Aluminum Radiator D22 ZD 30

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Been a while

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Howdy all, I had a high temp issue that turned out to be a cracked overflow pipe! Yup! That little bit of plastic on the filler cap that connects the overflow tank.. Didn't realise untill it was hanging off in my face mind you..
So, replaced the radiator with a flea bay alloy one to fix the issue. Job done, yup, definitely fixed the issue and the gauge shows 1/4 and not sitting at a 1/3 where she sat normally .. nice...

I do an hour trip and stop to check works and notice the lower hose is still cold, yes cold! Oook, out with the old thermostat and back in with the original Nissan one, no change! On the gauge or the lower pipe... Hmm got me...

Anyway, to be on the safe side I brought a new thermostat and fluids for her and are in the process of doing a coolant flush.. just thought I'd post a pick of the difference in makes of thermostats..

The one on the left is the original and the one on the right is the new "high flow" one... The Nissan one is twice the weight! It's a heavy made thing and I'm wondering if the lighter spring in the new one may get the water circulating ... well, I'll find out eh
That's all I can do for her, radiator, water pump, thermo, flush and the blue coolant and we'll see I guess...

Also, I cut the core out from an old thermostat to do the flush and went for a drive to get things warm/hot and the water temp gauge didnt move...
It got hot'ish but not what You'd say running temp, a good 20 min drive with an "on off" at the supermarket and nothing!

Do people not run thermostats in these ZD's? I mean can you not?
 

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Horatius

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The factory thermostats on these start opening around 82-84C and are fully open (10mm) somewhere around 95 C if I've read the manual correctly. I can drive for a while before it get's to that temperature, on a cool night chugging along at 80kph on flattish roads it'll never get there (will stay 70-75C). It might be hotter at the thermostat itself, but not much I wouldn't think.

I have one of those thermocouples that measures the temperature of the motor itself, had a water temperature gauge as well for a while (they read almost exactly the same) . If I'm travelling long stretches down mountains it'll often drop and stay in the 60's. So with no thermostat your gauge not moving with a quick trip to the shops would be normal.

The factory gauge is somewhat useless anyway. Mine shows that it's up to full temperature at around 44C and then it just stays there, at 100C it's exactly the same.

I wouldn't worry too much about the temp of the hoses, you might be second guessing yourself there. I just take it for a couple of short runs, top up, then go for longer run or two and top up if necessary until I'm confident it's full.
 

Horatius

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ps. Had the wrong engine re thermostat. Manual for zd30 says 82 C opening temp, and at 95 C will be open by more than 10mm. Which I'm guessing is fully open.
 

Horatius

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pps. If the car isn't overheating, the coolant level is full and the thermostat is in properly (not sure if you can put them in backwards, think they only fit one way), why worry about it?

Thinking the car is up to a temp where the thermostat should be open can't really be done from the factory gauge. Like I say, that gauge reads normal anywhere from mid 40's to about 110-120 (think coolant under pressure boils about 130).

The genuine thermostat is probably the better one. Good quality.
 
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Erick

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U may think ur doing ur engine a favour by running colder or no thermostat but believe me ur not. Most engines these days have cold start enrichment until temp gets to around 60 degrees in some cases. And ur engine tolerances are set up for normal running temps. And a bottom hose being not very hot is ok as thermostat reads temp at exit of engine and let’s just enough coolant past to keep that. So coolant going in can be quite cool The test is to leave it idling standing still with no air going thru radiator by blocking air flow or disabling any fans and see if bottom hose heats up. Should only take a couple minutes.
 

Horatius

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Generally your wasting your time idling the car up to temp (on the gauge) and expecting the thermostat to open and get any significant water flowing through it. You'll grow old waiting for that to happen unless it's an exceptionally warm day (and probably even if it is).

Only real way to check a thermostat is to take it out and heat it up in water. If you want to check the upper/lower pipes, a good run on the freeway will make sure it opens (unless it stuffed then you'll overheat lol). The faster these cars are driven the higher the temperature they run at.

Agree that they're designed to run roughly around 76-95 C (range of thermostat, once open it closes again mid 70's C), read once from someone who reckoned they had design experience with these small diesels (yeah, who knows lol) that tolerances are worked out at a temp around 85-90C.
 

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U may think ur doing ur engine a favour by running colder or no thermostat but believe me ur not. Most engines these days have cold start enrichment until temp gets to around 60 degrees in some cases. And ur engine tolerances are set up for normal running temps. And a bottom hose being not very hot is ok as thermostat reads temp at exit of engine and let’s just enough coolant past to keep that. So coolant going in can be quite cool The test is to leave it idling standing still with no air going thru radiator by blocking air flow or disabling any fans and see if bottom hose heats up. Should only take a couple minutes.
Ahhhh the warm up/ start up did cross my mind regarding thermostat removal.. just curious...
 

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Ok, well we flushed and we replaced and what i did notice is that the original nissan one ran cooler... noticed it more so after fitting the new Trident super flow one yeaterday...

Yeahhhh I'll be putting in a new genuine one in for sure...
 

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I have a 2003 D22 ZD30- it overheated . Thermostat was fouling when opening. Replaced thermostat with genuine Nissan part thermostat. Also replaced radiator -no issues since . I did think about removing guts of thermostat ( leaving body to act as a bit of back pressure ) but was persuaded otherwise; from performance I think correct decision.
 

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I have a 2003 D22 ZD30- it overheated . Thermostat was fouling when opening. Replaced thermostat with genuine Nissan part thermostat. Also replaced radiator -no issues since . I did think about removing guts of thermostat ( leaving body to act as a bit of back pressure ) but was persuaded otherwise; from performance I think correct decision.
Ahhh good to know bloke..I just noticed that wear mark and after reading your post, I think we might have it ;) thanks...

I have a Nissan one coming, now I've just have to catch $70 worth of new blue coolant to replace it ... dangit!

I was amazed on how cold she ran with out the thermostat in! And I mean cold, the heater was juuuust warm, and for my heater that's saying something... I can cook on my heater vents lol seriously I could cook an egg ;) I've burnt my hand from the dash vent heating him that little steel clip on the back of the c.b Mic! True story!
 

Erick

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Yes. These things are one of the few vehicles I’ve ever owned with excess-if that’s the right word-cooling capacity
 

Jimjet61

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Sometimes an excess of cooling and a stuck open thermostat can cause overheating. I used to fix large tractors, that do all their work at low speeds so have huge radiators and fans, often when a farmer complained of overheating I would find the thermostat stuck open, this seemed counterintuitive, but the high flow through the radiator didn't allow sufficient time for the heat exchange to occur efficiently. Cooling system is also a bad name as it is a temperature control system, as stated in some other comments, engines run most efficiently at a set temperature, with engine tolerances engineered to work at that temperature, air cooled engines run bigger tolerances because of the wider temperature ranges they operate at but are not as efficient as liquid cooled ones.
 

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Sometimes an excess of cooling and a stuck open thermostat can cause overheating. I used to fix large tractors, that do all their work at low speeds so have huge radiators and fans, often when a farmer complained of overheating I would find the thermostat stuck open, this seemed counterintuitive, but the high flow through the radiator didn't allow sufficient time for the heat exchange to occur efficiently. Cooling system is also a bad name as it is a temperature control system, as stated in some other comments, engines run most efficiently at a set temperature, with engine tolerances engineered to work at that temperature, air cooled engines run bigger tolerances because of the wider temperature ranges they operate at but are not as efficient as liquid cooled ones.
Thanks man, I'm slowly working it out! I've also read that going from 2 core to 3 can cause issues with the ZD- any thoughts?

The Nissan thermo arrived and there is slight differences in the two Genuine Nissan ones... look on :)

Notice the codes stamped into the two?? Same temps... mine is an 03,,,, and the one that came out of it is stamped 03 2, 2003 Feb?? You think?
Got me..
Shes in now and that just leaves the cap if there is a problem. It will be interesting to see where the dash gauge sits now.

Weird, with the new radiator in and the aftermarket thermostat in, the gauge sat where she always had. I took that one out to check what the temp rating was and thought whilst it's out I'll try the old genuine one... It noticeably dropped it down, so for peace of mind I went a new genuine one...
The new one is definitely heavier and beefier than the aftermarket one but still not as heavy as the original one that came out of it .. Patrol one maybe???

Some pics
 

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Ok, no different with the new genuine thermostat compaired with the aftermarket one, both sit at the same spot on the gauge.. The genuine old one must have been faulty to a degree..




And noooooo, CRC didn't help it :)
 

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Yes. These things are one of the few vehicles I’ve ever owned with excess-if that’s the right word-cooling capacity
And they're a weird set up with the thermostat positioning ... I'll be chasing up a new genuine cap for the radiator too, and that's about all I can do for it...
 

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