So Confused Gal
 

I have an 1981 Mercedes 300SD that has never been a problem (of course batteries, tires, etc doesn't count).

I loaned her out to someone who took her on a 10 hr round trip road trip to STL and now she runs rough, and its been a couple months and the "rough" is REALLY "rough" with vibrating the whole car (my son says its like a massage).

When its in gear and I press on the accelerator it stops (both, rough & vib), but in neutral or idling, it LOUD, ROUGH, and VIBRATING.

I replaced the air filter my son recommended, did nothing to help the problem.

I haven't done any "real" maintenance in 5 years, about 40K miles. Someone suggested the fuel filter, but reading this site there appears to be 2 fuel filters and I don't know the location of either.

Can anyone tell me if they think that could be it, AND where I would find the fuel filters? Also, is it like right on top or do I have to dig into the dark areas of the engine to get to it/them? And, do I have to remove parts to get there?

PLEASE, if you have the answers I would appreciate assistance. Also I wouldn't object to an email for faster info as she sounds like she's about to give up on me if I don't get her fixed (oh yeah, I'm pretty poor and unemployed right now so I can't just run to a mechanic). gayleannherron@gmail.com

Does an oil change count as "real" maintenance? 40k is a long time...

You need to have the valves adjusted too.(maybe motor mounts) Fuel filters, Primary is a little plastic cylinder(about the size of a film canister..If you're old enough to know what that is:D) attached to black hose that comes from the drivers side firewall. The secondary looks like a silver(or black) can of soup up top in the front on the drivers side of the motor by the power steering pump. Try the search feature or maybe someone with an om617 (that's the motor in your car) can post some pic's. Welcome to the forum, it's always good to see women who care to know more about their cars.

sounds like bad diesel or maybe even gasoline was put in the tank!

:eek::eek::eek: I does sound like that could have occurred and caused some serious engine damage.
It doesn't sound like a filter problem to me.

I suggest talking to the friend before getting carried away. Was fuel added? Where was it purchased (Type and name of store)? Did the person know your car takes diesel? Did the person use the GREEN filler nozzle? Could it have been Bio-diesel? Don't panic until you get us some more information. And put a comma right after pretty in your original post and you will get plenty of help. Thanks

I'm embarrassed....
 

Sadly, the last oil change on my baby was so long ago I couldn't tell you when. I have attempted it a couple times over the past couple years, but each time I hear they either don't have the part (filter) or they won't do my car. I know most mechanics will order the part and it will be brought over, but apparently Walmart and oil change places don't do that, or just didn't want to hassle with it.

The oil is black (like coal) and thick, so I know it HAS TO HAVE an oil change, and since I have an appt on Monday at 8:30am to have the diesel mechanic check it out (the vib & rough running - he suggested fuel filter and something about additives or ???), but I plan to have him do the oil change then.

Can an oil change make the can run rough?

I am gonna go outside when my headache goes and open the hood and look for the filters. It sounds like the clear one by the firewall should be pretty each (oh don't I assume?) but the other kind of scares me, if I screw it up I am definitely SOL for getting my kids back and forth from school the rest of the week (of course, my daughter would be excited at that concept - she's 8, 3rd grade, hates getting up early to go to school).

Hey, thanks guys....

I considered the gas verses diesel with the loan, but that was several tanks ago (about a year) although, it was at that time it started. I did ask them, and they knew it was diesel (it was my estranged husband at the time - and no he wouldn't have done something on purpose).

IF it was a gas verses diesel, what would have to be done since it has been SO LONG AGO to reverse the problem, if that is it.

IF it is major, or expensive, I fear I will have to give up my car. Its not that I want to be in denial or suppress the reality of the situation, but I'd rather start easy and simple (inexpensive) and then see where I end up.

All the required pieces can be ordered (inexpensively) from this web site. See the "Buy Parts" link at the top. A good diesel engine oil is Shell Rotella T synthetic 5w-40 that is available at Autozone and most local auto parts stores. It's important that you use a diesel rated engine oil. Sadly, regular oil changes are what will keep the car alive for a long time. If it has honestly been 40k miles since the last oil change, the prognosis may not be good. Or it could just be something simple. Hard to tell without seeing it.

What city are you in? There are enough people here that know this model inside and out and I'm sure would be glad to take a look at it. At a minimum we could likely recommend a good diesel mercedes mechanic in your area.

Sounds like you have the will to do your own easy work like oil changes, filter's and fluid changes. Save some money and do the oil change yourself. PEP Boy's will usually stock the filters, if not a MB dealer is always an option(but the most expensive) and if your doing the work, you'll save money. Hopefully a list member is close by and can help. Sadly 10K on a good synthetic oil is usually OK and around 5,000mi on a good turbo diesel non-synthetic oil is considered a regular change.

Hopefully the valves aren't so tight that the lobes on the cam are worn away.
Do you smell raw diesel fuel around the car?

Valve adjustment procedure
http://www.dieselgiant.com/valveadjustment.htm

Oil Change
http://www.dieselgiant.com/mercedesdieseloilchange.htm
http://www.dieselbenz.info/maint_oil_change.htm

Primary filter
http://i37.photobucket.com/albums/e9...cleaning02.jpg

Secondary filter located to the left of the gloved hand at 9:00
http://i37.photobucket.com/albums/e9...einstall28.jpg

Hi, back again. No smell of diesel other than what you would normally smell. Slight leaks on oil and tranny fluid, but not significant - just not fun on garage floor. I don't put a lot of miles on this car, it was my back-up car until I gave away my other car (I felt sorry for a gal who had no car). I live in Branson Missouri, I go to the store, to drop off & p/u kids at school, and that a few other errands per week. I probably put no more than 50 miles a week on it, so that might be good, that might not be so good.... may also explain why oil looks like crud oil (dark & thick) on the dipstick.

No offense, but what guys, especially mechanically inclined guys, say is "easy enough" work, still sounds PRETTY COMPLICATED to me.

I went and saw what I think was the little fuel filter by the driver's side firewall (near the power steering thingy), it had an in and out tubing, but still kind of spooky to mess with. I am assuming I would just take those two tubes off the filter and replace it...... RIGHT ??????

I could probably do that.

The bigger fuel filter, is it in a compartment with a wingnut closer to the front about mid-way still on the drivers side on the top? If so, I saw it, but to get me to open something closed is impossible unless I know it is the right thing.

IF IT IS, once I open the wingnut, what can I expect? If it is too complicated, can I just replace the top & wingnut and not screw it up?

thanks guys, sorry I am such a pain
.

Lets go back to when the car was loaned out. Did you drive it the next day and is that when the vibration started or did it take awhile for it to start. A time line would be nice. Lets just look at a couple things, car is on a long trip and guy sees low priced fuel at ACME RIP-u-OFF gas station. Not his car so it doesnt matter. Problem is no one ever stops at ACME so the fuel is growing fungi, full of water and rust from the bottom of the tank. It could happen and cause down stream problems.

2nd option, guy borrows car for long trip and cranks it up, doesn't matter not his car, hits a bump at 115 mph and the landing breaks a motor mount. It could happen. If your son is at home its time for some mother son time and do some checking and some maintenance. It's easy and rewarding. Thanks

That was going to be my first guess. The fact that the car was running fine before you lent it to someone who took it on a long trip raises the question: What happened on that trip? Putting bad fuel ... or the wrong fuel ... would be an easy thing for someone to do. If someone filled it with gasoline, you'd know it by now (:eek:). But it could just be bad fuel, or maybe some kerosene, or who know what else. Maybe the person tried to put an additive in it to "quiet it down.":rolleyes:

I'd start by asking the person you lent it to a few questions ... the first being "Did you put any fuel in for me?"

Definitely get that oil change done! Oil change is a great place to start for an aspiring DIYer ... the first thing I ever learned to do under the hood! As folks said, you can order a filter online for a reasonable price (click "Buy parts" up above). I use Rotella 15w40 ... you can get it at Walmart, Pepboys, etc. You definitely want a diesel grade oil! Yes, the lack of an oil change could certainly negatively affect your engine by causing wear on bearings, rings, cylinders, etc. My guess would be, given the sudden onset of the problem and the fact that it's limited to idle, that your problem is something else. But changing the oil is a must either way.

Beyond that, I'd look at a valve adjustment. May just be a coincidence that it started to sound rough now. A valve adjustment can really smooth things up. I wouldn't guess fuel filters are the cause ... usually if you have a clogged filter, you notice it first when the car is under load, or at least in my experience. It would not be limited to idle.

Also, I'm not sure how the idle control is set for the 617, but it may be the case that the idle setting got bumped and it's idling too low, causing it to stumble. I could tell you about that on my 616 or my 603, but someone else will have to fill you in on the 617.

Welcome to the boards. After you get the car running nice and smooth again, you probably want to catch up on some other maintenance ... a good idea to flush the brakes at least and maybe do a coolant flush and make sure you've got the correct coolant in there. Lots of help for those things -- and many others -- on this forum!!!:)

The best is to have a mentor at your side, again hopefully someone will chime in who's close to you. There are some tools that are required along with your willingness to get a little :rolleyes: messy. Fluid changes and a diesel purge are with-in your reach. A vavle adjustment is not...well not yet:D

Usually a fuel starvation problems from filters being clogged is discovered at highway speeds with a loss of power during acceleration not a rough idle. Especially since it smooths out when you apply the accelerator.

My top 3 in the dark gusses
1)Motor mounts
2)Valve adjustment
3)Fouled injectors or IP issue.

I'd say do an oil change. That poor car probably has some uber SLUDGE.

Gayle I'm with you on this as well. I joined this site with 0 mechanical ability. Nowadays I have 15 :cool: on the mecho-skill-abilometer. Dieselgiant does a great job of breaking down routine maintenance into easy work.

And like others have said. We're all very helpful here in answering some of the mundane questions.