Running a little hot - cooling system

[RH318is]

Had the car in for brakes and a wheel bearing and had the shop look at the cooling system as well because it had just started doing this - temp. would raise while sitting at a stop light. From about the 1/2 mark to in the middle between the 1/2 and 3/4 marks.

The shop said the following:
Coolant a little low, at the bottom of the reservoir
Pressure tested and found no leaks, but cap is old and leaking
After topping off coolant, test drove and temp. gauge was fine
Checked fan clutch, good
Checked thermostat via radiator hoses, good
Hoses and belts all looked good
Recommend new cap and coolant flush

In the end they topped off the coolant and put a new cap on. The car ran good for about a week, I noticed some liquid on the ground a couple days ago, touched it. Didn't feel/look like oil. Today, the temp. starts doing the same thing. Sitting at stop lights it's starts moving up.

Any ideas? Would a flush help? Could they have missed a leak?

What's the safest temp. to let the engine get up to before (seriously) worrying about a cracked head?

[jlevie]

Running hot at idle or during stop and go driving is usually caused by a bad fan clutch, a bad thermostat, or a combination of those. In some cases, a partially blocked radiator or a bad water pump impeller can be added to the list of causes. But the pace to start is the fan clutch and thermostat.

[ethirtydavid]

Thermostats are fairly cheap - when you are driving around getting airflow before you reach the red light, does your heater blow hot? Because if it does then that means your thermo has allowed the coolant to enter into the second half of your cooling system. If this is the case, I think it's safe to say your thermostat is not the issue..

Pressure testing is nice to have done, I wouldn't worry about a cracked head just yet..
You said you saw some liquid under your car.., if you parked your car while it was still a bit hot then some extra coolant could have dripped out from the coolant overflow hose as coolant rushed back to the reservoir.

if you think they may have missed a leak -turn the car on and let it heat up, move around inspecting hoses and watch the ground for drips..

[RH318is]

Thanks guys. Some additional info I didn't have time for earlier. The same shop replaced the thermostat, fan clutch, did a coolant flush and replaced hoses I think it was 2 years ago. Yes, 2 years ago. According to the invoice I told them the car was running hot when sitting in traffic and too cool when driving.

Right now it's basically sitting at 1/2 way and then goes up when sitting still, definitely not running too cool.

What do you think I should do first? I don't really think it's leaking, I noticed some fluid after it had been sitting for an hour.

[Todd Black 88]

Fan clutch.

[RH318is]

Ok, here's a more accurate description.

First, with freeway driving the temp. gauge sits just under or right at the 1/2 mark (65-70 mph). Appears to perform normally.

While driving on city streets it's about the same right at or just under the 1/2 mark. When idling or sitting at a light the needle starts moving up usually to near/at the middle between the 1/2 and 3/4 mark. When I start moving from the stop light the needle moves back down to just under, or even slightly more, the 1/2 mark.

I do get hot air out of the heater.

I guess I can still drive it this way as most of my driving is freeway. The question would be what's the hottest temp. reading that safely away from cracking the head, up to 3/4?

The fan clutch was replaced two years ago along with the thermo., doesn't this sound like the thermo. might have gone bad again?

[///M42 sport]

I had similar symptoms. I noticed a leak in my overflow tank. It would usually spew coolant right after I parked the car and the temp rose. I ended up replacing the radiator which fixed the problem. But the overflow tank and also be replaced by itself.

[Todd Black 88]

Fan clutch.

Your description fits fan clutch failure perfectly. Its only really in use when the car is stationary. The temp drops when you draive away because the air in front of the car is now going through the rad and taking the heat away. This is supposed to be done by the fan clutch when the car is stopped.

[jlevie]

That description fits a fan clutch or thermostat... Both can be tested, but you will have to remove the thermostat to test it.

[HST]

Are you missing a fan blade by any chance?? Other wise replace the fan clutch and thermostat.

[prb44t]

I am having the same problem... If the fan clutch were bad, when the car is parked at idle the radiator fan would it still work? And correct me if I am wrong but isn't there some warning if the radiator fan isn't working? I remember reading somewhere that it causes the blinkers to fast flash or something??