Problem on the road today

[Michael M.]

Re: Problem on the road today

Edward, I agree on the fan clutch. I had the Eaton fan clutch that Joe Lucia recommends, the same one sold by GM. This time though I am buying the one in the GM box, this way I am sure I am getting the right stuff (although I am paying more for it). In fact, most of the parts I replaced as part of restoring the cooling system were identified through this Technical Discussion Board (fan blade, fan clutch, AIR pump pulley, radiator, etc), so I am fairly certain everything was correct. I probably just screwed up when setting the fan to fan shroud clearance.

My car is not judged, so I just make sure I have good quality parts on it that fit right. Since the engine is modified for more power, I am not hesitant to use a heavier duty part if I feel it necessary (such as going to polyurethane motor mounts or a Dewitts radiator, or better u-joints, etc.).

I'll post pictures of the damaged parts this weekend. Thanks for all of the replies.

[Michael M.]

Re: Problem on the road today

OK guys. Sorry for the delay. Here are the pictures of my damaged cooling system parts. Pretty sad.

By the way I think I determined what caused the problem. In my installation of the fan shroud and fan shroud seals, I used an upper fan shroud seal that was too wide which spaced the fan shroud out farther toward the fan. The high rpm at which I was driving probably flattened the fan out a bit which caused it to contact the fan shroud. The rest is history ($1,500 worth of history approximately ). As I stated in a previous post the motor mounts were in good shape.

Damaged Fan Blade and Fan Clutch.JPG

Damaged Fan Shroud (2).JPG

Damaged Radiator.JPG

Damaged Radiator (2).JPG

[Michael M.]

Re: Problem on the road today

Some of the guys wanted to see the pictures and this thread got buried over the weekend. TTT

[Ronald L.]

Re: Problem on the road today

I agree with DaveP, this hit something really hard and ALL the energy went into one fan blade at one specific point. Up close pics of both sides of that blade might show the contact point better. If the blade flexed and started to eat up the shroud, you would not have a catastrophic let go, just shaving of the shroud. Was this fan clutch a rebuild by one of our 'rebuilders' or a GM original part? What does the underside of the hood look like at in this area?

[Michael M.]

Re: Problem on the road today

Ronald and Dave, all good points. The jump in RPM was due to a downshift, so it wasn't a gradual climb to 6000+.

Nonetheless, it does make sense that the fan hit something solid, but I'm not sure what. There was no damage to the underside of the hood at all. It doesn't appear that the fan clutch hit anything but rather the front cover plate came apart. The fan clutch was a current GM fan clutch and the fan blade was a Paragon model. All were correct for my car according to current information on this TDB.

This weekend I will take some close up pictures of the fan blade on the leading edge and see what it shows. The only metal in the area was the fan shroud bracket which secures the fan shroud to that metal piece which extends the length of the top of the radiator and has the rubber baffle/seal on it. I can take a picture of the bracket also and see if shows any hint of being contacted by the fan.

At such high rpm suddenly, couldn't the single (now bent) blade have contacted and "clearanced" the shroud, thus bending the blade and destroying the shroud. Then of course the bent blade hit the radiator again and again. But once the fan shroud was "clearanced" the following blades would not have the interference of the fan shroud since the first blade did all the work. This is my current theory, but I don't discount any other advice or suggestions.

Additional pictures can't come until this weekend because I am traveling this week. Thanks all and keep the ideas coming.

[Ronald L.]

Re: Problem on the road today

To bend steel to that extent means that the 1st thing the fan hit was thicker and harder than the fan blade material. SMC shroud is incredibly fragile and can't bend steel as thin as it is.

I think we need to see the bolts on your water pump too, something let go at a catastrophic rapid rate. I would expect the front of the fan clutch came off on impact.

[Michael M.]

Re: Problem on the road today

Water pump and mounting bolts were intact, as were fan clutch bolts to water pump hub and fan blade bolts to fan clutch. You're probably right, though, that fan blade is bent at an extreme angle. Probably something metal. I am replacing all rotating components (including the water pump, even though it looks OK). It may have hit that metal bracket over the top of the fan shroud. I'll examine it closely.

[Ronald L.]

Re: Problem on the road today

So what you are saying is that the fan, clutch-hub was bolted - intact to the water pump when you came to a stop?

If the fan was rotating, after it took out the first blade, it would still have energy to at least bend the tip of the next blade. Its almost as if the fan clutch asy was dropped.

A revolution shock can snap bolts and would send that mass flying. It did not go up and wipe out the hood, are there marks on the crossmember, alternator or front end engine mounted components on the right side?

I would be nice to see a picture of the damage before parts removal.

[Michael M.]

Re: Problem on the road today

Ronald, you are correct. The fan clutch was properly mounted to the water pump when I came to a stop. The front cover of the fan clutch was found below the heater fan motor assembly in the engine compartment but the remainder of the fan clutch was intact. I will check the remainder of the engine compartment for signs of damage. Obviously, I have already disassembled the parts from the car and I don't have pictures with the damaged stuff still on the car. It's a mystery.

[Ronald L.]

Re: Problem on the road today

Just maybe that fan clutch was defective and the yellow chromate cover came out and the next blade came around and clocked it - does it have a huge gouge? E=mc* so that means that energy that went into the one fan blade came from another component you have there in your hands or on the car.

[Domenic T.]

Re: Problem on the road today

The radiator is soft but at the speed of the blade, it could have bent it.
I saw marks on the top that took a hit.

DOM

[Michael M.]

Re: Problem on the road today

Yes, I must say that I've never downshifted before like I did that day. Oh, and by the way, never will again. The engine performed well, although I will bring it to my engine builder to have a look see, after it is all put back together.

Dave, explain to me the deceleration arc versus acceleration. I get that on acceleration the engine wants to twist and so pulls on the driver side engine mount.

So when you downshift, obviously the engine rpms and resultant torque increase significantly and suddenly. So you are saying that the stresses on the motor mounts are the same on a downshift than if I was turning 5,000 rpm in 4th and merely lifted off the gas, allowing the engine to slow itself down?

[Michael M.]

Re: Problem on the road today

Thanks Dave. I do know how to double clutch and heel and toe, but I'm probably not that good at either, and I guess I never dreamed this would result.

Anyway, lesson learned. Albeit, an expensive one.

I'll still inspect the fan blade for metal to metal contact as well as some of the underhood components and see if that sheds any more light on the mishap.