Eliminate thermostat. Good idea or not?

[dutchgeordie]

I have had overheating problems too many times with the thermostat often at fault. I normally only drive the car in nice weather, certainly not in freezing temperatures, never even below 6 or 7 degrees celsius.
I am therefor thinking about basically eliminating the thermostat, closing of the re-circulation to the radiator and having the route to the engine permanently open.
Is this a good idea or will it be bad for the engine as it will take (slightly) longer to warm up?

[TX82FIAT]

While the thermostat T is a common failure point because there is often air stuck in the T causing the thermostat to not open or the thermostat itself fails. I'm not sure I would remove mine if I lived in a cold weather climate. The bypass allows the coolant to reach temperature sooner and then circulates through the entire system. A quicker warmup in a cold weather start is a good thing before motoring down the road. If only a summer driver than maybe.

[MattiR]

Hi

I am driving my Spider only when +10C or warmer, so very interesting idea to eliminate thermostat. Should the water hose come then direct from bottom of the radiator to water pump? And then block the hose from T-connector to thermostat? Then hot water will go from head to radiator, gets cooled in the radiator, and then from bottom to waterpump and further to engine. Probably a bit easier to get air out from cooling system as well.

[TX82FIAT]

I think you would have an L pointing to the drivers side (left front) coming out of the head rather than a T. You could cap off the T. You would take out the thermostat and run the lower radiator hose on the right side to the pump. This would create one loop of coolant through the radiator rather than the short and long loops. You would need to reconfigure the lower hoses a little.

[GeorgeT]

The PO of my Spider ('82) had simply "gutted" the thermostat allowing free flow of coolant. I didn't notice it until when driving cool weather going downhill the temp would drop. I did replace it as I drove it all year round in hot and cold weather. If you eliminate the thermostat consider bypassing the heater core too as it won't be needed as is another area for leaks in the cooling system.

[MattiR]

The PO of my Spider ('82) had simply "gutted" the thermostat allowing free flow of coolant. I didn't notice it until when driving cool weather going downhill the temp would drop. I did replace it as I drove it all year round in hot and cold weather. If you eliminate the thermostat consider bypassing the heater core too as it won't be needed as is another area for leaks in the cooling system.

Thanks George!
I'm not sure what "gutted" means, but would be good prevent the free flow from head to pump, and force the hot water to go first to radiator and only after that to pump.

[RRoller123]

My opinion is that it is not a good idea. These cooling systems are perfectly fine when everything is in working order. You may need a flush, could have an air block, or a radiator clog/block, trapped air, T-Stat in backwards, a bunch of things. Better to just get it working right, and then they seem to keep these cars plenty cool enough, even in Summer heat. The engine likes the stability that the T-Stat provides too. Constantly increasing and decreasing temp of the block, head, oil, etc is not a good thing.

[tima01864]

Always have dreaded replacing the coolant, Last time with a timing belt water pump exchange. I followed the procedure in the manual, I think the trick to it was filling slowly, Taking a 4 cup measuring cup and filling the radiator slowly. Heard a nice gurgle and continued with the procedure. Started the engine anticipating massaging the hoses, maybe adding the prestone Tee, Went to temperature and the fan kicked on. Never so easy with my 1608's I may not of been doing this right. I agree as above with Rroller123 on bypassing the thermostat.

[TX82FIAT]

Add the T fill on the hose to the heater as the highest point in the system it makes running a few cycles and burping the car much easier. +1 on the keeping the T Stat in place. Unless you have some type of highly sensitive electric pump the T stat mechanically helps stabilize temp just fine. With the block and head design you are going to have some expansion so why stress the system any more than needed. Again, I would only consider if driving in warm weather or if you had some alternative means to keep temperatures in a tighter range.

[SteinOnkel]

The thermostat also limits the flow rate of the entire system. The longer the coolant is inside the radiator, the cooler it gets. If it just blasts through unrestricted, it will overheat.

Bad idea. Fix it right.

[JohnMc]

I have not tried it on the Fiat but you might want to look up "vacuum filling coolant" on google.
Seems pretty cool. I had a 1980 FI and it was a pain to get the coolant full.

[TwinFast]

The thermostat also limits the flow rate of the entire system. The longer the coolant is inside the radiator, the cooler it gets. If it just blasts through unrestricted, it will overheat.

Bad idea. Fix it right.

Yes the thermostat limits the flow rate to the engine .... but only during the heating process. At the moment the engine has reached the optimal temperature the thermostat becomes open and the coolant flow is no more restricted and go freely inside the radiator.

I use my 1978 Spider since 3 years without any thermostat. It's a Californian Spider imported to France with only the thermostat housing and nothing inside. The car reach the optimal temperature very quickly even if the climate in the north of France is cooler than the south of California ...

I also have the same overheating problem than all the Fiat 124 drivers and i just found the reason ...

I used an infrared thermometer and found that the temp switch is always cooler than the rest of the cooling system and the engine. When the temp gauge is around 190/200° F the temp switch is only at 175°/180°F . So the fan start later when the temp switch reach 190° ... and the temp gauge reading more than 220°F.

My solution is to put a low temperature radiator fan switch activates the cooling fan at 180° F

[SteinOnkel]

A thermostat in "fully open" setting will still restrict flow more than not having one at all. This is why you are overheating.

Guys, it's not complicated. The factory did not put in a thermostat because they needed to get rid of them. An internal combustion engine is designed to run most effectively in a certain temperature range. This is dictated by the engine design and achieved with the thermostat. Removing it is a completely asinine bandaid "fix".

[TwinFast]

A thermostat in "fully open" setting will still restrict flow more than not having one at all. This is why you are overheating.

Guys, it's not complicated. The factory did not put in a thermostat because they needed to get rid of them. An internal combustion engine is designed to run most effectively in a certain temperature range. This is dictated by the engine design and achieved with the thermostat. Removing it is a completely asinine bandaid "fix".

Thanks for the advice. I'll consider to invest some fresh euros in a new thermostat

[18Fiatsandcounting]

I think we're arguing amongst ourselves here, but I have to agree with SteinOnkel on this. The coolant flow through an engine has to be designed to allow heat transfer from the block and head to the coolant, and then from the coolant to the radiator core where the heat is radiated away. If the coolant flow is too fast, there isn't enough heat transfer occurring, and the engine heats up, although the temperature gauge may not show it.

Another important point to make: The temperature shown on the gauge is what the sensor thinks it reads at a particular point in the radiator, and this temperature may not be reflective of reality. The extreme example of this is if you were to drain out all the coolant, run the engine until it fries, all while noting that the temperature gauge never moved from its rest point. Why? The location of the temperature sensor never saw any hot coolant, since it was all drained out.

Many things could cause erroneous temperature readings: bad sensor, inaccurate gauge, blockage in the radiator near where the sensor is, low coolant, insufficient (or too much) coolant flow, etc. Heck, the gauges on my '69 124 all move up slightly when I turn on the headlights, so it looks like I've got more gas (whoo-hoo!!!), higher oil pressure, and 10 degrees higher temperature. I have no idea whether the readings are more accurate when the headlights are on or off...

My advice: Keep the engine the way it was designed and use a thermostat.

-Bryan