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Spring start up 635. Rebuilt last year. Noticed old style (bolt) fan clutch cycling, then wobbling. Shut down, the center bolt is loose.

Not enough room to access without pulling the radiator. (?). Reading, as I swear I tightened that bolt, I see, " Tab washers," referenced ? Which I don't remember untabbing or seeing.

Just like to know all the checks and tricks: lock tight ?, tab washers, clamp, tighten to,...to avoid playing radiator games more than once.

T.Hanson wrote:Spring start up 635. Rebuilt last year. Noticed old style (bolt) fan clutch cycling, then wobbling. Shut down, the center bolt is loose.

Not enough room to access without pulling the radiator. (?). Reading, as I swear I tightened that bolt, I see, " Tab washers," referenced ? Which I don't remember untabbing or seeing.

Just like to know all the checks and tricks: lock tight ?, tab washers, clamp, tighten to,...to avoid playing radiator games more than once.

Hi Tom
This just happened to me. I'm thinking I didn't get the tangs of the hub washer into the slots on the hub

Came loose on the way to a 40 degree autocross so I said screw it and took it off. Cut my hands pretty good snaking it out of the area without pulling radiator. It's back on now and happy.

Thank you. Guess I'm back, can't live without easy answers. All I have to do is keep clicking until I figure out how this over engineered spam deflector works. No offense, I know it's better for the ex spam eraser crew.

Don't know what was wrong with it. Hub okay, sleeve okay but it wobbled until the last quarter turn on the bolt. Now tightened until the pulley slipped in the belt. Tight. The way it is I don't see undo forces trying to loosen it. Must not have leaned on it before.

No idea how anyone does it with the radiator in place.

I thought I had the same problem, and wrestled a box end wrench (10mm?) on it. It was tight. It tuned out to be the bearing in the water pump going south that made the whole thing wobble. I ended up taking the radiator out anyway to change the water pump. Not too bad. I'm thinking about just using distilled water without the antifreeze next time. It would be easier to dump the coolant (water sans antifreeze) which was the biggest problem. It doesn't get much below about 45F here anyway. Hope your is just a loose bolt.

Bruce wrote: Not too bad. I'm thinking about just using distilled water without the antifreeze next time. It would be easier to dump the coolant (water sans antifreeze) which was the biggest problem. It doesn't get much below about 45F here anyway. Hope your is just a loose bolt.

Bad idea on straight water. Water is corrosive and antifreeze both has corrosion inhibitors and raises the boiling point, both of which are good things. Environmentally it has it's problems, especially with disposal here in California, but IMHO it's just the price that has to be paid.

T. Hanson: My previous experience with a bolt-on fan clutch was on a 2800CS many years ago. Do I recall correctly that the bolt is a reverse thread? If so, there should not be a lot of torque required due to the rotation of the engine. Anyway, I had to pull the radiator everytime because I could not get the bolt to pull out after loosening - not enough clearance. If you have a stick shift, radiator removal is not too time consuming. Better to play safe than to risk radiator damage or skinned knuckles.

The bolt on clutch with the bolt thru it is right hand thread, the screw on, where the whole clutch screws onto the water pump, is indeed left hand thread. And yes it is veeeeerrry tight in there, especially if it's ever been pushed in some, like my old Bav. Eventually the motor mounts were soft enough if I hit the brakes hard, I could hear the fan lightly hitting the fins of the radiator