My "friend" mixed some inadequately filtered veggie oil with diesel in
the tank of his 1982 300D turbo. The car ran fine in the drive for 20
minutes, but started chugging & died once he got on the freeway. Upon
inspection, his filters were clogged & it appears the injector pump
spits from only one port.
Is there any chance of de-gunking such an IP, or is it likely
replacement will be neccessary?
Any suggestions for IP replacement articles?
Well, it's cheap and easy to do and might be worth a shot. Run two
or three can's of diesel purge through it as directed on the can.
Basically you disconnect the fuel suppply and return lines and put them
into a jar into which you've put the diesel purge and run the engine
off it. What it does for a smoky, sick rough engine is nothing short
of magic and given the price (a few bucks) and time (half an hour tops)
I'd suggest you start with that and cross your fingers.
Need Mercedes parts? http://parts.mbz.org
Richard Sexton | Mercedes stuff: http://mbz.org
Since the fuel filters are clogged - the small clear plastic one and the
metal spin on - one can suppose little or no fuel is reaching the
injection pump. Thus its minuscule output. I doubt the injection pump is
affected. Change both filters and prime the fuel system with the hand
primer pump that's next to the plastic filter. BUT prime the system with
purge or DIESEL injector cleaner and run the motor on that until it's
That leaves the fuel tank and fuel line to be drained, or not, depending
on whether the "bad" fuel was in fact bad or, as in the case of 100%
Bio, the fuel simply loosened 20+ years of fuel deposits inside the tank
and dumped them in the filters. If you retain the old fuel the filters
may have to be changed a couple more times before all is well again.
The miniscule IP output is the result of having already replaced the
filters & purging with diesel #2. I'll try forcing some diesel purge
through, but being that it won't currently start, I'll cross fingers &
T.G. Lambach wrote:
I'm trying to give you all the reasons I can think of to NOT mess with
the injection pump itself. The IP MUST be fed fuel for its "pumping
action" relates only to its 2,000 psi impulses to the injectors, not to
its own fuel supply. That's done by the engine's fuel pump down at the
primer pump's base.
Did you purge the air from the fuel system after the new filters were
mounted? Pump hand primer pump until no air bubbles are visible in the
The injection pump can be repaired by a Bosch center - phone book /
internet "diesel injection service." They do trucks and construction but
may point you to someone who can help you if they can't. Know where
you're going to take it before plunging into the job.
If you absolutely have to remove the IP it's essential to FIRST set the
motor to a known rotation point so the IP's timing is not lost. The IP's
drive gear has an intentionally missing tooth and a mark cut into the
collar behind the drive gear. Aligning the IP's gear with the collar is
24 degrees BTDC on the crankshaft so you need to turn the motor by hand
- right hand rotation - (pull and push on the drive belts) so 24 degrees
BTDC on the harmonic balancer is achieved - on the compression stroke of
#1 cylinder (look at #1's cam lobes through the oil filler opening they
should BOTH be pointing UPward).
The engine manual shows the two oil lines from the oil filter to the oil
cooler being removed AFTER the filter is opened to allow the lube oil to
drain back into the motor (and not onto the floor). The oil filter
housing is then removed so the IP can be pulled out. A new gasket is
essential as are clean surfaces or it will leak afterward.
Before loosening the IP's three mounting bolts note their position and
scribe onto the IP and the motor some marks to use later to achieve the
same IP position and thus the same injection timing as current - without
having to time the injection.
The IP is lubricated by engine oil (and has a small oil pipe to it.
Prior to its reinstallation you ought to fill 1/2 pt of lube oil into it
(there's a fill plug near the top rear, above and slightly aft of its
lube oil pipe)
Getting the picture of why NOT to remove the IP?
If it were my car I'd (i) be absolutely assured that the IP was getting
lots of fuel and if the problem persisted (ii) remove the IP's high
pressure lines (but not the hold down clamps) and from each well remove
the spring and plunger and crank the motor knowing that diesel fuel will
be spilled - the idea being to flush fuel through the IP. I'd remove the
IP only after all else failed.
I hope this helps get your car back on the road.
Believe me,TG, I have no desire to venture into hostile territory, but
I will if neccessary. Thanks for the map.I've purged the air to no
avail & will try spring/plunger approach next. Will keep you posted.
T.G. Lambach wrote:
In the words of the sagacious Lenny Cohen, "Hallelujah!"
Having executed all the aforementioned suggestions two days ago, when
only one IP port would emit/secrete, I began to admit defeat.
Today, before departing for the wreckers w/ torches & jackhammers, I
tried once again, & up she fired.
Perhaps trickle-down (fuel) economics came to play. Perhaps it was
To quote the recondite Mickey Jagger, "Thank you, Jesus. Thank you,
Thank you, Rickey, TG, Tigie.
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