SR weird overheating problem...

[ILikeMy240sx]

Problem: The car overheats with thermostat but when I take the thermostat out it does not over heat.

Steps taken: Tried three different thermostats and they all made the car overheat. They all refused to open up causing the radiator to be cold but the engine hot. Also, I changed out the water pump but that didn't do anything. I made sure there are absolutely no bubbles in the system.

I am really out of ideas on this one... What could cause the thermostat to not open up?

[ILikeMy240sx]

BTW, if I take the thermostat out, the cooling system works perfectly fine... The gauge sits right in the middle but the cabin heater air isn't that hot...

[9240sx]

Are you sure your not installing the Thermostat in backwards??What kind of Thermostat are you using??For what Car,And what Brand???

[ILikeMy240sx]

Yeah, im 100% sure Im installing it the right way. Jiggle valve up top and the spring assembly goes into the housing...

I have bought 2 thermostats for 91 Sentra SE-R and a Nissan thermostat for the same year and model.

It's a redtop.

[9240sx]

That is a weird problem??? Maybe your putting to much RTV and its getting around the thermo and acting like glue to were the thermo door opens.And locking it shut.I forget the amount Nissan says you have to use but its small,Like 1.something MM all the way around and alittle on the bolts.

[9240sx]

Ok i check my FSM and its says to only put 2mm of RTV.Hope that helps

[ILikeMy240sx]

I kindda figured that might be the problem so I tried it with no RTV at all and yeah... that still didnt work..

[Hijacker]

check for blockage throughout the cooling system.

i've seen where someone put too much stop leak in the radiator causing the radiator to get too hot (which would account for the car cooling off with now thermo in). another thing is to check for kinks in the cooling hoses (radiator and heater core hoses)

[ILikeMy240sx]

It was the coolant temp sensor and the switch for the gauge...

I replaced both sensors with a 93 KA sensor and everything works fine. The gauge reads correctly (although I need to get a REAL temp gauge) and it doesn't run like crap...

I guess the SR sensors are weird and was telling me it was overheating when it wasnt... very very odd.