1990 ES250 odd Water temp sensor issues
10-12-13, 10:23 PM
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1990 ES250 odd Water temp sensor issues
Hello All, Hopefully you Lexus fans can help here. My classic started overheating and I have it narrowed down to what the repair manual calls a Water temperature sensor. Called
Napa and ended up with a coolant temp sensor, this is so not the right part. So did some research and cant find a 'Water temp sensor' anywhere. Read the forums a bit a see some talk about the ECT. I thinking since this was the first year there must be something wonky going on. Any thoughts?
Napa and ended up with a coolant temp sensor, this is so not the right part. So did some research and cant find a 'Water temp sensor' anywhere. Read the forums a bit a see some talk about the ECT. I thinking since this was the first year there must be something wonky going on. Any thoughts?
10-12-13, 10:57 PM
#2
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There are two coolant temp sensors. One near the distributor, and one on the thermostat housing. This is the one (called a water temperature sensor) the ECU uses to control the cooling fans. Speaking of, do the fans spin at any point? If you remove the connector for the sensor on the 'stat housing, the fans should run all the time.
10-13-13, 12:19 AM
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Yep and both appear to be that same part, but the sensor I pulled looks nothing like the coolant sensor that I got from Napa. Through search and a friends assist though I found that the 1990 Ls 400 has a fan switch looks almost exactly like the sensor I pulled. Again this has 2 sensors one at the water inline on the therm housing and the other is on top right where the water out heads back to radiator. I really thing that since this was first year of the Es250 or lexus of any kind things got wonky.
10-13-13, 12:21 AM
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There are two coolant temp sensors. One near the distributor, and one on the thermostat housing. This is the one (called a water temperature sensor) the ECU uses to control the cooling fans. Speaking of, do the fans spin at any point? If you remove the connector for the sensor on the 'stat housing, the fans should run all the time.
Yes when I pulled the connector the fans do start spinning.
10-13-13, 09:52 AM
#5
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Do the cooling fans cycle when the engine is at operating temperature? How did you come to the conclusion that the issue is with the temperature sensor? You might have a clogged radiator, air in the cooling system, failing water pump, bad cooling fan ECU (unlikely) etc. etc. Does the engine overheat at idle, at freeway speeds, in traffic?
The cooling system on the 2VZ-FE engine is very reliable including the fans, nothing wonky or iffy about it. The engine does have head gasket issues sometimes, it almost always happens because the engine has been severely over heated, or low quality coolant has been used.
The cooling system on the 2VZ-FE engine is very reliable including the fans, nothing wonky or iffy about it. The engine does have head gasket issues sometimes, it almost always happens because the engine has been severely over heated, or low quality coolant has been used.
10-13-13, 12:06 PM
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Do the cooling fans cycle when the engine is at operating temperature? How did you come to the conclusion that the issue is with the temperature sensor? You might have a clogged radiator, air in the cooling system, failing water pump, bad cooling fan ECU (unlikely) etc. etc. Does the engine overheat at idle, at freeway speeds, in traffic?
The cooling system on the 2VZ-FE engine is very reliable including the fans, nothing wonky or iffy about it. The engine does have head gasket issues sometimes, it almost always happens because the engine has been severely over heated, or low quality coolant has been used.
The cooling system on the 2VZ-FE engine is very reliable including the fans, nothing wonky or iffy about it. The engine does have head gasket issues sometimes, it almost always happens because the engine has been severely over heated, or low quality coolant has been used.
Fans never run, but if it gets hot I can turn the car off then turn the key to on, may take couple turns but then the fans kick on. when started though the fans kick off and never run while engine is running. Car seems to overheat whether idle or driving. I checked all relays for continuity, the only issue I see there though is all the relays in that in the front of the fuse box there seem gunked up. I cleaned it as well as I could thinking it was just not making proper contact.
My thought is that if the thermostat is issue fans would still kick on. Same goes for water pump wouldn't the fans still kick on?
As far as the wonkiness. On the door sticker it shows manufacture of 11/89, is it possible when they put the car in production at first they would use this coolant sensor that is completely different then the part I got and use this fan switch that doesn't even show my car uses?
Oh and on the subject of the cooling ECU where the heck is it? Was thinking maybe behind glove box and I need to take that out.
10-13-13, 12:27 PM
#7
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The ES250 is mechanically identical to the Camry V6, which was in production from 1988-1991. Not much was changed from the first year to the last, a knock sensor was added (your car has it) which increases engine power slightly. Other than that, mechanically I can't think of anything that was significantly changed over the production run.
What happens if you pull the connector on the water temp sensor and drive the car, will it overheat? I sent you a private message.
...looking at the service manual, it simply states that if the fans don't run at all when the engine is at operating temperature, replace the sensor.
What happens if you pull the connector on the water temp sensor and drive the car, will it overheat? I sent you a private message.
...looking at the service manual, it simply states that if the fans don't run at all when the engine is at operating temperature, replace the sensor.
Last edited by LeX2K; 10-13-13 at 12:30 PM.
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10-13-13, 02:38 PM
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The ES250 is mechanically identical to the Camry V6, which was in production from 1988-1991. Not much was changed from the first year to the last, a knock sensor was added (your car has it) which increases engine power slightly. Other than that, mechanically I can't think of anything that was significantly changed over the production run.
What happens if you pull the connector on the water temp sensor and drive the car, will it overheat? I sent you a private message.
...looking at the service manual, it simply states that if the fans don't run at all when the engine is at operating temperature, replace the sensor.
What happens if you pull the connector on the water temp sensor and drive the car, will it overheat? I sent you a private message.
...looking at the service manual, it simply states that if the fans don't run at all when the engine is at operating temperature, replace the sensor.
10-13-13, 02:41 PM
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But the one for the water outlet looks right. What are the chances that these have gotten switched at some point in this cars 23 years of life? Guess I'll pull the other sensor and compare.
10-13-13, 03:18 PM
#11
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Have you tested the resistance of the sensor as per the service manual? I would not trust NAPA to give correct info myself.
10-13-13, 06:23 PM
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OK I put on my big boy shorts and did the test. Decided I was done with just throwing parts at it. The resistance checks out, so I guess it's not the sensor after all.
I checked for continuity on the relays but not the operation. Again haven't ever done this so big boy shorts back on.
Thanks Lexus2000, I'll update on results of relays.
10-13-13, 06:52 PM
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OK I think my assuming has made an *** of myself. I assumed since both fans did not operate that I only need to check relay for fan#3. Well relay 2 has no continuity between 2 and 6 when the black probe is on 2 and the red on 6, when I switch them it moves to 2.5, but still should zero out right? I think this is all just bad relay, but when i did the test for operation ran the leads from battery to 2 and 6 I got continuity. Lesson learn.
10-14-13, 12:04 PM
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The ES250 is mechanically identical to the Camry V6, which was in production from 1988-1991. Not much was changed from the first year to the last, a knock sensor was added (your car has it) which increases engine power slightly. Other than that, mechanically I can't think of anything that was significantly changed over the production run.
What happens if you pull the connector on the water temp sensor and drive the car, will it overheat? I sent you a private message.
...looking at the service manual, it simply states that if the fans don't run at all when the engine is at operating temperature, replace the sensor.
What happens if you pull the connector on the water temp sensor and drive the car, will it overheat? I sent you a private message.
...looking at the service manual, it simply states that if the fans don't run at all when the engine is at operating temperature, replace the sensor.
10-14-13, 01:22 PM
#15
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If it was me I'd replace the thermostat and go from there. Make sure you properly bleed out the air, the symptoms you are having sound like air trapped.
