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Is there a way to tell which fan clutch and water pump I've got in mine without pulling the old ones out? Everywhere list two types: 1) fan clutch bolted to water pump or 2) spin-on type. Not sure which one to order when trying to replace water pump. Fan clutch is in good condition.

Yes, the spin on has a large hub nut in back of the fan, on the WP side, 32MM. It is on almost all 80-81 E12s The bolt on has a 13MM head bolt on the front or radiator side of the fan. The spin on type is LH thread.

Pictured is the late type spin on.

Thank you. It appears I've got the 13mm nut on the front of the fan, guessing that means it's the bolt-on type. Any tricks to changing removing the fan clutch to change the water pump?

Skinny fingers and a thin wrench or pulling the radiator. Make sure the washer with tabs seats properly. It's pretty straightforward. Oh, basic water work, use Permatex #3 on the gasket and anti seize on the water pump bolt threads. It will ensure it's leak free and able to be removed the next time.

I would recommend converting to the later spin on style clutch and water pump. I did that on my M535i and the pump and clutch cost half what a new bolt-on clutch would have cost.

He's got a good fan clutch, he just needs to replace the water pump. And I know a guy here with 3 or 4 good used early style fan clutches he's be happy to part with for a reasonable price.

So upon further inspection and research, I think my fan clutch may indeed be shot. What's involved in converting to the newer style? Is it as simple as a new water pump and fan clutch?

To pull the radiator gives you some room to work, of course, but it may mean new hoses & anti-freeze. Which isn't a bad idea.
If you don't want to take it out, I strongly suggest taping a good size
gift box size cardboard to the radiator to protect your knuckles and the radiator fins.
Regular cardboard is just too thick.
Are you aware of the final bleed using the valve on top of the thermostat housing? Very, very important!
Good luck,,,,Greg

GripGreg wrote:To pull the radiator gives you some room to work, of course, but it may mean new hoses & anti-freeze. Which isn't a bad idea.
If you don't want to take it out, I strongly suggest taping a good size
gift box size cardboard to the radiator to protect your knuckles and the radiator fins.
Regular cardboard is just too thick.
Are you aware of the final bleed using the valve on top of the thermostat housing? Very, very important!
Good luck,,,,Greg

I do plan to remove the radiator. I just want to be sure there's no extra hardware required to switch to the spin-on type of fan clutch with a new compatible water pump. Am I correct?

Also, I'm aware of the thermostat housing bleed screw. Is there another one I need to bleed? Thank you in advance.

parker wrote:So upon further inspection and research, I think my fan clutch may indeed be shot. What's involved in converting to the newer style? Is it as simple as a new water pump and fan clutch?

There is something else, you need a different water pump pulley. Bolt on has a square bolt pattern, screw on has a diamond shaped pattern. That is all that comes to mind.

Yes, you do need a different pulley. I have a few around if you decide to go that route.

Sorry to hijack, but this got me thinking about my fan/clutch - it seems to be running all the time, which makes me think the clutch is gone.

I have a spare clutch, mine's the older type with the 13mm bolt. Is there a way to secure the water pump pulley in order to loosen this bolt? Otherwise the pulley slips on the belt and I can't get enough purchase to crack the bolt.

TIA

Mike W. wrote:

parker wrote:So upon further inspection and research, I think my fan clutch may indeed be shot. What's involved in converting to the newer style? Is it as simple as a new water pump and fan clutch?

There is something else, you need a different water pump pulley. Bolt on has a square bolt pattern, screw on has a diamond shaped pattern. That is all that comes to mind.

Thank you. Think I'm going to go this route.