'01 Camry coolant temperature

[Falcon_LS]

I posted about this vehicle previously, a '01 Camry with the 5S-FE 2.2L and just over 38,150 miles as it stands now. Engine oil is Mobil 1 0W-40, if it matters, with a OE Denso filter (Thai version).

The initial problem was that the coolant temperature remains just a wee bit above the cold mark on the gauge, and never reaches the half mark. The only time you see the temperature rise is when the engine is left to idle. Only then does it reach a bit under the half mark. The thermostat was replaced with an OE Toyota unit, as was the coolant temperature sensor (OE as well). The problem did not go away.

I used an infrared temperature gun pointed at the top of the radiator, and it read 60 C/140 F, which is low compared to the 82 C/180 F the thermostat is set to. This was when the temperature gauge rose up a bit.

Driving it tonight on an open highway, I hit 100 MPH and immediately noticed the coolant temperature gauge was under the cold mark - i.e. where it points to when you start the engine first thing in the morning. I dropped down to 75 MPH and the temperature went back up to the cold mark. Ambient temperature was 13 C/56 F.

The only other thing that springs to mind is a sensor located by the cooling fans on the radiator (on the bottom left (passenger) side). Any 5S-FE gurus know what else could be considered an offending part? I'm having a hard time tackling this one. Thanks!

 

[Quest]

Sounds like a bad thermostat (I know, you just replaced it with a factory Toyota unit)again in your case.

Q.

When in doubt, take the unit off and with a thermometer also in a pot of water (bring it up to a boil slowly as you watch the temperature rise), and see how it behaves.

 

[Chris142]

The stat is what controls the engines mimimum temp. If it's running too cold all it can be is the stat.

 

[mechtech2]

AT this point, it's probably the sensor.
Also check the connections and wiring.
It could be the dash gauge.
And still, it MAY be the thermostat.

 

[JustinC25]

How is the heat while driving ? It can be rather anemic in these cars at idle, but when driving it should get rather hot.
If not then you have a bad t-stat. I'd pull the t-stat out and do the boiling water test. It's cerainly easy enough to pull in this car. You may also have a fault sensor. It is located at the bottom of the radiator, on the left side if looking at the rad from behind.

 

[Falcon_LS]

Many thanks for all the input and assistance! I removed the thermostat this morning, and put it in water whilst monitoring temperature with a digital thermometer. At 82 C/180 F, the thermostat fully opened. Needless to say, for $10 I replaced it with another OE Toyota one. I still have the same problem, so I suppose that scores that one off.

Even whilst driving in summer, with an ambient temperature of 60 C/140 F, the engine just does not reach operating temperature. The temperature rises when the vehicle is not moving, but as soon as the vehicle moves, the temperature starts falling and eventually returns to just over the Cold mark.

To save time, the next step will be to replace the sensor on the bottom of the radiator. If that fails, I'm going to start going through the wiring.

 

[Quest]

Originally Posted By: Falcon_LS
Driving it tonight on an open highway, I hit 100 MPH and immediately noticed the coolant temperature gauge was under the cold mark - i.e. where it points to when you start the engine first thing in the morning. I dropped down to 75 MPH and the temperature went back up to the cold mark. Ambient temperature was 13 C/56 F.


While the temperature sensor maybe faulty, that still doesn't explain why when you fly down the highway the needle drops below
"Cold" mark, and when you slow down, it creeps up again but never high up and beyond the "C" mark (just a tad higher).

To me this is still a sign of cooling/circulation problem. Living in the Northern equator, all I could say that anything that keeps the engine water jacket temperature consistent would be your water pump, your thermostat and/or combination of both. Since your car is running cold instead of hot, and assuming that the temperature sensor is working properly (there should be a resistance reading available if you search online, I don't have it handy at this moment), cannot see why it would fluctuates like that on the highway.

I'm more worry about your engine consistently running cold and that will cause accelerated deposit accumulation on the oil conrol ring/piston ring lands area which will subsequently lead to oil burning issues when the oil control rings get stuck.

Q.

Lastly, also check to see if your electric radiator fan is running in an "odd" way causing over-cooling of the engine

 

[Falcon_LS]

Quest, sorry I meant to say it reaches operating temperature (just under the half mark) when the engine is idling. When the engine speed increases (even if I'm just revving it slightly in park/neutral) the coolant temperature drops to a tad higher than the "C" mark.

As you mentioned, my biggest worry is the engine as well. Running cold is not exactly doing it any favours, so I'm looking to get this sorted ASAP before anything else comes up. The sensor located on the radiator controls the fans, so I'm hoping that will resolve the issue. Going to have to get this out the way tomorrow, as it's a public holiday today. The sooner it's out the way, the better.

 

[Silk]

Get it put on a scanner and see what the computer is seeing as the temp.If the computer is seeing such a low temp it will be doing things as if it was at that temp (pulling the choke out) It should be running rich with a high idle.If it's running perfectly then I think the computer is seeing the correct temp,and you are not.

 

[JustinC25]

Here is the EWD for the fans on a US Model:

http://www.mediafire.com/?tmzhm42ylw0

Note: This applies to both the 5S-FE, and 1MZ-FE engines. Any differences are noted in the EWD.
I got this directly from TIS.

Justin

 

[KrisZ]

Are the fans running continuously? If not, the sensor is OK. Also if it was a faulty sensor, the car would come up to the operating temp and the reading would be erratic, instead the reading follows a bad thermostat symptom.

From the description, it looks like the thermostat is somehow being by-passed, assuming the t-stat is ok.

I would completley remove the t-stat and run the car that way, see if anything changes, if the readings are still the same it means you have full coolant circulation all the time.

 

[eljefino]

You can't draw too much conclusive from the radiator temp as that varies. It's outside the thermostat loop and can be anywhere from slightly above ambient to fan turn-on temp. That's why your fan sensor is on the rad. The one(s) that supply your dash gauge and ECM are on the motor within the thermostatically controlled loop.

IMO the next step should be to cover 3/4 of the rad with a piece of cardboard, if it warms things up you still have a thermostat problem. Maybe there's a rubber seal around the thermo flange that a previous mechanic discarded or something?

 

[mechtech2]

I am wondering why a rather new design vehicle specs such a cold thermostat. It hurts cruising gas economy and efficiency. Heat is lost to the cooling of the head and cylinder walls, instead of being used to push down on the piston.
ALmost everybody uses 195 F or up nowadays.

 

[Falcon_LS]

Originally Posted By: Silk
Get it put on a scanner and see what the computer is seeing as the temp.If the computer is seeing such a low temp it will be doing things as if it was at that temp (pulling the choke out) It should be running rich with a high idle.If it's running perfectly then I think the computer is seeing the correct temp,and you are not.


Unfortunately my OBD-II software does not work on this vehicle. The software needs to be Toyota specific, and is only available through the dealer. There are places that scan for codes outside the dealer, but their scanners do not monitor engine, coolant, trans, etc. temperatures.

Originally Posted By: JustinC25
Here is the EWD for the fans on a US Model:

http://www.mediafire.com/?tmzhm42ylw0

Note: This applies to both the 5S-FE, and 1MZ-FE engines. Any differences are noted in the EWD.
I got this directly from TIS.

Justin


Much appreciated, thanks very much!

Originally Posted By: KrisZ
Are the fans running continuously? If not, the sensor is OK. Also if it was a faulty sensor, the car would come up to the operating temp and the reading would be erratic, instead the reading follows a bad thermostat symptom.

From the description, it looks like the thermostat is somehow being by-passed, assuming the t-stat is ok.

I would completley remove the t-stat and run the car that way, see if anything changes, if the readings are still the same it means you have full coolant circulation all the time.


Just removed the thermostat, going to drive around like this and see if there are any changes.

Originally Posted By: eljefino
You can't draw too much conclusive from the radiator temp as that varies. It's outside the thermostat loop and can be anywhere from slightly above ambient to fan turn-on temp. That's why your fan sensor is on the rad. The one(s) that supply your dash gauge and ECM are on the motor within the thermostatically controlled loop.

IMO the next step should be to cover 3/4 of the rad with a piece of cardboard, if it warms things up you still have a thermostat problem. Maybe there's a rubber seal around the thermo flange that a previous mechanic discarded or something?


Thanks for the tip.

Originally Posted By: mechtech2
I am wondering why a rather new design vehicle specs such a cold thermostat. It hurts cruising gas economy and efficiency. Heat is lost to the cooling of the head and cylinder walls, instead of being used to push down on the piston.
ALmost everybody uses 195 F or up nowadays.


To prevent pinging. The Camry recommends 91 RON fuel. With a high ambient temperature, you experience knocking and have to go the next grade up. Whereas with a cooler temperature setting, you do not experience this problem.

 

[Silk]

Originally Posted By: Falcon_LS

Unfortunately my OBD-II software does not work on this vehicle. The software needs to be Toyota specific, and is only available through the dealer. There are places that scan for codes outside the dealer, but their scanners do not monitor engine, coolant, trans, etc. temperatures.

No,you won't get OBDII out of a Toyota of that year.But other scanners will - my Snap-On scanner gave good live data on Toyota,and most other Japanese cars too.But we did have a cartridge specific for the Japanese Domestic vehicles in NZ.The Launch scanner will give excellent coverage of Japanese cars.There is no need for a dedicated Toyota scanner - just a good one.

 

[BearZDefect]

Originally Posted By: mechtech2
I am wondering why a rather new design vehicle specs such a cold thermostat. It hurts cruising gas economy and efficiency. Heat is lost to the cooling of the head and cylinder walls, instead of being used to push down on the piston.
ALmost everybody uses 195 F or up nowadays.
Because the 5S-FE is an old engine design, perhaps?

Falcon already put forward a better explanation.

I just changed the thermostat on one (1999) last month, was also susprised that the OE temp was 180. In my case, the new thermostat solved the problem. The OE-style thermostat I bought came with a new seal, which I installed.

 

[Quest]

IMHO regardless of what the factory spec'ed for their OE thermostat temperature range, it is vital to your EFI engine's proper running so don't play backyard mechanics with your factory Engine or you'll damage it as a result.

For example: if your engine is designed and programmed to run on 180F thermostat, never run a 190/195F unless you've made changes to the engine and timing. For an overly hot water jacket may lead to pre-ignition, or poor fuel economy, or emissions issues (or all of the above).

Lower than factory spec'ed temperature thermostat will lead to engine running too "cold", which will lead to deposits issues esp. on the piston oil control ring area, subsequently lead to oil burning issues as the oil control ring cannot effectively "scrape" the oil film off the cylinder walls due to jamming.

Factory designed/spec'ed temperature thermostat is designed for all the aforementioned factors in mind all the way from the initial engine R&D stage to the product phase and it's meant to provide the longest, if not most consistent/reliable service that the engine designers originally spec'ed for. Anytime one deviates from the original spec then shortened service life of the engine due to aforementioned issues are pretty much guaranteed in the picture.

Q.

 

[mechtech2]

Well sure - a cooler thermostat will allow more ignition advance.
But it is better for efficiency to get the temps up, and back off the ignition advance.
Full throttle is a lot more rare and is another story.