ALDA Adjustment on 603 motor - PeachParts Mercedes-Benz Forum

Maverick · #1 01-27-2002, 07:11 AM

I thought I would tackle an ALDA adjustment this morning but had a few questions before I start:

Is it possible to damage the ALDA by removing the plastic cap and backing out the setscrew 1&1/2 turns?

Can I clean the ALDA in parts cleaner or brake cleaner? It seems a bit cruddy between the ALDA and the IP. What about compressed air?

Thanks in advance…

Mav

psfred · #2 01-27-2002, 11:49 AM

Mav:

You won't damage the ALDA by adjusting it, although the one on the 603 usually doesn't need it.

Don't clean with brake parts cleaner or carb cleaner, etc -- I don't know what the diaghram is made of and suspect it wouldn't be a very good idea to ruin in.

Also, I would check that the pressure lines from the manifold to ALDA were in good condition, and there are not plugs in the lines before adjusting.

Remember, this car has a trap catalyst, and does NOT show smoke like a diesel without one -- by the time you see significant smoke, you will be seriously overfueling. Mine produces just barely visible smoke at full throttle, usually only noticable at night in the headligts of the car behind me. If you have traces of soot on the rear of the car after highway driving, your ALDA is set just right.

Peter

Maverick · #3 01-27-2002, 01:40 PM

Peter,

Thanks for the advice on the ALDA.

I was wondering about the lack of smoke at full throttle. In fact usually, the only time I saw smoke was at night with someone behind me with their lights on. After backing out the ALDA set screw 1&1/2 turns, I did notice a puff of black smoke today in bright sunlight but only for a moment. 0-60 was unchanged at about 12-13 sec. Additionally; I think that the idle might have crept up a bit. Is this possible?

My next project is replacing either the timing chain, some of the guides or both. The car sounds like an intermittent rattletrap at idle. Sounds like the chain is slapping around inside its housing. Any advice on whether or not a backyard (barn) mechanic should tackle this task?

Thanks again…

Mav

psfred · #4 01-27-2002, 06:04 PM

Mav:

If your performance didn't change, put the ALDA back where it was. All you will do is burn more fuel if it is set too high, there is no other performance change, rumor aside.

12-13 sec is a bit slow, but not by much -- factory spec for the E300D is 10.7 with trap oxidizer, a little less with the catalyst, I would expect a couple seconds longer for the W140, as it is heavier, in spite of the extra engine size. A new chain may help -- if the old one is stretched, the injection timing is late.

Timing chain is the same on this car as any other with a ratcheting tensioner -- take the tensioner out and reset it (I don't know the details yet, haven't checked mine), then grind the pins down on a link of the chain, press them out to break the chain, attach the new chain with a temporary link, turn engine over by hand to draw chain through whilst holding tension on both ends, then wrap chain over cam and install permanent link by swaging the pins down. Not difficult as long as you never let tension off the chain. Huge pain in the ass if you drop it!

Peter

Maverick · #5 01-27-2002, 08:29 PM

Peter,

It sounds like I need to use a cutoff wheel of file to remove a link of the timing chain. But how the heck do you turn the motor over with all that compression? Do you think that the tensioners can be replaced without removing the chain?

And finally, can you recommend a reasonable shop manual for the 126.135/603.970 (’91 350 SDL)? I have seen CD versions for $150.00 but would like a Haynes Manual for a whole lot less if available.

Mav

Billybob · #6 01-27-2002, 09:12 PM

On Ebay motors there is an official MB 602/603 engine manual

http://cgi.ebay.com/ebaymotors/aw-cgi/eBayISAPI.dll?ViewItem&item=600940635

I just bought the same manual new for $87 LOL But it is extensive.

As for a CD this deal is about as good as it gets

http://cgi.ebay.com/ebaymotors/aw-cgi/eBayISAPI.dll?ViewItem&item=600940635

I just bought one for $80 including shipping, in spite of the low starting price and the No Reserve it seems like you can never win one of these auctions for less tha $70 I watched them for at least a month before I anteed up. Never having actually seen or used an authentic MD CD it appears that mine is a pretty good facsimile. At least it appears to as confusing in the same ways that the official MB version is said to be in some of this forum's threads. P. S. I haven't been able to find a Haynes for a 126 or a 603 don't think they have one.

psfred · #7 01-28-2002, 09:15 PM

Mav:

Dremel tool works great for grinding the pins off a link. They only need to have the swaged bit in front of the face ground off.

You need a special tool to push the pins out of a link, and you need it to swage the new link in place as the last step. Don't use screw links or clipped "master links" as a permanent installation -- several posters on this forum have had chains break for using these temporary links permanently. Very expensive, as you will definitely bend the rods in a 603.

A breaker bar or standard 1/2 ratchet handle is sufficient to rotate the engine by hand -- the compression leaks out past the rings when you rotate the engine as slowly as you do by hand -- the Volvo, which has higher compression, turns almost as easily as my sister's gas Volvo. If it gets stiff, just wait a few seconds. You can also pull the injectors if you want. I'd leave the glowplugs in a 603 -- way to difficult to get in and out!

You wouldn't want a Haynes, anyway, not all that good. I vastly prefer the MB manual.

Peter

stephenson · #8 01-30-2003, 02:25 PM

Hi Guys,

Doing a search and this threat turned up ...

I was not aware my '91 350SDL had a trap catalyst ... does it?

Did you do the timing chain replacement? How hard? Noticeable improvement in any way?

Was going to note the sound you mention may be related to the accessory drive belt tensioner or shock ... 8 of the shocks have been replaced on mine. Getting ready to replace the tensioner with the hopes won't have to keep doing this.

George

gsxr · #9 01-30-2003, 05:34 PM

1- Only use the MB factory service manual. Forget Haynes. End of discussion.

2- The 603 does NOT repeat does NOT have a ratcheting tensioner. It is spring loaded and fed with oil pressure but doesn't have a detent like the older OM61x engines did. The 603 tensioner requires no resetting.

3- Yes the rattle noise could likely be the belt shock. They have a frighteningly short lifespan and make one hell of a racket when the bushings fail. At idle with the noise present, press on the side of the shock body and see if the noise goes away (use a screwdriver or broomstick if you're nervous about sticking your fingers that close to the fan.)

4- All the cars have a catalyst in the exhaust. The "trap" refers to the "trap oxidizer" which was only used in 1986/87 and has been recalled. The proper name for the new part, used on 90-up models, is "oxidation catalyst" - not "trap catalyst".

5- I agree, don't dink with the ALDA if the engine is already running well, and the 0-60 time is near factory spec. MB only recommends a 1/4 turn, not 1.0-1.5 turns, btw (although usually it does require more than 1/4 turn to revive an IP that's low on fuel delivery.)

HTH,

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