inactiveuser92616

your engine is designed to operate at one specific temperature. All the components inside the engine were made in such a way that at that temperature, everything lines up nicely, your oil is the right viscosity, your pistons seal well, etc. Higher or lower than that temp and the expansion of the non similiar materials is unequal, leading to larger gaps and non optimum operation.

The Hammer

Thanks, your resposes are quite informative.

I guess the same conclusions would apply to installing a lower temp thermofan switch. The replacement I bought is 82/92C; perhaps I should get an original spec 92/102C

541 enthusiasts2

i have a porsche 944 and just rebuilt the top end before the engine did overheat now it does i have to turn on the fans manually and a fuse for the foglights blew and i saw smoke from the diver side. also im running no thermostat is that a problem too? any ideas?

DHS928

You need to restate your issues, did the car overheat and you had to rebuild the head? (Fix a warped head?) is your electrical harness correct? The temp switch should control your fans, also over about 30mph you usually do not need the fans because your airflow will be sufficient. The thermostat is designed to keep your engine at a proper temp for max effectiveness, also by stopping the flow in the radiator it gives more time to cool the fluid. Even race cars engines use stats, if they didn’t need them they would not have them. So please re- state your question?

Dan

V2Rocket

Running without a thermostat will not cause the engine to overheat.
Max temperature is entirely up to the ability of the radiator to dump the heat out, which at low speeds is up to the radiator fans. As said above, by around 30mph there is enough airflow coming through the radiator that the fans aren't really needed anymore.

Thermostat sets a temperature "floor", not a ceiling.

Regarding the idea of the thermostat as a sort of speed limiter for the coolant, that's not really the case. Anything you can do to increase coolant flow will result in more heat being dumped out of the system (raises system efficiency). In the heat exchange equations more flow, whether water or air, still makes overall efficiency go up. What most often happens is that the thermostat (or the giant washers sometimes used in race cars) help keep the coolant pressure inside the engine higher (much higher than the radiator cap rating) which ensures the coolant 1) fills all the voids in the engine and 2) doesn't boil at extreme hot spots.

Gage

Another consideration in not using a thermostat is that the bypass port within the waterpump will never be closed. This will affect the flow rate through the block and radiator and may cause uneven (elevated) temperatures at the rear of the cylinder head.

541 enthusiasts2

it was the thermofan switch i have fixed it already. I fixed the head because of a valve issue

541 enthusiasts2

I have a 1985 Porsche 944 and the security wires shorted out because someone put the bypass wires in the wrong spot making the short and now my car won't run. What do I do?

walfreyydo

I havent been running a thermostat for 5 years now (car only driven in the summer) and have not had any issues. I only know this because I recently pulled off the hose to the waterpump and to my surprise discovered nothing there.

541 enthusiasts2

did you see my question? I really need help

walfreyydo

Start a new thread, you bumped an old thread (related to thermostats) that has nothing to do with your problem.

541 enthusiasts2

how do i do that im new to this

GPA951s

Running no t/stat on the street might not cause severe issues but on the track might cause it to overheat. The water needs “ time” too cool in the radiator, with no t stat it just blows through.. this is the reason “ twin pass” radiators are used in race cars the coolant spends twice as much time in the rad.

curtisr

Having a thermostat means the engine will gradually reach the desired operating temperature. This is a good thing. In sport we used the analogy of a race horse versus a work horse. If you're a race horse then we need to work our way up to racing heart rate and the reverse at the end of the event. If you're a workhorse well, that ain't happenin'.