zombiewolf513

Only 10 degrees difference between inlet and outlet doesnt seem accurate. The cold side of my radiator can be grabbed at operating temp, but the hot side will burn your hand. 100*F IS extremely low for normal driving conditions. But if the sensor is in the lower radiator hose your temp reading is going to be much lower than the upper hose. I suggest the upper hose for a temp reading, so you know the hottest the water is getting, not the coolest.

KiLLeR2001

No. You want the sensor in the lower hose so you know what temperature is entering into the motor. Why would you care about whats coming out of the motor when its going to be getting cooled down by the radiator?

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RalliartRsX

Because you need to know just how the engine is heating up the coolant or just how efficiently the cooling system is working.

Think about it: Placing it in the lower hose will tell you absolutely nothing in regards to how much heat is being transferred into your coolant (essentially). Now, with this, since that figure (heat transfer rate. Probably not very linear), given the boost/power level will be fairly consistent for a given coolant flow, if for whatever reason your outlet coolant temps are high, if you lower the first part of the equation, since its proportional, that means your ending temp will be lower by default.

You have to work on what the engine itself is doing in regards to transferring heat to the coolant as that is the object you are focused on cooling and having inlet temperatures give you no reference on heat transfer rate.

Think about it a again. How do you even know how much the radiator itself is cooling (if its even working) if you have no reference inlet temp (outlet of the engine/upper outlet) to begin with

KiLLeR2001

I don't really have the time to argue for another few pages so I will just lay it out in order of best to worst locations for your temp sensor.

1. OEM temp sensor location, will accurately tell you the temperature going into the engine, regardless of the thermo's current state (open/close).
2. Lower hose, will be a little less accurate, especially if the thermo hasn't opened yet.
3. Upper hose/outlet, by far the least accurate, will make you think your car is overheating when its not. And because of it you will be cooling the car too much.

I use to think the upper hose area would be the best spot for the temp sensor, and then I graduated from high school.

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corby_baby

wrong. upper hose is the proper place.

zombiewolf513

Why do I care if my coolant is 83* C on the cold side if Im boiling it on the hot side because the thermostat is seized?

I'd rather think Im overheating when Im not as opposed to overheating and not knowing it.

Whats up Corby? its white rice

ixfxi

you guys are _fucking_ wrong


first off, i've experimented and have had the sensor mounted in quite possibly, every location known to man. i've had it mounted on the block's coolant passage. i've had it mounted on the outlet after the thermostat. i've had it on the cold side of the radiator.

what you want to monitor is the coolant temp at the head, PRE THERMOSTAT. this means, use the stock location and you'll be just fine.

if for whatever reason that is not an option, the hot side is acceptable. however, it will be dead cold and you wont have any readings until the thermostat opens. the fun thing about this setup is it tells you that your thermostat is working right.

last and worst location is the cold side. your readings will be totally delayed. the values you will get are still usable, but vague. on cold days when the thermostat closes you will have very cold readings.

e1_griego

+1.

Had sensor in all spots, stock location is what I prefer. I figure, if Nissan engineers decided that was the right spot for the stock sender, then that's where I should put my sender. I think I put more faith in Nissan r&d than most people, though.

zombiewolf513

Whats the thread pitch on both sensor ports?

RalliartRsX

+2

I actually data log both ports (upper and stock Nissan location) as Nissan engineers get it right about 99% of the time of anyone else I speak to and the aftermarket .

One thing I did notice however is in the upper radiator hose, the temperature reading in comparison to the ECU was about 10 degrees higher (with a standard deviation of +/- 2 degrees F) than what the ecu was reading from the stock location

TheRealSy90

Ahem, isn't the lower hose PRE themostat? And I want to retain the oem temp gauge so i'd rather not remove the oem temp sensor... I can't see there being much of a difference in temps wether it's in the oem spot, or 8 inches away in the lower hose right before the thermostat housing...

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RalliartRsX

I will just leave this image here. If you look at the coolant track (and I am thinking about this right), the coolant the temp sensor seas should be the same (or close) by the thermostat as it is by the upper outlet?? I am assuming the two nipples at top are coolant sensor port for both ECU and gauge cluster

ixfxi

thank you - you ask me, excellent, excellent question. you are one of the all intelligent users on zilvia

it depends on which motor we're talking about. thermostats simply control the flow and can be installed on either the cold side or hot side. whats important is that the thermostat is in the engine coolant stream. this way it actuates accurately based on coolant temp.

the way i did it on my sr20det is that i trashed the oem sending unit and installed my vdo sender there. you can either re-thread the port or in my case, re-thread the sending unit and use a crush washer. remember, the oem sending unit and gauge are totally inaccurate. scan tools, FC commander, etc.. get their readings from the ECU temp sending unit (3 wire sensor) that is mounted directly next to the gauge sending unit.



^ m10x1.0 - gauge sending unit



^ m12x1.5 - ecu sending unit

i'm going by memory here, so dont hold me to these measurements

KiLLeR2001

Coolant temp sensor on the KA/SR is definitely two wire. I think the unit itself is grounded and the two wires coming out of the sensor are power and signal. The temperature switch for the gauge cluster is one wire.

Let's not forget that from the factory cars with A/C have a temperature sensor in the lower hose.

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RalliartRsX

So I was under that same impression for a while, but this is somewhat inaccurate (escuse the pun). It's not that they are inaccurate, the range of motion of the stock cluster sending unit is not entirely linear. So, it will mostly show in the "middle" for a temp range of say 180-220. Outside of that range, the range of motion is different.

A friend of mine did this test recently (probes in both upper/lower hose as well as stock probe) and the temp gauge itself was shown to be fairly accurate in it's calibrated range. Now, is this range useful for a non-stock engine?? That is left up to interpretation

RalliartRsX

And this right here proves nothing about location........

I refuse to follow the advice of someone who ends a debate with ".......and then I graduated high school", especially with widely general and blanket opinions and statements throughout your argument.........

KiLLeR2001

Very well, but I refuse to follow the advice of someone who's online forum name is the combination of a shitty car company's performance division and a Honda chick car, the Acura RSX.

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RalliartRsX

Incorrect on both fronts..........

Back on topic:
I am not saying I am right. But please prove me wrong. I also posted the coolant flow path which explains what flow path of coolant behind the thermostat, upper/lower inlet, etc is. If you want to have a discussion, can you tell me if the two "nipples" in my picture from the FSM are for temp probes? If so, then, as my assumption, the temp behind the thermostat is the same that is exiting the head (read: upper radiator hose or close to the temp of the coolant temp exit on the upper hose), which in turn, means your lower hose placement of the probe is incorrect as the temp pre thermostat (lower hose) would be different as temp post thermostat (exit of head).

Meaning: your probe location would be incorrect........But again, prove me wrong as I am trying to convery correct information here and not just throwing around blanket statements

KiLLeR2001

The picture you posted doesn't work, so start off by fixing that.

I am simply going off the fact of OEM locations where temperature is read.

Coolant temp sensor and temperature switch are in the waterneck after thermostat.

A/C temp sensor is in the lower hose.

There is no temp sensor in the outlet / upper hose. And I don't know of any make/model that takes a temperature reading coming out of the outlet for the main ECU temperature sensor (most accurate temps) from the factory. Not saying they don't exist, but I don't know of one.

I swear this argument is like the goddamn cold vs hot side BOV location.

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RalliartRsX

What I am saying is, go look up the FSM and the coolant track (the picture is directly from there). If you are assuming directly behind the thermostat is what is leaving the radiatoras opposed to what is leaving the head, then there is an issue.

Just go look up the FSM and come back to me as unless you have the correct flow path, you have no idea what is directly behind the thermostat..........

The image has been redirected to below. Look at the FSM image below and tell me what flow path is right behind the thermostat?? Also, are the two "prings" above the thermostat the temp probes?? Because if so, that shows its the coolant leaving the head the probes are measuring.......

KiLLeR2001

I guess the only thing left to do is put a temperature sensor in the inlet and put one in the outlet. If the temperatures read the same, then you would be correct. If they are any different, even 1 degree, you are wrong. Confident enough to conduct this experiment? Willing to move your ECU temp sensor from the stock location to the outlet and see how differently your car runs?

Sorry buddy, but there are a lot more factors involved than just flow pattern.

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RalliartRsX

Sorry, I must have edited when you posted.

And my question regarding the two "prongs" in the picture?? If those two elements are indeed probes, then they are reading outlet temps.

unijabnx2000

x2 only OEM

zombiewolf513

If that's accurate, there would be no difference between having the sensor in the stock location and in the outlet.

RalliartRsX

Thank you zombie. I would personally follow the FSM as compared to following "opinion". Now, this is assuming the FSM "prongs" are indeed probes (which I am 90% sure they are).

ixfxi

calm down killer, thats not a temp sensor - thats a thermoswitch.

the thing you guys are missing is: what coolant flow is effecting the thermostat?
answer: the coolant that flows through the head and block.

this is the coolant that you want to monitor when it comes to temperature. this is where the stock sensors are located, regardless if they are 1 wire, 2 wire or 3 wire, etc... all the sensors are located there.

as for the OEM gauge, they serve little to no purpose as they do not have markings and cannot provide accurate readings. you're better off acquiring your readings from an obd2 port or via fc commander, etc... OR, a proper coolant temp gauge that reads from the stock location.


killer, the only purpose to mounting a sensor on the hot pipe or cold pipe (to and from the radiator) would be to monitor the radiator's performance. i've already done both and can tell you that the reading from the cold side is the least accurate. the reading from the hot side is better. but the best sensor location should be in the coolant flow path (block or head) behind the thermostat.

TheRealSy90

Hmm, I wonder if either my autometer temp sensor or my Defi temp sensor will thread into the oem gauge sensor location? It's just going to bug the shit out of me having the factory guage not doing anything regardless if it's accurate or not...

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ixfxi

sometimes the resistance value of the aftermarket sending unit will crossover and give the OE gauge a usable value so that it works like stock

basically, worse comes to worse - install the aftermarket sending unit in the stock location. install the stock sending unit somewhere else where accuracy is not a concern.

TheRealSy90

But there isn't anywhere else to put a temp sensor according to this thread lol.

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ixfxi

of course there is. the debate we were all having solely had to do with one thing: accuracy

when used with the stock gauge, the oem sending unit is not accurate - so its not as critical. simply install it on the hot side (upper hose) and be done with.

come on man, gotta use your noggin