hi.
could someone please tell me where the engine coolant temp sensor is located on my 2002 tj magna wagon 3.5lt. i think i need to replace it. i have changed the radiator flushed and "burped" it replaced 1 of the fans that was'nt working bought new relays and new thermostat. have no leaks, coolant level is not decreasing and oil is the colour its meant to be yet it is still overheating so im thinking it may be time to replace the engine coolant sensor...now if i only knew where it is...

thanks for any help and advise greatly appreciated

Maybe check the thermostat....Front passenger side near battery for sender

thanks... have put a new thermostat in it.. thats why im thinking the sensor might be buggered.

If you are loosing water and its not leaking or going into the Oil there is only two other options. Its pushing it out the overflow when driving or its going out the exhaust. Over flow one is easy to test, get a 600ml coke bottle and mount on under the end of the overflow hose so it catches anything that comes out of the hose and you will quickly see if it.. The other is damage to the head gasket between water and cylinders so water is just slowly going into the engine and been burnt off. You can sometime get symptoms like rough idle or an extra engine rotation or so before it fires on start up if water is in the cylinders.. How much water are you loosing over what time...????

hi
it's not losing any water.

If you're not losing coolant and your radiator cap is serviceable and of the correct rating I assume you are relying on the temperature gauge to know that the engine's overheating. If this is the case can you describe what the gauge is showing, ie. does it start at cold and rise steadily all the way to hot, or does it usually sit somewhere in the middle and only rises when you rev the engine (or the other way around)?

EDIT: There are two sensors, one for the gauge and one for the ECU, both are under the air intake at the passenger side of the engine.

no coolant loss..rad cap is new..yes relying on temp guage. when in driveway and let it idle for a while it rises to halfway then when drive even 500mtrs it rises steadily up to the hot end of guage. when pull up and open bonnet dont hear any bubbling or boiling noise and theres no steam.

So I assume you've put the correct quantity of coolant mix in.
I suspect the temperature sender as well, but I wanted to add another possibilty; collapsing hose.
Collapsed hose will block coolant flow too. Worth checking them, maybe when hot feel how soft/firm they are (with a cloth, they're hot obviously). (Top and bottom).

Test to perform: run it in idle in the driveway and let it get up to temp (ie. one of the fans comes on). If the temperature is maintained at about 50% on the needle with the rad fan switching on and off there's nothing wrong with the gauge sender unit.

i bought and changed both hoses..they arent collapsing.

with it up to temp and the fan coming on it still went up to hot.. the motor didnt seem to have a great deal of heat coming off it could hold hand on motor for a few seconds without burning.

Probably either gauge or sender unit then, I'm guessing. I've not heard of either failing before but others may have. It's probably worth getting it checked out professionally just to make sure it isn't actually overheating, but if the cap is the right type and it's not releasing coolant into the overflow bottle that's pretty good evidence for the coolant temperature being within spec.

thank you for your help. ill change the sender unit over the next couple of days and if that dont work i think it will be a trip to the shop..

hi
it's not losing any water.

Sorry my bad.. Though you said Coolant level is decreasing, you said coolant level is not decreasing..:)

well have tried just about everything i can think of to fix overheating problem and nothing has fixed it..done radiator, hoses, clamps,thermostat,new fan,and sender unit still overheating any other ideas before it goes to the shop? trying to fix myself as can't really afford to take it to shop.

thanks

The temperature sensor is a variable resistor. It is placed in a circuit with the gauge. As the temperature increases, the resistance drops, allowing more current to flow through the temperature gauge to the engine and then to earth. You can disconnect the gauge and check its resistance with a multimeter. I don't have the resistance/temperature values for your car but a typical value (Pajero) is 104 ohms +/- 13.5 ohms @ 70 Deg C.

Also, check the wiring to the temperature sensor. If it sags when it gets hot, it may be shorting out to earth, thereby causing the gauge to indicate high. Further, the gauge is not linear. For example, midway would be about 85 Deg C and the red mark is probably about 100 Deg C. so the increase is probably not as bad as it seems. However, the gauge should not be going near the red mark at any time, so it is worth checking.

You say you have replaced the thermostat. I would remove it and put it into a saucepan of water and boil it. at about 85 Deg C it should start to open and by 90 Deg C it should be fully open. Just because it is new doesn't mean it is working properly.

Another one to check: - Are the fans working when it gets hot? And if they are, are they pulling air through the radiator or are they trying to push it forward?

hi again this might seem a silly question but i have found a oil leak on 1 of the 3 plug thingys that sit on top of the part where i fill the engine oil up ( i have no idea what these plug things connect to or what they are called). could this be the cause of my overheating problem?/

thanks

The engine coolant temperature sensor resistance is as follows:


20 degrees = 2.1 to 2.7 kOhms
80 degrees = 0.26 to 0.36 kOhms

hi again this might seem a silly question but i have found a oil leak on 1 of the 3 plug thingys that sit on top of the part where i fill the engine oil up ( i have no idea what these plug things connect to or what they are called). could this be the cause of my overheating problem?/

thanks



Can you please take a photo to show us the area you are referring to?

sorry to be a pain but the only way i could get a photo on there was to set it as my profile pic hope you can see that ok

Hi Selena,


You need to sign up to photobucket or some other photo sharing site and upload the photos there and then link them here between and tags.


Those three are the spark plugs with the leads going to the distributor. There should be three more under the intake manifold.


Not sure if a leaking spark plug seal will cause a suspect overheat issue.

Thank you all very much for your help.. The magna is all fixed and i done it my self with help from you guys.. It turned out to be a new faulty thermostat. so all that work i did changing everything wasnt really needed but at least it all should last awhile now..:D :facejump:

What was the brand and part number of the faulty thermostat?

And also brand/part # for the one that worked.

not sure threw it out as soon as found it faulty and threw out the packaging for the new one sorry cant say

Another advertisement for buying genuine parts.

Mitsubishi parts are so much cheaper than most other car manufacturers, and sometimes even cheaper than generic branded junk from Repco etc. I ordered a rare part at my local dealer for the manual gearbox in my 380, there was only one in the whole country, so they had to freight it over from Sydney.

Price - including GST and freight - $14.

I had similar "overheating" problem in 2009. A full (and expensive) check of the cooling system left us with the sender as the problem. I think it was about $80 from Mitsubishi dealer in Geraldton (we were on a trip around Australia). I changed it in the caravan park where we were staying... just needed to carefully drain a litre or so of fluid out of the radiator bottom tank tap so it didn't spill when I removed the sender. It's all worked perfectly ever since.

The temperature gauge sender looks like a brass bolt with a single wire attached to the top of it. It's the smaller of the two sensors just to the rear of the thermostat housing. Don't forget to put the coolant you drained back in the system.