1967 caddy cooling fan question

[BK911]

My Google Fu is weak.
Hoping someone here can help.
Loosing coolant and trying to figure out where.
Temp gauge doesn't work yet so not sure if over heating, but it looks like most/all is coming from the over flow tube.
Even when only running for a few minutes.
With engine off I can spin the fan pretty easily even though it's belt driven.
Read some years may be on a clutch but couldn't find anything '67 specific.
Wiring diagram doesn't show anything and no wire that I can find near the fan.
Pic below shows fan removed from something.
Any idea what?

[BK911]

[asphaltgambler]

The fan assy above uses a clutch; pictured that uses engine speed and air temp from the radiator to engage. Internally it has thick fluid, mechanism and a bi-metal spring on the outside.

It is supposed to 'freewheel' in certain conditions like at rest. But when turning the fan you should feel some to a fair amount of resistance depending on ambient temp.

Based on what you said, I'd replace it with a OE / OEM unit available online.

[BK911]

Thanks for the reply!
So the fan does spin when engine is running, but I wasn't sure if it was because of the little bit of resistance.
Glad I didn't stick a screw driver in there!

Any thoughts on an electric fan conversion?

[wdfifteen]

Engine running only a few minutes and coolant is spewing out the overflow, and the fan is turning? I don’t think the problem is the fan.
The cooling system obviously worked for years. I’d find out why it isn’t working now before investing in an upgrade for an undiagnosed problem.

[LWJ]

What happens when you run with the radiator cap off?

Could be big bubbles pushing out coolant. Could be other.

Try above and report back.

Don't start replacing things until you have diagnosed it.

[Mike80911]

Flush out the system and make sure the water is flowing through. Check to make sure the thermostat is opening and is the proper temperature rating for that car. Many of the old cars lose some anti freeze through the overfill tube when the radiator is full. Running the car without a temperature gauge or at least an idiot light is a recipe for disaster so you really should get a working gauge soon. An aftermarket gauge is easy enough to install. I like flex fans much better than clutch fans you might want to change that out also to the biggest diameter seven blade fan you can fit. There are also products that make the antifreeze cool better like water wetter. Good luck

[pavulon]

And a fan shroud

[Zeke]

Run a Flex fan w/o the stupid fluid drive. AND add a shroud as memtioned.

[BK911]

Freaking water pumpers!!
Looks like tstat is stuck barely open.
About $10 with a gasket.
Another quarantine project.

[asphaltgambler]

A few things. Yes the fan always turns with / close to engine RPM at low speeds. Think of it as a sliping clutch in a drivetrain where when not locked up lags behind. It is a genius design and very effective balancing air flow pulled through the condenser / radiator and temperature. DO NOT remove it and start installing aftermarket solutions. GM engineers spent a lot of time and testing to make this work AND reduce drag / fuel consumption. Each application hff as a differing number / pitch of fan blades as well as the clutch itself.

There should be a fan shroud already in place, it needs to be intact. If the air pulled through the radiator reaches a certain temp, the clutch will lock up 1-1 and you'll know because it's a little noisy with the hood open. By your OP the clutch is worn out, replace it with quality OE unit then go back and see where you are. Most of the failures in that setup is it slips too much and starts to overheat. But they also will fail the other way and stay locked up sounding like an airplane on the runway.

Don't overthink this, replace and then post again.

BTW - all the fan blades in these applications are staggered- anyone care to guess why?

[masraum]

Originally Posted by asphaltgambler

A few things. Yes the fan always turns with / close to engine RPM at low speeds. Think of it as a sliping clutch in a drivetrain where when not locked up lags behind. It is a genius design and very effective balancing air flow pulled through the condenser / radiator and temperature. DO NOT remove it and start installing aftermarket solutions. GM engineers spent a lot of time and testing to make this work AND reduce drag / fuel consumption. Each application hff as a differing number / pitch of fan blades as well as the clutch itself.

There should be a fan shroud already in place, it needs to be intact. If the air pulled through the radiator reaches a certain temp, the clutch will lock up 1-1 and you'll know because it's a little noisy with the hood open. By your OP the clutch is worn out, replace it with quality OE unit then go back and see where you are. Most of the failures in that setup is it slips too much and starts to overheat. But they also will fail the other way and stay locked up sounding like an airplane on the runway.

Don't overthink this, replace and then post again.

BTW - all the fan blades in these applications are staggered- anyone care to guess why?

Sounds about right. If I was in that situation, I'd replace the fan clutch, radiator cap and thermostat. The first is probably worn out and the second two are cheap, easy insurance and could be not quite 100%. Agreed that there should be a shroud for the fan, and that's important to the functionality of the fan/cooling system.

[Instrument 41]

Original radiator? Water pump?

[BK911]

Removed the tstat this morning.
Haven't tested it yet, but it looks ok and the spring functions.
There are 4 passages in the tstat housing; 1 to each head, 1 to heater core, and 1 inlet. The ~1/4" inlet appears to be filled with rtv or something similar.
Not really in the mood to tear this thing all apart, but here we go!
Going to remove the housing and see what it looks like.
Slippery slope, here I come!

[GH85Carrera]

As mentioned that fluid and spring fan combo allows the fan to spin at engine speed at lower RPMs but as the engine RMP get higher is "slips" and does not have to spin at full engine speed. The water pump should be really pumping at higher RPMs. If everything is working as designed and you sit in traffic for a while and get the engine hot, the fan will indeed spin at full RPM and it will roar with a lot of noise and wind drag. That is fine for a short time to get the engine to cool down, but you don't want that roar as you cruise at 75 MPH as it is not needed.

[RANDY P]

Upper hose has pressure, water pump should be OK. If it overheats and spits while at speed, it's not the fan. Maybe radiator cap lost it's seal.

Probably a cracked head or a HG. Also suspect if the upper hose is unusally hard after running awhile and parked.

[BK911]

The smoking gun; water pump discharge filled with rtv chunks.
No idea how many miles driven this way.
No what?
Keep digging?

[Bob Kontak]

Originally Posted by BK911

The smoking gun; water pump discharge filled with rtv chunks.

Rubbery? Not stop leak pellets? (which should have dissolved if used - I think)

Water pump install where someone went nutso on the RTV?

[BK911]

Yup, water pump discharge has o-ring.
Somebody went crazy with the rtv.
Still have final cleaning, but look at all the gunk.

So I have a new water pump and housing.
Also have cams, intake, and dual 4 barrels.
Pull the heads and have them decked?
Install new cams and induction while I'm in there?

[RANDY P]

you'll spend more time screwing with it than just yanking everything and replacing it. New wasserpump, tstat and a good flush.

Call it a day.

rjp