been testing the motor that I just put in my lx450.
I don't have a scan gauge yet or an alternate temp sensor.
It sure seems like it is about to overheat although the stock
gauge warms up to the midpoint and hasn't budged higher.
My question is, should you be able to touch the valve cover
when it's running, or would it be too hot to keep your hand on, at
normal operating temperatures? Seems like it's running hot if you
can't touch it. In the meantime I will improve
my temperature gauge situation.
thanks

 

[greentruck]

ripple,
Yeah, checkout the Raventai temp gauge mod thread. It's a pretty cheap mod and works great.

I see you're in Leadville. Keep in mind the altitude, which is going to present a whole different set of symptoms than lower down if you're going by touch based on your experience down there.

Of- course, maybe you're lucky enough to be a townie there and my last statement may make me look like a fool.

But get a gauge on things that you trust. The stock gauge will let you get well into the early parts of overheating before it nudges into the danger zone -- at least down here near sea level. That won't show up by just reading the stock gauge, which worries many of us enough to get better temp readings.