1960s AC thermal fan clutch late 390 engine

[Clewisiii]

About 5 years ago I bought a new fan clutch from a Cadillac seller. I know they just repackaged another clutch and called it Cadillac and charge more.

Well after sitting for years the clutch is leaking. So I wanted a new one for the rebuild.  I went through 6 auto parts stores with them trying to match it up. I bought one wrong one from them, and I bought one wrong one from Amazon.

Finally the correct one is a Haden 2710. I thought the caddy seller put a brass bushing in the box to help it fit. But the Hayden box also came with a bushing. The Hayden part can be bought for $30. The caddy sellers ask $75-100

[V63]

I cooked an engine once due to a fan clutch that failed, my only warning was the temp light came on and due to traffic situation I couldnt escape to shoulder fast enough.

Then engine was so hot it would NOT shut off... it was dieseling, I couldn't get it to stall by putting it in drive, the car drove with ignition off. I was able to get the fuel supply shut off to kill it.

I didn't know what was at issue until I finally realized the fan was no longer pulling enough air.

I was DONE with fan clutches after that 😤 I convert all mine to fixed blade (flex fan)

[Chopper1942]

You say your fan clutch is leaking. How bad is it leaking? It is normal for there to be a small amount of fluid leakage around the seal. If you want to check the fan clutch for operation, run the engine up to normal operating temperature and let it run for awhile. Get a 1"x2" about 3' long, with the engine off place the end of the board against the tip of a fan blade. Have someone start the engine. If the fan pushes the board away, the clutch is OK. If you can hold the fan, you need a new clutch.

If you have a fan clutch or a getting one for a spare, open the box and check the clutch orientation of the clutch in the box. Store with the aluminum clutch down.

Most of the clutches are the same expect for the length of the hub and the hub bolt pattern. Now as you can see, the bolt pattern is slotted so it can be used on different applications.

[Clewisiii]

You say your fan clutch is leaking. How bad is it leaking? It is normal for there to be a small amount of fluid leakage around the seal. If you want to check the fan clutch for operation, run the engine up to normal operating temperature and let it run for awhile. Get a 1"x2" about 3' long, with the engine off place the end of the board against the tip of a fan blade. Have someone start the engine. If the fan pushes the board away, the clutch is OK. If you can hold the fan, you need a new clutch.

If you have a fan clutch or a getting one for a spare, open the box and check the clutch orientation of the clutch in the box. Store with the aluminum clutch down.

Most of the clutches are the same expect for the length of the hub and the hub bolt pattern. Now as you can see, the bolt pattern is slotted so it can be used on different applications.

It left a puddle in the bag. Made a mess.

[Clewisiii]

The biggest issue was the diameter of the flange. Most were 2.6. We need less the 2.4 to fit the fan over it.

[Chopper1942]

That's what happens when the fan clutch is not stored correctly. Just because the label may be right side up, it doesn't mean the part is in the box correctly.  Especially with fan clutches, you want to inspect them at the parts store or as soon as you receive it.

[Cadman-iac]

  Chopper is right, these have to be stored correctly to prevent the fluid from leaking.
The right way to store them is standing it upright in the same position as it would be in when installed on the car. It's not completely filled with silicone, only about halfway, and when spinning it all goes outward to engage the unit as needed.
I've had some that I've removed from vehicles and kept for decades without issue by keeping them in the upright position.
And some seepage around the seal and the front on one's with the coil and shaft that engages it  is normal. Even a new one will leak when laid down on it's front or back side.

  As for testing one to see if it is still working, I have seen some guys use their hand to hold the fan, but I don't recommend that method.
Chopper's method would work better, but don't totally block the fan, because if the clutch is still functional, that can ruin it. Just "attempt" to prevent it from spinning initially at startup, and let it go if it wants to spin free.

Rick