engine and drivetrain Fluctuating temperature after replacing most of the cooling system

[gordon415]

Yesterday I replaced the radiator, thermostat, water pump, and hoses (all from Walloth & Nesch). I filled it with coolant slowly and heard it burp a few times as I was doing it. Drove it around, checked the coolant levels when hot, when cold, added more coolant as needed, and all seems good. Did that last night and again this morning. Don't see leaks anywhere. 

 

Drove it it on the highway today and the temp gauge started creeping up to 2 o'clock when I was going up hill. It would even out to 3 o'clock going downhill or flat. It didn't fall much lower than 3 o'clock at any point in time, which I thought was weird since the radiator is the extra-cool W&N special. Stat is 80 degrees and brand new. Heat works fast (and drops the gauge quickly when driving up hill). 

 

Are these just things that happen when a new stat is breaking in, is there an air bubble, is the stat defective, or did I screw something up? 

 

 

[Son of Marty]

Did you have the heater valve set to high heat when you filled the system? It sounds like air in the system with the car cold try loosening the heater hose on the left side of the heater box with the heat set on high and the nose of the car raised up a little and burp the air out of the heater see if it helps. 

[gordon415]

I'll give that a try. The heater was set to high, but glad to hear it might just be an air bubble causing the problem. Thanks for the help. 

[conkitchen]

Sounds like there might be a head gasket leak. 

Is there condensation on the oil filler cap and or and milky sludge? steam out the exhaust even after warm up? 

Another test which is easy is test the radiator coolant for exhaust gas intrusion. Any repair shop can do that for you or I believe one can buy the test kit at the local air fresher, spray on cleaner and oil change auto parts store. 

[xferboy]

although it doesn't sound like its an issue, ground your temp gauge (and fuel, since you're there), just to be sure.  A piece of thin gauge wire to one of the funny nuts behind the gauges, then a jumper across to the other.

 

My temp guage would jump from 2:45 right to 1:00.  I could wiggle the connector at the back of the gauge panel and it would come back down.  After grounding, no funny jumps in temp reading.

 

 

[gordon415]

7 hours ago, Son of Marty said:

That did the trick! I could hear it burping when I slowly pulled that heater hose free. I took the same drive I did this morning and the temp gauge didn't go any higher than 3 o'clock. Woo hoo! Thanks for your help!!!

 

6 hours ago, conkitchen said:

Sounds like there might be a head gasket leak. 

Is there condensation on the oil filler cap and or and milky sludge? steam out the exhaust even after warm up? 

Another test which is easy is test the radiator coolant for exhaust gas intrusion. Any repair shop can do that for you or I believe one can buy the test kit at the local air fresher, spray on cleaner and oil change auto parts store. 

I looked under my oil filler cap and all was good. Thanks for the suggestion.  I'm glad it wasn't as big of a deal as oil and coolant mixing. Phew! 

 

5 hours ago, xferboy said:

although it doesn't sound like its an issue, ground your temp gauge (and fuel, since you're there), just to be sure.  A piece of thin gauge wire to one of the funny nuts behind the gauges, then a jumper across to the other.

 

My temp guage would jump from 2:45 right to 1:00.  I could wiggle the connector at the back of the gauge panel and it would come back down.  After grounding, no funny jumps in temp reading.

 

 

My gauge has always bounced around a bit and I usually have to smack the top of the dash in the morning to get it to start working. It wasn't what was causing the fluctuation in temp, but you reminded me that I need to finally fix that. I grounded the fuel and temp gauges before my drive and no more bouncing. One more thing to check off the to do list! Thanks.

 

This was the first time I took the instrument cluster out and found a few loose wires and an odd-looking nut sitting back there. One loose wire was for the cigarette lighter, so I got that working again. The other was a single yellow wire with a female connector end. I have no idea what it's doing or where it goes. I do have problems with the instrument lights, license plate lights, and sidelights working consistently. I wonder if that wire would have anything to do with that, or if I need to see if anything is loose on the hazard switch (my 02 is an early '71 so it has the old hazards on the left side of the dash). I need to check a wiring diagram. 

[Son of Marty]

50 minutes ago, gordon415 said:

That did the trick! I could hear it burping when I slowly pulled that heater hose free. I took the same drive I did this morning and the temp gauge didn't go any higher than 3 o'clock. Woo hoo! Thanks for your help!!!

 

 

 

Some are harder to purge than others, I never could figure out why, must be a karma thing.