new to me car - PeachParts Mercedes-Benz Forum

JPA · #1 09-26-2006, 10:33 PM

[FONT=&quot]Hi, I just picked up a w123 82 300D turbo diesel. The car had been parked and sitting for three years before I got it. This is the situation now. When I got the car home I noticed that the engine shook quite a lot, like it shook the whole car. If you up the idle (by pushing on the connecting throtle rods the engine will straighten up). The car apears torun fine and strong. Turbo kicks in nicely and all that but the shaking? It does seem like a cylinder is not firing. My mechanic suggested starting with a compression check, which I guess I will have to do. A friend suggested that I up the idle until the engine does not shake. I did that, I put it at about 8 on the tachometer and now the car smokes, but smokes quite a bit. What gives? Keep in mind I know diesels very little.. I have come across the site mention of an ALDA… what is that?? Also these things have two gas filters? Where are they? I would appreciate any help I can get. If it turns out to be a low compression problem then I guess I am sunk! I hope it’s not.

SD Blue · #2 09-26-2006, 11:32 PM

Seriously, the reason I say this is he is not familiar with MB diesels. A compression check would be way down the road for things to check.

If it has been sitting awhile, it may be as simple as the injectors may need a good Italian tune-up. A good run down the highway does wonders. Diesels are happier when they run.

Other things to check:
fuel filters
motor mounts
valve adjustment
rack dampner pin adjustment
injectors

If you have biodiesel available in your area, a good run on B20 will help with cleaning the fuel system. Power Service, Marvel Mystery Oil, Redline Diesel Catalyst are some additives that folks have mentioned to help clean the fuel sytem.

stcbenz83 · #3 09-26-2006, 11:47 PM

Sounds like maybe it needs new motor mounts. which are cheap and are a DIY

also check out this site
www.dieselgiant.com

it is wonderful and has ALOT of DIY

yes there are 2 fuel filters, not gas

heh they are on the drivers side. one looks like a mini oil filter and the other one is a clear plastic one

also since it was sitting for 3 year it porbably has bad diesel in it

sublettm · #4 09-27-2006, 11:15 AM

I would hazard a guess it could simply be motor mounts and possibly the little engine shocks. The engine shocks on my wife's car are shot and there is more shaking going on than there should be. Since I haven't replaced them, I now have the luxury of replacing the air filter housing as the bushings broke loose on it and now the mounting bracket is broken. There are several avenues to go down before you get into the compression testing.

Mr.Kenny · #5 09-27-2006, 12:25 PM

Seriously; new motor mounts will do wonders on a shaking engine.

Also do a lubro-moly 'Diesel Purge' on that sucker & drive it hard.

t walgamuth · #6 09-27-2006, 11:04 PM

you can also isolate the problem by loostening the metal fuel lines on the injectors one at a time til you find the one that doesnt make the engine slow down. ( assuming it is actually missing). then once isolated you can switch the injector to another cylinder and see if the problem follows the injector or stays with the cylinger.

if it follows the injector you can replace it and fix the problem.

motor mounts and air cleaner mounts as noted above will make a heck of a racket too.

tom w

JPA · #7 09-28-2006, 11:47 AM

thank you guys for all your feedback. I will start slowly, let me expose my ignorance again and ask, is there something special I need to do to change the fuel filters?? do I just take them out and put the new ones on? I have not been able to find instructions on it. after this I will put new diesel on it and crank it down the highway at ridiculous speeds... thanks!

SD Blue · #8 09-28-2006, 12:12 PM

The fuel filters are a cinch. Do them once and you can practically do them in your sleep.

The in-line, clear filter is pretty self explanatory and just needs a screwdriver and something to plug/clamp the fuel line to keep fuel from going everywhere while you change it.

For the spin-on (looks like a small oil filter) you need a socket for the large bolt on top, that goes to the middle of the filter and just spin it off when loosened. Place the new filter face-to-face on top of the old and invert to fill the new filter with fuel.

After you install the new filters, pump the primer pump till you hear the pressure valve vent fuel to drive the air out of the system. If it is the white knob type, you have to unscrew it first to pump. If it's the new black one, you just push to prime.

Haynes has a good manual for the W123 Diesel that will cover the basics and is available at many auto parts stores. Also, MBCA.org has the CD for maintenance for about $20 I believe.

For the Italian tune-up, no high speeds are necessary. Just do an easy warm up and then a few strong accelerations and finish with about an hours drive.

barry123400 · #9 09-28-2006, 05:38 PM

Sdblue, putting the filters face to face and inverting will dump water and dirt right into your new filter if present. It is better just to fill the new filter with new fuel before reinstallation. Over time there will always be a little water lurking at the bottom of your old fuel filter and dirt as well. Sometimes even a lot. I know its hard to have a little fuel around for a filter change but getting enough to fill a two litre pop bottle for example will do quite a few fuel filter changes. These cars unfortunatly have no other water separator device than that filter as well as no warning circuit that there is a lot of water present. That is one reason to always try to fill up at a high volume outlet. But even that is really not good enough but better than the alternative. A fuel conditioner should be added in the winter months if you are in a climate that freezes. About once every two years I will have a major experience with water in the fuel from a vendor even with the semi precautions I take. One good shot of water through the injection pump can ruin it. Even if not terminally damaged it will shorten it's life somewhat. Just like putting sandpaper in there. One serious shortcoming of the 123s that is not totally understood by me with the high price of these cars when new. Even 85 volkswagon diesels for example have a large water trap plus provision to drain the lower contents of the fuel filter. Plus most importantly an electrical warning system with dash indicator if water is present. If nothing else carry a spare fuel filter in the trunk and a wrench to change it in a tupperware type container. I have had frozen filters a couple of times. I guess in desperation you could remove a fuel filter and thaw it out and reinstall. But if the filters froze its probable the line is ice obstructed as well.

SD Blue · #10 09-28-2006, 09:06 PM

You mentioned several factors. If you live in an area with condensation problems, fill up at low usage stations, or areas with considerable low temperatures then this is great advice.

I haven't had any of those issues here in my area but then again, I'm lucky.

Seriously, I do take a fuel sample, into a clear mason jar, from the old filter to see if there is any sediment or water issues. A trick I picked up from my days in aviation.

Blevinsax · #11 09-28-2006, 09:15 PM

Quote:

Originally Posted by barry123400

...putting the filters face to face and inverting will dump water and dirt right into your new filter if present...

Someone here also recommended filling the fuel filter with Diesel Purge when changing it - sounded like a good idea to me. You get a mini-purge when you start the car again.

JPA · #12 10-02-2006, 06:44 PM

I need to adjust the valves. Some one told me that I could rent the special wrenches for this job? Is anyone here in my area (Chapel Hill, NC that could lend them to me for an afternoon? if not where can I rent them? thanks fellas.

JPl

SD Blue · #13 10-03-2006, 11:14 AM

Quote:

Originally Posted by JPA

I need to adjust the valves. Some one told me that I could rent the special wrenches for this job? Is anyone here in my area (Chapel Hill, NC that could lend them to me for an afternoon? if not where can I rent them? thanks fellas.

JPl

If you go to the main ShopForum page there is section for Tool Rental and I'm not sure if they are available there. That would be the only rental I know of. They are available from several places if you want to buy them. A couple of tool vendors on E-bay, PerfomanceProducts4Benz.com, www.samstagsales.com and others, have them. They are nice to have and make the job much easier but are not required to be able to do the job. I have done my valve adjustments several times without them. The size is 14mm and one of the wrenches needs to be a little thinner to loosen the locking nut.

JPA · #14 10-04-2006, 09:07 PM

Hi gentlemen, good evening. Well a friend came over and we did a compression test and tested all the injectors. The injectors tested fine, no deposits on them and a nice mist. The compression; well, we think the gauge might be faulty. Perhaps it needs to be recalibrated? These are the numbers down the line from the front to the back, 220, 280, 280, 240, 220. What do you all think??? This weekend will give time to a valve adjustment. BUT! should I be worried about those numbers??

OMEGAMAN · #15 10-04-2006, 09:25 PM

Have a look at the rack damper pin. These things will run really well on fairly low compression. If the pin is not adjusted or weak the engine will idle like it has a missfire.