Fasteners “backing out”

[JHZR2]

Because I’m on hour 4.5 waiting for a tow, I’ve started to think about how my fan clutch falling off came to be.

This is more a geometry/dynamic movement question regarding how fasteners back out, so I think it warrants its own thread.

I’m tired, hot, dehydrated, so I can’t visualize well.

What I know is this:

- it still was generally by the water pump, I guess the bolt for the pump was still in the bore of the water pump pulley slightly. It’s not like the fan flung all around underhood.

- maybe 25 miles before this, I felt like the engine was idling slightly low. No idea if this is related. Not sure I’d have found a loose fan anyway.

What I know about the fan is this:

- the engine turns clockwise if I look at it from the front. So right rotation

- the bolt that holds the fan in also is a right hand thread, right is tight.

- The clutch is designed to turn… ccw???!? Note the arrow. Note that this side in the photo would be facing the front of the vehicle. The other side has a male end that inserts into the female socket of the water pump.

Could this item be entirely wrong? Was that why it was always on? I did drive it for maybe 500 miles or so before it came off. But if it wants to be spinning the other way, could that be the issue? I can’t see how that would cause the bearing in it to seize up tight, as I can’t spin it by hand.

But how could this happen? I’d suspect a stuck bearing might cause the whole thing to change speeds at a different rate than the engine during acceleration or deceleration, and ultimately cause the bolt to loosen? It is only an Allen bolt and isn’t torqued very tight. There’s limited space to do anything to even get it off.

So what could happen? I know it was installed and torqued correctly.

Thanks for your insights!

 

[supton]

Because I’m on hour 4.5 waiting for a tow,

I have no idea about your question--but my condolences on such a wait.

 

[JHZR2]

I have no idea about your question--but my condolences on such a wait.

AAA is worthless. I’m canceling my membership.

 

[RoadDukie]

What a horrible way to have to start a new discussion. Sorry for your situation. At the mercy of the road pirates.

BTW: I also canceled AAA this year after 15 years. It didn't go well.

 

[JHZR2]

What a horrible way to have to start a new discussion. Sorry for your situation. At the mercy of the road pirates.

BTW: I also canceled AAA this year after 15 years. It didn't go well.

I’m still sitting on the side of the road. They had no eta. For a 26ish mile tow it’s going to cost me $275. But AAA still had no eta.

 

[RoadDukie]

Oh my gosh, it's the middle of the night and you're still there? This is awful.
I can't imagine how you feel right now, but it can't be good.

Good luck brother. Is there anybody else with you?

 

[Chris142]

How far are you from civilization?

 

[Lubener]

I would bite the bullet and get it towed home at your expense if you plan to fix it yourself.I wouldn't wait for AAA if you are still on the road side. . AAA is going to tow it to the closest AAA approved facility, not a 26 mile tow back to your home.

I would probably change the water pump too. Its lifespan likely has been affected being attached to that fan clutch.

 

[JHZR2]

Oh my gosh, it's the middle of the night and you're still there? This is awful.
I can't imagine how you feel right now, but it can't be good.

Good luck brother. Is there anybody else with you?

Nope. Home now. Not fun.

So, back to how and why did this thing back off and fling my fan??!?

 

[Shannow]

You can see where the bolt head (or washer) fretted as it undid...my guess is that there's some torque reversals, on what appears to be unkeyed, or otherwise located attachement.

Rocking back and forth can work things loose, and that can include (for example) a locked up clutch on over-run.

Clutching here, as not heaps of info (yet).

 

[JHZR2]

You can see where the bolt head (or washer) fretted as it undid...my guess is that there's some torque reversals, on what appears to be unkeyed, or otherwise located attachement.

Rocking back and forth can work things loose, and that can include (for example) a locked up clutch on over-run.

Clutching here, as not heaps of info (yet).

Yes, locked up clutch, had that from day one… was under the impression that some were just made like that.

The fact that the bearing is very tight, like I can’t get it to spin at all, means another opportunity for the whole assembly to lock up.

The clutch is a pretty simple design, a male “knob” on the clutch inserts into a female bore in the water pump, and an 8mm cap head allen holds it together.

My dodge Cummins clutch screws on. But it is a left hand thread, so you tighten it ccw onto the engine which spins cw as you look at it from the front.

This fan clutch bolt screws in the normal clockwise direction on an engine that spins clockwise, unless the pulley configuration spins it opposite…. But I’m pretty sure from this FSM graphic that if the crank spins CW, the WP does too…

 

[JHZR2]

This was an interesting read, and I did notice some slop in the wp threads when I worked the bolt in just to see the fit and if the threads were damaged….

Why do nuts fall off bolts even against gravity?

fastfixtechnology.com

 

[Trav]

Is it possible the fan is the wrong one for that engine?

 

[Astro14]

How far are you from civilization?

Well, he’s in New Jersey, so, I’ll spare you my smart-Alec response and suggest it’s just how AAA works these days…

 

[tmorris1]

AAA is worthless. I’m canceling my membership.

They used to be great, but not anymore. They dispatch from hours away when there is someone closer and I have had them cancel the tow call without notifying me. Horrible.

 

[JHZR2]

Is it possible the fan is the wrong one for that engine?

The clutch perhaps.

Note the arrow marked on it.

The OM603 turns CW when you look at it.

Chinesium at its finest? Perhaps also why it was always engaged??

 

[BMWTurboDzl]

I always thought these bolts were reverse threaded. In any case I hope you got home in time. Our flight out of Newark on Sunday night was delayed 4 hrs. Didn't get home until 3 am.

 

[JHZR2]

I always thought these bolts were reverse threaded. In any case I hope you got home in time. Our flight out of Newark on Sunday night was delayed 4 hrs. Didn't get home until 3 am.

The clutch itself on my Cummins is. This bolt is not, and seems to just be there to hold the bearing and slip fit in place.

The bolt also has some up-down and sideways play when I push on it in any direction, threaded into the wp.

 

[wpod]

Bolts can loosen in time despite being high quality and torqued properly even with lock Tite. Aluminum expands differently that steel. Stuff happens. Last summer a hydraulic hose leaked on my tractor and I had to take lots of stuff apart and It took longer tightening all the loose bolts I found than changing the hose. Also Years Ago I had a flat bottom drag boat and everything was solid mounted and with the engine vibrations, v drive harmonics and the prop vibration etc. the fasteners needed checking on a regular basis. I am sure one of our A&P could maybe chime in as I learned lots from my A&P friends decades ago. A&P know lots of stuff .

Well, he’s in New Jersey, so, I’ll spare you my smart-Alec response and suggest it’s just how AAA works these days…

AAA at one time was the cats meow in rapid service I was/ am a member for decades.

 

[eljefino]

Airplanes use lockwire/cable, and lots of it.