1HZ (diesel) coolant temperatures? (3 Viewers)

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dmarsc10

dmarsc10

Joined
Apr 17, 2020
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Location
Australia
Hi all,
Just wondering for those of you out there who have installed an aftermarket, and more accurate temp gauge what your readings are... and what you regard as acceptable operating temps for the 1HZ?
I've recently had a Redarc gauge installed in my 79 series 1hz with aftermarket turbo...
EGT max's out at around 400 degrees C... but coolant temp constantly in the high 90's (Celsius)... and can see over 100 degrees without even working it too hard....
What's everyone else see coolant-wise??
 
Last edited:
80c to 110c Has your radiator been flushed properly?
 
It’s not a 1HZ but I do have a 1HDT 80 series with a Defi temperature gauge with the sensor installed on the upper radiator hose. It’s never gone past 90C even during long uphill climbs. It’s usually around 83-85C during normal driving
 
mudgudgeon said:
How do you know the standard sender is any good? Have you verified the temperature reading somehow?
Click to expand...
Not 100% sure it is... just trying to get an idea of whether or not my temps are "normalish" before replacing parts... (although a temp sender is cheap... so might be worth doing anyway)... 👍
 
HRTROB said:
It’s not a 1HZ but I do have a 1HDT 80 series with a Defi temperature gauge with the sensor installed on the upper radiator hose. It’s never gone past 90C even during long uphill climbs. It’s usually around 83-85C during normal driving
Click to expand...

Cheers mate... definitely running cooler than my cruiser...
 
Somehow you need to verify the temperatures you are seeing are real. Maybe buy or borrow one of those infra red thermometers.
Are your radiator hoses firm when it warms up?
What kind of driving makes the temp rise above 90? All of my 1hzs have been around 85-90c on the freeway at 100. To push them over a 100c I would have to go hard up a hill.
 
roscoFJ73 said:
Somehow you need to verify the temperatures you are seeing are real. Maybe buy or borrow one of those infra red thermometers.
Are your radiator hoses firm when it warms up?
What kind of driving makes the temp rise above 90? All of my 1hzs have been around 85-90c on the freeway at 100. To push them over a 100c I would have to go hard up a hill.
Click to expand...

So low to mid 90's can be seen around town, high 90's to 100c (and above) can be seen on the highway... (temp climbs when going up hill... as expected)...
And the weather is quite cool here at the moment...
I haven't felt the hoses when hot yet... but I believe the Redarc gauge to be accurate as I used to see the factory gauge rise slightly above the middle... which would indicate the engine was starting to heat up more than what is acceptable....
Thinking the thermostat might need replacement...
Possibly not opening fully??
 
dmarsc10 said:
Thinking the thermostat might need replacement...
Possibly not opening fully??
Click to expand...


Maybe, but 1HZ t/stats are not normally a problem, especially OEM. They either open or they dont if there is a problem

Check the hose pressure. Lack of pressure allows them to heat up quicker.
Using any coolant?
Fan belt tight?
 
roscoFJ73 said:
Maybe, but 1HZ t/stats are not normally a problem, especially OEM. They either open or they dont if there is a problem

Check the hose pressure. Lack of pressure allows them to heat up quicker.
Using any coolant?
Fan belt tight?
Click to expand...

Good to know the thermostat isn't usually an issue... looks like it's in a painful spot to get at in behind the alternator/turbo etc... don't want to replace it if it's unlikely to be the problem...
Will check hose pressure next time I get a chance....
The belt seems tight... and it's not using coolant...
Should the hose pressure be noticeable at say 90c??
Appreciate the help here...👍👍
 
dmarsc10 said:
Wherever the standard temp sender read from... the standard temp sender is now being used for the after market gauge...
Click to expand...

Just had a look... the temp sender is in the spot just behind/above the oil filter (see picture).... and looks new... (installed with the aftermarket gauge)
Screenshot_20200526-101620_Gallery.jpg
 
Are you using the factory sender with the aftermarket gauge? If so, I would question if the output from the factory sender is correct for an aftermarket gauge, most gauges come with their own sender
 
dmarsc10 said:
Good to know the thermostat isn't usually an issue... looks like it's in a painful spot to get at in behind the alternator/turbo etc... don't want to replace it if it's unlikely to be the problem...
Will check hose pressure next time I get a chance....
The belt seems tight... and it's not using coolant...
Should the hose pressure be noticeable at say 90c??
Appreciate the help here...👍👍
Click to expand...


Ive only ever replaced a t/stat with the engine out, but I don't feel its a difficult job in. Im not sure you need to remove the alternator, but that's a job that gets easier after a few times.

I test the t/stat by hanging onto the top radiator hose from a cold start. When the t/stat opens from a fast idle, you can feel a flow of warm coolant through the hose if its working ok, it takes about 5-10 minutes. But its a definite change of temps and will get warmer.

Hoses should be firm, not rock hard. Rock hard is a often a sign of a head gasket leak.
Pressure in the system stops big steam bubbles forming around the cylinders. Once bubbles form in your cooling system basically throws its hands up and surrenders.
A bad rad cap is often the root cause.

The position of your sensor is right in the cylinder head.
I'm wondering if its giving you the temperature of the combustion chamber rather than the coolant. Temperatures in those areas get a lot hotter than the coolant.
Normally the sensor is on the coolant outlet where the top radiator hose connects to the head.

Did anyone alter your injector pump fuel settings when the turbo went on?
 
roscoFJ73 said:
Ive only ever replaced a t/stat with the engine out, but I don't feel its a difficult job in. Im not sure you need to remove the alternator, but that's a job that gets easier after a few times.

I test the t/stat by hanging onto the top radiator hose from a cold start. When the t/stat opens from a fast idle, you can feel a flow of warm coolant through the hose if its working ok, it takes about 5-10 minutes. But its a definite change of temps and will get warmer.

Hoses should be firm, not rock hard. Rock hard is a often a sign of a head gasket leak.
Pressure in the system stops big steam bubbles forming around the cylinders. Once bubbles form in your cooling system basically throws its hands up and surrenders.
A bad rad cap is often the root cause.

The position of your sensor is right in the cylinder head.
I'm wondering if its giving you the temperature of the combustion chamber rather than the coolant. Temperatures in those areas get a lot hotter than the coolant.
Normally the sensor is on the coolant outlet where the top radiator hose connects to the head.

Did anyone alter your injector pump fuel settings when the turbo went on?
Click to expand...

I see there is a sensor at the top radiator hose... but my aftermarket gauge is definitely using a sensor in the cylinder head... this might explain things..(ie higher readings than would be expected for coolant)...
I suppose this might not be an issue if I can get an understanding of the difference, and relationship between the temps in these two locations?.... i.e. just know and expect to see 10c warmer on my gauge (combustion chamber) than what the coolant actually is...
Would I be able to simple dip say a kitchen thermometer in the top of the radiator (into the coolant) and compare any temp difference??
Turbo was installed by previous owner... but I don't think the pump has been messed with too much...(no smoke... low EGT... low boost... about 8 psi)...
 
dmarsc10 said:
I suppose this might not be an issue if I can get an understanding of the difference, and relationship between the temps in these two locations?.... i.e. just know and expect to see 10c warmer on my gauge (combustion chamber) than what the coolant actually is...
Click to expand...

Yes, as long as you are sure thats the problem

Would I be able to simple dip say a kitchen thermometer in the top of the radiator (into the coolant) and compare any temp difference??
Click to expand...

You'll have to take the radiator cap off under pressure, not my favourite job.
Thats why I suggested the infra red thermometer
 
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