Thermostat Issue/concern

[Tottie]

Hi guys, just a quick question that I hope someone can help me with.

I recently replaced my thermostat and water pump. Now my car normally would warm up until 90 degrees and then the fan will come on.
Now after I replaced the water pump and thermostat my fan kicks in at 98 degrees (constantly) and brings it back to 90 degrees. I know it must be because of the thermostat that kicks in at 98 degrees. Is this anything to be concerned about? Should I replace my thermostat? is 98 degrees to hot for the car? please any help would be appreciated

Thanks.(2004, VW Citi Life, 2l8v ADY)

[panic-mechanic]

Thermostat does not make the fan come on. It open the water circulation from the engine only to the radiator.
Perhaps you mean thermo switch?

[THANAS]

98 sounds about right for the fan activation point, the thermostat should only open at 87 degrees.

[Tottie]

fan switch yes. sorry. thanks for the feedback. my only concern is my heat gauge never went past 90 degrees before. now with the new pump and thermo it goes up to 98 degrees before fan kicks in. is this not much of a concern? I'm just concerned my car might run too hot.
Thanks again.

[panic-mechanic]

On at 98 and off at 90 is just fine.

[amstel18]

off topic but your username reminds me of this song...

[Tottie]

Thanks for the feedback guys, much appreciated. now i can sleep peacefully.

[Tottie]

Hi guys, an you please assist me on another issue on the same topic. This morning i started my car and let it war up. At 90 degrees i noticed my top radiator hose is hot (normal), bug the bottom one cold. I kept on to monitor ot only to realise the bottom one got hot when the fan came on. The fan kicked in at 98 degrees. Does this mean my thermo is opening at 98 degrees? My fan use to kick in at 90/92 degrees with the old thermo. Now it kicks in at 98 with new thermo. Thermo i bought from GW a week past weekend. Should i replace the thermo? It worries me sitting in traffic. I also noticed foam like brown stuff in my water bottle when i toped it up earlier. But oil still clean. Any advice would be appreciated. Thanks

[THANAS]

Post some photos.

[Tottie]

Ive added some coolant so its not there now. But it looks like the brown water dirt that cooks loose when water is hot.

[Tottie]

Just in a foam form

[panic-mechanic]

This shortening of words / terms is a mess in this discussion as it makes it unsure about which item you are talking about.
So clarity
Thermostat is a device that opens a port (and closes one in these motors) and it moves a plate at a given temperature. It is a thermo mechanical device - no electrical connection. It is found at the bottom of the waterpump in this car
Thermo switch. In this car it sits at the bottom left of the radiator and has an electrical connection. it closes a circuit at a certain temperature.

SO when the engine is cold the THERMOSTAT is closed which stops water flow to the radiator and instead allows the water to only circulate in the engine. So the hoses attached to the waterpump that goes back to the head will get hot but the bottom radiator hose will stay cold. and so will the radiator bottom. top might feel sligthly warm. So the result is that there is no hot water in the radiator at this stage so it stands to reason that the thermo switch will also not activate.
Once the water reaches the thermostat opening temp and that is usually around 90 degrees the thermostat will start opening allowing the water to go through the radiator and at the same time it's other side starts to block the bypass flow through the motor. Now the radiator will start heating up and all the pipes will get hot. Once the entire system reaches the temperature that the THERMO SWITCH activates at the fan will run until it get to thermo switch cutoff temp when it will stop the fan form running and that cycle will now continue.
So what you are feeling is perfectly normal and indicate a correctly working system.
Please use full words in this context otherwise you just make it hard for people to understand.

[Tottie]

Hi,

Thanks Panic-Mechanic. Sorry for the bad typing, I was typing from my phone as fast as i could.

I totally understand your explanation. It's just that when my temperature reaches about 98 degrees, THEN only does the bottom hose get hot and the fan kicks in immediately. At 90 degrees my bottom hose is still cold.
My fan previously kicked in at about 90 degrees before I replaced my Thermostat.
Thus I'm assuming my THERMO SWITCH should normally activate my fan at about +- 90 degrees. But because my Thermostat is only opening at +- 98 degrees (I'm amusing), my Thermo Switch activates the fan as soon as the hot coolant reaches the Thermo Switch.

Hot coolant continues to circulate the engine until the temperature reaches 98 degrees (with old Thermostat it didn't go past 90 degrees), Thermostat opens at 98 degrees then the fan kicks in immediately dropping the temperature back to 90 degrees. It will follow this cycle continuously. Only when I'm driving on the freeway it will be constant at 90 degrees but then the fan does not come on.

This is the theory I have at the moment. Could this be correct? I'm thinking of getting a new Thermostat that opens at about 89 degrees. Is there perhaps a specific number I should ask for at Goldwagen?

Sorry for the long stories. I just want to ensure my car is sorted as it's my only means of transport to work and I drop my wife and kids as well.

[panic-mechanic]

The thermostat should open at a temperature lower than the thermo switch kicks in.

[Tottie]

Yes correct that's why I was concerned why my bottom hose did not get hot and temperature was close to 98*C. Only got hot at about 98*C and the fan kicked in.
I will be replacing the Thermostat and Thermo switch at the same time.

Thanks again.

[Tottie]

Hi guys,

Just an update on this to close the loop. So on Saturday I replaced the Thermostat and fan switch, but had no luck. Fan still kicked in at 98*C. Yesterday while I was at home I sat and just tried to think back at all the things I original replaced when the fan starting to kick in at 98*C. I then realised I also replaced the Water Temp Sensor. Luckily I still had the old one. I removed the new one on the car and fitted the old one back and whala everything was back to normal. fan kicked in at +-90*C and doesn't move pass that mark.

Thanks for the help guys

[panic-mechanic]

So the display was incorrect while everything else worked fine. Always the risk of changing a whole bundle of stuff at the same time