Vehicle is overheating

[Thunderbolt]

I realize the thermostat is set to control the engine temp, But that only controls the max temp the engine will get without the stat opening. If the fan is cooling the radiator faster than it needs to, when the stat opens the engine temps drops more than it needs to until the coolant in the engine warms back up. I have experienced it a few times. I am not saying a flex fan can't be used just that it wouldn't be my choice. The flex fan also robs power since it is on all the time. If it does not work properly with what came on the truck something isn't working properly. The size of the radiator, size and function of the fan, water pump ,radiator cap and the ratio of the antifreeze all play their roll in the engine temp and if any one has a problem the system will not function properly.

[Doug Rodrigues]

Well, if you're worried about these issues, just replace anything defective with stock components. That should put your mind at rest. But I should mention that after I installed my flexi-fan, my engine didn't run one bit different temperature wise, nor did the fuel consumption change. The fan was noiser, but for me personally I had the peace of mind knowing that no fan clutch was going to go bad again at the wrong place at the wrong time. It's just my personal opinion.

**But while we're on the subject of over-cooling: Would it be accurate to say the in sub-freezing weather as in 10 degrees below zero, would a stock fan with the stock fan clutch over-cool the radiator? What effect would it have on the engine? Think about it. The thermostat isn't there to open at it's maximum temperature, it's there to raise the engine temperature to normal operating temperature at which the thermostat is rated for. For example, a 195 degree thermostat will keep the engine very close to 195 degrees. It's not a maximum temperature....it's the normal operating temperature.

[Thunderbolt]

Doug, I am not trying to argue because I believe you have a valid point. What your last reply said about the stat is exactly what I meant I just didn't word it right. It actually does control the max temp which is what the operating temp is. If you have a 160 thermostat in there under normal circumstances it will run around 160 and lokewise with any other temp stat. Does this mean the engine can't get hotter ? Absolutly not ! The stat starts to open as the temp approached 160 or whatever temp stat you have and is fully open by the time it reaces that temp. All things being normal that temp is what the engine will run at. Change coolant ratio, or have a bad fan or a restriction to flow and the engine will rise above the stats temp. I have had several trucks through the years that I tried flex fans on and some of them just didn't seem to like them.. Will it hurt anything ? probably not. I never said anything about fuel mileage. I do know that the optimum operating temp for the 88 and up chevy trucks is 195 and this is where they are designed to run. I have never had a clutch fan just up and konk out on me and I check mine often and when they spin to freely or get play in them I replace them with a heavy duty one. I know flex fans are good,But there is nothing wrong with clutch fans and my whole point of my first reply was to get that point across. If the clutch is bad replace it is all I am saying. If the clutch fan worked for as long as it did why change it ?? My fan on my truck moves just as much air as a flex fan if not more and I don't have to listen to it all the time. My 92 had 180,000 miles on before the fan acted up, But it never overheated. I put a hevy duty clutch on and 45,000 later it still works. My 98 is on 175,000 and the fan still works great. All I was trying to say is if a vehicle works for 70,000 miles with certain components and one finally needs replacing why change it to a different type when the ones that were on there worked that long ?? Also if a clutch fan is suspect in overheating and it is replaced, But the vechicle still runs hot so you put a flex fan on and it runs a little cooler you still haven't fixed the problem and something else isn't functioning properly.

[Doug Rodrigues]

But that's my point...putting on a solid fan won't make it run any cooler. The thermostat will still maintain the engine temperature to it's designed temperature. Next to no circulation will occur if the thermostat remains closed. The thermostat forces the engine to rise to it's designed temperature. If the temperature goes higher than the thermostat's designed temperature, then the thermostat is stuck closed, or there is crud in the radiator which prevents adequate heat exchange, or there is no liquid in the radiator. Radiators which have mineral deposits don't dissipate heat fast enough. They'll work okay in cold weather, but when hot weather arrives the engine overheats.....a good reason to use distilled water with the anti-freeze instead of tap water. Maybe my postings are just adding to the confusion....but I'm not confused.

[Thunderbolt]

I see what you mean and I agree.