2 core versus 3 core radiators

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Originally Posted by Hodge

Mine is identical. Once it hits half way it does not move no matter what. Although once warm, I have NEVER seen my coolant temps go out of 86-91 range. I am reading that from my scangauge. How accurate would that be Evil??? I have really pushed the car a few times and highest ive ever seen was 91C.

Edit: BA probably hates me for hijacking the thread again :P

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I dont hate.... it is a such a strong word.

And no Eric no problem I welcome all the discussion as this is a topic that has many misunderstandings and so much to learn from others, its also the time of year to nut this sort of stuff out.

time to nut this stuff out was last winter before the temps rise, weather wise

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Originally Posted by threedogs

time to nut this stuff out was last winter before the temps rise, weather wise

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Hindsight hey John........

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Originally Posted by nissannewby

Due to a diesels nature (compression ignition) if the engine is not at the right temp the combustion is harder to achieve and you can end up with something called diesel knock.

Have you never heard a diesel start when it's dead cold?

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While testing that piston slap seems to go away with oil pressure after start up. Because td42's are simple mechanical injected they don't compensate by adding more fuel with lower water temps to warm the motor up quicker. You can see how sensitive they are when you block the egr which is used to help atomise fuel with heat in that on the td you won't get a flat spot during warm up unlike a petrol motor

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Originally Posted by Bloodyaussie

They sound awesome...... bit like me when I wake nowadays!!!

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Never heard a diesel moan and windge before......

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Originally Posted by the evil twin

Uuummmm... yes and no.
I agree with the delta T across the thermo but not how it works

Thermo's aren't an open and shut device, they are dynamic.
That means they will begin to open at 'x' temp and be fully open at 'y' temp.
Traditional engine thermos are wax pellet versus spring but bi-metallic is slowly becoming in vogue

Using hypothetical numbers and ignoring bypass circuits for ease of explanation.
At 85 degress my hypothetical thermo begins to open and pass coolant with a much lower temp from the Radiator to flow thru the engine
The thermo will settle at a percentage open, lets say 10%, where the coolant takes on heat energy from the engine and circulates thru the Radiator and has a temp of say 90 degrees.

Once the engine load starts to get significantly higher the coolant exiting the engine rises to, say, 95 degrees the thermo will open a tad more.
Lets say it now finds equilibrium at 50% open and 95 degrees.
The thermo cannot start to close as the heat is holding it open against it's mechanical pressure trying to move it closed.

The only thing that will move the thermo either further open is a further increase in engine load and thus coolant temp or towards close is a drop in engine load and the thermo mechanical pressure overcomes the expansion and begins to close.

If the thermo gets fully open, lets say 105, there can be no increase in coolant flow and any more load will cause the engine to overheat.

It is precisely for the above reasons that virtually all vehicle manufacturers use non linear temp gauges without a numbered scale.
This is actually quite a good idea because the temp of coolant exiting a vehicle engine is never constant but if it is within the 'normal' range then who really cares.

As an example my CRD dash temp had no discernible movement from it's "happy spot" just under 1/2 of scale if the engine sensor was between 80 ish degrees and 100 degrees.
From 100 to 106 it would move towards the upper limit mark.

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On the bench uts a bit different coz you will notice that a 82*c thermostat will start opening roughly at 65-70*c and fully open by 80-83*c. I'm going to go thru basic operation of the thermostat but as one side heats ups (usually the bottom) the spring softens and looses its tention To allow water to pass thru usually at a lower temp which will cool the spring and its tention close the thermostat till it equals all if the cooling system.

On my 4.5 the gauge will show NOT from 64*c-96*c and will creep up at a higher temp.

The zd has more electronics to run more efficiently alot like carby vs efi so it will be significantly affected by water temp coz of the coolant temp sensor adding and decreasing fuel with different temperatures

intresting read, currently looking into rad options for my tb42e turbo, not so much overheating but rad is of an unknown age (at least 7 years) and plan is to up the boost early this year so will need more capacity to keep it cool

Even with the "simple" td42 there are things that are in place for when it's cold. Things like glow plugs help when cold and more often than not they actually operate until a certain operating temperature is met. Temperature on a diesel does affect it, no doubt of that at all. Not to mention like any other engine design it is meant to operate at certain tolerances in a certain temperature range for least amount of wear and efficiency, this engineering side of applies both to petrol and Diesel engine design.

Sorry George but your a little out of your depth with the understanding of the diesel. Please just comment on what you know instead of guessing.

I'm not trying to discredit you as you do have quite a bit of knowledge.

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Originally Posted by nissannewby

Even with the "simple" td42 there are things that are in place for when it's cold. Things like glow plugs help when cold and more often than not they actually operate until a certain operating temperature is met. Temperature on a diesel does affect it, no doubt of that at all. Not to mention like any other engine design it is meant to operate at certain tolerances in a certain temperature range for least amount of wear and efficiency, this engineering side of applies both to petrol and Diesel engine design.

Sorry George but your a little out of your depth with the understanding of the diesel. Please just comment on what you know instead of guessing.

I'm not trying to discredit you as you do have quite a bit of knowledge.

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Why would you say I'm guessing then??? Doesn't make sense??

You're right I don't know much about diesels but what I do know is we're talking radiators and cooling systems, yes it affects the lubrication system and the viscosity of oil but unlike petrol like I said before doesn't use water temp for the fuel system. Water does not flow thru the injector pump to heat tje fuel and the glow plugs heat the air inside the combustion chamber not the fuel or water. Gq td42s don't have an ecu so why do they have a coolant temp sensor?? That would be for the glow plug relay which is on a timer from what I have seen while testing and as far as I could see when that coolant temp sensor got to a certain resistance the glow plugs wont get power. Now correct me if I'm wrong but if a diesel was affected by water temp like a petrol it would have a ecu to control the fuel delivery to aid in not only performance but also in speeding up the time it takes to get to NOT ?? From what I can see the leter model stuff does, like a petrol you richen up the a/f mix to raise combustion temps, to heat the coolant faster, to get to NOT quicker, to run more efficiently to use less fuel not to mention lessen wear and tear.

So now after this little lovers tiff what have I guessed? ? I'm curious and would like to know ?? I don't like being wrong and if you knew me well you would know I wouldn't speak if I was

not wanting to "buy" into the above comments, but I am thinking (and am very likely wrong........ almost always am.........)

is there a different temp setting for the Petrol thermostat V's the Diesel one?

wouldn't the petrol one open quicker than the diesel one?
or
atleast regulate the water flow differently?

I'm curious.......

my TD42 is getting hot when towing my van........ so I am watching this for some insight to help me........

I just purchased thermostats for my petrol and diesel and they sold me the same one for both 4.2 engines. Haven't checked if they fit yet.

My TD42 just spent every hill from VIC to coffs sitting on 3/4 temp (bout where the fan kicks in)
And EGT's of 500/550 so I will be seriously looking into the 3 core rad next time , never got the car this hot in the Simpson and Kimberly .

I did remove and clean radiator before trip and it was covered with mud just from the 2 trips to matts so I don't see mud clogging a 3 core as any more of a problem

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Originally Posted by Bigcol

not wanting to "buy" into the above comments, but I am thinking (and am very likely wrong........ almost always am.........)

is there a different temp setting for the Petrol thermostat V's the Diesel one?

wouldn't the petrol one open quicker than the diesel one?
or
atleast regulate the water flow differently?

I'm curious.......

my TD42 is getting hot when towing my van........ so I am watching this for some insight to help me........

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Originally Posted by liftlid

I just purchased thermostats for my petrol and diesel and they sold me the same one for both 4.2 engines. Haven't checked if they fit yet.

My TD42 just spent every hill from VIC to coffs sitting on 3/4 temp (bout where the fan kicks in)
And EGT's of 500/550 so I will be seriously looking into the 3 core rad next time , never got the car this hot in the Simpson and Kimberly .

I did remove and clean radiator before trip and it was covered with mud just from the 2 trips to matts so I don't see mud clogging a 3 core as any more of a problem

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This is for both, what gauge are you going by the factory gauge or and aftermarket one ?? If the its in good condition have you had the radiator tanks removed and the core cleaned out internally to see if the tubes are blocked??