Engine cooling


Well-Known Forum User
Two questions:-

Should the two cooling fans run all of the time or kick in when the car reaches a certain temp?

Will the signal from either the CHTS or water temp sensor cause my stalling problem if it gets too hot -ie switch off before causing any serious problems?

Think I may have made the dumbest basic error, thinking there was a problem with my chts, when actually it is doing the right thing and switching the engine off!

Thought my fans were not kicking in because it wasn't heating up enough before cutting out. Managed to get it running longer with a resistor in the chts circuit - didn't stall but still no fan kick in -so switched off. Radiator cold, top water pipe hot, bottom cold. Possibly a blockage or coolant temp sensor sticking (has been replaced in last year) or possibly water pump? Any thoughts?

Z31 Turbo 1987


Engine cooling fan(s) are controlled by two temperature sensors in the base of the radiator. Temp switch #1 turns on first fan at 90 degrees C. Temp switch #2 cuts in at 100 degrees C. Non-A/C cars have just one fan which is two speed. A/C equipped cars (and some modified cars) will have the second fan which comes on with the second speed of fan #1. Second fan will also operate when A/C is switched on regardless of temperature.
Check that your two radiator coolant caps are fitted the right way round - plain cap on the engine high point and sprung cap on the reservoir.
Is the thermostat opening?


Z Club Member
I can't properly remember, my had Z31 had A/C, I believe one fan run when it reached a certain temp, then if it got hot, the second fan kicked in, or if I switched on the A/C, the second fan would also kick in.


Well-Known Forum User
Thanks Mike/Chas.

Pretty sure the car was hot enough for both fans to be kicking it. Doesn't seem like the thermostat is working, presume this allows for the flow of water around the system once warmed up. As the lower pipe was cool, I am assuming there is no flow.

I'll have a look the the FSM check the connections and locate and remove the thermostat for checking. Thought it had been replaced recently, but looks like pump and thermos were done back in 2006.

I seem to have an excessive amount of water coming out of the exhaust (not all of the time), but not in the engine oil, think this may be pressurised water not being circulated forcing its way into the engine seals?



Active Forum User
Chappo i was opening my radiator cap nearly every 2 days and noticed i had to fill it up with at least a pint i also had water running out of my exhaust i spoke to my mate about the problem who is a car machnic. And told me he had a car with same probleme and told me about a pproduct he used called. K-Seal cost £10 its a product from U.S.A. It worked for me i have no more problems with loss of water it ( it also claims Head Gasket repair Block/head Sealer. Radiator Stop-Leaks) for £10 pounds it is worth a go hope it helps Raymond