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normal temp range
Old 29-06-2017, 04:11 PM
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justbruce justbruce is offline
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Default normal temp range

Quick question.
For members who use an OBD reader.
What is your temp range when driving?
I've re-rebuilt my engine and I reckon it is running hot.
Outside temperature is less than 10C.
With cruise control set at 100kmh on undulating open road, my temperature varies between 90 and 100 degrees. On a long downhill stretch it drops down to 87.
At 10 - 12 PSI boost, the temp is constant. Above 12 PSI the temp rises.
This is without carrying any load.
All the following is new; head, radiator, fan&clutch, hoses, and thermostat.
I cleaned out the block when the head was off.
I've lost count t of how many times I have flushed the cooling system.
At 50 the temp gauge starts moving, at 65 the needle is pointing at the clock adjusting knob. It doesn't move above this.
I've been told, diesels run at about 80.
If there is a problem? If so, I want to fix it before I start towing in summer.
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Old 29-06-2017, 10:25 PM
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Old.Tony Old.Tony is offline
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Diesels don't run at 80C, at least not our D40s. Our glow plugs don't turn off until the coolant reaches 85C and the viscous couple for your fan doesn't come on fully until 91C.

Mine generally sits around 93C, moderate hills will see it rise to 95-96C. If I do NOT pay attention when towing, it'll quickly shoot to 101-102C up a hill before I back it off and start changing down the gears. I try not to let it reach 105C - that's not a dangerous temperature, it's the temp where the electric fan cuts in to assist the main fan.

On a long downhill, my car also cools to marginally below 90C.

I'd say your temps sound perfectly normal.

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Old 29-06-2017, 11:57 PM
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Czechmate Czechmate is offline
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Ive rattled on about this one before on this forum

If you want your rig to run cooler, pull the viscous fan clutch off, open it up and add 2-3 bottles of Silicone Oil to the oil reservoir inside

This makes the fan drive at lower temps and hold in for longer once its engaged

I did it when I replaced the stock fan clutch on my D40 with a new Dayco one

before i installed it i split it open and added 2 small bottles of Toyota silicone oil to the reservoir

Now I can hear it run a lot more frequently, it kicks in when the temps at around 89 degrees, and the D40 now sits at around 87-89 degrees on flat ground

Also when we replaced the timing chain in my YD25 and put a new head on, my mechanic said "keep this thing cool" as the yd25 engine is very small with big water jackets, so theres not much metal there to act as a heatsink when the power is pumping out

This is the stuff you need. For some reason Toyota are the only mob in Oz to supply a good quality fan clutch silicone oil at a decent price


Having the fan drive more will obviously consume a little more fuel, but its a small price to pay for a cool engine

I think people get caught up in sexy "Hi-tech" theories of engine cooling, like adding electric fans, using waterless coolant, changing thermostats, putting in huge imported radiators (which are mainly junk by the way) etc

Realistically this is by far the cheapest, easiest and most logical way to move more air through the radiator

youtube vid of someone cracking open a fan clutch and mucking around with the silicone oil inside:
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Old 30-06-2017, 12:19 AM
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Originally Posted by justbruce View Post
With cruise control set at 100kmh on undulating open road, my temperature varies between 90 and 100 degrees.
see whats temps do going up a hill. 110c start to panic.

100c on the flat with 10c outside temps, doesn't sound good.
i would expect to see it down around 90c at the most.
my reason for that is on the flat your not putting much fuel in and even if fan is working poorly 10c air temp is more than sufficient for good cooling.
most diesels would be barely opening the thermostat when driving on the flat.
uphill is a bit different as your pouring in more fuel.
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Old 03-09-2018, 08:56 AM
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rickyb9999 rickyb9999 is offline
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Default temps

I run around 87-90 on the flat. If I'm towing the temp hits around 91-92, it does rise higher to 100-105, when going up long hills. My vehicle is fully accessorized bullbar etc. The trick to keeping the engine cool, is to use the revs and drop a gear especially when towing and on hills and it keeps the temp down to 100. I also drop a gear when on sand and the same trick works. If you are constantly using the turbo the temps will rise a lot quicker. Only once have i hit 115. this was towing on sand for a lengthy period of time, without a break. The aircon turned off telling me the vehicle was running way to hot. Best thing to do in this situation, pull over, leave the vehicle running till it cools. Slow and steady always wins the race :)
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