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Car temperature guage fluctuating

after successfully replacing my clutch and reassembling my 2003 eclipse RS, i now have a problem. When driving, the temperature gauge fluctuates between halfway and the quarters of the way up. its all good-ish. unfortunately, when i turn the heater on, it runs hot for a little while, and then gets very cold. tonight i almost went into the red on the temp gauge when i turned it off after it got cold on me. what should i be looking for? HELP!!!

Check the coolant level and make sure it is full. There may be a air bubble causing the heater problem but there may be head gasket problem and exhaust gases are getting into the coolant and causing the trouble. Have a block check done to see if that is happening.

how can i check for an air bubble? i drained and removed the radiator hoses to gain better access to my transmission, could that have cause the air bubble? also what would cause a head gasket problem during a clutch replacement?

You probably just have air still trapped in the cooling system. If you don’t have any air bleeders, I’d just - carefully - run the car from cold to hot with the radiator cap off for a few warm up cycles while tapping & squeezing on the upper radiator hose.

I think the above post is correct.

i drained and removed the radiator hoses to gain better access to my transmission, could that have cause the air bubble?

Certainly. I would expect it.

will check after school today. winding things down for the school year, so i should have time. I’ll let ya’ll know the results.

To get the air out of my 2000 Blazer’s cooling system I put it up on ramps to get the radiator as high as possible. I remove the radiator cap and start the engine with the heater running, as the engine warms up the trapped air should work its way out. I watch the radiator level and add coolant as needed.

Ed B.

The quickest way to remove trapped air in a cooling system is, get the engine up to operating temperature. With the engine idling, slightly loosen the clamp for the upper radiator hose. Take a flat bladed screwdriver and slip it between the radiator hose and the hose neck of the radiator. Allow the engine to idle until all the air is purged from the cooling system. Retighten the hose clamp.

Tester