Engine Getting Hot While Sitting Still and In Gear

[catrains]

when an engine runs hotter stopped that is most all the time fan clutch...

if it was a radiator issue that would cause it at all vehicle speeds..as well as the T stat..

also radiator is with debris on it ...mud ?

 

[radlynx]

it's possible it's the fan clutch but in my opinion, I would replace the cheap part first which is the thermostat.

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.

 

[ghs215]

Here is my advice as it comes with experience with my runner.

Radiator Cap needs replacement. To check, when you see your temps creep up, go under the hood and squeeze the top rad hose. Is there any give or is it freaking rock hard? If there is any squish, your rad cap is letting just a tiny bit of pressure escape. Remember back to physics:

Pressure * Volume = Temp

If if your pressure from the water pump is constant (idle) and the volume is fixed (closed system) then your temp should be constant.

But if your rad cap is leaking (into coolant overflow tank) which will proportionately lead to pressure drop, then your temp will rise inversely.


PS...If I'm correct, and probably are - you owe me a beer :beer:

 

[waypoint]

[MENTION=90911]MT Runner[/MENTION] did you ever get it fixed? This was a tough troubleshoot and posting your outcome will help the next guy with this issue.

 

[nevada]

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

a clogged heater core will never cause an engine overheating problem. in fact, pretty much all vehicles have a valve that prevents the coolant from entering the heater core when you select COLD on the heater controls. this would essentially be the same thing as a clogged core, IE no coolant flow.

heaters are secondary systems, they are there for passenger comfort only, and are not necessary for proper engine operation.


as to the OP, it sounds like maybe a bad water pump. I have seen the blade rot off, when that happens, you need higher rpms to get the fluid moving. I would also take a good look at the clutch fan, as mentioned above.

 

[MT Runner]

[MENTION=90911]MT Runner[/MENTION] did you ever get it fixed? This was a tough troubleshoot and posting your outcome will help the next guy with this issue.

Sorry, I still haven’t been able to really get to this yet. It’s been a busy last couple of months traveling for work, etc.
Once I get to replacing the fan clutch and get an answer I’ll be sure to post back here with my findings.
As much as I want to get this fixed and fully plan on it, it’s a relatively easy thing to monitor and make sure it doesn’t get to hot as I’m in the vehicle. So it just hasn’t been top of my priority here lately. I’ll get it though!

 

[MT Runner]

So the answer is......

The thermostat.

I’ve been busy at work lately and haven’t had the time to get to it myself. I finally took it to a local shop that specifically works on Toyota's, Honda’s, Subaru’s, etc. I explained the deal and told him my not so professional opinion was that it was the fan clutch, but since they had the 4Runner there and I have almost 200k on it, go ahead and just replace the thermostat also.

I found out that the fan clutch is totally fine and they ended up replacing the whole thermostat housing assembly and new coolant. All seems to be good.