Has anyone tried .... coolant temp sensor - Toyota Nation Forum : Toyota Car and Truck Forums

royp · 01-04-2012, 10:37 AM

Has anyone tried to replace the coolant temp sensor on the '94 camry or similar without draining the coolant? The cts is on the housing where the upper radiator hose goes into the block. My thought is you could (on a cold engine) pull the old cts out and stick a new one in without losing more than a few ounces of coolant. I'm sure i'ld lose more if i drained and refilled. Just wondering if anyone has tried that yet?

bdy0003 · 01-04-2012, 10:56 AM

I haven't tried it. I could be totally wrong on this one, but it sounds like you will incorporate air in the system, thus causing your car to overheat (if you were to drive it as is). You would have to burp the air out of the system in order to get the air out.

royp · 01-04-2012, 11:06 AM

I'm thinking the radiator cap and reserve tank will compensate for any air introduced, just as they do when you do a complete flush and fill.

winkda · 01-04-2012, 12:10 PM

I plan on changing my cts today too and plan on removing old one and putting my finger on the hole till i get the new one in.I also plan on removing the top radiator (on the engine) so that the escaping coolant will not draw air to replace it. I'll probably lose more coolant but may not have to burp it.
What kind of problems were you experiencing that prompted you to change out the cts?

royp · 01-04-2012, 01:02 PM

First off there was no CEL. It ran fine when cool or cold. Once the engine was at operating temp it showed intermittent problems of idleing up at stops to about 2k rpm when I put the car in park or nuetral and then dying when I would press the gas pedal. It also showed odd shift points on the highway where shifting seemed to be late and it would have trouble locking into OD. Since the problem was intermittent it was hard to diagnose but I finally figured it out by disconnecting the coolant sensor while it was having problems and it cleared right up. That was after spending a couple hundred bucks on other stuff - all needed though.

winkda · 01-04-2012, 06:58 PM

Just wondering if your engine is a v-6 or 4 banger? On my 1992 v-6 ..3v..all data says the sensor on the thermostat housing is engine fan sensor. There are two on the tube that runs into (out of ?) the heater core, right around the throttle cable hook-up area. Those it (all data) said are (1) the water temp. / ecu and (2) fuel injector temp sensor. I've been having problems with up shifting and OD when cold so set out to replace the water temp./ ECU sensor. I had read on another search that the sensor on the thermostat housing was that sensor. When i got the sensor home it wouldn't fit the connector, so i tried it on the other two sensors and if fits . So I checked with all data and replaced it anyway. Needless to say my shift problem still exists, so I'll be heading back to napa and match the sensors up by sight.

***fenixus*** · 01-04-2012, 09:49 PM

on 4cyl model yes I did that without draining the coolant.

simple unplug, unscrew the old one out (maybe a tea spoon of coolant spilled), put the new copper gasket and new sensor in, tighten to 14ft-lbs with a 19mm deep wall socket (fits over the connector).

on V6 it's not possible as the sensor location is lower than the pressure cap and upper rad hose. on 5s-fe the sensor is pretty much at the highest point (or at level with pressure cap).

Quote:

Originally Posted by royp

Has anyone tried to replace the coolant temp sensor on the '94 camry or similar without draining the coolant? The cts is on the housing where the upper radiator hose goes into the block. My thought is you could (on a cold engine) pull the old cts out and stick a new one in without losing more than a few ounces of coolant. I'm sure i'ld lose more if i drained and refilled. Just wondering if anyone has tried that yet?

winkda · 01-05-2012, 06:39 AM

Quote:

Originally Posted by fenixus

on 4cyl model yes I did that without draining the coolant.

simple unplug, unscrew the old one out (maybe a tea spoon of coolant spilled), put the new copper gasket and new sensor in, tighten to 14ft-lbs with a 19mm deep wall socket (fits over the connector).

on V6 it's not possible as the sensor location is lower than the pressure cap and upper rad hose. on 5s-fe the sensor is pretty much at the highest point (or at level with pressure cap).

winkda · 01-05-2012, 06:56 AM

Fenixus,I am wondering if you could tell my what color the cts/ecu connector is on 92 V6 3V? I thought i saw on one of your earlier posts that you owned the same car,could be mistaken though.Anyway want to be sure of the specs of the sensor before i check the ohms.

royp · 01-05-2012, 08:12 AM

I have the 4 cylinder with the S5 engine. I changed out the temp sensor last night and did not drain the coolant. I had a new sensor with gasket/washer ready to go and just plugged the hole with my finger then quickly inserted the new sensor. Maybe lost a ounce of fluid or less. This would be the way to do it in my experience. And yes the new sensor has cured all my ills for now.

winkda · 01-05-2012, 08:16 AM

Congrats hope it's the cure all fer sure.The V6 has three cts and I'm confused (as NAPA) as to whats what.

***fenixus*** · 01-05-2012, 07:41 PM

ehh, I don't know how the sensors are lined up on 3vz-fe unfortunately.

here is a pic from later 1mz-fe:

the Engine Coolant Temperature sensor for E.F.I. (used by ECU) is the one with gray plug on left in picture (green plug on 5s-fe on driver side of engine) and new shiny golden/brass/copper base and having 2 wires to it.
the other one on right from it in the picture, is the ECT dash gauge sender having grey plug, silver/steel base and only 1 wire (on 5s-fe this sensor is on opposite side of engine, right next to ECT for EFI).

other 2 ECT switches (on V6 there are two or three on older models, 5s-fe uses just one) used by rad fans are in crazy locations (one usually at passenger side bottom of radiator). maybe someone has a diagram handy for 3vz-fe, it should explain it all.

Quote:

Originally Posted by winkda

Fenixus,I am wondering if you could tell my what color the cts/ecu connector is on 92 V6 3V? I thought i saw on one of your earlier posts that you owned the same car,could be mistaken though.Anyway want to be sure of the specs of the sensor before i check the ohms.

winkda · 01-06-2012, 08:03 PM

Thanks for the pic.Not the same as v6 fer sure.I now have a bigger fish to fry, knock sensor code 55 yee haw, don't think it's the sensor per say but wiring.Been reading on threads that that's usually the problem.

***fenixus*** · 01-07-2012, 01:21 AM

that picture is from 1mz-fe (6 cylinder).

anyways, good luck with Knock sensor problems, "only" 3 things to check, knock sensor itself, wiring and the ECU.

Quote:

Originally Posted by winkda

Thanks for the pic.Not the same as v6 fer sure.I now have a bigger fish to fry, knock sensor code 55 yee haw, don't think it's the sensor per say but wiring.Been reading on threads that that's usually the problem.

96v6wagon · 01-21-2012, 02:56 PM

Fenixus:
Thanks for posting that picture. I want to replace my ECT sensor, but can't figure out how to remove the old one. The locking tab is facing inward, towards the engine, and I can't see how it unlocks, or figure out how to get it off.
Do you suppose I could just use a flex-head wrench to get the sensor loose enough that I could turn it and then get the locking tab undone?
Or what would you recommend?

BTW - my 96 v6 doesn't have any of the described symptoms, just getting really BAD mpg, and seems to be getting worse. Now it's in the 17 range. Usually it's about 20 in town. I thought maybe the sensor is causing it to run rich.