Water Temp sensor and Fan Sensors

[D2BBA]

Hi peeps,

Following the bursting of a coolant pipe on Saturday im going to fully sort the rest of my cooling system. First things first though, I need to solve a long standing problem:

My water temp gauge doesnt work (nor does the coolant buzzer). This aint a biggy as I have a Greddy gauge and a Commander to watch the temps. Odd thing is my fans dont come on when required either. I use the AC button for low fans and have a simple fan overide for high speed. This flattens the battery when left for a while, so its time for a proper fix!:Hammer

Question really is where are the sensors located? Are they both next to the water pump, behind the SMIC? (green and black conector).

Also wondering if replacing the thermoswitch for an FC one will help whilst im on? I've already done the thermostat. Does the switch help to dictate fan speeds?

Sorry for long post!
Chris :)

[ro284]

Iv'e done that thermoswitch mod Chris, if you search Thermoswitch mod by
ro284 it may help,
cheers Bob

[ianelvar]

There are a few sensors for coolant temp and level. The two on the back of the filler neck ( quite a pain to get to ) are the ECU temp sensor, and fan thermoswitch. The one on the front is the coolant leven sensor. The temp sensor for the gauge is on the left hand side of the block tapped into the rear housing. It's hidden right by the oil presure sensor. Mine didn't work till i fiddled with the white connector between the engine loom and the dash loom, which is hidden right up near the big grommet where the engine loom goes through the bulkhead.

[D2BBA]

Cheers for that fellas!:)

Any idea what I have to strip to get to the back of the coolant neck. I take it the SMIC comes out, which will be removed to access the thermoswitch anyway.

Ta
Chris

[Frankie]

I've also done the FC thermoswitch mod. Its quite tricky to get to. You have to remove the crossover pipe, intercooler pipes and the alternator to get at it.

And you'll need a closed end 17mm spanner to take it out as a socket set will not fit. The space is very limited and the connector and wire will be very brittle.

Pulling the alternator is the most time consuming part and be careful when removing it as there are 2 small oil lines running underneath it.

[D2BBA]

Quick update guys...

Stripped everything down and found that both the ECU temp sensor and thermoswitch on the back of the filler neck are knackered. Sensor on the front is OK but wiring is shot. Im going to check the wiring now following Pip at WGT's advice.

I have new silicone hoses, a set of fans and a temp sensor on the way, however I cant find anywhere that stocks a new thermo switch. Can anyone help? If I ask Mazda im gonna need a part number too!

Ta
Chris

[ianelvar]

I've got a spare filler neck which should have one attached. Want me to look for you?

[nikp]

Actually - i believe the temp sensor that's by the oil pressure sensor is the sensor that's used for the temperature gauge.

The other sensor is used for the turning on of the fans.

[ro284]

Rx motors would have a Thermo Chris, My wiring had also broken down from the Thermo and the fans did not come on all all, untill i rewired the feed from the Thermo direct to the Fan relay (no3 i think)
Bob

[ianelvar]

Actually - i believe the temp sensor that's by the oil pressure sensor is the sensor that's used for the temperature gauge.

The other sensor is used for the turning on of the fans.


Very true, but if the ECU temp sensor is knackered that's not good either.:eek

[nikp]

Very true, but if the ECU temp sensor is knackered that's not good either.

Not at all!

The coolant alarm uses the temp sensor that is by the oil pressure sensor. If that's not plugged in, the alarm goes off. The coolant alarm is basically a metal rod that uses the water to ground itself - so if the alarm never goes off, maybe it's been grounded somewhere. The wire goes directly from the coolant level sensor to a plug that is located near the power steering pump. I have read that's it's meant to be a white plug, but i found mine was in fact black. Not sure if that helps really! :p

[D2BBA]

Think they must all be duff lads. Fans never come on unless i overide them or hit AC. The water gauge and alarm also dont work even when i lost all water!!!

Called RX but only 2nd hand FD switch

[nikp]

Have you checked the fan relays first?

[ro284]

Well it's good to know the fans are working, when you overide the sensor are you connecting the relays direct to a supply or supplying the fans direct to test them? i would have thought a second hand Thermo would be ok, i used a 90 deg one S/H from RX The one i took outwas 106 deg, the wire from that to relay 3 had broken so rewired it, have you got a good earth on the engine?
good luck
Bob

[D2BBA]

Have you checked the fan relays first?

Yeaj, checked relays and they all work ok, must just be ALL the sensors instead! :(

Chris

[D2BBA]

Well it's good to know the fans are working, when you overide the sensor are you connecting the relays direct to a supply or supplying the fans direct to test them? i would have thought a second hand Thermo would be ok, i used a 90 deg one S/H from RX The one i took outwas 106 deg, the wire from that to relay 3 had broken so rewired it, have you got a good earth on the engine?
good luck
Bob

Thanks for that guv, think i'll just run a wire directly to replay number 3, and save having to test along the length of the existing wire!

Will also give RX another call to see if he has a 2nd hand FC thermo in yet.

Ta
Chris

[ro284]

While you are at it Chris you could run a wire to a switch in the cabin, to overide the Thermo in traffic in an emergency, i know you can switch air con on but i think you dont need cold air all the time, then when you get the FC thermo (mine rated at 90 deg. ) the fans actually come on at 100c and cool motor down to 95c and will do that all day, but hopefully the traffic jam will have then cleared! i'm going to Tims this week to collect my mates rebuilt FD, anything i can do?
cheers Bob

[D2BBA]

While you are at it Chris you could run a wire to a switch in the cabin, to overide the Thermo in traffic in an emergency, i know you can switch air con on but i think you dont need cold air all the time, then when you get the FC thermo (mine rated at 90 deg. ) the fans actually come on at 100c and cool motor down to 95c and will do that all day, but hopefully the traffic jam will have then cleared! i'm going to Tims this week to collect my mates rebuilt FD, anything i can do?
cheers Bob


Be great if you could enquire about a thermoswitch for me while your there matey! Probably one of those things that can be better sorted in person rather than by me over the phone!


I'll pay whatever Tim needs, plus postage and a drink for yourself! :)

Regarding the overide to relay 3, I've currently got an overide switch fitted. Was sorted by my local auto electrician, however it must have a bad earth as it drains the battery! Thought it would be just as easy to remove it!

Give me a PM if you need guv!
Chris

[ro284]

Waiting for the call to say 'come and get the car' and i'll ask Tim when we were there, if i can get get one from him i'll PM you then,

Regarding the overide to relay 3, I've currently got an overide switch fitted. Was sorted by my local auto electrician, however it must have a bad earth as it drains the battery! Thought it would be just as easy to remove it!

I think The thermo earths the wire from /to the relay to the engine when it switches on sensing the temperature it's rated at, i wonder if that wire is connected ok to Thermo, but this should only work if the ignition is on, perhaps the fan is wired to be on when the ignition is off, causing the battery to go flat, how long does it take for the battery to drain?
Bob

[D2BBA]

Hi fella,

Only takes a day or two and the battery is gone. Happened over aand over resulting in the need for a new battery. Aint tried with the new one, just disconect the negative at the mo.

Switch only works with ignition on if this helps (or could it be that the fans only come on with ignition???). Always have switch in off position when parked and only use switch when temps rise over what AC switch can handle!

Be great if you could get a thermo for me! May have to ask around if they havent called you by tomorrow afternoon though, as keen to get her back together on the weekend (even if weather is bad!)

Thanks mate :)
Chris

[Rixio]

http://www.mazdarotaryclub.com/forums/showthread.php?p=294499#post294499

Lots of usefull info on here :)

[nikp]

Yeah, but nothing that really covers the electrics of it.

[D2BBA]

Cheers Rixio,

Some good general tips there. :)

Will have to replace all of my std coolant pipes I think. Samco kit only came with two main rad pipes. If you know anyone that can supply the other bits or has the measurements to save me time, then give me a hola!

Chris

[nikp]

These guys don't do kits specifically, but they do stock lots of various silicone hoses. I've used them before, they are good.

http://www.viper-performance.co.uk/

[Rixio]

I bought all original Mazda hoses because they are already pre-bent to fit properly...

[D2BBA]

Cheers lads, will have a look to see which hoses I need and which option will be the best for the cash!

Just the thermoswitch to go and I can start to reassemble No.5!......

[ro284]

Hi Chris, had the call today to pick up my mates FD tomorow afternoon,from RX motors so will try and get a used Thermo off Tim , the one i got from him is 90 deg the one that came off my FD is a 106 deg, i think there is a 95 deg one availiable, not sure which model. if there is any choice at all which would you prefer? if it helps mine switches the fans at 100 deg (on my guage) takes it down to 95 in about a minute!
Bob

[D2BBA]

The lowest temp one available please matey. Mine was a 106 deg one, so anything is better than that! I would even take one of those again of a lower temp one couldnt be found!

Thanks again mate!

Just PM when you can with payment method and i'll get you my address. failing that if you want to call me from Tims im on 07714757481 and I could pay him direct!

Thanks :)

Chris