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Hi everyone, was hoping someone could help with a problem my r33 gtst has developed. When driving the car above 40mph the water temp needle starts dropping slightly just below the middle level and would stay there untill idle. 

When the car is idle the needle is near enough to the middle. When it's cold weather the needle will once again stay below the middle level.

Could this be the thermostat? How do I check it? 

Any help is appreciated. Thanks 

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https://www.sau.com.au/forums/topic/482047-r33-water-temp-low/
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in any reasonably modern car, the temperature gauge does not actually show you a straight indication of the coolant temp. They have been setup so they show cold over on the left, "normal" about 80-110o will be in the middle, and then it will suddenly shoot up over say 110.  Any variation you are noticing is not an indication of an actual problem.

If you want to actually monitor the coolant temp you need to either read the ECU data eg via a consult compatible display, or add a separate coolant temp gauge.

While true that the coolant temperature gauge is "dumb" and won't show proper coolant temperatures, if you actually notice it dipping more than parallax error would allow then it's very likely that there is a problem. Get a Consult cable and Nissan Datascan and run some logs to see what the coolant temps actually are in those cases. If it's dropping below 80C first step is to replace the thermostat.

I would probably want to be sure of the issue before actually replacing the thermostat, from what I can tell it's a real pain in the neck to replace.

Edited by joshuaho96
On 27/02/2021 at 6:39 AM, Duncan said:

in any reasonably modern car, the temperature gauge does not actually show you a straight indication of the coolant temp. They have been setup so they show cold over on the left, "normal" about 80-110o will be in the middle, and then it will suddenly shoot up over say 110.  Any variation you are noticing is not an indication of an actual problem.

If you want to actually monitor the coolant temp you need to either read the ECU data eg via a consult compatible display, or add a separate coolant temp gauge.

Thanks for the reply. It has always been dead in the middle. Just recently started dropping towards the cold side when I drive fast over 40mph. When at idle it will come back up to almost the middle. I will get a proper water temp gauge and see what that reads. 

On 27/02/2021 at 8:00 AM, joshuaho96 said:

While true that the coolant temperature gauge is "dumb" and won't show proper coolant temperatures, if you actually notice it dipping more than parallax error would allow then it's very likely that there is a problem. Get a Consult cable and Nissan Datascan and run some logs to see what the coolant temps actually are in those cases. If it's dropping below 80C first step is to replace the thermostat.

I would probably want to be sure of the issue before actually replacing the thermostat, from what I can tell it's a real pain in the neck to replace.

Thanks for the reply. I will get it checked out before I replace the thermostat 

7 hours ago, DaymoR32 said:

if you are talking in mph im assuming you are british or american? 

Whats the ambient temperature wherever you are at the moment?

 

 

Thanks for the reply. It's winter here the temperature dropped to - 3c couple weeks ago. Now it's been around 5 to 7c. Could that be the reason? Could the air intake be sucking in cold air and cooling the engine? I do have an hks mushroom intake without any sort of box around it. 

On 2/28/2021 at 11:09 PM, 020king said:

Thanks for the reply. It's winter here the temperature dropped to - 3c couple weeks ago. Now it's been around 5 to 7c. Could that be the reason? Could the air intake be sucking in cold air and cooling the engine? I do have an hks mushroom intake without any sort of box around it. 

As others have said replace the HKS trash pods before the foam disintegrates and gets sucked into the turbos, they suck at filtering too which can cause engine wear over time, you'll see more silica content in the oil as a result. That has nothing to do with the coolant temperatures though. If you're driving -3C conditions then it's hard to say, especially if you're running a low temp thermostat and the heater. 5-7C you shouldn't see the engine dropping below thermostat crack temp in normal operating conditions.

On 04/03/2021 at 2:27 AM, joshuaho96 said:

As others have said replace the HKS trash pods before the foam disintegrates and gets sucked into the turbos, they suck at filtering too which can cause engine wear over time, you'll see more silica content in the oil as a result. That has nothing to do with the coolant temperatures though. If you're driving -3C conditions then it's hard to say, especially if you're running a low temp thermostat and the heater. 5-7C you shouldn't see the engine dropping below thermostat crack temp in normal operating conditions.

Why do soo many people hate on the hks mushroom intake? I understand in hot temps it ain't gonna be good but here in uk we rarely get hot summers and if at most 2 months of summer. 

 

I also hardly drive the car it's a weekend toy have put 1k miles on in 1 year. I get that the mushroom filter can disintegrate but surely if you change it every year it shouldn't? 

But Yh il look to see if it drops any further /gets worse, then start looking at replacing thermostat 

1 hour ago, 020king said:

Why do soo many people hate on the hks mushroom intake? I understand in hot temps it ain't gonna be good but here in uk we rarely get hot summers and if at most 2 months of summer. 

 

I also hardly drive the car it's a weekend toy have put 1k miles on in 1 year. I get that the mushroom filter can disintegrate but surely if you change it every year it shouldn't? 

But Yh il look to see if it drops any further /gets worse, then start looking at replacing thermostat 

Look, your reasoning is just stupid on your coolant temp theory. You may or may not have a problem, but as Duncan mentioned earlier you've got no idea what your actual water temp is as your going purely by the gauge on the cluster.

That means jack shit.

"Normally" warmed up at anywhere between 70 - 90c the gauge will point slightly below horizontal - IF your gauge sender is correct. Yours probably isn't. Replace it for a start as they are not expensive.

There is a coolant sensor for the gauge and and one for the ecu. You need to see what your ecu sensor is actually reading.

For example, my 32 gauge cluster indicates a bit high when warm, pointing above the horizontal. I know it's not hot as indicated by the cluster as the engine ECU sensor as read by the Haltech will be reading fine at 80c. FYI stock thermostat opens at 78c.

This is basically the same principle for the oil pressure cluster, it's hardly accurate and you need a REAL oil pressure sensor as there is no ecu oil pressure sensor standard, just a gauge cluster one.

You need real sensors with a real way to be able to measure them.

And yes the HKS filter is garbage as mentioned.

10 hours ago, 020king said:

Why do soo many people hate on the hks mushroom intake? I understand in hot temps it ain't gonna be good but here in uk we rarely get hot summers and if at most 2 months of summer. 

 

I also hardly drive the car it's a weekend toy have put 1k miles on in 1 year. I get that the mushroom filter can disintegrate but surely if you change it every year it shouldn't? 

But Yh il look to see if it drops any further /gets worse, then start looking at replacing thermostat 

http://mkiv.com/techarticles/filters_test/2/index.htmlbkbk

I also recall reading a report in which poor air filtration caused damage to hot film MAF sensors like those used by the R35 will cause the surface of the film to become pitted and damaged. It's also generally well accepted that the silt taken in by the engine will also get into the oil as elevated silica content. I don't recommend anything other than dry paper filters as a result.

The stock airbox is really not as bad as people claim it to be, people insist on changing what isn't broken though.

15 hours ago, BK said:

Look, your reasoning is just stupid on your coolant temp theory. You may or may not have a problem, but as Duncan mentioned earlier you've got no idea what your actual water temp is as your going purely by the gauge on the cluster.

That means jack shit.

"Normally" warmed up at anywhere between 70 - 90c the gauge will point slightly below horizontal - IF your gauge sender is correct. Yours probably isn't. Replace it for a start as they are not expensive.

There is a coolant sensor for the gauge and and one for the ecu. You need to see what your ecu sensor is actually reading.

For example, my 32 gauge cluster indicates a bit high when warm, pointing above the horizontal. I know it's not hot as indicated by the cluster as the engine ECU sensor as read by the Haltech will be reading fine at 80c. FYI stock thermostat opens at 78c.

This is basically the same principle for the oil pressure cluster, it's hardly accurate and you need a REAL oil pressure sensor as there is no ecu oil pressure sensor standard, just a gauge cluster one.

You need real sensors with a real way to be able to measure them.

And yes the HKS filter is garbage as mentioned.

Thanks for your input. Any recommendations for aftermarket water temp gauges? 

6 hours ago, joshuaho96 said:

http://mkiv.com/techarticles/filters_test/2/index.htmlbkbk

I also recall reading a report in which poor air filtration caused damage to hot film MAF sensors like those used by the R35 will cause the surface of the film to become pitted and damaged. It's also generally well accepted that the silt taken in by the engine will also get into the oil as elevated silica content. I don't recommend anything other than dry paper filters as a result.

The stock airbox is really not as bad as people claim it to be, people insist on changing what isn't broken though.

Thanks nice good bit of info to know 

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