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Installing Coolant Temp Sensor

jjman

By jjman,
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jjman Mentor

jjman

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Hi people,

just about to install the aftermarket coolant temp sensor and gauge.

Just wondering, which radiator hose should i install it in? the top one or the bottom one?

iv got no idea which way the coolant flows in those hoses n am sure it would be important with regards to which hose i put the sensor in...

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jjman Mentor

jjman

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thought so. cheers again peeps.

Also is there any way to ascertain if the thermostat is working right?

my car runs fine and normal and doesnt overheat but i notice if i drive on a really cold night the temp gauge goes back down quite low. (if normal operating temp is the usal dead flat 90degrees of angle on the dash temp gauge, or just below so prob 85 degrees of angle, id say when it is cold it drops down to about 70 degrees of angle)- see diagram

Is this normal or perhaps is my thermostat sticking open and therefore letting too much cold water flow through?

post-68049-0-98179500-1322626132_thumb.jpg

mad082 Grand Master

mad082

Posted
Posted

the stock gauge isn't that accurate. it will sit in the middle of the gauge over about a 15 degree temperature range and won't actually move above the middle until the temp is about to go critical.

if the gauge is dropping below the normal temp when driving then the thermostat isn't closing properly and the temp is probably dropping down to about 60-65 degrees at a guess.

another way to tell if the thermostat isn't operating correctly is by how long it takes to warm up. it should come up to normal operating temp within about 5 mins of setting off (will be longer if you let the car sit and idle up to temp). there is also the chance that the car is fitted with a lower temp thermostat.

jjman Mentor

jjman

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cool. cheers for that.

Perhaps my best line of attck would be install the temp sensor and be able to get a sense of what my temps are actually doing n then act accordingly.

As noted, the stock gauge is a bit of a joke really...

mad082 Grand Master

mad082

Posted
Posted

you could always get a consult cable (or consult display), then you can read the ecu's temp sensor (different one to the dash).

although a new thermostat is probably cheaper than both of them (and not hard to install). you could just buy a new thermostat and put it in. and if it happens to stabilize the temps then you are ahead.

jjman Mentor

jjman

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you could always get a consult cable (or consult display), then you can read the ecu's temp sensor (different one to the dash).

although a new thermostat is probably cheaper than both of them (and not hard to install). you could just buy a new thermostat and put it in. and if it happens to stabilize the temps then you are ahead.

ahhh, this sounds good. I was planning on getting a consult cable and logging software. I didnt realise you could see the coolant temps in digital degrees format though.

back to the issue at hand tho. The readout ill obtain from the consult interface with the OEM temp sensor- how accurate would this be? or is it still a bit ambiguous?

If it is accurate i might just check and monitor it this way and therefore avoid installing the whole aftermarket temp sensor and associated gauges...

jjman Mentor

jjman

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cool. Another query i have (excuse the ignorance) is that if i replace the thermostat does that also include the temp sensor in the 1 unit or is it a different component?

Im just htinking i could replcace the thermostat n still be seeing stange temp behaviour if the sensor is also faulty..?

also how much of a job is it to change the thermostat? do u have to drain the whole cooling system? any gaskets or seals need doing?

mad082 Grand Master

mad082

Posted
Posted

takes about 20 mins to change the thermostat. you do lose a bit of coolant but not that much. it's just 3 bolts to remove the thermostat housing.

the sensors though don't come with the thermostat and i think they are in different locations. from memory the thermostat is in the lower coolant hose and the temp sensors are in the top hose.

jjman Mentor

jjman

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yep its in the lower hose.

Gotta admit thought that all i can see happening when i undo those 3 bolts on the thermostat housing is coolant pissing out of it, and alot of it.

The level of the housing is halfway down my radiatior. So wouldnt half my coolant come pissing out?.

Also how do these thermostats work? Iv got the a replacement OEM one and i can see the spring and mechanism on it but cant move any part of the mechanism by hand (tho im not applying much force as im not sure if trying to move the mechanism by hand is bad for it). How does temperature make the mechanism work? theres no solenoid on it or anything...

cheers

mad082 Grand Master

mad082

Posted
Posted

they work off the properties of metal changing with heat (expanding and contracting). no solenoids or anything like that.

the thermostat should be hard to open by hand, but should be possible. very hard to test them though as they will often open when put in boiling water, but you can't be sure whether they are opening too far or not enough. generally i say when in doubt, replace it.

as for losing the water when pulling off the hose, there is a drain plug in the bottom of the radiator. if you have a bucket or 2 handy and just drain some of the coolant out into that. then when you pull out the thermostat you will lose bugger all coolant.

jjman Mentor

jjman

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they work off the properties of metal changing with heat (expanding and contracting). no solenoids or anything like that.

the thermostat should be hard to open by hand, but should be possible. very hard to test them though as they will often open when put in boiling water, but you can't be sure whether they are opening too far or not enough. generally i say when in doubt, replace it.

as for losing the water when pulling off the hose, there is a drain plug in the bottom of the radiator. if you have a bucket or 2 handy and just drain some of the coolant out into that. then when you pull out the thermostat you will lose bugger all coolant.

cool. replaced it on the weekend. All seems to be working alot better now (warm up and also maintaining temp when driving.)

cheers again for the info mate. You're a champ.

jjman Mentor

jjman

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one final questoin for you. How does this cooling system work vai the thermostat.

by this i mean- after removing the housing it looked like the thermostat appears to completely block the flow of coolant (unless of course it opens.)

is this the case? and if so what is the water pump doing when the thermostat is closed?

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