Thread: Whirring noise (from pump?) 300tdi

Check that the injector pipes are not knocking together/vibrating.

Originally Posted by sierrafery

Hi all. I know nothing about 300tdi engines can somebody tell me please what can be the cause of that background(whirring) noise? eventually what's the cure. It's a '98 D1

Hi sierrafery. You've helped with my D2 issues, allow me to return the favor as best I can. You need to get the Tdi300 equivalent of a D2 Nanocom - looks a lot like a stick - one of those automotive stethoscopes from supercheap etc or more painfully a screw driver to the ear.

I can hear the noise on the vid.

Surprising how much easier it is to pick the noisy bit using the 'stick'. Had a noisy injector obvious in n0#1 but checking the other 3 with the 'stick' showed another was starting to talk as well but wouldn't have picked it otherwise. You could have an injector issue but the noise i've experienced is more like a quickly paced small bell ring changing in line with rev changes and no amount of engine noise seems to be able to hide it.

On that side of the engine you have the injector pump, the injectors, the fuel lift pump (red plastic covered manual lever use when bleeding system) that runs off an engine cam, the brake vacuum pump that is also cam driven.

Fuel lift pump. There is a spring that tensions the lift arm that rides the cam from memory. I've actually found one of those springs in the sump pan. Could the cam driven arm now with no srping be rattling around loose over the cam? The injector pump itself in a primed condition pulls its own fuel and you would not even miss that the fuel lift pump is no longer working. Long shot.

Are the brakes good? If not then you may have a loose poppet valve rattling around in the vacuum pump. There's also a one way valve that might rattle, in the small plastic housing pushed into the vacuum assist unit bolted to the firewall.

Lots of black oil down the side of the engine. Could be a very loose cap on the vacuum pump allowing air to escape with oil making that sort of noise you get when you blow through the mouth piece of a burst balloon. A loose welch plug in the lid.

Could be a failing injector pump. Was it blcknight who described how a plate inside the unit looses its hardened coating and starts to wear badly. Haven't heard what a failing unit sounds like in that regard.
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There are two cables on the injector throttle - one is the kick down cable if auto - it has a lock nut that might rattle if not tight, but that's clutching at straws to be the cause.

Loose tappet? Cover is easy to take off. Adjustments easy to do.

Again long shots. Trying to think of things rev related. Timing belt starting to fail. Shove a hooked bit of wire in the plug hole at the bottom of the timing cover and see if you pull out any belt fluff, Rubber hose from turbo to the top of the injector pump cracked? But then tuning would be off, smoke etc.