I have not driven or listened to another OM603 (87 300SDL 170K) other than my own, now just on the road a couple of weeks. When I started it for the first time and after a few minutes running, it started to rap real hard then as quickly as it appeared, it went away. Last week, the no.5 injection connection at the IP failed and leaked leaving me to 5 cylinders for the rest of the trek home. After replacing the no.5 fuel tube no more leak but the engine began rapping loud and hard just as in the beginning. This time I nailed the pedal to the floor briefly, up to around six grand and the single rap dissapeared. The last couple of days the engine has clattered diesel clatter louder than normal and seems rough, then it'll run quiet and smooth for a short while before clattering again. It's clattering loudly more often than not now.

My guess is lifters, and if so, I would like to replace all of them if I can. I did this once a long time ago on an International pick-up and what a difference it made!

If this is my problem, can I replace lifters without removing the head, or is there something else that may be the issue at hand???


Sooty Taillight

HI sooty

I replaced a few on mine a few years ago. It was no problem!! Take off the rocker cover, loosen the camshaft bearing caps (careful!!) and I had enough room to tilt the cam and change the loose ones.

But if its too tight then its better to remove the cam. Keep an eye on the chain that it doesnt fall.

as an aside, I wonder is your problem lifters? I had a clatter from my engine too and the lifters made no difference. Turned out compression was low on a few cylinders, bad gasket, and rough cyl bores. Trouble.
Anyway.......in the Haynes manual it shows how to check the lifters, push them down with a wooden rod and measure the clearance between lifter and cam lobe. I'm afraid I dont have Haynes man to hand for the clearances. make sure it is not on the lift portion of cam, otherwise no clearance. Do this before you take the cam bearings and timing chain off. As far as I remember you may have to remove the rad,fan, belt and some other bits to get at the crankshaft nut to turn the engine. See what you can get away with.

Good luck
Gerard

To dismiss the possibility of a fuel problem, run the engine at the rpm that induces tapping, loosen the fuel lines one at a time and see if cutting fuel to a particular cylinder makes the noise go away. If so, it's a dirty injector or some other fuel problem. If the noise persists, it could be a lifter. If you drive a lot, you might want to see if switching to Mobil 1 clears the noise. It won't happen overnight. It could take 10K miles for Mobil 1 to do it's magic and it's pretty much a life commitment at that point. If you're like me, 10K comes every 2 years so a quicker solution might be warranted. If you do replace the lifters, there is a specific loosening sequence for the cam bearings based on having the engine at #1 TDC.

Must be a very special 603 that revs to 6000rpm. The governor should hold it to the spec of 5000rpm +/- 200rpm

Sixto
95 S420
87 300SDL

Thanks guys for the advise. As I looked into past threads I found more info concerning my 603 and based on what I've read I could have a bad, or several going bad injectors possibly and I know that at least one of them weeps and it isn't the return hoses, I just replaced all of those and are now leak-free.

Also I might mention the last time I filled up I calculated approximately 31 mpg combined. Somewhere I read someone claiming 40 mpg hiway!

I'm glad to know that the lifters can be replaced without pulling the head.

Other than that, I'm really happy with this diesel benz. What a ride!


Sooty Taillight