Hello friends. I have a question about my trusty 300. On Saturday I cruised it for an hour up I-75, the car ran beautifully. My temp gauge indicated that at highway speed, the engine was operating at around 185-190 degrees. Mind you, I have removed the thermostat from the car, because here in Tampa the weather can get warm. The radiator appears to be newer, replaced by the previous owner. So my questions are: is 185-190 degrees a little too warm for highway speed driving? If I were to upgrade to a better radiator, what would I get, and where would I get it. Specific model numbers and specific websites would be most helpful. Thanks a lot, Rich in balmy Tampa
This is just an assumption and correct me if im wrong but I always thought the thermostat also helped keep the coolant in the radiator longer to cool it down better? And 195 is great by the way. Sent from my LG-H811 using Tapatalk
I agree with you Matt. The temperature is fine, but it really needs a thermostat to "slow" the water down. If it doesn't "touch" the inner walls off the water passages long enough it cannot absorb the heat of the engine.
Thanks Gents for the posts. I'll assume all is OK at my current operating temp. I took the stat out because warm up isn't an issue here in Tampa...this winter we never got below 45 degrees. As for the water flow, I'm of the mind that the faster circulation is aiding in the cooling. That's my story and I'm sticking to it! Actually, it's quite tropical here, so I'm sticking to just about everything!p
No, not the case at all. Standard thermodynamics, faster the coolant moves, the more heat that will be transferred, just like more air that passes through the radiator the more energy is transferred, exact same principle. If you slow down the water the only thing that happens is it spends more time in the block getting hot and more time in the radiator cooling down, and it's a push on energy transfer, but you will see swings in your engine temperature. If you have a good radiator and no thermostat you shouldn't see temps over 130-140F. If you are, you are running at the max capacity of your cooling system, and no thermostat will get it lower. Running a thermostat does three things. The obvious is restricting water flow to keep the temperature higher than the radiator would keep it otherwise. The less obvious is keeping the engine hot enough to boil out the water that builds up in the oil. For this you really need a minimum of 180F coolant temp for a fair period of time, and a pcv system helps too. Water breaks down the oil additives and makes it more acidic which eats internal parts as well as creates sludge. Hotter is better. The next less obvious thing is to create extra pressure in the head since it's a restriction, which keeps boiling bubbles from forming around the exhaust port. Once the bubbles form the exhaust valve and seat get real hot, real fast, so the slight "extra" pressure of the restriction have that advantage, though the system as a whole is typically under a few pounds of pressure already.
Slightly misleading as you still need a restricter in place of the thermostat to control flow otherwise cooling can fail due to too fast flow and minimal heat transfer
X2. If the OP's temperatures cooled down at low speed, I'd say the radiator has seen better days. With no stat, it should run way cool if the radiator is up to snuff.
Not true, the radiator becomes the next restriction and the same effects happen, only less efficiently since the rubber radiator hose will have some flex to it (as opposed to the metal of the head and engine block) when the bubbles want to form around the exhaust ports. If you have a good water pump, (small water pump pulley, high end electric water pump, etc) then the cooling system pressure can be kept up fine with the radiator as the restriction. The other issue of not running a thermostat is not getting the engine up to a high enough temperature to clean out the oil, since the thermostat should be setting the MINIMUM engine operating temperature.
My 50+ years of racing and my engineering degree disagree. I've seen many people with hot running engines make their problem worst by removing their thermostat, 100% of the time. If you remove the t'stat, at least put a washer in that has the same opening as a fully open t'stat. I would never run an engine without a t'stat, cold running engines are self destructive.
If your not going to use a true Tstat then at the very lease put a restrictor in there to slow down the coolant so it stays in the rad a bit longer. 195 is not bad but 180 would be better.Take your old stat and cut the center out. put just the outer ring back in place.
Yeah, if you pull the thermostat in a marginal cooling system and the water pump doesn't produce enough flow/pressure to let the radiator be the restriction the water will boil in the heads and once the boiling starts its a run-away condition, things get hotter real fast (as I said in my second post). IF the water pump has a smaller pulley on it or get a nice 55gpm electric water pump, that changes things. 99% of the time a stock water pump won't produce the pressure and most people that swap pulleys tend to slow the pump down rather than speed it up which will make a running hot problem worse, despite the water having more residency time in the radiator. I'm pretty sure we are arguing the same point. Run a thermostat and running too cold is bad for engines. :TU:
I'm not sure the radiator is the point of most restriction even without a t'stat. We have put 1 partition in the upper tank and 2 in the lower so the coolant zig-zags through the radiator, even with that it flowed well. Doing that forces coolant into the "dead corners" of the radiator that usually don't get much flow making it more efficient. Anyway, someone may have taken this t'stat out because of an over heating problem. With it out, it should be running 150 tops. There could be a partially clogged radiator, junk in the block or a pump that's not working at full capacity. I once bought a car that had a new pump and no water was flowing at all. I started the engine without the t'stat housing on and the water just pooled in there. It turns out when the previous pump went bad the impeller went back and hogged out the housing so the gap between the housing and impeller was so big it wouldn't pump, changed the housing and it pumped like crazy. Buick timing covers can get electrolysis damage in the pump housing area if the cooling system wasn't flushed often enough. It's almost impossible to find one in a salvage yard these days without electrolysis damage.
I always thought of water flowing too fast thru the radiator and not enough heat transfer to being able to run your hand quickly thru/over a flame and it not burning you, verses going slowly thru the flame and your hand gets hot:shock:
The one time I removed a thermostat, on a car that didn't have an overheating issue (dumb teenager) the car barely got over 120F, and every time I've had a thermostat fail open the cars hadn't gotten over 140F, so my observations match the assessment of a thermostat-less car with a normally performing water pump and radiator should always run lower than any thermostat you can purchase. Like I said earlier, for all the extra time your water spends in the radiator getting cooler, it's spending an equal amount of time in the engine getting hotter. See if holding your hand over the flame for five seconds at a time, then away from the flame and over a fan for five seconds then back on the flame for five seconds and see if your hand cools down fast enough... A safer, real, test of course would be using a piece of aluminum plate and a temp gun. Then test it with the aluminum in constant motion back and forth over the flame and fan. If your rhythm and data tracking is good you'll see the average temperature of the aluminum in both tests should be the same (same amount of energy transfer). But you'll see that the temperature data on the one test for holding the plate over the flame then over the fan for a period of time will have larger swings in the max and min temperatures. Increasing the fan speed and/or increasing the pace of the aluminum will drop the average temperature, but increasing the time the plate spends over the flame and over the fan will only widen the max/min range and not change the overall average temperature.
I still disagree with the theory that straight flow thru without restriction that it spe d equal time in block and radiator. As I have done so and ambient temp and engine speed has a lot to do with this. It will run much cooler in cold temps hotter in hot temp. Air flow from fan or from driving changes it also. Actual engine size and load on engine varies it also. Not to mention on a diesel enging without the pressure build from heat you will cavitate a engine block . I suggest keeping a thermostat in engine and keep proper temps the engine needs to operate properly on street . long term use could cause problems
