Vibration at Idle 300D
randal...@gmail.com
predates the advent of pumps incorporating a rack dampener adjustment,
I was confronted with what to do about the deep, coarse vibration that
was occurring at idle. Adjusting the idle speed did not help, as the
engine then idled too fast. Following a posting here, I went ahead
and changed the inline and canister fuel filters. That made a
remarkable difference. I was then able to set the idle down to where
it should be. I am still not satisfied with the level of vibration
that remains at idle. I am beginning to question whether my Mercedes
shop actually change the engine mount vibration absorbers when they
did a complete engine rebuild earlier this year. Changing engine
mounts have always quieted my engines down in the past. For instance,
my last 300D, I had adjusted so that it was so buttery smooth at idle,
it was a pleasure to behold. Then again, that was a four-cylinder
diesel, whereas the current one is a five-cylinder OM617.
Does anyone have an opinion as to whether or not this engine might
smooth out better once it is fully broken in? The currently has only
around 1,500 miles on it.
Thanks!
Tiger
him check out the engine.
How about the injectors... are they rebuilt? Are they balanced?
randal...@gmail.com
I will. I am taking the car back to the shop in the morning. I
changed the filters, and the engine is not sufficiently improved. I
will have the mounts changed again. I'm willing to bet that the same
injectors went back in after the engine was overhauled.
randal...@gmail.com
By the way, how are injectors balanced? Are they done by a shop that
rebuilds injectors?
Thanks.
Tiger
sure every injector outputs at the same pressure rather than just the same
size shims to set the pressure.
The pressure varies regardless you install the same parts... so that is why
it is painstaking to balance all the injectors. Even Bosch rebuilt injectors
are not balanced.... I never tested mine as my new tester was not working
and I have to send back the old cores..
Also the orifice does wear out over time so it pays to have new orifice at
the same time.
randal...@gmail.com
Ah ha! This I did not know. I will look into getting this balancing
done immediately.
Thanks.
Roland Franzius
The data are for injectors DNO SD 220 (W123 300D)
ejection pressure
new 115-123 bar
used ~100 bar
The maximal difference for injectors in one motor is 5 bar!
The chapter about adjusting the gas leverage parts to avoid idle sawing
oscillations is very detailed and gives exact distances in mm. E.g. the
long one needs a plastic coating for damping reasons.
--
Roland Franzius
randal...@gmail.com
> randallbr...@mac.com schrieb:
Hmm. In all my years of diesel Mercedes ownership, I have never had
to deal with injector issues.
Is it possible to buy new Bosch injectors and have them properly
balanced at a diesel shop?
Thanks very much for the information.
JD
FWIW, my indy shop went through 19 new Bosch
injectors before getting 5 that were acceptably close.
Cordy
>> Is it possible to buy new Bosch injectors and have them properly
>> balanced at a diesel shop?
>>
>
> FWIW, my indy shop went through 19 new Bosch injectors before getting 5
> that were acceptably close.
AFAIK, there's a variable thickness ring installed on the base of the
injector body, to 'fine tune' the pressure of each single diesel spray,
in order to balance them. It's quite simple for a professional to adjust
the injectors to work in the same pressure range, simply using
pre-calibrated thickness series and an injector tester.
It's not the right procedure, to try to find 4 or more injectors with an
acceptably similar pressure, just taking them out of the box... I guess
your indy shop didn'use this kind of injectors (or doesn't know this
info? Mmm... I don't think so...).
In general, I'd suggest to try to find a specialist in injectors and
diesel pumps: a repair shop specialised in Delco, Bosch, Magneti Marelli
systems, depending on the brand used in your car. Usually Bosch, for MB,
but of course it's not a general rule.
Even better: an OLD specialist. One with white hair :-) ... sometimes
the new generations tend to think that 'electronics will do the job'.
But with older vehicles there's no electronic control for a lot of
functions now controlled with microprocessors!
JD
My indy guy *is* one of those white hair guys with
decades of factory/dealer experience. That's how
many he had to go through to find 5 that were
close enough to tweak.
DougS
I've been looking at rebuilding my injectors on my own. These are the
resources I am thinking about using.
This kit includes a pressure tester, and shims to adjust the release
pressure.
https://mercedessource.com/node/7148
And I'm thinking about installing these new nozzles on my injectors
when I take them out to rebuild them.
https://mercedessource.com/node/4753
Mercedes Source isn't the cheapest parts I've found, but I've ordered
a few things from them (most recently their valve adjusting wrenches),
and they have good customer service. They also include instructions
with almost everything you buy. That helps a lot for some of these
projects.
heav
engineer there, says that my pump does not seem to have anything wrong
with it. He now wants to see my injectors, so I am going to take
those off later this morning and send them on to Gus. He is going to
send me a different pump anyway, because sometimes, he says, a
different pump that also has no problems is sometimes just different
enough so that the harmonic vibration disappears.
I will keep the list posted.
Paul
randal...@gmail.com
Paul--
Thanks, and please do keep us posted, as this is the same problem I am
having. My M-B technician believes I should install another injection
pump too, as he has had problems adjusting and timing mine, and
believes it to be faulty. If your problem goes away by changing
pumps, then, I am going to go ahead and find a new pump also.