Normal Diesel Clatter or Impending Doom?
 

I've noticed on my recently acquired '82 240D, that when the engine's cold, there'as a pronouced rattle at idle that sounds somewhat louder than normal. It sounds as if two of the cylinders are knocking louder than the other two. Car has about 170,000 miles. After warmup, it sounds like a normal 4 cylinder diesel.
Should I be concerned?

Happy Motoring, Mark

I'd not worry about it, they make all kinds of noises when cold sometimes, its their way of saying "brrr!!!" ;) Most likely its fine, especially with 170k, if its been at least somewhat maintained, thats very low miles for a 616 4 cylinder engine, they can last a loooong time. Since it sounds fine when warmed up I'd not worry, it may just be worn injectors or something.

mine makes the same sounds, and mileage wise you can swap those 1 and 7 around. 2 days ago it was smoking somewhat right when i started it, but that was because i did not preglow it and just cranked it. then just when i was going to let it rest and turn it off, it fired as i pulled the key. so when i started it again with the preglow it was fine.

i find that it helps to give the gas pedal a short nudge just as it starts, then it does not make that clatter for too long.

Mark-

As long as it starts easily when cold, I wouldn't worry too much about it. Have you checked/adjusted your valves and eyeballed the wear on your timing chain? If you are falling in love with her, you might want to treat her to some new injectors or , at least, a bottle of Diesel Purge.

Rick

So far, she's been starting easily down to the mid '30s, but I always wait till the glow-lamp goes out. Maybe I am 'falling in love'. At least lately, I'm driving her more than I am my '98 Nissan. She's been running so well, I'm afraid to mess with the engine but do plan to check the valve adjustment. There's been no noticeable smoking. Fuel mpg has hovered around 23-24 in mostly local driving.

I did a search and found references to something called 'nailing', but the opinions and remedies were all over the map. Most seemed to recommend new injectors, but then there were discussions about who even makes good injectors anymore- Bosch, India, Italy? I'll check with Phil first.

Happy Motoring, Mark

Engine noise
 

My 77 300d was making noise when cold, and got worse with time, until it was there all the time. This was fuel knock in my eng. and I finally bought and replaced the injector nozzels a few days ago. A world of difference!!
I used the Bozio nozzels. Smooth and quiet. This was the best money that I have spent on my car so far.
To answer your question about cold start noise, a little is normal, just the nature of the beast.
Enjoy your 240, these cars seem to have their own personality.

Those are the Italian ones. How much were they? PartsShop wants about $55 for the Bosch injectors.
I'm not going to rush into replacing them, as long as the cold-clatter isn't something dire.

Happy Motoring, Mark

Mark-

The Bosios run about $29 for the nozzles only. You disassemble the injector and replace the nozzles. Check Diesel Giant's website. I installed them in my 300SD a few weeks ago but haven't driven it much since. Doesn't seem to be emitting a black cloud anymore. It will take some running to clean out the prechambers.

Rick

well, I did a valve adjustment today. What a pain (literally, as I kept smacking the same finger that I injured working on another car last week!) Most of the valves were too tight. I may just be imagining it, but maybe there's a bit more power than before. I've been getting 22-24 mpg city and only 25 highway. Hoping that improves a bit too.

Happy Motoring, Mark

Too tight...someone trying to quiet their diesel? :laugh2:

I have been fighting off the cold-start knock for a while. I notice that there's a very definite lack of power when cold as well. Purge helped, as did a proper valve adjustment, but I'm pretty sure I'm going to have to go the new injector route soon. 175k miles on the ticker, btw.

No power when cold I consider normal. The oil vicosity being thicker seems to take it's toll. I guess how poor would be the hard thing to quantify. On a really cold morning with a 240d there is almost no acceleration. When a friend of mine pulled away it was perhaps zero out that morning or close to it. He did not allow even a minute to warm up. That engine was almost new with normally good power for a 240d standard. Perhaps even exceptional power. Another contributating factor might have been the temperature of the combustion chamber to support the ignition of the fuel. The heat of compression is probably lower than normal as the coldness is infiltrating the ciylinder perhaps. Speaks volumes for using synthetic in these cars in colder climates I suppose. Whatever you do make sure not to pull out into traffic with a really cold 240d using normal oil.

Car was cold when I drove off after the adjustment. (but the temp WAS 70 degrees today!) It seemed a bit more peppy, and didn't need to rev so much before upshifting to second. Hope this translates to better mpg, although even my current figures are a big improvement over most of the gas Benzes I've owned.
I'll check my mileage for a couple weeks, then consider a purge.

Happy Motoring, Mark

23-24?:confused: is urs an auto?

mines a manual with 250K on the clock and i get 28 city and around 33 highway

Yep, mine's automatic. Mileage hasn't been up to what some claim for a 240D, but I'll see if the valve adjustment made any difference before attempting any other improvements. Even 22-24 mpg is slightly better city mileage than my '98 Nissan Altima, so my 240D is still an acceptable alternate daily-driver.

Other question - Is there any adjustment or synchonization required between the throttle plate and injection pump on an '82 240D. Unlike those on carburetors or gas injection, the throttle-plate on this car appears to be designed so that it leaves a wide gap in the opening, even when fully closed. When I got this car, the plastic bushing near the air-filter housing had a deep groove worn in it and the linkage to the throttle-plate was extremely sloppy. I added a brass sleeve to the bushing and the linkage is now much tighter, but I didn't attempt any other adjustment, and as the throttle-plate is designed with this wide gap, I'm not sure if I made any difference.
Of course my Haynes manual provides almost no information on diesel throttle linkage or adjustments. Any opinions?

Happy Motoring, Mark

If what you're callin a throttle plate is the butterfly valve at the intake manifold then its completely irrelevant. The car will actually run fine with or without it open or closed, and linkage there is always sloppy. The diesel develops practically no vacuum of its own, a question of complete fuel combustion of diesel fuel creating its own gasses..... not like mixing gasoline with air for critical ratio with what you're used to driving. And its a direct injection engine, you understand, no mixing of fuel with air in manifolds or cyl head ports.

Cold running engine diagnosis on these beasts is a howling joke - try crankin it up stone cold in the shop and your pals will run to get a fire-extinguisher, swearing the engine will blow up. Normal cold start nailing sounds like ball peen hammer striking steel and is precomb chamber and inject related - nothin to worry about. The noise sounds metalic but it aint metal striking metal at all.

Meanwhile injectors hardly ever wear out because diesel fuel acts as lubricant. Same for injector pumps and bores, rings, valve seats and even guides - one of the secrets of diesel engine longevity.

Gasoline engine mechanics like to sell glow plugs and injectors to diesel customers, dunno why. GP's aint engine performance related and niether GP's nor Inj's ever wear out as a complete set. You can find a bad diesel injector using a stethoscope if 1 or 2 start nailing when *warmed up* after the engine's got 225k miles or so. And then swap the suspect inj to another cyl and nailing will follow it there.

I think that's good advice to use some 'diesel purge' one time only. And then follow up with 4-6 oz DieselKleen per tank for cetane boost and internal cleanliness maintenance. You want immaculate clean piston crowns free of carbon buildup, also clean pre-comb chambers to help with more complete combustion and hence better fuel mileage. And yeah, a city driven 240D automatic can accumulate more then 1/8" carbon on piston crowns that severely robs performance and economy.

And switching to synthetic oil is one of the most performance enhancing things you can do for the 240D immediately noticable and helps with fuel mileage too. Added about 2mpg to mine.

Mark

The "throttle plate" you are referring to was added when the EGR valve was added to the 82-83 240D. I had the same hopelessly floppy linkage on my '82 and I retrofitted pre-82 intake (sans butterfly valve) and exhaust manifolds and got rid of the EGR. I don't know if it improved the car as I never drove it with all the EGR clutter before, but it sure doesn't seem to have hurt anything ( I get up to 36 MPG). I don't know if you can get away with this if you have smog testing.

Rick

I was pretty sure my repair didn't really affect the engine performance much, but I hate to have stuff as worn & sloppy as my linkage was, so I feel better sleeving the damaged bushing.
No emissions testing here in Northern Virginia, for diesels prior to the OBD II equipped '96 and newer models. Would I gain anything if my EGR system were to accidentally become disabled?

Happy Motoring, Mark

Just a cleaner intake.

It never hurts a diesel to provide it with as much filtered air as possible. If you can lose that butterfly (or disable it in the open position) I would think that would be a good thing. And , if you keep the EGR, disable it. Search for ways on this forum.

Well, my 'new' diesel came dangerously close to impending doom this morning. Went to take the 240D out for some errands and had just backed to the curb when I noticed a big shiny black lake in the driveway. By the time I pulled back in, 'Miss Diesel' had dumped a gallon and a half of Rotella 15w40 engine oil! I found one of the oil filter-cover studs stripped out of the case. Turns out the PO had replaced the other stud with a bolt from underneath. So two hours later, after replacing the stud with a similar repair-bolt, driving my Nissan to Wal-Mart for some fresh Rotella and two sacks of kitty-litter, refilling my engine and covering the oil spill, I was finally on my way.

So glad this didn't happen at night, or last Sunday afternoon on the beltway, on my way to/from the antique radio meet in Davidsonville MD.!

Happy Motoring, Mark

My OM616 turbo with manual non ALDA IP nails when taking off, then it becomes quiet, I live with it, many think I am about to drop a rod, its perfectly normal for this engine, most OM616 turbos survive abuse and last up to 400,000+ miles with ease and little maintenance here.

Mark, they can also rattle to pieces. Rubber hoses touching each other will wear through. If an air filter container comes loose it will sound like you've thrown a rod. Rough luck on oil can problems, yeah you're lucky it happened in the driveway. Have seen filter seals that dont quite fit and then leak - wix is notorious for this. The usual installation procedure is to put the rubber ring on the cap lid not the cannister, but you probly know this already.

Yeah, it wasn't the gasket. I guess 25 years of wrenching on the filter studs took it's toll on the aluminum. The PO repaired the one by inserting a bolt up through the filter-case stud hole and today was my turn to do the other.
I do have an oil-pressure question. I've noticed after warmup, that I'm usually getting between .8 bar and 1.2 bar on the guage at idle, though occasionally it does read somewhat higher if it's been shut off for a few minutes. My owner's manual says at operating temperature it may drop, at idle speed to .5 bar safely, though some on this forum insist that minimum oil-pressure should be much higher. I hear no bearing noises, though with the diesel clatter, it's hard to tell. The oil guage does go to max pretty quickly - usually by about 1200 - 1500 rpm.
(This all was happening before today's oil leak.)
I'm wondering if I should check the oil-pump pickup screen?

Happy Motoring, Mark

Mark,

Have you checked the two very small o-rings on the central shaft that protrudes down from the oil filter cap? It has been said here in the past that if they are not nice and supple, it will hurt idle oil pressure. Mine were like graphite when I did the first oil change, and they fell off in pieces!!

Another issue is later model oil pressure guages can spring a leak. Seen this on a couple of cars. Generally an '83+ problem.

My '82 240D was built in late '81. 3 months ago, I had the cluster out and apart when I repaired the odometer and there was no sign of a guage oil leak then, and I'm not seeing any now (at least nothing is dribbling from the dash).

After the holidays, I'll check my filter 'O' rings. I'm also wondering if the tube could have been damaged when the cap stud worked loose. If the tube is OK and there's no improvement after new rings, maybe I'll inspect the oil pump screen. I was thinking of switching to Rotella Synthetic. I saw some, that I think was 5w40, at Wal-Mart yesterday. What do you think?

You will notice an incredible performance improvement with synthetic, no downside that i can think of. The first oil change will pull alot of sludge after 2,000 miles. That in itself might fix the oil pressure problem. Have never pulled the pan on an m616. And the oil pump should be fine. The only MB prone to oil pump probs of which I'm aware was the old 190c. Meanwhile replacing the entire 240D filter can and bracket involves a few allen bolts notso easy to reach. Am glad you like the diesel. Get used to one and it will be hard to get away from.

I don't think It's going to need the whole filter can. The bolts inserted through the former stud sockets have solved the tie-down issue. However, I'm a bit concerned that when the filter cap worked loose on one side, it may have bent or cracked the center pipe. As the oil pressure is still above the minimum, I'll limit my diesel-driving till after the holidays, when I'll have a chance to re-check all this.

Happy Motoring, Mark

We had some nice weather today, so I pulled the filter cover to inspect the center tube and 'O' rings. No damage to the tube but the rings were hard as rocks and one was cracked. Unfortuately, there wasn't any improvement in oil pressue with new 'O' rings. So my next step probably will be to drop the lower oil-pan and check the oil pump screen, unless I can find or rig an adapter to fit a test guage to the oil pressure line connection. Has anyone removed the upper oil-pan on one of these with the engine in the car?

Happy Motoring, Mark

Dropping the lower engine block casing just to look at the oil pump screen - are you out of your mind? Try synthetic oil and replacing the filter cannister first. And there looks to be spring loaded oil pressure valve in the filter cann according to parts book (mod 123) catalogue B plate 18/3.

Lucas Long drain oil
 

I don't know if it would help, but I saw this stuff at Auto Zone, Lucas Long Drain Oil. It stays on the gears longer, and prevents dry metal-to-metal starts. You add it in to your oil, I think. It's not a total oil replacement, but I'm not sure about that. They have a little wheel thing you play with, shows you the difference between regular and long drain oil. Big difference! They also say (if you call them), that it will make your engine last a lot longer.

jeff
1991 300d, 99k

http://www.bobistheoilguy.com/images/lucas/lucas.htm

Take a look here, quite interesting.

No. I'll be dropping the lower oil-pan to check the pump screen. I'd only remove the lower engine-block casing (AKA the upper oil-pan) if needed to check/replace bearings. So I was just wondering if anyone had removed the upper pan with the engine in the car, say with the engine mounts blocked up an extra 2 or 3 inches? I've been able to remove the oil-pan on many cars, including an '85 W201 190D, this way.

Happy Motoring, Mark

My problem is not dry-starts, but loss of oil pressure after warmup. If it's a bearing problem, I think it won't be cured by oil-thickeners. and if my pickup screen is clogged, thicker oil with just make things worse.

Hot-idle has dropped steadily over the 1500 miles since I changed the oil (Rotella 15w40) & filter. It started out at around 1.2 - 1.5 bar after a 30 minute freeway run. I wasn't really alarmed till yesterday when it dropped below .5 bar after 20 minutes of non-freeway driving. The guage still tops out by approx 1500 - 2000 rpm. Strange thing is, after I shut it off for several minutes, the hot-idle pressure recovers to around 1.2 on the guage (but still drops to around 1.0 or less after several more minutes driving). So I'm wondering if I'm getting cavitation in the oil-pump due to a restricted pickup screen.

I know my guage could be goofy and I should be checking the oil-pressure with a test-guage, but I can drop the lower oil-pan and check the screen right away vs the time I'd need to track down or rig up an adapter for the test-guage.

As for any suspect oil pressure relief valves, my Haynes manual is pretty worthless on locating or checking it/them.

Happy Motoring, Mark