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Possible cooling jacket blockage


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While changing the head temp sensor in my '83 280ZXT, I noticed that when removing it (under #5 spark plug on the passenger side) I didn't get a flow of coolant.

I know this sensor is supposed to be immersed in coolant, so I may have some kind of blockage keeping coolant from flowing freely into that area. Not good.

My thought is to pull the sensor again, remove the radiator cap and try shooting some compressed are into the mounting hole. That hole is about 1/2" in diameter, so I should be able to get a good fit for an air nozzle with tape around the tip. I have a variable pressure valve for my air compressor so I can limit the pressure to perhaps 30 PSI, which is roughly 2X the pressure the cap holds. I don't think it would be a good idea to shoot 80-100 PSI in there.

I want to eliminate any blockage, but I really would prefer to avoid pulling the head.

Any helpful thoughts about this idea?

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Relax. There is no coolant access there. You have no blockage. Study the sensor body, you will see no fluid sealing mechanism. It is just measuring the temp of the aluminum head to gauge engine temperature, which should be very similar to coolant temperatute.

Clean the body and hole to ensure good thermal conduction, but most problems people have is with the electrical connection to the sensor being dirty and corroded causing false resistance values that throw off the ECCS resulting in an overly rich condition while warming up.

Check the sensor resistance values at 20C and 80C using the FSM charts on page EF & EC-87 to check if its reading correctly, and clean the connector and pins thoroughly. Make the measurement at the ECCS connector to include the connection at the sensor to see if its making good contact.


Edited by zKars
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