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Discussion Starter #1
my 76 300D makes lots of valve noise when cold, even after warming up (coolant temp) after running for about 30 min. it almost goes away, but at part throttle condition (crusing down highway) there is still some minor valve clattering. also when cold, full throttle seems to quiet it down a bit. anyone have any ideas ? maybe fuel injectors ? clean/rebuild or replace ?
 

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Discussion Starter #2
valve adjustment

I suppose (after reading throu the forum in more detail) I need to adjust my valves
I am very capable DIY just looking for a procedure, and valve clearance measurments

thanks

-Jason
 

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Discussion Starter #4
OK so I adjusted the valves this weekend, and no change in the valve noise
it sounds like bad pinging from a gas engine.. any ideas ?
 

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Starting with the simple things, try running a diesel fuel system cleaner throught it and change the fuel filters. Also, it is a good idea to check the stretch of the timing chain when you adjust the valves. If the fuel is clean and the timing is correct, then bad injectors are a possibility.
 

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Discussion Starter #6
I think it was better the last time I ran a fuel system cleaner, but it also has a cetane boost in it as well, which I am thinking was what helped. I am going to try another tankfull of "boosted" fuel, and double check my results.
if a boosted cetane number helps considerably what does that point to ?
also like I said, at full throttle the noise goes away... is it starved for fuel ?
and full throttle gets closer to the correct amount ? and boosting the cetane # justs masks the problem by burning the "less" fuel more efficently when cold ? but when hot, the "less" fuel or possibly bad atomized fuel (bad/dirty injectors) is able to run okay because the engine is good and hot.

also what is the knob /adjustment wheel on top of the injection pump for ?
 

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OK, first if by the "knob" on top the IP you mean the thing with a vacuum line going into it and square (on your car I think), you do not want to mess with it. That would be the ALDA, which controls the fuel mix. This is supposed to be a one-time only adjustment, though sometimes tweaking the adjustment can help, but that is a last resort.

As for your other questions, if at full throttle it goes away, that could mean that the injectors are clogged but properly atomizing when max pressure is applied.

This may answer your cetane questions:

http://www.buyduralt.com/cetane.html
 

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Discussion Starter #8
could it totally be injectors ? i t sounds exactly like pre-ignition "pinging" in a gasser
but according to this it could be just injectors.

http://www.thebenzbin.com/diesel-injector.html

can the injectors be rebuilt ? or is it eaiser to just buy new ones ?
 

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Yes, it COULD be the injectors. I will have to inject the usual and obvious disclaimer of diagnosing sounds on a forum like this, but this is a common problem for high mileage engines.

Anyway, yes they can be rebuilt, and yes it is much easier to buy them than rebuilding. Be sure to replace the heat shields and place them correctly when you replace the injectors.
 

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Discussion Starter #10
I definitly think its the injectors, I have a set on order. but I would also like to check the timing. is there a procedure somewhere on someones website ?

I suppose I neeed to buy a manual .. any suggestions ?
is the Haynes book any good ?
does MB still sell the factory manual ?

thanks for the help
 

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Discussion Starter #11
spoke too soon, looks like the timing is simply loosen the IP and moving towards the engine is RETARD and away is ADVANCE..

found a few articles after a search
 

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Discussion Starter #13
wow thats great ! Just what I need, but does that exist for the 115 chassis cars ?
if not no big deal, the 123 chassis from a drive train perspective is very close and thats pretty much what I am looking for anyway..


thanks!
 

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Sorry, I'm not aware of one for 115 chassis cars. Enjoy.
 

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jfraley:

Injectors have to be "tuned". You can't just order them and stick them in like glow plugs. They all have to respond within a certain pressure range relative to one another. Shims are used for the adjustment, I believe.

-Scott
 
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