Darinm

I'm trying to chase down a ghost cooling issue. The reason i call it ghost is the gauge shows my engine running hot at random times, but the infra red temp gun shows otherwise.

When i rebuilt my engine recently while installing it, i broke the flat tab on the temp sensor on the head, so i replaced it with an O'reilly sensor for my car. I mention this since it's the only thing in that chain that is new.

Randomly i will get my temp gauge go up sometimes pegged yet when i pop the hood, i can still see coolant flow (clear tube inline with upper radiator hose), my infra red temp gun shows in multiple places temps anywhere between 150 and 185 so i know the motor is not overheating.

My only thought is possibly the sending unit is bad ? I know there is no air pockets due to the clear tube. Is there a certain resistance i could check on the sending unit when it shows running hot ?

I've searched the other threads and checked everything i was able to read including the collapsed lower hose which it's not. I've replaced the thermostat and now out of ideas.

Thanks in advance.

69Vett

start with verifying your sender unit and gauge.
remove sending unit, connect long wires to sending unit.
connect car gnd. to sending unit body/threads, use a hose clamp to secure gnd.wire.
set sending unit in pan of water, with a thermometer.
water begins to boil at 212 F. verify your car gauge with 212F.
verify thermometer also agrees with boiling point, then check lower temperatures 160 against the thermometer.

you can use a long extension cord, (DO NOT PLUG INTO wall) to get to the stove,
by using short jumper wires to the temperature plug and gnd. on the car.
then on other end of X-cord, use short jumper wires to sending unit.

The C3 cooling systems can be difficult to get all air removed from the system,
so be sure you air filling in a manner to avoid air trapped in system.

Big2Bird

Does your lower hose have a spring inside?

Darinm

Sure does. I saw that in another thread.

Darinm

Is there a doc anywhere on this procedure ? I've read that trapped air could cause this anytime the air bubble hits the sensor, but no clue how or what you would do to avoid this ?