Engine Oil Problems - PeachParts Mercedes-Benz Forum

arimus · #1 11-21-2006, 07:26 PM

I have had a 1982 240D for about 3 months so far and it is a great car, I am currently having some problems that i was hoping someone here would recognize.

Two days ago I got on the freeway and after getting up to about 60mph i noticed a the engine was making a repetative grinding/tapping (like a ball bearing in an alluminum can, only more aggressive). I let off the gas to pull it over and it died on me, so i finnished pulling over and shut it off. After a sec I tried starting it and it started right up, but I was still getting that noise (very loud at the high end of 2nd gear) and could not get above 40 (although i didn't really try all that hard). I got it the remaining mile or so home and during the drive noticed the oil pressure was not as high as it should be and that the temp was a little hot, although not detrimental. I checked oil levels and everything is fine although it looks like I have a small oil leak.

Anyone have and ideas? Need any more information?

Thank you
-arimus

JimSmith · #2 11-21-2006, 09:21 PM

There really are not that many problems with a Diesel like the one you have that happen at one end of the rpm range and not at the other. If you have the hood open and start it, can you give some indication of where the noise is coming from and how loud it actually is? If the problem is serious you will be able to detect some signs of the problem, even at idle. From what you have described, if anyone could tell you what the problem was, they would be very wealthy as they could win lotteries every week. There is just not enough information.

Oil pressure dropping as engine conditions change is something to watch. Nearly all of these cars will have an oil temperature vs. pressure character you have to become familiar with in order to be comfortable. At idle the oil pressure can drop quite low, if the engine is hot. Once you apply throttle and the engine starts to take a load, the pressure should peg at "3" or "45" depending on how your gage is calibrated.

These engines are also pretty noisy, but the noise is very regular, and you get to the point where you actually enjoy listening - it is so regular it becomes reassuring to listen to it. There are things that can upset the sewing machine like regularity - and these are often things that fatigue due to vibration and heat. Like the little air cleaner mounts, or the EGR connection, or any of the belt driven auxiliaries on the front of the engine. And the valves or valve train/gear. The valves are driven by a chain that has a bunch of sprockets and driven loads besides the valves, as well as a chain tensioner and various guides. All this stuff makes noise and they are all susceptible to wear and when they stop working correctly they can make more noise.

So, after all that, you need to see if there is something seriously wrong and then narrow things down. Look into the radiator/reservoir and see if there is oil there, or look at the oil on the dipstick and inside the oil fill cap and see if there is any white goo. Oil in the wrong place or water in the wrong place is a sign of a head gasket failure, which could contribute to higher temperatures and a change in oil pressure performance.

If there are no signs of a head gasket failure, you will have to turn the engine back on and listen carfully to find out where the noise is coming from. Poke around looking for loose parts. If it sounds like it is inside the front of the engine, you may have to take the valve cover off and look in and around the chain, the guides and valve train. Also, check the throttle linkage out carefully. It is a bit of a Rube Goldberg arrangement, and can loose a rubber bushing here or there and let the engine idle go too low (stalling and low oil pressure), as well as make noises as parts now rattle against each other.

Until you find and correct the problem I would be somewhat hesitant to run the engine for any significant length of time. So, my suggestion is look around and report back. With more info, someone will be able to help. Jim

kerry · #3 11-21-2006, 09:25 PM

Need more info. How many miles on the car? Could be a timing chain problem. Possibly a vacuum pump problem but I dont really see how this would cause lower power. Do you still have vacuum? Did the brakes get hard? Did the shut off valve work?

iNeon · #4 11-21-2006, 09:30 PM

Check your alternator mounting bolts

PatricdeBoer · #5 11-21-2006, 09:39 PM

Quote:

Originally Posted by iNeon

Check your alternator mounting bolts

Yes, definitely do! I rebuilt a vacuum pump, replaced a timing chain tensioner, adjusted the valves and replaced both engine mounts on my mom's 240d. I was standing there scratching my head over the running engine and my brother
walked up and touched the alternator bolt and presto....problem solved.

Sam1951 · #6 11-22-2006, 08:22 AM

Is this noise still there when the car is still, not moveing, or only when moveing??
Sam

arimus · #7 11-22-2006, 12:01 PM

JimSmith:
Thank you, that was very informative. As soon as I get home from work I'll try look for some of those things. I did check the radiator and the oil, the radiator was free of oil/froth and the oil was alright (no white goo) except that the oil was very dark/dirty.

kerry edwards
Thanks, the car has about 350k miles. The vacuum and brakes are acting normal (i just replaced the master cylinder). Shut off valve working fine.

iNeon and PatricdeBoer
Thank you, I will check that out when i get home just in case.

Sam1951
The noise is there moving or stopped, but only at higher than idle rpm's. When it first happened my friend was in the car and he couldn't hear it (the way the pedals vibrate is half my hearing, so i don't blame him) but when i stopped it he got out and i gave it a little gas while not in gear and the sound was very obvious then.

rrgrassi · #8 11-22-2006, 12:09 PM

Is is a manual or automatic? I had a chevy gasser that made noises like that just before the torque converted imploded and sent fragments to the tranny oil pump, which then completed the falling dominoes cycle. This happened at 60 mph. Only thing salvagable of the tranny was the shell.

arimus · #9 11-22-2006, 12:19 PM

rrgrassi
It has a manual transmission.

rrgrassi · #10 11-22-2006, 12:59 PM

To rule out clutch, pressure plate, etc, on flat level ground, engine off and tranny in high gear, brakes off, see if you can roll the car. If it slips and grinds, and engine does not try to spin, you found the problem.

barry123400 · #11 11-23-2006, 09:33 PM

Aramus, how are you doing with your problem? Any more signifigant clues? Ball bearing bouncing around a can is hard for me to relate to. A slightly hotter engine will develop slightly lower oil pressure. How far did your oil pressure sag? The two forty has a pattern of failure. Your milage might be about right if it is the original unrebuilt, unmantained engine. Loosen the number one injector line off a little. Any change in the noise? I know the engine will be rougher but am only interested in the noise. If the same do number two and listen closely as well. Then report what you experience. You may have found something simple by now already. Let us know and try what I suggest if stumped. Do you have any highly knowlegable car friends to help where you are? If what I suggest does nothing I think you should look under timing in the archives. I want you to check and see if you have slipped your chain a tooth or two. My suggestions are not based on very much but a rough outline of your driveability problem. Plus the now lack of power. Plus trying to get my mind around the noise description. We are here to help if possible. You may learn a lot to get through this if what I suspect is true. While worth the effort in my opinion. Anything unusual you notice now even if you think it means nothing post it. There are some excellent minds on site that might be able to add a solution to your description. I also realise you are not very familar with this site yet but welcome.

arimus · #12 11-27-2006, 04:06 PM

Sorry it took so long to respond, loooong weekend. I really apprieciate everyone who has given me input so far, thank you all.

To recap and add in what i found out over the weekend, I will list all the symptoms a little more clearly ^^.

1. The problem only occurs after 10-15 minutes of driving (So once the temperature goes up).

2. When the engine gets hot and starts to make noise, it only does so at higher than idle RPM.

3. As soon as the noise starts, the oil pressure drops dramatically (oil pressure is usually at 3 whenever i am giving it gas, even if only a little; it drops to a little under 1 when giving it gas after the problem occurs).

4. The engine struggles to get from 35-40mph and has trouble going faster than 40mph. From what I could tell the noise seemed to be coming directly from the engine.

I talked to a friend of mine who is fairly knowledegable when it comes to cars (although, not much diesel experience) and he said it sounds like my Oil Pump is bad.

Does this sound like a reasonable assumption based on the symptoms? Is there any easy way to find out for sure?

If it is the oil pump, is this something a casual mechanic could do in a weekend with a friend? (i don't have my own garage, but could use a friend's for a weekend).

Any help regarding this is greatly appreciated. Thank you.

-Arimus

kerry · #13 11-27-2006, 04:10 PM

It's definitely an oil pressure problem. I'd be more inclined to think it is a leak if it operates well when cold. I'm guessing that once the thermostat for the oil cooler opens, oil is being lost somewhere in the hoses or cooler, reducing pressure to the rest of the system. Don't drive it like this.

rrgrassi · #14 11-27-2006, 04:52 PM

Sounds like a failing oil pump. Have you pulled the pan to check the condition of the sump screen? You could have junk settled to the bottom of the pan that decides to block the sump screen after the engine warms up. Not a good idea to drive it like that. Low oil pressure kills an engine rapidly.

arimus · #15 11-29-2006, 01:22 AM

Ok, I think I got a few good ideas so I am gonna replace the oil pump, oil filter, gaskets, and any lines I can get replacements for. Other than that I'll clean up the screens and check all the connections and test any lines I can get to. Thank you for all the input/advice. I am hoping to be done by the weekend so I will report back with anything I find out (hopefully good news!).

-arimus