For the last few days my car has been making a slight whining noise only when accelerating and more during the low speeds. We replaced the water pump in december and the belt with it since it snapped. This morning now there is a concerning rattling almost grinding noise when driving. Does anyone have any ideas what this could be? Thanks for any help you can provide

 

Did you replace the viscous clutch when you did the water pump? They tend to wear out evenly, since they've been spinning together for however many thousands of miles.

 

I did not. Other than pulling the water pump is there a way to test this? And would it only make noise when pressing on the gas and low speeds only? Thanks

 

You should be able to spin the fan by hand, with the engine off of course! But it should only spin about 1/4 of a turn then stop. It has been described as feeling like there's peanut butter inside the clutch. It's common for the fan to make a loud whirring noise on startup, then calm down as the viscous fluid heats up. If it doesn't go away, it could be a sign that it has seized. (You'll know for sure if you can't spin it by hand.) The rattling/grinding noise could be also be a sign of a bad clutch. Or, hopefully not, it's out of balance and has worn out the bearings in your new water pump prematurely.

 

Ok. I'm at work and just went out on my break and tried to spin my fan and I can keep turning it non stop. So does than mean I'm in the market for a new viscous clutch?

 

Can you spin it "wheel of fortune" style with multiple revs? It shouldn't be like that, and I'm not sure how it could fail that way. The viscous clutch on my discovery feels more "free" than any other clutched fan I've used, but I still can't get a complete revolution out of it. Now, I can spin it 3/4 turns all day long, if I want. This is normal.

Usually it fails seized and it won't move at all. So it sounds like yours is working fine, but as has been mentioned in a previous post, it's a good idea to change it when you do the water pump.

When I had my 540i, a failed viscous clutch was like the Disco's front drive shaft failure. it would fail and allow the fan to overspeed, the stress would shatter the blades sending shrapnel severing the coolant hoses and puncturing the radiator.

If you didn't get off the road, you could overheat the aluminum engine and be forced to do a head-gasket repair which was multi-thousands of dollars since the average Joe can't set a VANOS head without special calibration tools. It was a cheap and easy part, and became a preventative maintenance replacement per water pump change out, much like we disco owners put in greasable u-joints.

 

I apologize. In one push it turns roughly a quarter of the way or so. So I guess I'm back to square one? Thanks for your time any way.

 

That's as it should be. It might be an unrelated issue, requiring further ponderings...

Does it make the noise when you're revving it in the driveway, while the vehicle is in motion, or both? Any noticeable change in how the steering or brakes feel?

 

I found after crawling under my car it appears I have some bad u joints on front drive shaft

 

Definitely want to get those fixed! If, heaven forbid, one breaks loose it could smash into your transmission, knocking a hole in the casing. And that, as you could imagine, is a bad day.