Windshield Washer Pump, W210
 

I shut my car (99 E300) down yesterday and noticed a really strange sound coming from under the hood - sizzling, popping, hissing, ticking.

Finally tracked it down to the windshield washer fluid pump, which must be starting to leak a bit of air (unless this is normal behavior!) I'd just used the washer fluid before pulling into the garage, so this makes sense. It stopped after a few minutes.

Any ideas? Cost and ease of replacement, if needed?

bmisf,

I am not sure about the W210, but the other models (W124 and W123) are not a big deal to replace, except for the cost. I am sure they are not giving them away. Never heard mine hiss or make any noise, but you may have a leak that is dripping on the exhaust manifold. That might make noises. If the pump keeps working I would try looking for a leak as I doubt the pump is the problem if it keeps working (hissing coming from an electric motor driven pump is usually a sign of the pump expiring).

Jim

sounds to me like the egr or wastegate control valves leaking mine did the same a few weeks ago , they look just like a windscreen washer pump. the egr control valve is located on the inlet manifold side of the engine compartment & the wastegate valve is located beside the turbo. i replaced both of mine
yours may only leak occaisonally, so dont rush into changing them just yet.

This kind of noise is normal - it's caused by residual vaccum leaking thru the transducers that control boost and EGR. My 98 and 92 diesels do the exact same thing. I'm a but surprised you could hear the ticking without raising the hood - you must have pretty good hearing.

Thanks, all - I'll keep my "ear" on it, since everything seems to be working fine for the moment. All good suggestions for where to look if it seems to get worse.