1973 Dodge Fan Clutch

[1970FuryConv]

Another Fan Clutch question.
I was not intending to replace my fan clutch. I left it sitting on a table and went on vacation for a week. The center under the spring filled with a clear goo/thick fluid that has a gray tint. This pic is after I used rags to remove the fluid under the spring. Questions

• Does AC clutch have a front seal that can leak out its clutch fluid?
• If not, what causes this issue?
• The spring seems small. What does it do to help the clutch operate?
• I guess mine is junk, unless the seal can be replaced. I am guessing correct?
• Thanks, Ben

Aftermarket, judging by the slots

 

[triple red]

A leaking clutch is junk.
The hot air coming from the radiator heats the spring. It turns and opens the valve ports and the silicone fluid can enter the working area and engage the clutch.

 

[Trace 300 Hurst]

It's not the seal.

Fan clutches must always be positioned (and stored) with the forward (spring) side down, or in the vertical (in the car) position. Otherwise, as you have discovered, the silicone oil inside (goo) will slooooowly leak out. I recall that the box for a new clutch, and I think the clutch itself, had a "This Side Down" marking to prevent the goo from leaking out. Anyway, with that goo leaked out, your clutch is done.

The spring isn't a spring. It's a bimetallic strip (like in older home themostats) to open and close a valve in the clutch (based on temperatures) to control the flow of the goo.

Think of the clutch as something very similar to a torque converter.

Here's the full info:


And here's the fix:

 

[Big_John]

As Trace said, it was stored wrong.. and why I never would buy a used one because they are always stored wrong.

$37 from Amazon for a Hayden 2747 (my recommendation) https://www.amazon.com/Hayden-Automotive-2747-Premium-Clutch/dp/B000C3F370

 

[1970FuryConv]

It's not the seal.

Fan clutches must always be positioned (and stored) with the forward (spring) side down, or in the vertical (in the car) position. Otherwise, as you have discovered, the silicone oil inside (goo) will slooooowly leak out. I recall that the box for a new clutch, and I think the clutch itself, had a "This Side Down" marking to prevent the goo from leaking out. Anyway, with that goo leaked out, your clutch is done.

The spring isn't a spring. It's a bimetallic strip (like in older home themostats) to open and close a valve in the clutch (based on temperatures) to control the flow of the goo.

Think of the clutch as something very similar to a torque converter.

Thanks, Trace
It's strange that storage face down doesn't bring in gravity and cause leakage.
I'll watch the video.
Based on your rec, @triple red, and Big John, I ordered Hayden HD 2747 from Amazon. I ordered expedited delivery and Amazon has a warehouse close by in Petersburg, so I should have it shortly. I'm not sure of engine condition, so OE fan clutch is not in my budget. We need to see if the 360 is an oil burner.

 

[Trace 300 Hurst]

It's strange that storage face down doesn't bring in gravity and cause leakage.

I ordered Hayden HD 2747 from Amazon.

Face down (spring down) has nothing to leak from. Face up, it leaks out the shaft as there isn't really a seal there. In the vertical position with the engine off, the oil level doesn't come near that seal. When running, the oil is slung around the perimeter of the housing. Nothing to leak.

The Hayden unit will do just fine. I bought the Tony's item for the full reproduction look.

 

[Trace 300 Hurst]

I never would buy a used one because they are always stored wrong.

Always!!

 

[1970FuryConv]

As Trace said, it was stored wrong.. and why I never would buy a used one because they are always stored wrong.

$37 from Amazon for a Hayden 2747 (my recommendation) https://www.amazon.com/Hayden-Automotive-2747-Premium-Clutch/dp/B000C3F370

Face down (spring down) has nothing to leak from. Face up, it leaks out the shaft as there isn't really a seal there. In the vertical position with the engine off, the oil level doesn't come near that seal. When running, the oil is slung around the perimeter of the housing. Nothing to leak.

The Hayden unit will do just fine. I bought the Tony's item for the full reproduction look.

I think it's an odd design to have something leak because it's stored wrong. I'd rather have no spring, no opening, and no leak > same performance regardless of temperature. But I usually learn the hard way. No exception today.

 

[triple red]

One of my daily drivers, a 1982 Mercedes 200D, has the fan directly mounted to the engine without a clutch, nothing can leak there. The downside of this is that the car slowly warms up in the winter month because of the always working fan. To have a fan clutch is not a bad thing I think and it´s easy to replace.

 

[Big_John]

I think it's an odd design to have something leak because it's stored wrong. I'd rather have no spring, no opening, and no leak > same performance regardless of temperature. But I usually learn the hard way. No exception today.

Actually, it's a matter of the seal around the shaft acts like almost any other shaft seal. That is that it's not "watertight". Stand an engine up on it's end and oil will leak past the rear seal or the front seal (if on it's nose). The seals are meant to contain the fluid splash, not fluid. The level is actually below the seals. Anything else would be more expensive and wouldn't last long.

The one without a spring was just used in HP cars, like the Hemi, where there was no A/C and it was just about the slippage at higher RPM. You want the spring.

 

[thethee]

Face down (spring down) has nothing to leak from. Face up, it leaks out the shaft as there isn't really a seal there. In the vertical position with the engine off, the oil level doesn't come near that seal. When running, the oil is slung around the perimeter of the housing. Nothing to leak.

The Hayden unit will do just fine. I bought the Tony's item for the full reproduction look.

Had mine stored spring side down when I changed my timing chain and it still leaked some. Guess I'll add "fan clutch" to my shopping list..

 

[Trace 300 Hurst]

I think it's an odd design to have something leak because it's stored wrong.

Lots of things go bad if they're stored wrong. Food, wine, medicine, machined steel parts, vinyl record albums.....

Actually, it's a matter of the seal around the shaft acts like almost any other shaft seal. That is that it's not "watertight".

Exactly. When I stated above that there isn't really a seal, I should have said it's not "sealed". A fancy, leak-proof seal would restrict the free rotation of the clutch vs. the shaft, somewhat defeating the purpose of the temperature-compensating clutch unit. And that seal would wear out, unlike the "loose" dirt seal that is there now.

 

[1970FuryConv]

Actually, it's a matter of the seal around the shaft acts like almost any other shaft seal. That is that it's not "watertight". Stand an engine up on it's end and oil will leak past the rear seal or the front seal (if on it's nose). The seals are meant to contain the fluid splash, not fluid. The level is actually below the seals. Anything else would be more expensive and wouldn't last long.

The one without a spring was just used in HP cars, like the Hemi, where there was no A/C and it was just about the slippage at higher RPM. You want the spring.

I guess the dissimilarity it that if you store an engine with the top facing up, nothing leaks because gravity holds the fluid at the bottom.
If you store a clutch with its front facing up, gravity is overpowered by (pressure within the unit?) and it leaks anyway.
I probably don't understand how the clutch fluid reservoirs work.

I didn't think of this so Amazon got a 2747 sale

 

[Trace 300 Hurst]

If you store a clutch with its front facing up, gravity is overpowered by (pressure within the unit?) and it leaks anyway.

What? Gravity is what causes the goo to leak out past the seal, onto the downward-facing shaft/bolt flange. There is no pressure or vacuum within the unit. The oil is just "there", oozing past the seal when stored face-up.

If you have a glass of water right-side up, it doesn't leak out. But if you turn it upside-down, gravity causes that water to run out because there's no seal at the top of the glass.

 

[1970FuryConv]

What? Gravity is what causes the goo to leak out past the seal, onto the downward-facing shaft/bolt flange. There is no pressure or vacuum within the unit. The oil is just "there", oozing past the seal when stored face-up.

If you have a glass of water right-side up, it doesn't leak out. But if you turn it upside-down, gravity causes that water to run out because there's no seal at the top of the glass.

Hi Trace,
I was saying that I don't understand the internals. If the glass is upright, it can't leak because its only opening faces up. If the only opening in an AC clutch faces up, it leaks. I was just trying to understand why. Maybe the indent for the spring extends far enough down that it intersects the top of the fluid in the reservoir. Maybe the front seal is a one-way valve actuated by gravity so it doesn't leak when facing down, although some are saying it does leak when facing down. I'm at work and need to look at your video.

 

[polara71]

I had one hanging on my garage wall for ten years. Last year I gave it to Wyatt. I had no idea there was a storage procedure. I did it right by accident

 

[bigmoparjeff]

I think the leakage is only an issue on used clutches. I don't think a fresh one will leak if you set it down the wrong way, though it's probably not good to store one long term upside down.

Jeff

 

[1970FuryConv]

I had one hanging on my garage wall for ten years. Last year I gave it to Wyatt. I had no idea there was a storage procedure. I did it right by accident

Better than me destroying one in like new condition, by accident. Doh!
New HD clutch 2747 Hayden is now supposed to arrive Saturday. Then I'm back in business. Yay-Ah!

 

[1970FuryConv]

Here's the full info:

Great Video. Thanks Trace.
Learned a lot. Also, resistance to turning when the viscous fan clutch is cold means almost nothing, except there might be some fluid in the reservoir. I bought new HD unit to be sure. My 360 engine had some problems with coolant loss in the past because the owner did not replace core plugs. I don't need to add overheating to the mix.

 

[Trace 300 Hurst]

Good luck with all that. Despite the frequent discussions here about overheating, our cars were designed to go all day in hot weather. Over the decades, the components degrade, radiators get cruddy and have reduced flow, composite (plastic) water pump impellers lose their vanes, blocks get full of sludge....all these conditions increasing over time at the same time....a slow towards insufficient cooling. And we can add failing fan clutches to the list!