With 125K on the clock, I've done glowplugs twice, fuel lines, resealed the injector pump and made my headlights shine like new all thanks to help found here. I can now offer help to anyone in those areas but the latest malady has me a bit stumped.

When cold (not ambient air but engine/driveline), the car has a very distinct elevated level of intake noise. It sounds as if the airbox has been opened up and exposed. As the engine warms, it subsides to ultimately nearly original levels as I recall them. Perhaps related, perhaps not, the transmission shifts much more firmly (particularly first to second) than when fully warmed at all throttle levels. The problems exist and go away together.

Any thoughts or suggestions will be greatly appreciated.

Check the airbox for light warping. On the side that faces the middle the top part of the airbox has a tendency to warp, allowing air to pass, not through the filter....

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#dieselFLEET
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'97 E300
'99 E300

Are you absolutely sure it's intake noise?

I've heard of at least one other board member who had a fan clutch in his '99 E300 that engaged all the time and roared.

I wonder if your fan clutch is working backwards...engaging when cold and freewheeling when warm?

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2005 Pathfinder LE
2001 E55
1998 M3
1982 320i