MadCityRich

I have a question about the proper operating temperature. When I'm driving, the idiot gauge on the dash shows needle at the half way point. Not a big deal.

On my OBD-II scanner (DashDaq2), the coolant temperature reads between 199 and 212, depending on how hard it's being pushed, but mostly right around 203.

203 degrees seems a bit hot for operations. I would have expected about 180 degrees.

Could this be due to the difference in where the gauge vs ECT are taking temperature readings? Could it be an error in my OBD-II reader? On my Subarus, the engine coolant temperature settles right in the 180 to 185 range, which seems about right.

I'm at about 143,000 miles and replaced the radiator last spring with an aftermarket unit. I've also got an external transmission fluid cooler mounted in front of the radiator, though it's still plumbed through the cooler in the radiator.

Maybe time to try a new thermostat?

Any opinions/experience will be a help.

Thanks,
MadCityRich

1990yota-pickup

i dont think you have a problem at all...

1990yota-pickup

if u get over 220 then have a problem..

Ironmike4x4

I have an factory rated 180 thermostat and my scan gauge rarely even goes up to 200 unless it's summer time and I'm out 'wheeling. Have you done your timing belt yet? If not and you've already got 90k miles I'd go ahead and have the timing belt done along with the water pump and thermostat. 203 is an okay number but like yota-pickup said if you hit 220 you'd better start worrying.

1990yota-pickup

you maybe just need to put some coolant boaster stuff in the coolant..

1990yota-pickup

check this out i found this on 22r tech notes


FUEL SYSTEM: Twin side draft carburetors are a natural choice, but the EFI system will work excellent if the vehicle is originally equipped with one. (Some manifolds for the dual carbs have poorly designed water outlets that may cause overheating.) Long duration cams will seriously affect EFI engines, since combustion pressure drop dramatically even with high compression pistons. A fuel pressure adjuster may be needed. The Weber 32/36 or 38DPS are good upgrades for single carb set-ups. For carburetors, use a low pressure, high volume fuel pumps. Do not try to regulate lower fuel pressure with an adjuster because volume will also decrease. A fuel return line is mandatory to allow the fuel pump and carburetor to function properly. For any kind of performance do not rely on Toyota's mechanical or electric pump, they do not have enough volume. The 22RTE with any upgrade will need a higher output pump. The fuel pressure regulator should also be upgraded.

DailyDrive

Operating temperature is what your thermostat is set to. Factory should be 190F AFAIK.

If everything is working properly, and you are not in extreme ambient temperatures, it should not go more than a few degrees away from thermostat rating. And should always settle dead on the thermostat temperature when driving smoothly.

1990yota-pickup

hey i just found this on 22r/re tech notes

you may already know this you may not


FUEL SYSTEM: Twin side draft carburetors are a natural choice, but the EFI system will work excellent if the vehicle is originally equipped with one. (Some manifolds for the dual carbs have poorly designed water outlets that may cause overheating.) Long duration cams will seriously affect EFI engines, since combustion pressure drop dramatically even with high compression pistons. A fuel pressure adjuster may be needed. The Weber 32/36 or 38DPS are good upgrades for single carb set-ups. For carburetors, use a low pressure, high volume fuel pumps. Do not try to regulate lower fuel pressure with an adjuster because volume will also decrease. A fuel return line is mandatory to allow the fuel pump and carburetor to function properly. For any kind of performance do not rely on Toyota's mechanical or electric pump, they do not have enough volume. The 22RTE with any upgrade will need a higher output pump. The fuel pressure regulator should also be upgraded.



check out this site http://www.toysport.com/technical%20...tech_notes.htm

FogRunner

There is nothing wrong with seeing the OBD-II report engine temp around 200-210F when running with a 190 degree thermostat.

To reason why the temp your seeing is about 10-15 degrees over the thermostat is because of the design of the cooling system and the placement of the coolant temp sensors.

The ECM and the engine temp gauge each have their own separate sensor. Because of the ECM coolant sensor is mounted on the front of the engine right in line with the coolant coming of the heads. The coolant here has fully cooled the engine and just came off the heads so it tends to be about 10-15 degrees hotter than the thermostat rating.

Now getting back to the gauge on the dash. Because of the design of the gauge you won't see any quick fluctions unless they are of a large amount.

The reason for this is the temp gauge is a "time/temperature" averaging type of gauge. For slight increases in temp it takes the gauge seeing that temp for 20-30 seconds before it changes to indicate that. But with changes of a large amount quickly it will reflect that.

The reason for this is prevent customers from seeing the gauge going up and down with hard acceleration or heavy loading up a hill and think there is a problem.

Also if you look at most other engine's cooling systems the thermostat is normally mounted on the top of the block by the heads. On the 3.4 its mounted on the bottom hose lower on the engine so it will see a better average temperature and keep the engine temp more stable despite intermittant hard loading.

So don't worry about seeing a touch over 200F its normal.


FOG

mt_goat

I concur with FOG

1990yota-pickup

I TRIED to tell him from the start.. but you got all technical there fog runner...

MadCityRich

Thanks! I figured nothing was wrong and I'm pretty OCD about keeping up with maintenance, but had to be sure about the temps. 4Runner runs like a top and I want to keep it that way.

I had a suspicion it was just a sensor placement issue and I appreciate the confirmation.

MadCityRich

FogRunner

I was re-reading the thread and saw the above. I have a transmission cooler also in front of the radiator but the transmission is piped to it ONLY and I kept the radiator out of the circuit.

With just the cooler in normal traffic on a hot day I never see above 175F and with it locked up on the highway it hangs around 125F. The only time I saw it get up to 200F was going up Pikes Peak with a car full of people.

Under hard acceleration the transmission does develop a good amount of fluid pressure which is the cause of the radiator transmission cooler tank failures that are commonly discussed around here.

Transmission fluid doesn't need to be warmer than 90-100 degrees to function properly. And it doesn't need to get hot to evaporate water like engine oil does because there is no combustion loading up the trans fluid with water.

If you do live in a northern area where you have allot of really cold weather you can get a by-pass thermostat that will keep it around 140F. The winters are mild down here and the cooler I have has two larger channels in it that act as a bypass at lower temps so even when its 40F outside it hangs around 100F when on the highway.

So I would seriously consider taking your radiator out of the transmission fluid circuit, because if the radiator tank ruptures you have a VERY VERY expensive problem when that coolant gets into your transmission.

But I'm like you in regards to maintaining your 4runner. I do all the work myself down to timing belts, waterpumps, valve covers, ETC.

And I'm pretty OCD also about that stuff also and it drives my wife nuts but I have never been broke down on the side of the road.


FOG

BigBallsMcFalls

188 normal road driving 60 deg out

212 normal sitting in traffic hot day

224 about the max it should ever go. fan should be able to take this down

eddieleephd

Really if you are really Ocd and can not handle the thought of yotas running hotter than most other vehicles then you can change the thermostat and anti-freeze and see what the obd says then.

However I concur that there is no issue at all and typical!!

DailyDrive

How many vehicles have you personally driven while monitoring the coolant temp coming in via ODBII?

96743runner

My scangauge's coolant temp reading never went over 190 degrees. Most of the time it runs at 188 degrees. But that's probably because it doesn't get really hot where I live.

skjos

My ScanGauge reads coolant temp consistantly between 189 and 193.
Just more data to throw into the mix.

eddieleephd

This is one question I should have asked first.

When was the last that you did a coolant flush and thermostat replacement??

DailyDrive

eddieleephd, so how about my question? How many vehicles have you personally driven while monitoring the coolant temp coming in via ODBII?