Engine Getting Hot While Sitting Still and In Gear

[MT Runner]

Looking for some expertise here on what might be going on.
2005 V6, 197k+ on it right now. This has been going on for the last few months now.

I’ve had a scan gauge in the 4Runner for the last 5+ years, so I’ve always paid pretty close attention to the exact temp that it runs at.
Once the engine is warm, in the past it always ran between 190-195 degrees, driving, stopped in traffic, didn’t matter.

Now when I’m cruising along, the temp has been in the 195-200 range consistently, not alarming, but it is higher than in the past.

Where the issue is, is when I’m in traffic, a drive through, anywhere I’m stopped but the vehicle is still in gear, the engine temp starts creeping up. 202, 207, 212, then the light turns green, I start moving and the the engine gets back down to 197-198.
If I put it in neutral or in park, the engine will get up to about 204-206 and hold steady there.
It’s only when I’m stopped but still in gear that it continues to creep up. I sat in my driveway the other day to kind of test that out and see if it would hit a max and hold steady, it didn’t. I got to 238 before I turned the car off and let it cool off. (Someone told me that the fan kicks on at 235, I was 99% sure that was wrong, but I let it get up that high just to make sure)

I’ve checked the coolant, it’s not low, off color, etc.
I had the radiator flushed last summer, about 16k miles ago.
I’ve gone to the car wash and really cleaned out the ac condenser and radiator to make sure it wasn’t all plugged up with dust, bugs, etc that would prevent air flow.
I just changed the oil the other day, it was normal from what I could tell.

I even towed our camper (about 3500lbs loaded)earlier this summer and it was completely fine, ran about 198 the whole trip.

Any ideas of what’s going on here?

 

[RobD]

Fan clutch?

 

[thennen]

Looking for some expertise here on what might be going on.
2005 V6, 197k+ on it right now. This has been going on for the last few months now.

I’ve had a scan gauge in the 4Runner for the last 5+ years, so I’ve always paid pretty close attention to the exact temp that it runs at.
Once the engine is warm, in the past it always ran between 190-195 degrees, driving, stopped in traffic, didn’t matter.

Now when I’m cruising along, the temp has been in the 195-200 range consistently, not alarming, but it is higher than in the past.

Where the issue is, is when I’m in traffic, a drive through, anywhere I’m stopped but the vehicle is still in gear, the engine temp starts creeping up. 202, 207, 212, then the light turns green, I start moving and the the engine gets back down to 197-198.
If I put it in neutral or in park, the engine will get up to about 204-206 and hold steady there.
It’s only when I’m stopped but still in gear that it continues to creep up. I sat in my driveway the other day to kind of test that out and see if it would hit a max and hold steady, it didn’t. I got to 238 before I turned the car off and let it cool off. (Someone told me that the fan kicks on at 235, I was 99% sure that was wrong, but I let it get up that high just to make sure)

I’ve checked the coolant, it’s not low, off color, etc.
I had the radiator flushed last summer, about 16k miles ago.
I’ve gone to the car wash and really cleaned out the ac condenser and radiator to make sure it wasn’t all plugged up with dust, bugs, etc that would prevent air flow.
I just changed the oil the other day, it was normal from what I could tell.

I even towed our camper (about 3500lbs loaded)earlier this summer and it was completely fine, ran about 198 the whole trip.

Any ideas of what’s going on here?

Not an expert here, just a few things to check.

First, the fan did not engage at 238 degrees? I would think that it would, but not sure of the temp. Has to come on sometime.
Thermostat binding.
Radiator fins rotted away.
Water pump fins worn.

 

[Joe-Runner]

Thermostat?

https://www.rockauto.com/en/catalog....0l+v6,1431016,cooling+system,thermostat,2200

 

[MT Runner]

Not an expert here, just a few things to check.

First, the fan did not engage at 238 degrees? I would think that it would, but not sure of the temp. Has to come on sometime.
Thermostat binding.
Radiator fins rotted away.
Water pump fins worn.

When it was at 238 I did put in park for a second and looked under the hood and the fan was going at that time, but didn’t seem to be going all that fast.
I think it had been going for awhile, I had just heard that it didn’t come on until 235 which is what I thought didn’t sound right, I think it comes on far before that.

 

[AuSeeker]

Looking for some expertise here on what might be going on.
2005 V6, 197k+ on it right now. This has been going on for the last few months now.

I’ve had a scan gauge in the 4Runner for the last 5+ years, so I’ve always paid pretty close attention to the exact temp that it runs at.
Once the engine is warm, in the past it always ran between 190-195 degrees, driving, stopped in traffic, didn’t matter.

Now when I’m cruising along, the temp has been in the 195-200 range consistently, not alarming, but it is higher than in the past.

Where the issue is, is when I’m in traffic, a drive through, anywhere I’m stopped but the vehicle is still in gear, the engine temp starts creeping up. 202, 207, 212, then the light turns green, I start moving and the the engine gets back down to 197-198.
If I put it in neutral or in park, the engine will get up to about 204-206 and hold steady there.
It’s only when I’m stopped but still in gear that it continues to creep up. I sat in my driveway the other day to kind of test that out and see if it would hit a max and hold steady, it didn’t. I got to 238 before I turned the car off and let it cool off. (Someone told me that the fan kicks on at 235, I was 99% sure that was wrong, but I let it get up that high just to make sure)

I’ve checked the coolant, it’s not low, off color, etc.
I had the radiator flushed last summer, about 16k miles ago.
I’ve gone to the car wash and really cleaned out the ac condenser and radiator to make sure it wasn’t all plugged up with dust, bugs, etc that would prevent air flow.
I just changed the oil the other day, it was normal from what I could tell.

I even towed our camper (about 3500lbs loaded)earlier this summer and it was completely fine, ran about 198 the whole trip.

Any ideas of what’s going on here?

Fan clutch?

^^^This^^^!

First off your T4R doesn't have an fan that kicks in at a certain degree range, it has a direct drive mechanical fan with a fan clutch driven by the serpentine belt, a fan clutch allows the fan to rotate even when the engine is off but the fan will not freewheel it will have tension from the fan clutch restricting it from turning completely freely, even though the pulley the fan and fan clutch is bolted to will not turn, and as such when the engine is running it allows the pulley to turn faster than the fan, by doing this it takes less power from the engine to turn the fan even though it allows the fan to turn fast enough to draw the required air through the radiator to properly cool the engine.

When the fan clutch wears out the proper tension/friction within the fan clutch has been reduce so that the fan is able to turn too freely and as such is not turning fast enough when the engine is running at idle to cool the engine properly.

You can sorta check the fan clutch by turning the fan by hand when the engine is off, normally you should be able to turn the fan but it will have a fair amount of tension on it, if the fan turns really easily with little tension the fan clutch is worn out and needs replacing

 

[AuSeeker]

Here are 3 fan clutches that should fit your T4R so you know what a fan clutch looks like.

The fan blade bolts to one side and the other side bolts to the pulley.

https://shop.advanceautoparts.com/w...actionSrc=Form&searchTerm=radiator fan clutch

 

[MT Runner]

^^^This^^^!

First off your T4R doesn't have an fan that kicks in at a certain degree range, it has a direct drive mechanical fan with a fan clutch driven by the serpentine belt, a fan clutch allows the fan to rotate even when the engine is off but the fan will not freewheel it will have tension from the fan clutch restricting it from turning completely freely, even though the pulley the fan and fan clutch is bolted to will not turn, and as such when the engine is running it allows the pulley to turn faster than the fan, by doing this it takes less power from the engine to turn the fan even though it allows the fan to turn fast enough to draw the required air through the radiator to properly cool the engine.

When the fan clutch wears out the proper tension/friction within the fan clutch has been reduce so that the fan is able to turn too freely and as such is not turning fast enough when the engine is running at idle to cool the engine properly.

You can sorta check the fan clutch by turning the fan by hand when the engine is off, normally you should be able to turn the fan but it will have a fair amount of tension on it, if the fan turns really easily with little tension the fan clutch is worn out and needs replacing

That’s great info, I think that’s it. I just went and checked the fan and it spins relativey freely. Not a complete freewheel, but not a lot of tension either.

Any ideas of ball park figures to fix this?

 

[AuSeeker]

That’s great info, I think that’s it. I just went and checked the fan and it spins relativey freely. Not a complete freewheel, but not a lot of tension either.

Any ideas of ball park figures to fix this?

If you or a freind have any basic mechanical skills and a wrench or 2 the proper sizes you can replace the fan clutch rather easily, so then it just the cost of a new fan clutch, I do all my own work on my T4R so I can't say what your local mechanic would charge you, so you may want to call a shop if you can't do it yourself.

I should be able to replace the fan clutch in around 30 minutes or less I would think, so a shop would most likely charge you for a full hour of labor.

 

[MT Runner]

If you or a freind have any basic mechanical skills and a wrench or 2 the proper sizes you can replace the fan clutch rather easily, so then it just the cost of a new fan clutch, I do all my own work on my T4R so I can't say what your local mechanic would charge you, so you may want to call a shop if you can't do it yourself.

I should be able to replace the fan clutch in around 30 minutes or less I would think, so a shop would most likely charge you for a full hour of labor.

Great, thank you for the help!

 

[wcjeep]

Moving and parked heat increase? Infrared heat gun. About $25 on sale. Check the thermostat housing. Does it match the gauge / Scantool? Radiator upper and lower hose look OK? Is the lower hose collapsing? Are the Temps on the radiator uniform left to right, then top to bottom?

How old are the radiator hoses? If excessive age, swap them and heater hoses when performing thermostat swap.

 

[00_4runner]

Looking for some expertise here on what might be going on.
2005 V6, 197k+ on it right now. This has been going on for the last few months now.

I’ve had a scan gauge in the 4Runner for the last 5+ years, so I’ve always paid pretty close attention to the exact temp that it runs at.
Once the engine is warm, in the past it always ran between 190-195 degrees, driving, stopped in traffic, didn’t matter.

Now when I’m cruising along, the temp has been in the 195-200 range consistently, not alarming, but it is higher than in the past.

Where the issue is, is when I’m in traffic, a drive through, anywhere I’m stopped but the vehicle is still in gear, the engine temp starts creeping up. 202, 207, 212, then the light turns green, I start moving and the the engine gets back down to 197-198.
If I put it in neutral or in park, the engine will get up to about 204-206 and hold steady there.
It’s only when I’m stopped but still in gear that it continues to creep up. I sat in my driveway the other day to kind of test that out and see if it would hit a max and hold steady, it didn’t. I got to 238 before I turned the car off and let it cool off. (Someone told me that the fan kicks on at 235, I was 99% sure that was wrong, but I let it get up that high just to make sure)

I’ve checked the coolant, it’s not low, off color, etc.
I had the radiator flushed last summer, about 16k miles ago.
I’ve gone to the car wash and really cleaned out the ac condenser and radiator to make sure it wasn’t all plugged up with dust, bugs, etc that would prevent air flow.
I just changed the oil the other day, it was normal from what I could tell.

I even towed our camper (about 3500lbs loaded)earlier this summer and it was completely fine, ran about 198 the whole trip.

Any ideas of what’s going on here?

Alright, so this sounds EXACTLY like what is going on with my 4Runner.

Its not the fan clutch... The problem is most likely a blocked heater core. I know this is the worst news but at least the engine didn't overheat! I, just like you, are fairly attentive to various operations of my car. I caught the same thing start happening on my last road trip. I started to have to downshift manually and rev the engine whenever I stopped for a prolonged period of time. This was the only reason I could keep the temperature down.

Do this test: allow the car to begin to overheat, when it first begins overheating apply the throttle in park (or neutral) and rev the engine to 1500-2000 RPM and hold it there. There may be a momentary jump in temperature in the first few seconds, but it should begin to cool.

Also: while stopped and engine warmed up to operating temp, turn on the heat on full blast. Typically a heater core will result in loss of heat while the car is not moving. You could miss this symptom because most of us have no need for heat in the summer.

To test thermostat: (and my guess is that the thermostat is not your issue) allow the car to warm up, touch the upper and then lower radiator tubes (carefully they will be very hot, or infrared gun them) they should both be warm/hot. If one is seriously off in temp, then it can be the thermo.

Hope this helps. Unfortunately the entire dash needs to be removed to replace the heater core. Its costly as far as labor goes. May as well do the evaporator core at that mileage so an a/c recharge would be in order. Best of luck! My money is on the heater core... Most mechanics, unless they really know cars, will go on a wild chase replacing the coolant, radiator, thermostat, fan clutch, water pump etc before they finally track the ACTUAL problem down

 

[thennen]

Agree with AuSeeker. Additionally, when the engine is nice and warm/hot, and turned off, the fan should be much more difficult to turn if the fan clutch is good. It will turn more freely when cool.

 

[radlynx]

it could be just the thermostat

Looking for some expertise here on what might be going on.
2005 V6, 197k+ on it right now. This has been going on for the last few months now.

I’ve had a scan gauge in the 4Runner for the last 5+ years, so I’ve always paid pretty close attention to the exact temp that it runs at.
Once the engine is warm, in the past it always ran between 190-195 degrees, driving, stopped in traffic, didn’t matter.

Now when I’m cruising along, the temp has been in the 195-200 range consistently, not alarming, but it is higher than in the past.

Where the issue is, is when I’m in traffic, a drive through, anywhere I’m stopped but the vehicle is still in gear, the engine temp starts creeping up. 202, 207, 212, then the light turns green, I start moving and the the engine gets back down to 197-198.
If I put it in neutral or in park, the engine will get up to about 204-206 and hold steady there.
It’s only when I’m stopped but still in gear that it continues to creep up. I sat in my driveway the other day to kind of test that out and see if it would hit a max and hold steady, it didn’t. I got to 238 before I turned the car off and let it cool off. (Someone told me that the fan kicks on at 235, I was 99% sure that was wrong, but I let it get up that high just to make sure)

I’ve checked the coolant, it’s not low, off color, etc.
I had the radiator flushed last summer, about 16k miles ago.
I’ve gone to the car wash and really cleaned out the ac condenser and radiator to make sure it wasn’t all plugged up with dust, bugs, etc that would prevent air flow.
I just changed the oil the other day, it was normal from what I could tell.

I even towed our camper (about 3500lbs loaded)earlier this summer and it was completely fine, ran about 198 the whole trip.

Any ideas of what’s going on here?

 

[MT Runner]

A few things to report back on here, maybe it gives someone a little bit more clear picture of what it might be.

I did a few things that were listed above to test some stuff.

While at a long light this afternoon, the engine got up to 206. I put it neutral and revved it to about 1600-1700 and held it there. Sure enough the temp came all the way down to 190 within a matter of 15-20 seconds. I put t back in D while I was sitting there and it went right back up to 204 before the light turned green.

When I got home I sat in the driveway with it idling in P and it was a pretty steady 204. I then turned the heat all the way to HI and the fan on high. I let it do this for about 2 minutes or so to really see what it’d do. The temp got all the way up to 211 doing this and consistently bounced between 207-211. I turned the fan off entirely and let it sit for about another minute, the temp came back down to 204 pretty quickly and held there.

Then I turned the engine off and popped the hood to check out the radiator hoses. The upper hose was hot, to the point I’d just tap it with my hand to feel the heat, definitely not going to hold my hand on it too long.
The lower hose was warm, but I could actually put my hand around it and hold the hose. So there was a clear temp difference in the two.

So... does this mean it could be the heater core because of the revving test I did that 00_4runner recommended?
A thermostat because of the difference in temp between the hoses?
A fan clutch because of the relative ease that the fan spins at when the engine is off?

Combination of one or more of them?

 

[AuSeeker]

A few things to report back on here, maybe it gives someone a little bit more clear picture of what it might be.

I did a few things that were listed above to test some stuff.

While at a long light this afternoon, the engine got up to 206. I put it neutral and revved it to about 1600-1700 and held it there. Sure enough the temp came all the way down to 190 within a matter of 15-20 seconds. I put t back in D while I was sitting there and it went right back up to 204 before the light turned green.

When I got home I sat in the driveway with it idling in P and it was a pretty steady 204. I then turned the heat all the way to HI and the fan on high. I let it do this for about 2 minutes or so to really see what it’d do. The temp got all the way up to 211 doing this and consistently bounced between 207-211. I turned the fan off entirely and let it sit for about another minute, the temp came back down to 204 pretty quickly and held there.

Then I turned the engine off and popped the hood to check out the radiator hoses. The upper hose was hot, to the point I’d just tap it with my hand to feel the heat, definitely not going to hold my hand on it too long.
The lower hose was warm, but I could actually put my hand around it and hold the hose. So there was a clear temp difference in the two.

So... does this mean it could be the heater core because of the revving test I did that 00_4runner recommended?
A thermostat because of the difference in temp between the hoses?
A fan clutch because of the relative ease that the fan spins at when the engine is off?

Combination of one or more of them?

When you turned on the heater did you get hot air out of the vents?

If yes then I don't think it's the heater core.

BUT

This is what I would do, especially if you can do the work yourself.

Replace the thermostat, it's the least expensive and easy to do and if it's never been replaced this would be a good time to do it, go OEM, don't cheap out on this because many have had issues with after market, if it solves the issue, great you're most likely done.

If the issue is still there then next if you didn't get hot air out of the vents, I would disconnect the heater core hoses (be careful not the flex the metal tubes of the heater core very much when removing the hoses or you could crack them where they are soldered to the core and they will leak) and use a garden hose to see if water flows through it easily, if it does I don't think the heater core is clogged and the issue, if water doesn't flow easily then you mostly likely have some blockage, try the opposite direction with the water flow and you maybe able to backflush some of the clog out, I would say to try some compressed air but it's risky, if the core is clogged it's most likely from corrosion and compressed air may cause muliple leaks in the core, or unless someone put some stopleak in it at some point could cause blockage.

If it's the heater core you're looking at a very labor intensive and expensive job to have a shop do it and as suggested I would also do the AC evaporator at the same time since they're both there more or less together and you don't want to do this again if the evaporator goes bad later, this is also a job a novice shouldn't be doing and also make sure any shop you choose is familar with the job because the entire dash has to removed along with many other parts and conponents and it all has to go back together correctly.

If the heater core dosen't seem to be clogged move on to replacing the fan clutch.

Just an FYI, if the fan clutch is going bad, revving the engine will do what you experienced of the temperature dropping because the fan even with the fan clutch being weak will spin faster and thusly cool the engine.

Let us know what you find out.

 

[thennen]

Still going with fan clutch. Again, it should be difficult to turn by hand when hot. Check that.

 

[MT Runner]

Thanks for the input. I did get hot air out of the vents when I had everything on high, so I guess that may be a good sign.

Sounds like I’ll start with the thermostat and then on to the fan clutch. Really hoping that it’s not the heater core, I’ve heard plenty of horror stories about that with other vehicles as far as the cost goes.

I’m about to hit 200k and I’ve said I plan on seeing 300k, so it’s a repair I would ultimately do, I just don’t want to pay for it! Takes money away from other fun stuff I want to do.

 

[thennen]

Btw, my wife and I love Montana. It's our favorite state. Looked into moving a couple of times but couldn't pull it off. Hoping we can at least visit again soon in a new T4R.

 

[waypoint]

Sounds like I’ll start with the thermostat and then on to the fan clutch. Really hoping that it’s not the heater core, I’ve heard plenty of horror stories about that with other vehicles as far as the cost goes.

I'd do it the other way around, with the fan clutch being first. Malfunctioning thermostats impact cooling system performance under all operating conditions...if yours was stuck, it would overheat while the vehicle was moving, not cool down.

You don't want to keep overheating the aluminum heads & block or you risk blowing a head gasket.