ahofam123

Does anyone know the direction that the coolant flows on a 84 944 NA. Is it down the engine block through the thermostat up the radiator, or is it down the radiator through the thermostat and up the engine block?

I am just trying to diagnos a radiator problem and would like to see which hose should get hot

Cass944

i think it goes block, thermo, radiator, then heater core. i only think so because thats the way it came gushing out when i took mine apart. so im not really sure.

Cass944

no that doesnt even make sence. it should go from the radiator to the block so that the coolest fluid is always in the block, but thats just something i thought up?

SidViscous

Can't say for exactly on the 944. But every car I've ever seen the water pump was a pusher. the thermostat blocks flow to the radiator and heater core is taken just before the thermostat.

That demands that the water comes into the top of the radiator and down to the water pump, else you'd have to prime the water pump. Ours is a pressurized syste, but I doubt they would have the water pump sucking against gravity.

Coolant flow in a 911 is much easier to figure out.

triscadek

Don't know for sure, but I've been told that it goes radiator through the thermostat to the motor.

Sounds weird but I was told that it was backards of normal systems, I even heard the phrase "our cars" in the description.

jackstand951

this is one I sat and pontificated for many moons. Looking at the direction the water pump spins the water it looks like....
Water pump...block...heater core valve(if its open)...heater core...back to water pump. Also water can go Water pump...block...back to water pump...or top of block (air bleed off valve) front wards to radiator ..then water pump thermostat(and if it is open), then back to water pump. This is my current understanding of the 944 cooling universe. Someone tell me if I'm wrong...

944geek

On every upright car ICE I am aware of, the coolant flow always goes with gravity. Coolant flows through the engine to the top hose across to the radiator, down though the crossflow radiator where it is cooled as it descends and then up through the bottom hose into the thermostat housing. In this way the mass of the coolant is always assisting the water pump to draw water up through the engine.

944geek

That is backwards. Coolant is almost always gravity assisted. Otherwise your water pump is trying to push coolant uphill through the radiator instead of using gravity to help it go downhill though the radiator as it is cooled and keeping a head of pressure (mass) on the water pump to assist it in drawing the water up into the block/head. I would be very surprised if it was otherwise.

944geek

ICE upright engines are almost always gravity assisted. Water is drawn though the thermostat housing from the bottom radiator hose up though the engine block/head across the top of the engine, heating it and removing het load from teh engine as it goes( the head being the hottest part of the engine). it then goes out the top hose and across into the top of the radiator and down through the crossflow radiator out the bottom hose and back up though the thermostat. In this way the mass of the coolant assists the water pump. If it was opposite the water pump would always be working against gravity. If the water coming out of the radiator is too cool, the thermostat shuts and doesn't allow water into the engine. Eventually enough heat is transmitted into the cooling water column and radiator that the water in the bottom hose exceeds the thermostat temp and it opens. You can tell the direction of flow in your 944 by looking at the thermostat in the housing. The inlet is on the radiator hose side and the outlet is on the water pump/block side. Hot is up, cool is down... Use an infrared thermometer and you can see the lower hose is always cooler than the top hose. That is why the thermo fan switch is near the top of the radiator.

944geek

Quote:
Originally Posted by triscadek
Don't know for sure, but I've been told that it goes radiator through the thermostat to the motor.

Yep that's right. ICE upright engines are almost always gravity assisted. Water is drawn though the thermostat housing from the bottom radiator hose up though the engine block/head across the top of the engine, heating it and removing het load from teh engine as it goes( the head being the hottest part of the engine). it then goes out the top hose and across into the top of the radiator and down through the crossflow radiator out the bottom hose and back up though the thermostat. In this way the mass of the coolant assists the water pump. If it was opposite the water pump would always be working against gravity. If the water coming out of the radiator is too cool, the thermostat shuts and doesn't allow water into the engine. Eventually enough heat is transmitted into the cooling water column and radiator that the water in the bottom hose exceeds the thermostat temp and it opens. You can tell the direction of flow in your 944 by looking at the thermostat in the housing. The inlet is on the radiator hose side and the outlet is on the water pump/block side. Hot is up, cool is down... Use an infrared thermometer and you can see the lower hose is always cooler than the top hose. That is why the thermo fan switch is near the top of the radiator

Gage

Thanks for this physics lesson... been 21 years in the making

harveyf

It's been a while since I wrote the article linked below. There is a lot more info than the OPs original question but after reviewing the article, I agree with @944geek. Here is a cut/paste of the key paragraph.

I frankly was not sure what side was in and what side was out. A simple experiment determined what was what. I took my 944R out for a ride to get it warmed up. Then I aimed my infrared thermometer at the two hoses. The upper hose was a good 50 degF hotter than the lower hose. This told me that the hot water flows from the connection on the top of the cylinder head and the cooled water flows back to the connection at the water pump.

https://newhillgarage.com/2018/02/04...tem-explained/