87 300SDL Newb Questions - PeachParts Mercedes-Benz Forum

lt1fire · #1 12-14-2011, 11:36 PM

Back in summer I had some extra cash lying around and wanted to find a better DD than my 95 ranger that just didn't have the room I wanted. My other car is a 92 land cruiser that is jacked up and I use for off roading and isn't really DD friendly with its 11mpg. I saw an 87 sdl for sale locally here in charlotte, went and checked it out and ended up buying it for 1k.

It has 345k on the ticker but the gears aren't turning the odo anymore. But the engine was supposed to have been replaced 90k ago with a newer engine by the go the previous owner bought it off of. There is no blow by at all so it seems to be. Also the numbers on the air filter housing and the air pipe that crosses over the valve cover don't match.
The ones on the air intake pipe say OM 603 098 but I can't find any info on that model number. Does anyone know what it was originally out of???

This thing does need some work for sure (replacing all the TRE's right now and four new tires as well as all fluids and filters) Will need to be repainted.

It also is very loud at idle and smooth as glass at power when cruising. Any ideas what this may be? I've searched and found a million different threads with just as many suggestions but nothing every really noted as to what it was.
It is loud to the point that it is really annoying so i'd like to get that taken care of first. Quite a few threads point to the hydraulic lifter tappets that can get clogged and need replacing. Where would be the best place to buy those.
The only other thing is the slight surging it seems to do while cruising. Not harsh or violent but you can feel it.
I'm not new to working on cars just to diesels in particular but i'm a fast learner.

Any help on tracking down the engine code and the loud tick on idle would be appreciated.

lt1fire · #2 12-15-2011, 12:04 AM

The guy I bought it off had bought it as a project and replaced the entire exhaust system, the starter and the alternator all with OEM parts. He ran out of time to work with it so sold it to me for what he bought it for.

NJ300sdl · #3 12-15-2011, 08:15 AM

Look on utube for examples of proper engine sound. Your engine may be making normal noises. Change both fuel filters at engine, consider cleaning or changing tank filter as a first step for fixing surging problem.

lt1fire · #4 12-15-2011, 08:44 AM

Mercedes OM603 Idle - YouTube

it is a ton louder than this one

I've got replacements for all filters but didn't know there was a tank filter.... how do you get to it? Do you have to drop the tank?

JPUTT · #5 12-15-2011, 10:32 AM

The slight surge of the cruise system is an inherent issue with the 86-87 300SDL. It has to do with the vac system I have seen a modification service bulletin that MB put out that is supposed to correct the issue but I have never made the change with my 87 300SDL. It doesn't bother me that much.

I replaced my hydraulic lifters a couple years ago during a head change and it eliminated a valve tic problem I had for some time. Earlier I had switched to Mobile1 synthetic to try and solve the problem but it never did. The valve lifter did not cause the engine to be rough or loud, just a annoying valve tic that would come and go mostly noticed at idle.

If your engine is vibrating loud and rough it might be that your engine mounts are worn out. If the engine was changed out 90k ago you would think that the mounts would have been replaced.

The numbers you are reading on the crossover and air filter are the part numbers for those particular parts. Mine read R 603 098 15 07 and 603 094 02 04. Those are not supposed to match and are not the engine #. Your engine# should be a 603.961.

lt1fire · #6 12-15-2011, 11:13 AM

Quote:

Originally Posted by JPUTT

The slight surge of the cruise system is an inherent issue with the 86-87 300SDL. It has to do with the vac system I have seen a modification service bulletin that MB put out that is supposed to correct the issue but I have never made the change with my 87 300SDL. It doesn't bother me that much.

I replaced my hydraulic lifters a couple years ago during a head change and it eliminated a valve tic problem I had for some time. Earlier I had switched to Mobile1 synthetic to try and solve the problem but it never did. The valve lifter did not cause the engine to be rough or loud, just a annoying valve tic that would come and go mostly noticed at idle.

If your engine is vibrating loud and rough it might be that your engine mounts are worn out. If the engine was changed out 90k ago you would think that the mounts would have been replaced.

The numbers you are reading on the crossover and air filter are the part numbers for those particular parts. Mine read R 603 098 15 07 and 603 094 02 04. Those are not supposed to match and are not the engine #. Your engine# should be a 603.961.

ahh that makes sense i'll look on the block for the engine code then.

I watched videos of 603's at idle and this is not normal. More of a rattle than a tick. Although with diesels I don't know. (I grew up working on jeeps and muscle cars so i'm used to valve ticks) This sounds more like something is loose. I just went out and spent some time looking at it and listening and it sounds more like it is coming either the belt/pulley system (tensioner maybe??) or the very front of the head. Goes away as the rev's go up.

As far as the surging goes are you saying that there is a recall out there from MB on this??

Thanks for any help trying to get to know this diesel as soon as I can Maybe a 603 or a 606 into the cruiser is in my future.

JPUTT · #7 12-15-2011, 11:41 AM

Quote:

Originally Posted by lt1fire

As far as the surging goes are you saying that there is a recall out there from MB on this??

No it is not a recall. Just a service bulletin that told how to correct it by adding some vac control valves and extra vac lines. I will see if i can find it and post.

John

lt1fire · #8 12-15-2011, 11:42 AM

IMG_2240.MOV - YouTube

Here is a video of it at idle. As you can see no blow by from the filler cap and as the camera goes to the rear near the end of the clip you can hear how the idle should sound from one of these.

It is almost certainly coming from either the front of the head or around the belts/pulleys

jonbobshinigin · #9 12-15-2011, 12:08 PM

Stand in front of the car while it is idling and you will the see belt system, There is a shock and spring tensioner assembly. Take a piece of wood or the handle of a hammer and press down on the top bushing where the shock connects to block. The bushing gets worn out and rattles a lot. Report back! It only takes a second. You can use your hand, just be careful!

lt1fire · #10 12-15-2011, 12:23 PM

you mean the top of the shock right ...... it is vibrating a lot when i touch it and press but no difference in noise. I've taken a video of it and tried to link it but it needs to wait for moderators approval before it posts.

lt1fire · #11 12-15-2011, 04:05 PM

it does seem like there is a small leak somewhere from one of the first two injectors. Must be the seals, seems in reading that this thing can cause a loud idle.

lt1fire · #12 12-16-2011, 12:30 PM

Actually it is there throughout the range just a little harder to hear at higher revs.
The car is not registered and insured right now till I sell the ranger but i'd like to start working on this asap while its in the drive way. Let it sit and idle for an hour today with some ATF and Diesel Klean in the tank and it was always present. Not a constant beat like every time a valve opens or closes more like something is rattling around somewhere erratically. The car does drive fine though but it is a very loud and annoying sound that needs to be dealt with.

lt1fire · #13 12-16-2011, 12:32 PM

IMG_2240.MOV - YouTube

Here is a video of it at idle

Brian Carlton · #14 12-16-2011, 07:49 PM

Quote:

Originally Posted by lt1fire

IMG_2240.MOV - YouTube

Here is a video of it at idle

That's not good.

The rattle sounds like a very severe injector knock to me, although it's a bit erratic.

Do a test:

While it is running, crack each injector line, right above the injector...........one at a time............and see what happens to the noise. If it's a specific cylinder, the noise will disappear immediately when you take that cylinder out (by eliminating the fuel). The engine will become noticeably rougher and shake............just ignore this. You are strictly looking for the elimination of the noise based upon one specific cylinder causing it.

lt1fire · #15 12-16-2011, 08:11 PM

i'll give that a try tomorrow..... it is erratic sometimes it seems to go away for a little bit it is almost like something on the front of the block is rattling but I can't for the life of me see where. Its always good to learn these things straight away I guess. thanks for the suggestions.

I'm actually hope it is as simple as a bad injector.

Quote:

Originally Posted by Brian Carlton

That's not good.

The rattle sounds like a very severe injector knock to me, although it's a bit erratic.

Do a test:

While it is running, crack each injector line, right above the injector...........one at a time............and see what happens to the noise. If it's a specific cylinder, the noise will disappear immediately when you take that cylinder out (by eliminating the fuel). The engine will become noticeably rougher and shake............just ignore this. You are strictly looking for the elimination of the noise based upon one specific cylinder causing it.