Clutch fan info needed 69 Coronet BB

[Dennis H]

26 inch radiator. Green coolant, fresh flush. Shroud. 180 Superstat. Shot up to 210 in traffic and started to balk. got moving and it dropped to about 170 in less than 5 minutes. stopped, left engine run and observed the fan spinning. Shut off engine, now 183 by thermal temp gun at waterpump housing. I was able to spin the fan by hand, not completely free, but close. SHOULD the fan be rigid at op temp with engine off?

 

[themechanic]

This may help.

[video=youtube;qXpRSwa4P2A]https://www.youtube.com/watch?feature=player_detailpage&v=qXpRSwa4P2A&list=UUw-YHUueKo-9chXZY1bwEwQ[/video]

They talk fans about the 9 minute mark.

 

[Dennis H]

Interesting and informative, never saw that before. I don't want to throw parts at this problem without knowing what it is. Can fan speed be measured? It is probably the original fan. Should I just replace it anyway. If it is a not-moving only issue, it has to be flow right?

 

[Dennis H]

The resistance when spinning the fan is the same when dead cold in the am after overnight as it is at full warm up with engine off. Is this normal. Think the clutch is slipping? Hard to tell how fast it is turning at different temps.

After market ac. Is it the heavy duty thermal or regular? OEM 36956? Think it is related to a sea-level tune at 5000 feet?

 

[vin_vl29u]

My easy test for fan clutches. Turn off motor while watching the fan. Good fans come to a stop fairly quickly, tired ones seem to spin way to long. I've never measured a time, so it's hard to say, but anything over a couple seconds of spinning is to long for a/c car. Even a thermo fan will never trully "lock up" They will tighten up once it hits a certain temp, somewhere over 200 degrees.

I installed a non thermal hayden this spring, my old fan was tired. Temp gauges goes 1/8" past the first line in traffic with a/c running. Went with the non thermal because I wanted max cooling at slow speed. If I did more highway, I'd go with a thermal.