So I've read through a lot of the forums and checked most of what needs to be checked when the temp gauge goes higher than normal and the car begins to overheat. This just started about 3 weeks ago and as my daily driver I need to figure this out ASAP...

SITUATION:

When in stop and go traffic, sometimes the temp gauge steadily rises to around 70%-90% and I've never let it go higher than that (into the red for example). When the traffic frees up and I can drive at least 20 mph then usually the temp starts to decline. I've noticed a gross anti-freeze smell 3 times so far and when I pop the hood the hose has popped off the overflow bottle. I just bought a hose clamp to keep it secure. I've been lucky the last week to where the traffic has freed up to the point to where the needle on the temp gauge hasn't got to the red point...

I drove the car for 10 minutes to bring it to normal operating temp, and then stopped in a parking lot and popped the hood to watch for fan to turn on. In this car historically, the temp is "stable and normal" with the needle on the temp gauge around 1/4" below the half way point. When I watched for fan engagement yesterday it went to a little over 50% on the temp gauge and then the fan turned on. I let it idle for another 5 minutes, and the temp needle went up to the aforementioned 75% high level which is hot... This time the fan did not turn on..? Not sure what the issue is here.

REMEDIES TAKEN SO FAR

1. Checked for leaks - there are none
2. Checked radiator for blockage of fins (dirty, etc.) and all is OK
3. The fan itself obviously works, and was replaced within the last 10 months.
4. At the same time the fan was replaced, I also replaced the fan switch that is threaded into the engine block.
5. I checked levels of anti-freeze/water and they are ok.


All I can think of now from looking at all the other posts as far as possible other causes are:

1. Air bubble in system (but seems unlikely and I've never experienced this as an issue ever in 20 yrs working on cars)
2. The fan switch, although only 10 months old, has an issue where it only works intermittently
3. Bad water pump? - Isn't a "bad water pump" usually just referring to the fact that it is leaking water? It isn't leaking so does that mean that it is good? It is also fairly new (less than 40k miles to my knowledge).


Any help here is certainly appreciated...

 

How about the thermostat? Check the top and bottom radiator hoses after the car reaches normal operating temperature, if there is a significant difference, then your thermostat might not be opening.

 

Thermostat - good point...could be. Cheap enough to swap out really quick.. I'll check those hoses as well.

When you mean a difference you mean 1 hose is hard/filled with water and the other is not correct?

 

That could be another symptom. But I mainly feel for a temperature difference.

 

How many times have you overheated it?

 

I wouldn't say that it "overheated" - Its never been to the redline...I've been lucky so far to where it has stayed under the redline however it has me worried... I'll probably swap out the thermostat as a cheap precautionary measure.

Is it possible there is a relay in the wiring that turns the fan on/off that only works part of the time? Perhaps its on it way out?

 

If the temp is rising above normal than its overheating. If you started driving and the temps went back down to normal than its either the water pump isn't cycling the fluid like it should, thermostat isn't opening and also the fan switch isn't on the engine block its actually on the thermostat housing.

 

I replaced the radiator cap and haven't had issues since. The old cap was rated at like .9 bar and the new one I believe is 1.2 bar. So far so good.

 

good to hear, and for the record, your water pump can be shot without leaking at the weep hole. the impeller can be worn/sheared to nothing, have bearing failure, etc.

 

Update...car still overheating...

Replaced the thermostat with oem honda....still overheated.

Fan was still not turning on so replaced the fan relay in the underhood fuse box and bingo...the fan now works again.

Let the car idle until fan kicked on....fan remained on and coolant temp still rises as before all the way to 3/4 hot then I shut the car off... This is where it stands as of now.

When I begin driving again, the car quickly cools down.

Oil is clean.

Coolant is clean.

Plugs looked clean when recently changed.

I did notice since a/c has been installed it is overheating more often....could be a fluke not sure. Need to check if it overheats with a/c off.

What could it be now?

Water pump?
Radiator too small? Get del sol radiator?

 

water pump