The 85 300D I just got has a bad knock in the engine, here's the video

http://www.youtube.com/watch?v=vJVoQsqLTa4

Car came with a bad starter, got that working, adjusted the valves, replaced the glow plugs and fired it up, ran a can of diesel purge though also. Took it for a little drive, car has gobs of power... Any idea what the knock is? previous owner told me about it, said he'd been driving it that way for the last year before the starter gave out.

No evidence of a broken valve spring when adjusting the valves? Not a rod knock. Vacuum pump? Seems too high up for that. Sounds like it's in the valve train. Use a stethoscope to narrow it down.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Didn't notice anything, it was actually very clean. You could tell that it had not been adjusted in some time. Every single one was way tight. Other than that knock, it seems to run great. very little evidence of blow-by or burning oil.

previous owner said he had his mechanic look at it but he could pin point it either. Said it sounds like it was in the upper engine.

I'll try using a broom stick in the am to see if I can get closer to the sounds area.

The whole valve train sounded loud to me. Can you see oil being flung around with the fill cap off and the engine running?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

suns almost down so Ill have to check in the morning. How about running the engine with the valve cover off? I'm guessing that would be a huge mess....

Yeah, that's a messy proposition.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Sounds like the fan hitting the shroud or the belt hitting the the diagnostic sensor.

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

All good suggestions, hopefully I'll know more today. I had a rover once, wife pulled into the driveway with a similar knocking, turned out the be the alternator. Its so hard to tell without a stethoscope. Guess it might be time to invest in one.

I still don't believe it's something inside the engine yet. If it turns out to be I'm tempted to go ahead and get another engine for it. The car itself is in almost to good of shape to part out.

My impression is that the noise is not an engine killer. How long has it been driven with the noise?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I know its hard to count the frequency of the tapping, but if it is the same as engine RPM it is crankshaft related and if it is 1/2 engine RPM it is valve train related. Or do I have that backwards?

600 RPM idle will rotate the crankshaft 10 time a second. Your tapping didn't sound like 10 taps a second, it sounds slower than that.

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

http://www.fuelly.com/sig-us/40601.png

Some suggestions:

1. Vacuum pump -- have you checked the main vacuum supply?

2. Alternator shaft bearing failure, had this happen once and the noise was extremely hard to pinpoint, seemed to be coming from 'everywhere'

3. Timing chain tensioner spring? Have not had this happen myself but have been told it makes a clicking sound.

4. I have never had an injector sound like that, I would expect a more 'hammer' sound... but have you cracked the lines to check?

5. Fan hitting shroud -- I drove myself half insane trying to figure this one out once... I had leaned over on the shroud and pushed it down far enough for the fan blades to just barely touch it.

Looks like a nice car, btw....

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Going out to check the main vac. I bought a stethoscope, could not pinpoint the noise, but the alternator sounded fine with the scope right on it. I've done the injector cracking, they are all fine.

It's something goofy... I took it over to my Diesel mechanic buddy and he gave it a look over also... He also took his scope to it, and again could not pin point the noise. Car has plenty of power, more than my 300CD. Of course the belt for the A/C is off, so that makes a difference.

My thought on this is simple... just live with the noise until something goes. Car drives great otherwise. PO drove it a year like this... When and if it goes then maybe put the engine from my 300CD in it and get a new (rebuilt engine) for the CD. which would give me a chance to really have the car gone though and repainted (color change).

In the end I want the CD nice... The D'd are all just drivers.

This sounds very much like my noise except this is more advanced. Mine starts making the noise at about 1100rpm. At idle it does not make the noise. I so far think it's either a piston problem or injector pump/injector noise. The car has loads of power, very little blow by or oil consumption, and a smooth idle. I will be interested in what you find.

It's literally a 500 dollar car... so Im not going to go too deep into it. I'm just going to drive it. Everything seems to work, even the cruise control, I can live with the knock. You can't even hear it over the cars normally high noise at speed. I had the old starter sitting here, so it was free to rebuild. I also had the set of new glow plugs and the new valve cover gasket sitting here. So literally my total in this car is that 500 bucks. If the engine goes, I still have a wealth of parts for my other ones.

Running it into town now to get the plate on it. and going to drive it to Huntsville Al, which is about a 2.5 hour trip each way for me. Will be interesting to see how it does.

My compressor mounting bolts were loose, causing a lot of noise. I tightened them and the noise went away.