I adjusted the valves on my '84 300D 6 weeks ago and everything seemed fine.
On Saturday, I went for a 250 km drive in the country, cruising at up to 145 km/h (somewhat over the 100 limit) Fatmobile III purred like a kitten, although somewhat rowdy kitten at that speed with the sunroof open.

Today I note that she has developed what I thought to be a tappet rattle (OK Cam follower noise). Sounds like a tic tic tic at the motor speed. While driving up the last km to home (up steep hill) the noise got noticable louder. It became a TIC TIC TIC, still at the same rate.
I thought that perhaps I had a loose valve adjuster nut, so tonight I pulled off the cam cover and checked the valve clearances. all OK.
After restarting the engine, the noise is still there, but after a few minutes of idling, a new, rattling noise started. I shutdown the negine. I restarted the engine after checking for obvious external problems without success. The TIC is still there, as loud as before, but I haven't heard the rattle again.

Can anyone shed some light?
The car has a genuine 286 000 km on the clock & burns negligible oil. There is no smoke at startup or at full power.

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Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Sorry to hear this, but welcome to the club.

I understand that the vacuum pump can make a variety of noises that get interpreted as engine noise.

A fuel knock can still fool the best of them sometimes. It only takes a few minutes to loosen the fuel lines at the injectors one at a time to eliminate the possibility. A leaky injector dumps fuel into the engine all of the time so you have no fuel timing control and get detonation in the cylinder.

The word 'rattling' makes me think timing chain.

Hope it is something simple.

Run a can of Diesel Purge according to the directions, not just in the tank. See if the TIC goes away. If it does, it is probably an injector issue. Simple cheap test.

Have the injectors ever been changed? I got about 200k out of the factory injectors in my 240D.

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79 240D (no name yet) 203K Miles Maple Yellow
98 2500 4x4 HD Dodge 24 Valve Cummins TD
83 Chevy Van (Dead-Trans. shot)

After posting, I went back out to the car and started it up and loosened the injector lines. the engine idle dropped and the engine started to shake a little (guess the mounts & shock are OK), for each injector, with no change in noise (apart from lower frequency due to lower RPM)

With an injector pump problem, is this always (mostly?) accompanied by poor vacuum? Everything opens and shuts perfectly.

I don't have access to diesel purge, is ATF an acceptable alternative?

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

You said injector pump, did you mean vacuum pump? I can't answer either way, just trying to clear up confusion.

If cracking the injector lines didn't affect the noise I wouldn't expect a purge to either but it never hurts.

The cheap tool stores here sell a stethoscope that is sometimes useful for finding noises.

If you suspect internal engine failure of some sort an oil change to look for metal may be an option.

Oops, not thinking very clearly here (otherwise I would probably have solved my problems by now)
I did mean Vacuum Pump
My question should have read
"With a vacuum pump problem, is this always (mostly?) accompanied by poor vacuum? Everything opens and shuts perfectly."
Thanks for bringing my error to my attention.