Howdy everyone!!!!


I have done a search and can't find a definative answer to my problem.

I have a knock associated with no. 1 cylinder. If i crack the fuel line to the injector it goes away. I tried "purge" and it had no effect, except to increase idle RPM's about 300. If I take the lower oil pan off can I get to the bolts on no. 1 rod? It looks like removing the lower pan is relatively easy. Any sage words would be appreciated.

Lee Derby

__________________
'83 300D 283,000 mi.
'88 Jaguar XJ40 132,000 mi.(sold)
'88 Olds 88 190,000 mi.(given to grandson)
'81 300SD 313,000 mi. (given to granddaughter)
Maintained by Me and my offspring.
ESCHEW OBFUSCATION

is it nailing or knocking?

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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

Thanks boneheaddoctor, I'm not sure I know the difference between "nailing" and "knocking". But This is a metalic knock which sounds like a rod knock in a gasser. One more thing, I replaced the injector with one of unknown shape
with no change. Lee

__________________
'83 300D 283,000 mi.
'88 Jaguar XJ40 132,000 mi.(sold)
'88 Olds 88 190,000 mi.(given to grandson)
'81 300SD 313,000 mi. (given to granddaughter)
Maintained by Me and my offspring.
ESCHEW OBFUSCATION

Just to close-out this thread-The knocking was caused by the injection pump timing to just no.1 cylinder. Loosening the two screws holding no.1 pipe to the pump and moving the plate counterclockwise in small increments until the knock stopped did the job. Took 4 months to get it fixed but it works.


Lee

__________________
'83 300D 283,000 mi.
'88 Jaguar XJ40 132,000 mi.(sold)
'88 Olds 88 190,000 mi.(given to grandson)
'81 300SD 313,000 mi. (given to granddaughter)
Maintained by Me and my offspring.
ESCHEW OBFUSCATION

This is quite interesting.

I don't believe that anyone has ever done this that I can remember.

Many folks suffer from a "knocking" noise that can't seem to be diagnosed.

To find out that the injection timing is the cause.........................

i would never have thought you can adjust one cylinder timing separate from the others.... good work!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

We owe this tidbit of info to Brandon314259. All I did was follow his instructions. He may be young and overly tall but he is a great guy. Thanks again Brandon

Lee

__________________
'83 300D 283,000 mi.
'88 Jaguar XJ40 132,000 mi.(sold)
'88 Olds 88 190,000 mi.(given to grandson)
'81 300SD 313,000 mi. (given to granddaughter)
Maintained by Me and my offspring.
ESCHEW OBFUSCATION

The gentleman was observant enough to notice that upon release of his injector line nut rpm picked up by estimated thirty rpm. It at that stage was fairly obvious that #1 injector element was advanced in timing compared to the rest of pump. Shows that good observation skills do make a difference. Same effect might have been present with a bad injector but he was also astute enough to mention he had changed it with another and the symptom persisted.

deductive thinking on all of your parts. great!

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

It should be mentioned that this is a very tricky thing to adjust for most people.. The FSM says that if those nuts/bolt are moved it must be bench adjusted at a Bosch injection shop...
Be very careful if considering doing this...

Yes leathermag, you are quite right. Fortunatly by rechecking rpm drop from cylinder to cylinder he should land up prety close to engine design timing intentions. Just loosing the noise is of course much better than having it but you can proceed further. As it is the gentleman has gotten rid of the potentially damaging pre ignition on that cylinder. He can leave as is now as no harm will occur. Perhaps in the future the rpm drop method per cylinder should be one of the first checks when people complain of one abnormal noisy cylinder. Also is a good test to determine if you have a weak injector pop pressure as well possibly. That would be the more common culprit in the vast majority of cases. Unfortunatly because of the variables from cylinder to cylinder it is a method that you must also take into consideration other factors as well. You could make it absolute though by changing the injectors with their neighbours and then checking rpm drop when you loosen the lines again. Unfortunatly my 240ds have no tachometers. I woul;d not encourage people to try adjusting their pumps internal timing relationship because they might have overlooked something else. Preffer external verification of that type of problem and thorough check before going on the pump.

Since when you cracked the injector line the "knock" went away I would suspect a fuel related issue. Try switching that injector with another one, see if the "knocking" follows the injector.

You need a known good injector to test with.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

In my case I thought I had nothing to lose and everything to gain. And I marked the plate so I could put it back to it's original position. Although as I moved the plate I couldn't imagine being able to reposition it accurately, as it moves side to side as well as rotationally. I might have to move the plate back a little as I drove it a short distance today and it shook at idle but the acceleration was great. I think an Italian tune-up is the next step. It has been sitting in my driveway for a long time (About 6 months).


Lee

__________________
'83 300D 283,000 mi.
'88 Jaguar XJ40 132,000 mi.(sold)
'88 Olds 88 190,000 mi.(given to grandson)
'81 300SD 313,000 mi. (given to granddaughter)
Maintained by Me and my offspring.
ESCHEW OBFUSCATION

Lee, glad to hear you "nailed" it. Sorry, couldn't resist

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Lee, know you are 74 but then again there are 74 yr olds and 74yr olds. Guess I am just a young fellow at 63 this year. If the rough idle bothers you I would consider scribing the pumps position and try a small movement towards the retarded side. If that works out to smooth the idle and you still have pretty good acceleration thats were I would go. Some merit once in awhile to setting a pump timing position by ear. Before you move the plate again on top of injector pump do a drop in rpm test on the #1 cylinder and compare it to it's neighbour. That in my mind is the best way other than taking the pump to a shop to get it reasonably close compared to the other pump elements. From your description and other things. There might be an indication that the pump overall might be a little too far advanced. With the scribe marks on the pump and it's flange there is no chance of not being able to return to the present position if idle does not smooth. Also one other other thought. Assuming the rebuild 60k ago was done basically properly inside the block and compression across the board is assumed pretty even. Did you at any stage check the valve clearances? All this of course after you do the italian tune up but suspect that is not going to make too much difference as you purged the engine not many miles ago I thought. But I have been wrong before.