I seemed to have developed a miss in the 617 when its warm. Runs smooth when I first start it up. After it does a few revs and warms up she idles like its got a dead cylinder. Interesting nailing sound show up too. Goes away when it runs smooth.
I've recently adjusted the valves, changed filters, touched up the rack adjustment...
What next? Any ideas? Head gasket is the only thing I can think of.

230K miles. Been sitting alot lately.

No clue.

Pre-combustion chamber?

Pre-combustion chamber?

Do they act up when warm? How difficult are they to remove since I'll need to take 'em all out.

Check your valves again........if you didn't tighten things up right the valves will adjust themselves so tight you could get this symptom....in very short order.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Could be valves, but the conventional wisdom is that if it runs with a miss when hot the injectors are the problem. Might run a can of diesel purge through the system.

I'll try the purge.
It could use a purge anyway. I may recheck the valves as well although I'm pretty anal about that. I had an independent adjust a V6 Volvo once. He left one of the nuts loose and it found its way to the oil pump, cam chain area the next day on the way back from a friends funeral. Denied he did anything wrong.
One bad day I'd like to forget.

That's good advice to run some purge through it before wrenching the engine - mainlining 100% with jar delivery and return system to the same jar under the hood.

It's dead cylinder nailing that makes me think pre-comb chamber, although injector tip is first logical suspect.

A cheap stethoscope can help you locate the problem, so you dont have to attack all the injectors or all the pc chambers. After you've found where its nailing, try switching the dead cylinder injector to see if the problem follows it to another.

If the problem remains and doesnt travel with the injector, then I'd get professional help. But forget about taking it to regular gasoline mechanic. Ask around for somebody who is diesel certified.

Done a compression test lately? What makes you think the head gasket is blown?

an air leak into the fuel lines? If you recently replaced the prefilter, the little rubber fuel line that you probably reused might be leaking. runs good until the fuel that has air in it hits the injectors. my 2 ¢

http://www.benzbonz.biz



Marty

I'm trying to locate some purge locally. Any common stuff available that works? Otherwise, I'll order some LM.

Regarding the head gasket... I just thought maybe somethings giving when it warms. I doubt its that now though.
It is consistant. Runs smooth cold then dead miss when it gets up to temp.
Every now and then it hits on all five cylinders. Making me think its not a tight valve, gasket.

Just ordered a bunch of parts to start restoration on this car. Then this happens.

BTW, can one "purge" too much?

as far as the valves, remember heat makes things expand so a misadjusted valve that is tight to start will only become worse the hotter it gets holding the valve open all the time. This will give you a good miss. Mike

Ok, I've purged it (from a bottle)and the miss became very intermittant for a short while.
Now its back. Misses more often than not.

I have found it to be #1 by loosening each line at idle. Of course I started at the rear.

Any of the local auto parts places (napa, autozone...)have a socket that fits the injectors? I'll try swapping holes if I can find a socket.

What can I thread in there to do a leakdown test? Rule of thumb for leakdown?

27mm. Sears has them.

__________________


1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

I'm really puzzled now. I swapped injectors #1 and #2.
The miss did not follow the swap. However, it went away for a few minutes then returned after driving a couple of miles.

I did a visual comparison of the injectors and down in the PC when I had them out and saw nothing different.

It seems to me if it is a compression problem on #1 then it would be a consistant miss. I need to find the proper guage to check a diesel anyway.

I did notice a very slight bubbling around the PC on #1 after spilling diesel there. Could I have created a leak there when I removed the injector? Do they ever turn in the head?

On #1 making sure the pump section on #1 not leaking down it has to haveso much pressure to keep that injector popping and run a compression check on that cyc and maybe recheck your valve ajustment on that cyc

Today I re-checked the valve clearance and they were all within spec.

Figuring I didn't have a serious mechanical problem I took a chance and did an Italian tune. It appears to have fixed it for now. It still has a very intermittant miss. But, its much smoother. The car has been sitting for a while so, I guess it just needs to be driven.

I treated her to new rear shocks to make up for the abuse.

Next project is dropping the front suspension for a complete rebuild now I'm confident the engine is ok.


Ever notice the air breather rubber mounts on the 617 are prone to come apart. I've noticed the oil line going to the turbo worn thru on a couple of neglected turbo diesels where the breather rubbed due to broken mounts. This 300SD was no exception. I caught it before it had rubbed thru the line causing the turbo to be starved of lubrication.
Don't run with broken air cleaner mounts for very long. Cheap and easy fix.

Gotta sell the 300d to pay for tie rod ends, bushings ball joints...

Dan