cooling a 1hdt (1 Viewer)

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franklin40

franklin40

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I've got my 1hdt running well with a good tune. it is intercooled with an air water intercooler and i have it boosted to max 16psi. i typically run at around 600 to 700 degrees f on a summer day when at highway speed. only have a puff of smoke when shifting gears and otherwise none. i have done the tune up work with the intent of pulling a trailer. now that i have a few thousand km of trailering i wanted to ask about my cooling. i find that if i pull over 90 km/hr or into a heavy head wind my temp gauge (remember its the stock gauge from my gas engine) starts to read between the 2/3 and over heat mark. egt are constantly around 900-1000 while this is happening. short pulls up hills i have lots of power yet and egt get up to 1150 max but settles down once up the hill. it's the overall engine temps that i wonder about my cooling system not keeping up. has anyone else had their engine run this hot after a tune of the pump and boost? my radiator is the stock 4 core fj62 rad that was flushed and pressure tested. one thing i haven't tested is the clutch fan but at highway speeds this shouldn't be the issue. without trailer i have no troubles keeping temps down at the 1/3 mark on my gauge.

thanks for your thoughts!!
 
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I suspect the stock gauge is fairly conservative and your temps are fine. But the only way to know is to fit an aftermarket gauge that shows actual temperature.
I used the stock gauge on my FJ73 when I put the 1HZ into it and it worked fine.
 
roscoFJ73 said:
I suspect the stock gauge is fairly conservative and your temps are fine. But the only way to know is to fit an aftermarket gauge that shows actual temperature.
I used the stock gauge on my FJ73 when I put the 1HZ into it and it worked fine.
Click to expand...

I suspect the stock gauge is unreliable.
If it reaches red, it's not earning you you are going to overheat, it's confirming you HAVE overheated.

Your EGT probe, is it before or after turbo?
your figures are meaningless without knowing this.
Having the probe after the turbo is unreliable, and not a useful gauge of your tune.

Is your viscous fan hub engaging properly? Do you hear it roar when it is fully engaged?
The engine fan is crucial to cooling if you're pushing it to the limits, even at highway speeds it lasts a part.
 
egt probe is pre turbo for sure. what numbers should i be looking for for water jacket temps. ill check my fan too then as i guess it probably does matter when pushing it.
 
so just spun the viscous fan and it seems fine. it stops turning as soon as i take pressure off the blades. i cant make it spin freely at all. i'm looking for a good place to install another water jacket temp probe. would this spot just below and forward to the oil filter be a good place? there's a sensor there already but it's unused and i don't know what it's for. it's the green connector in the photo by my finger
IMG_4210.JPG
 
1150°f pre turbo shouldn't be a problem of your cooling system is good.

There's a bit more to the fan function than spinning it by hand :banana: :lol:

At times when you think the temperature is climbing, do you hear the fan?
You should hear it when it is fully engaged, if you're listening for it, you'll hear it over the engine and over road noise etc

Some light reading about fan set up
Blue fan clutch mod

You could also test your thermostat is functioning correctly, and check radiator cap is in good condition.
 
rad cap was new with rad flush and test two years ago. i think it's still ok. thanks for the article. it'll be some bedtime reading!

honestly i'm not sure i've heard the fan but ill turn off the music and give it a listen tomorrow.

could my intercooler rad be blocking too much of my engine rad? it's a big one
IMG_3626.JPG
 
mudgudgeon said:
1150°f pre turbo shouldn't be a problem of your cooling system is good.

There's a bit more to the fan function than spinning it by hand :banana: :lol:

At times when you think the temperature is climbing, do you hear the fan?
You should hear it when it is fully engaged, if you're listening for it, you'll hear it over the engine and over road noise etc

Some light reading about fan set up
Blue fan clutch mod

You could also test your thermostat is functioning correctly, and check radiator cap is in good condition.
Click to expand...

i read a little more about the blue clutch mod here

Tuning and Understanding your Toyota Viscous Fan Clutch

it seems like this will be a good place to start. i have much more understanding of how these things work and yes it's a little more than just spinning it to see if there resistance or free spin.

i have a gauge that will read water temp. in my picture in post five i believe the green connector is a water temperature sender. can anyone confirm this? also does anyone know the thread size for it? i don't want to pull it out to replace it with a sender that'll work with my gauge and have the wrong part to put back in
 
franklin40 said:
i read a little more about the blue clutch mod here

Tuning and Understanding your Toyota Viscous Fan Clutch

it seems like this will be a good place to start. i have much more understanding of how these things work and yes it's a little more than just spinning it to see if there resistance or free spin.

i have a gauge that will read water temp. in my picture in post five i believe the green connector is a water temperature sender. can anyone confirm this? also does anyone know the thread size for it? i don't want to pull it out to replace it with a sender that'll work with my gauge and have the wrong part to put back in
Click to expand...

I followed those instructions to have a go at mine. It made a huge difference.

It's a fix that costs next to nothing, just a little time, and a few $$ for the oil.

Be careful with the o-ring, I damaged mine and list all the oil in just a couple of weeks.
 
mudgudgeon said:
I suspect the stock gauge is unreliable.
If it reaches red, it's not earning you you are going to overheat, it's confirming you HAVE overheated.

.
Click to expand...

What temperature is overheating and what temperature does red represent? I have found it reliable in 4 landcruisers, when it moves there is a possible problem. I cant see those spikes on hills being a problem.
 
roscoFJ73 said:
What temperature is overheating and what temperature does red represent? I have found it reliable in 4 landcruisers, when it moves there is a possible problem. I cant see those spikes on hills being a problem.
Click to expand...

that's what i'm wondering too. i have a gauge that has my egt and boost and i have two more input slots left (zietronix-its a pretty sweet system). i'm going to install a proper water jacket temp gauge that tells the actual temp by just an arbitrary line. it's never gotten high enough to gonig to the red because i'm watching it like a hawk but it's moving upwards on the gauge if i push it. i've never boiled over and my coolant is full so i'm not losing a bunch onto the ground. i know there are lots of guys with this same engine way more tuned than mine and i just wonder if it's common to see them run hot when towing. my thought is no so i need to sort out where my weak link is in my cooling. i think my fan might not be engaging. i wasn't towing so my temps never got high but i haven't heard any fan noise after 1/2 hr of highway driving egts around 650 the whole time
 
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franklin40 said:
i think my fan might not be engaging.
Click to expand...

I don't think the fan does much at high speed. The flow of air through the radiator probably exceeds what the fan could suck through. The pressure on your hand when you hold it out the window at 100kph is much stronger than any air pressure you could get from the fan.
 
The fan definitely contributes at high speeds. I previously thought air flow from road speed should exceed what the fan is capable of, but not think the fan does play a part.
At high way speeds, if air flow is sufficient to manage temps the hub will cool, and the fan will not be fully engaged.
I've heard my fan cycle in and out at highway speeds in hot conditions. The fact it is cycling shows that the fan contributes. When it's engaged it brings temps down, the hub cools, it disengages, the hub heats up, the cycle repeats.


The standard thermostat should start to open at 76°c, and is fully open at 90°c.
My memory is normal operating temp should be around 88°c, give or take a few degrees, up to around 95°c.
I would consider 100°c as overheated, though it shouldn't boil at 100.

The cooling system is sealed with a pressurised radiator cap. Being pressurised raises the boiling temperature of the coolant. It's possible to run coolant temperatures up to around 110°c without having a boil over.
110°c is too high for normal running, oil starts to break down around 100C, and pistons and rings and other metal components expand, reducing clearances to the point where seizing becomes a risk, but it increases your safety margin. Superheated water still cools better than steam.
 
bump. anyone have the tread size for the water temperature sender pictured in post 5. i think toyota used bsp threads but i've heard npt is close and should work. just don't know if it's 1/8,1/4,3/8..... it's the one just in front of the oil filter. or is there a better place to put it? my upper rad hose doesn't have a bung to tap into like some people have
 
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