Offroad-Express

Can anyone tell me where the factory water temp gauge gets its readings from? Is it closer to the water entering the engine or exiting the engine? Had some drama today with my truck, one of which was the standard gauge going right up to JUST under H (hot) when the aftermarket gauge was giving me a reading of about 80'c. The aftermarket gauge pulls its reading from a temp sensor/sender in the top radiator hose (so the hot water exiting (or sitting in) the engine). I am not sure whether the aftermarket temp sensor is faulty, the standard sensor is faulty, or they were both accurate (but surely that's impossible?).

Any help much appreciated.

1kz engine?

not 100% sure on factory temp sender location but generally will be engine side of thermostat. of course your aftermarket one is the other side. so you may have a problem with the thermostat or the water level has gotten low which gives a false reading with the aftermarket one.

could be possible that the factory guage is set at 80c being hot, as water starts to boil around or just after this temp.

so to let u know temps can vary between engine and hose. i have a fan controller sensor in rad hose and an aftermarket gauge in alloy neck beside factory sensor.

sensor in hose 3 degrees cooler than gauge - used independant temp sensor to work this out,
gauge temps more stable than hose temp

you might already know this though

Yep i know they'd be hotter in-engine, it's the diff. between the 2 readings that has me worried.

Not sure what the factory gauge is set to? Before I did trans cooler and engine ran at 85'c onroad the standy gauge didn't read hot.

Yep 1kz engine. The water isn't low, it's still full to the brim and bright green. If the standy sensor is thermostat side of the engine wouldn't/shouldn't it give a cooler reading than the other side?

I don't know if I should be trusting what the aftermarket one was telling me or the standard one. Hope not the standard one because then it got hot as hell! Was on the beach in super soft sand. I'd stop as soon as it started creeping passed half (standard gauge) and it'd continue up towards H then drop back to just below half, all in about 3-4mins. Aftermarket one was between 75-80'c during all of this.

Going from this the standy sensor is on oil filter side, so opposite side of thermostat and same side as my aftermarket top-rad hose sensor?
http://www.icecorpproductions.co.nz/per ... df#page284

if the diagnostics plug can give out a reading of temp as i think the 1kz has a temp sensor as well for the ecu this will confirm which gauge is more accurate. but unless you can borrow one from someone you may have to pay a auto sparky to test. factory gauges are unreliable and aftermarket gauges can be good and bad pending on brands too

So it can give a temp reading or you are unsure?

should give a temp reading - but i not to clued on 1kzs. most readers for cars have temp display as ecu relies on water temp for various richness engine running etc

Yea i know the kz uses water temp, fuel temp and air temp so maybe ot would give a water temp reading, but, if the standy sensor is faulty won't the diag plug give a faulty reading too as that is where it will be coming from?

usually dash temp and ecu temp are separate sensors in most cars

bronx89 wrote: if the standy sensor is faulty won't the diag plug give a faulty reading too

No, as the gauge has a separate sender to what the ECU uses

usually the ecu has a temp sensor half way down the block while the gauge temp sensor is by the water outlet.

if the factory gauge is unmodded, by the time it reads hot the head is generally fu**ed.
if its been modded then surf forum has info on where the gauge sits at what temp.

water doesn't boil at 80c, its needs to be well over 100c depending on what pressure its under.

Standard gauge is un-modded. Wen it was getting up to almost H the aftermarket gauge was reading about 80'c.. Doesn't blow any smoke, no blowby, oil is normal colour and not milky, coolant is green. Don't think head is f***ed. Also when the standy gauge was getting up there the coolant overflow wasn't steaming or bubbling over or anything. Everything seemed "normal"... When got off beaxh drove home fine (although no powersteering as a hose burst/split and drained all the PS ATF out, try turning 33x12.5s with no PS! Tis a bitch haha).

fit an aftermarket in the factory sender position. get actual temp readings.

So put a new temp sensor/sender unit in the factory position and wire that to my aftermarket gauge? And flag the standard gauge altogether?

Yea think I'm going to do that actually.

Do you know what thread and size etc. the standard one is so I know what sort to buy to replace it? The sensor I have in the hose adapter at the moment is SHITHOUSE and the rubber seal thing on it is loose and the top portion of it can move in/out about 1mm. Need to find a solid one like in my old Sigma that has no rubber and a spade fitting on the end instead of a threaded stud/nut.

yeah ditch the factory one altogether.
will have to go hunt through catalogs but its probably 10x1mm thread.
edit: might be wrong. hilux 1kz is M16 x 1.5 so you could make an adapter.

Yea. Actually don't know why the f@ck I didn't do that in the first place. I think it was because I couldn't find the darn standard one!

Have just had another look in my 1KZ manual and truck and where it says it is - it isn't.

Can anyone tell me where the standard water temp sensor/sender units are in KZN130 1KZ Surf's?

Much appreciated.

EDIT: Ah just found it; passenger side just under and to the right of where the top radiator hose exits the engine. Man how the hell do you get them in and out!!

Would it really give that much of a different reading from in the top radiator hose? Being that close with no thermostat between them I'm sure the water would be virtually identical in temperature?

EDIT EDIT: Found this: http://seekpart24.com/jakoparts/coolant ... 34&at=3541 does that look right to anyone? Thread Size: M16x1.5

tweake wrote:edit: might be wrong. hilux 1kz is M16 x 1.5 so you could make an adapter.

Wait, so the standard water temp sensor is M16x1.5? What do I need the adapter for? Couldn't I just find a new M16x1.5 spade type water temp sensor and use that hooked up to my aftermarket gauge?

PS did you find that M16x1.5 in one of your catalogs?

bronx89 wrote:

tweake wrote:edit: might be wrong. hilux 1kz is M16 x 1.5 so you could make an adapter.

Wait, so the standard water temp sensor is M16x1.5? What do I need the adapter for? Couldn't I just find a new M16x1.5 spade type water temp sensor and use that hooked up to my aftermarket gauge?
[quote]

No, doing that means the sensor won't be calibrated to the gauge

smurf is onto it. need to use the sender that matches the gauge.
a lot of the aftermarket gauges around use NPT thread which is a special tapered thread. a lot of gauges use 1/8NPT which is about 10mm. hence the use of an adapter.

found the spec in tridon online catalogue BUT it was for hilux. no idea if surf 1kz is the same.

do what i did if there is enough room. i drilled and tapped gauge sensor right beside the factory sensors as there was enough room in the alloy housing.

I tapped an aftermarket sensor into the alloy housing in the top hose to head connection....In my case there was an area with extra meat in it....perfect for a drill and tap

Yep found after posting that the sensor needs to come with the gauge. So going to have to scrap my gauge and get a new one. I think I may go and get the following gauge today, had the mechanical version in my Sigma, from what I remember they come with the adapters so the sensor should fit into the standard hole. Will be interested in what readings i get. Used to get a running temp of 68-70'c, wobbled the shitty sensor last night and cabletied it in harder then when i took it around the block after fixing powersteering I was getting running temp of 85-88'c. Maybe the sensor was giving false readings all along

http://www.supercheapauto.co.nz/online- ... 3681#Cross

What aftermarket gauge do you have now? With all the issues you are having I would fit a decent gauge like VDO not a budget Trisco gauge. At least then you will know you can trust what I says.
I have fitted a VDO with the sender in the top radiator hose housing.

Can't recall the brand. It's not a big-branded gauge I know that though. I can't fathom spending $120+ on a gauge!! Had a Trisco mechanical gauge in my Sigma for years and it never did anything funky, didn't fail me once.

trouble is the big branded gauges are usually more accurate then the cheaper ones hence the above comment

I find that hard to believe unless they are cheap unbranded chinese crap. The majority of the time you'd be paying for the little brand label, not the performance/accuracy. I'm going to go with the elec. Trisco one. At least it's branded, and i've had good experience with the same branded gauge before.

i was talking to one of the automotive gauges repair crowds and they commented that even the cheap autogauge brand has decent electronics in it. just got crap housings.
some of their sensors are top quality and exactly the same as other top brands. some guys where buying the gauges just for the sensor and tossing the gauge. as it was cheaper than buying the brand name replacement sensor.

the only thing i would make sure i got is an alarm output, preferably an adjustable one that you can connect a buzzer to. very easy to go to hot and not see it cause your not looking at it.

tweake wrote:i was talking to one of the automotive gauges repair crowds and they commented that even the cheap autogauge brand has decent electronics in it. just got crap housings.
some of their sensors are top quality and exactly the same as other top brands. some guys where buying the gauges just for the sensor and tossing the gauge. as it was cheaper than buying the brand name replacement sensor.

the only thing i would make sure i got is an alarm output, preferably an adjustable one that you can connect a buzzer to. very easy to go to hot and not see it cause your not looking at it.

Yea agreed.

And yea I just went and got the elec. Trisco one but may take it back and look for one with an alarm/buzzer at a pre-set temp.

With regards to thermostats, a lower rated one (71'c) will not make an engine take longer to overheat when under intense load e.g. soft sand high revs for an extended period of time than a normal rated one (82'c) will it? Or does it help the engine take longer to overheat (or run hot) because it starts the cooling process earlier?

a lower temp thermostat helps because it starts getting rid of the heat earlier. however it also means the engine runs cooler at cruise which is not always a good thing.
tridon do a highflow one for the 1kz. i don't know how it compares to the stock one.