1969 Skylark running HOT!!!

[Brad]

Prior to an engine overhaul, this engine ran pretty hot. Still does. What I've done so far:
Engine overhaul
Radiator overhaul
All New hoses
New Thermostat
New Heater core

Could the fan clutch be bad? How can you tell?

[WildKitty]

I assume it's a 455
Have you pressure tested the cooling system?
Was the block flushed out?
What do you consider too hot?
My 445 runs about 200
Have you tried adjusting the timing?

[suntreemcanic]

Have you verified the gauge is correct?

[bob k. mando]

Could the fan clutch be bad? How can you tell?


when the engine is cold, the fan should be easy to rotate by hand.

idle the engine up to operating temp.

try reving the engine up by operating the butterfly linkage by hand.

does the fan seem to gain rpm with the engine or does it lag behind?

turn the engine off.

try turning the fan by hand, is it stiff?


of course, you could always just swap out the clutch drive for a direct drive fan. if that takes care of the issue, you know the clutch was bad.

[Brad]

I assume it's a 455
Have you pressure tested the cooling system?
Was the block flushed out?
What do you consider too hot?
My 445 runs about 200
Have you tried adjusting the timing?

The block and heads were vatted prior to rebuilding. That was my first thought because it had been running straight water (in California) for years and had lots of deposits. I haven't pressure tested the cooling system. It continues to climb past 210, then I get nervous and turn it off. The timing is set as well. And, it's a 350.
Thanks for the reply.

[Brad]

Could the fan clutch be bad? How can you tell?


when the engine is cold, the fan should be easy to rotate by hand.

idle the engine up to operating temp.

try reving the engine up by operating the butterfly linkage by hand.

does the fan seem to gain rpm with the engine or does it lag behind?

turn the engine off.

try turning the fan by hand, is it stiff?


of course, you could always just swap out the clutch drive for a direct drive fan. if that takes care of the issue, you know the clutch was bad.

Thanks Bob, Thanks for the info.

[Brad]

I got the Skylark started this weekend and the fan clutch is indeed bad. After the engine got up to 210, I shut is off and the fan spun freely like it did before I started it up.

[bob k. mando]

yepper, that's usually not a good sign.