StratfordShark

I've just lowered my S4 off jack stands on the front, where it's been for past few days.

Went for test run and no issues. But back in garage with engine running there was a clack-clack noise as fans span up and down.

With engine off I could rotate fan and the noise was the end of LHS fan blade just touching the surrounding shroud! This happened for just one of the blades on that fan.

I pushed and pulled at the shroud a bit, and the interference stopped.

Not happened before - would the plastic shroud have just bent slightly while car was on stands (crossmember was on throughout)? I had got her on and off stands at the jack points by jacking under the front suspension "skids" so I suppose the body would flex in region of shroud. Puzzling as the shroud is one piece, so I would have thought that if fan motor was located correctly (I hadn't had to remove them for the PAS fluid/reservoir change it had been on stands for) the blades would never touch the shroud? The shroud has no cracks or damage prior to this, and the fan blade did not damage the area it was striking so must have been very slight interference.

NC928S4

I had a similar problem. IIRC the shroud is attached to the radiator and I found that the LHS side of the shroud had shifted/moved towards the fan blade. I slid it back into position but the real fix was the radiator hold down brackets with the big rubber washers/dampeners. The brackets weren't creating enough downward pressure on the radiator so the radiator could move slightly fore and aft.

I removed the brackets and put a slight bend in them and reinstalled. Nice and snug now and no more occasional fan clacking.

123quattro

I would suspect something is going south with your engine mounts. They compress over time and the fan rides lower in the shroud eventually touching on the bottom. If it the top then it's something completely different.

SeanR

He doesn't have the mechanical so while you are correct on the early cars, this doesn't apply to the later cars.

123quattro

DOH. Thanks Sean.

Mrmerlin

is it possible that your jack was on the front radiator cross member ?
this would be enough to push the radiator out of place I would do an inspection looking for damage aslo check that the lower mounting points for the shroud are in the correct position.

remove the two top shroud bolts and move the shroud around

StratfordShark

Not guilty!

But I was wondering if all 3 tabs were in correct position at bottom. Of course I've just taken her off ramps now. I'm pretty sure tabs are ok though, as when they are not correctly fitted the plastic tabs at top don't fit over radiator nicely. I'll double check though, thanks a lot.

StratfordShark

This is interesting. I'm just back from a test drive for other items, and she started clacking again. I engaged a/c to keep fans on, and sure enough when I pulled rad/shroud forward the interference stopped. Pushing rad back was enough for fan to hit shroud again.

I was looking at those rubber mounts as I moved the rad, and noticed that they allowed slight movement. I'll have to try your trick with putting a bend in.

Thanks a lot,

Adrian

dr bob

Those radiator mounts are supposed to be flexible to allow the radiator to swell and shrink with temp change. On my car, the fan console moves with the radiator, so the clearance should stay constant as the assembly moves. Only if the assembly is twisted/torqued for some reason should that relationship change. If it is twisting/torqueing as it changes temperature, you mounts may not be allowing adequate movement in some particular direction. I've seen folks shim those rubber bumpers trying to eliminate movement. Better is to replace the rubbers with nice soft new ones, so there's some give to them.

My too sense...

StratfordShark

Thanks Dr Bob.

That relationship between shroud and radiator is what puzzles me. The shroud drops into 3 slots at base, and bolts to radiator at the top as well as is connected with plastic arms each side. With all that it's hard to see why pushing radiator back would cause blade to strike cowl.

Maybe I did miss a mounting tab at the bottom? Of course Murphy's Law says I've just put back the undertrays, and taken car off ramps, and even with mirror I can't check tabs from top! Whenever I replaced shroud I always needed to be under car to move the shroud tabs into correct slots.

Looks like I'll be lifting her again to check...

Leon Speed

Do you have a telescope mirror at hand? Very hand tool to check for example the slots from above.

StratfordShark

That's a good idea and I was poking around with my inspection mirror on flexible stalk earlier this evening. It looks like central tab is in correctly, but try as I might I couldn't get a view of the tabs on each side.

Will have to check it from underneath I think? Can you get a sight of your slots? If so then I must try harder!

Maybe I can just shove my hand down there and see if I can do it blind by feel?

Leon Speed

IIRC the tabs on each side are obstructed by the radiator hoses so the would be hard to see. The tabs are also viewable from the front, but then the front of the engine tray needs to be loosened.

StratfordShark

So I took off undertray and checked shroud tabs - they looked fine but to make sure I unbolted shroud at top and reseated them.

Also put in a small shim on LHS between top of rad and the rubber bumper. I could reproduce problem by pushing back on radiator, but it felt like more deflectionbthan would happen on the road.

Wrong. After test drive the fan was interfering again. I put in a wider shim but haven't tested yet. I'm not sure shim will work anyway asbwhen rad moves back the rubber bumper just deforms and doesn't prevent movement.

I would fit new bumpers but I don't see how they would stop movement back and forth if they were softer?

Strange as this is a new problem, and the only work I did just before it appeared was to change PAS reservoir which did not involve disturbing shroud.

If anyone has more ideas on this I'm grateful!

auzivision

I wonder as the fan motor ages if the bearing allows more lateral travel. Might check to see if one fan has more play than the other. Just a thought, maybe the shaft is moving instead of the shroud deforming.

Ironically, I have the exact same problem... except with one of my four muffin fans... the shroud get a squeeze.