1987 603 question - PeachParts Mercedes-Benz Forum

MBnewB · #1 10-12-2004, 08:43 AM

Can anyone tell me if the 603 is an "interferance" motor...ie, will valves meet
pistons,should the timing chain fail?.....I have been reading all kinds of threads
about "when" to change the chain...& fully understand the procedures to
check the chain stretch...but w/the hydraulic lifters vs the 617's where you are removing the valvecover for valve adjustments on a consistent basis...is
there a scheduled chain stretch observation in the MBZ's service program?...or
do you just open her up every so often to check the slack?....i've read a
hundred opinions on this...but, obviously want to know the downside,should the
chain actually be getting ready to go....my wife's 84 toyota has 326,000 on it
& the chain is fine....but that motor is cheap vs the 5995.00 less online discount i just found for a rebuilt 603......

TonyFromWestOz · #2 10-12-2004, 09:02 AM

Almost every modern diesel engine will have mechanical damage if the cam stops turning while the engine is running.
The rotational inertia of the crankshaft will drive the piston into the valves, causing bent valves, broken camshaft/cam bearing towers etc, even if it is only at low RPM.

Hatterasguy · #3 10-12-2004, 12:32 PM

Most people seem to change the timing chain between 200k-300k. The reason you want to change it is it will stretch a few degrees and that will cause hard starting. Although how much stretch depends on how often the oil was changed. I will do mine around 250k. I guess you could check it but a valve cover gasket is $70 so why bother checking it?

fahrgewehr2 · #4 10-12-2004, 12:58 PM

HOW much is a valve cover gasket for a 603 motor?

dieseldiehard · #5 10-12-2004, 01:16 PM

The 300SDL doesn't have cam towers to break but like all MB diesels, the engine will self destruct if the timing chain fails.
A timing chain wears (we call it stretch, but its really worn due to carbon in the oil that grinds away at the metal links) The result is it gets longer, so the timing changes ever so gradually over time. In the OM603 engine there is so much power available that a worn chain may be less noticeable than in the OM617 cars. One indication that you may have a worn timing chain is excessive smoking. I changed out mine when I had the head checked and valve guides replaced at 255K (noisy lifters precipitated that ordeal).
Early vacuum pumps in the OM603 are however prone to failing and the pieces (ball bearings) get loose and will cause the timing chain to lock up with total engine failure. I would be certain your SDL has the new version vac pump, and also the trap oxidizer should have been removed. If you are concerned about engine life, replacing the timing chain itself is not a major job but the tensioner and guide rails should probably be changed at the same time to bring the engine up to "like new" in that area.

dieseldiehard · #6 10-12-2004, 01:20 PM

Quote:

Originally Posted by fahrgewehr2

HOW much is a valve cover gasket for a 603 motor?

Around $15 the last one I bought.
Intake manifold gasket about the same, alittle more, who said $70????

Hatterasguy · #7 10-12-2004, 05:51 PM

Sorry got my numbers crossed!

Fastlane lists it for $19.

MBnewB · #8 10-24-2004, 03:37 PM

Well...after running like a fine Swiss Watch....it seems as i pulled out
of my parking space @ work the other day, the timing chain dropped into the
bottom of the engine....no real noises,just died from a little off idle....
190,000 or so clicks...never really heard any tell-tale noises....i sure WISH I HAD pulled the valve cover to check the chain stetch...(had intended on replacing prior to 200,000....now too late!)
...i will pull the radiator, the fan...the cross over tube,valve cover & glow plugs...& do some hand timed blow down tests w/pistons at bottom of strokes,to see if i can ascertain an idea of DAMAGE,prior to pulling the head...
if i am looking at 2,000 or so for a head/valve & at least a couple of pistons...i
may just go ahead & get that rebuilt 603 i saw for about $5,100.00 (w/the online discount vs the $5,995.00 list price)....damn i love this car,but maybe i'd be money ahead to get a 97-99 E300D w/that newer body style?....(but with a lot more complicated fixes to all the gadgets,i'd bet....)
....w/snow coming soon, I will be concentrating on my 4x4 needs for the next
weeks....i'll share what i find....bet me it's pretty ugly?

sixto · #9 10-24-2004, 07:45 PM

While you're at it, check the condition of the vacuum pump. I've never heard of a 603 chain letting go on its own. It usually does so because the vacuum pump threw shrapnel at it.

Sixto
95 S420
87 300SDL

Hatterasguy · #10 10-24-2004, 07:56 PM

If the vac pump let go at idle I wonder if maybe the chain isn't broken? Maybe their wasn't much damage, I can't beleive the chain failed so young.

MBnewB was the vac pump updated to the new style?

dieseldiehard · #11 10-25-2004, 12:33 PM

MBnewB, sorry to hear the engine died on your car.
I also believe the vacuum pump is possibly the reason for it to have failed. Let us see a pic of the vac pump cover.
Say you might consider my Indy in the SF Bay Area who could rebuild it for a lot less than $5K (provided it has no major damage) or he could even rebuild and install the OM603 engine he has sitting in his shop (from an '87 300TD exchange) I presume you would have to ship it down here, I could watch over the job if you'd like me to.
Or for $5K or less if you are lucky, you could buy a whole car with a running engine (not sure what kind of maintenance it might need however).

dieseldiehard · #12 10-25-2004, 02:52 PM

I just checked out eBay and spotted an SDL with a newly rebuilt engine with a new head

a new A/C compressor, etc and its got no reserve!
Looks like its had lots of TLC. What a parts car! (I hate to say that, it will probably go much higher than the present low price)

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2496999245&category=6330