Dear Forum

I've been driving my '78 300D non-turbo for two years in Oregon, at sea-level. I recently moved to New Mexico and drove the car out here from OR, now living at 7000ft. We got here in one piece, but the journey took its toll---one obvious issue was the radiator springing a leak

That's now fixed, but there are two problems still there, and I hope you guys can help at least diagnose potential issues I can get checked out. I don't know whether some of it is altitude exposing problems that are already there, or whether something has actually broken. Here are the two remaining issues:

(1) An irregular crackling/grumbling rattle. It's very noticeable under load, at a few thousand revs. Does not sound like usual diesel rattle to me.

In Oregon there was something similar on startup, but I would rev the engine once, the engine would sound like it was clearing its throat, and then ran smoothly--so I thought nothing of it. The much more noticeable crackling/rattling began on day three of the ride out here, around 5000ft in Utah (I don't know if altitude is responsible, or if something just broke at that point in the journey---so am just adding that information).

When I got here I took the car to get radiator fixed, and this rattle sounded really bad. What they did was give me an additive to clean the injectors, which they thought might alleviate the rattle/crackle, and which I put into a full tank. Since then, the rattle is disappearing much more quickly after start-up---usually after five or ten minutes of driving or idling it's running smoothly. Though I do now notice that having used up that first tank with the additive, and putting a new tank of fuel in, the rattle is taking longer to go away.

If it is a sign of something serious, I would like to know before something goes wrong....

(2) Second problem, and maybe or maybe not unrelated to above: the car has been much harder to start. I always had to depress the throttle while turning the key even in Oregon to get it to start, but here it's been needing full throttle for maybe 5-10 seconds after ignition in order to stay running. Yesterday it took three separate tries, a lot of throttle to eventually get started.

Temperature is decreasing, though still not supercold here, so I'm not sure that's the whole problem. Maybe around 50F when I start it in the AM, and a low of 30s F during the night. Glow plugs would be an obvious thing to test---but would it even start at all if they were faulty? And are there any other potential diagnoses?

Sorry for the long post but wanted to give a full description of symptoms. Thanks!
-James

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1978 300D non-turbo 383k (Claudia)

You may want to try a "diesel purge", or better, have your injectors tested.

Yes, sounds like your glow plugs are failing, test them too. The engine will eventually start depending how many of the plugs still have life in them.

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83 SD

84 CD

Are you pretty convinced that the sound is engine-internal? Could be your are cleaner mounts. Have someone rev it and reproduce the sound, and press your hand down on top of the air cleaner. If the sound goes away, then your set. It's common on these engines for the mounts, and the bracket to get tired/break.

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1989 300E 144K

Car ever had the valve clearances checked since you owned it? What is the fuel pressure like in the base of the injection pump? Condition of glow plugs seems suspect as well. Have you ever changed fuel filters? any air leaking into the fuel supply system? These cars are old and many have been seriously neglected.

A good general check up might be in order first. All the required knowledge to do it your self is in the archives. Compression test first to establish that you are not flogging a dead horse usually. Before this it is wise to at least check for valve clearances.

Seldom reasonable financially to turn to service garages for all these items on an older car. Then there is the matter of competance or lack of it to contend with. All garages are far from equal and more so on these diesels.

Check your Glow Plugs to see if any are no good. If you have the older Filiment/loope type Glow plugs when one goes they all stop working because the are wired in series.

If you do have the Older type of Glow Plugs the have updated Pencil types that you can install that are claimed to work much better and they are wired in parallel so that if one goes bad the other still work.

With all noises you can duplicate you can listen for them with a Mechanics Stethoscope or a piece of Wooden Broomstick with your Ear on one end and the other end placed on the item you want to listen to. Watch out for moving and hot parts when you do this.

From you explination it is hard to tell if the Addative decreased noise coming from the Precombustion Chamber or just smoothed out the Engine.
If it changed the noise coming from the Precombustion chamber you have a Injector or Compression (do the Valve Adjustment first) issues.
With an ouside issue of possible late Fuel Injection Timing.

When you get ready to do the Valve Adjustment and the Valve Cover is off. Rotate the engine in the normal direction of rotation and line up the Camshaft Drive Gear Timing mark with the mark on the Camshaft Bearing Tower. Do this exactly.
Look down the timng pointer and see what degrees the pointer is pointing to on the Crankshaft Damper. This will tell you an aproxomate of yor Camshaft Timing.
When the Engine was first built the Camshaft Timing was set at Zero Degrees (this is Top Dead Center on #1 Cylinder). As the Timing Chain and Gears Wear the Camshaft Timing become late/retarded.

As a side note I had a ratteling soung on my Engine and it turned out to be the Small upper most timing chain guide was loose.

On the Injectors the Stock Bosch Nozzles have a tiny hole drilled down the center of the Nozzle Pintel. That hole gets plugged with Carbon. The hole is there for idle and low amounts of injected fuel.

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84 300D, 82 Volvo 244Gl Diesel

Thank you guys, I appreciate all of those comments/suggestions/advice.

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It sounds overwhelmingly likely that the starting trouble and engine noise are two unrelated problems, so I took on the easier one first and tested the glowplugs. Four of them glowed red hot when hooked up briefly to the battery, and also had reasonable resistances across the contacts. The fifth---totally dead.

The resistances across the working ones was around 2 ohms or so. Is that OK, or should I replace all five? It is significantly higher than those tested here at diesel giant on an OM603.

So anyway I'm ordering a (at least one) new one today. Do you guys recommend particular types and a reliable place to order from? Someone had already done the loop to pencil and series to parallel conversion on this car, so I guess that this is maybe a slightly unusual type of plug.

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Thanks for your suggestions for troubleshooting the rattling issue. @mattbeliveau, I don't think it's the cleaner mounts, no, they feel solid---and @barry, yes I did have fuel filter changed three months back (though it was just before a 1500 mile trip from Oregon, so not as recently in terms of miles).

Let me give you guys some more symptoms and a youtube link with the audio (if that's allowed on the forum), and if you have time, that might help me diagnose this.

So the main other symptom (which makes it difficult to check exactly where this comes from) is that the clicking/rattling is hardly noticeable when the car is stationary. You can hear something of a rattle as I rev it in park here:

http://www.youtube.com/watch?v=tHjr9sL9juE

but the sound is totally different when the car is moving, here!

http://www.youtube.com/watch?v=8vr-6rRAZpE

That last clip is noisy b/c I'm putting my phone out the drivers window as I drive, but I could something up to make it clearer. It should be possible to hear the irregular clicking/rattling which is what I'm talking about, and at times it is much worse than that.

I had noticed this but not sure what to make of it. It still sounds engine-internal from what I can tell from the drivers seat, and also the sound goes *entirely* when the engine is fully warm. Is there anything else that would likely go away after ten minutes of driving?

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@diesel911 and barry: If it still sounds from the sound above like valve adjustment is a good bet, there is a garage here in Santa Fe (Mozart's Garage) which deals with several of these cars (they had a few there when I went, though you can't particularly tell from their website that they work with older Mercedes), which is where I'd go.

I am thinking about whether to do it myself---you're right, there are good guides here and the glowplugs were easy. But getting into the internals of the engine isn't something I've done before. Is there a list of owner's clubs on this site? It would be nice to call someone local if it all goes horribly wrong....

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1978 300D non-turbo 383k (Claudia)

quick update and a further problem....

I pulled out and tested glowplugs as suggested and found one blown. Replaced all five as they looked the same age, and kept the good ones as spares. Starting issue more or less resolved (but see below).

For the rattle, I took it to garage here that works on w123s to check valve clearances and fuel injectors---they were fine and the mechanic diagnosed rattle as piston slap. Makes sense I suppose give that the rattle recedes as the pistons get hot and expand a little.

New problem---cold weather starting. As in, it won't start. GPs are fine. I have rechecked the resistances of the new plugs (all seem good), and I have also (yes, I know, slightly dangerously) taken a glowplug out of its hole, but kept it hooked up and run power. It glows, and the others are all connected in parallel, so it looks like there aren't issues with the GPs or current getting to them.

Temp here is down to 10-15F at night, 30s during day. Could this be a problem with the diesel fuel itself? Also, the mechanic put in 20W50 oil at the local garage, where I had been using 15W40, but I didn't think this would affect the starting. Any other ideas?

Cheers and thanks for the help
-James

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1978 300D non-turbo 383k (Claudia)

Thes cars do need a block heater. As they age even more indication of one being needed as things wear. Ten to fifteen degrees at night just may be a lillte too cold for your engine.

You definitely don't want to use 20W50, especially in the winter (take a look at the owner's manual). You may have other issues too, but running that oil certainly isn't helping. I like 5W40 synthetic, especially in the winter.

OK, thanks. I assumed oil would be a problem this cold.

Looks like the dieselgiant inline block heater would be easiest to install. Anyone have any reservations about that as opposed to the heater that goes into the block itself?

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1978 300D non-turbo 383k (Claudia)

Consider also the altitude affects engine power up here. It makes for lower power in your non-turbo engine and probably harder to start. soooo....
you need everything top notch in that cold. valve adjustment is critical, glow plugs just as critical along with the relay to make sure they are "glowed" long enough.
switching to synthetic 5w30, as mentioned, will also help.
try using two glow cycles.
using a block or water jacket heater will make things much easier.
it only got up to 38 in Belen today, so tonight will be pretty cold (for this area).
roberto

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1985 300SD
1998 Jetta TDI
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