injector pump, vegetable oil conversion
dougc...@gmail.com
i have 1982 300SD 240K miles, that has been converted to run on
vegetable oil. I brought the car in to the shop b/c the acceleration
was extremely poor, and it was stalling quite often. I've had the
timing chain replaced, the intake and exhaust valves cleaned, the
diesel tank removed and cleaned, and still the same problem remains.
The mechanic is suggesting I rebuild the injector pump, as it may have
become clogged or lost its proper functionality. Any thoughts on this?
Should i just replace the engine instead? I dont think that the problem
is related to the veggie system, as even when those new components were
removed, the engine was not running properly (on regular diesel fuel)
...
thanks,
doug
Roger
<dougc...@gmail.com> wrote in message
news:1151038948....@u72g2000cwu.googlegroups.com...
the injectors opening at the correct pressure.
Veg oil does not have the lubricating properties of hydrocarbon based
diesel and its an often reported problem of injection pumps that do not
have their own lube oil resevoir.
Richard Sexton
Has this shop ever seen one of these cars before?
What does the compression test out to?
When was the last time the banjo bolt was cleaned out?
The stalling suggests the rack damper bolt is screwed in too far.
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Tiger
> Veg oil does not have the lubricating properties of hydrocarbon based
> diesel and its an often reported problem of injection pumps that do not
> have their own lube oil resevoir.
No, it is quite the opposite of what you said. Veg oil has MORE lubricating
property than diesel.
Tiger
diagnostic... replace the fuel filter first. The reason is depending on how
well the person filtered the WVO... if he didn't do a good job, then the
filter will clog up pretty much within one tank.
T.G. Lambach
Given the motor's 240K miles, have an independent M-B shop do a
compression test on it. That will tell you the motor's internal
condition and whether it has sufficient compression to run as it ought
to or needs an overhaul. This will cost some $ but will give you a good
estimate of the motor's remaining useful life.
Or you can nibble at the problem and hope to stumble on a solution - or
ultimately discover that the motor needs an overhaul.
Nibbles (in approximate order of effort and cost):
1. Throttle linkage - with the engine shut down watch the throttle
linkage while an assistant works the accelerator. When accelerator is
floored the lever between the injection pump and the block - yes behind
the IP - should reach its full throttle stop (limit). If it does then
that's not the problem. Proceed.
2. At the very aft end of the motor's intake manifold - close to the
firewall - is a "banjo fitting" attached to the intake manifold by a
hollow bolt. Remove the bolt and clean it out with a wire; do the same
to the banjo fitting. Reassemble and don't over tighten the bolt. Follow
the plastic line attached to the "banjo" to ensure it's not broken or
disconnected from its destination valve and then check it further, all
the way to the injection pump. Examine the termination point - that's
called the ALDA - a device to put added fuel into the motor during
acceleration. Unfortunately it has an adjustment on its top center that
dummies attack; some ruin the device. Does yours look like its been
adjusted or opened? The motor's acceleration will be poor if it's ruined.
3. Look at the small clear fuel filter below the injection pump. Replace
it if its color is very dark. You may as well replace the larger spin on
metal can fuel filter that's aft of the power steering pump. You'll then
have to purge the air from the fuel system - that's done by unscrewing
the round knob and pumping the primer pump that's next to the small
clear fuel filter until the air bubbles have left the clear plastic fuel
lines.
4. There's an adjustment on the aft end of the injection pump whose
function is to dampen the hot idle oscillations of the fuel rack and so
ensure a relatively smooth idle. As was pointed out earlier this may be
too tight and so cause stalling. But I doubt that's the problem here.
5. You say that the timing chain was replaced - by whom?
If by an experienced mechanic at an M-B shop it's probably OK but if
not, then the engine's valve and / or injection timing could be
incorrect. Badly retarded injection will allow the motor to start but it
will lack spirited acceleration (even on a diesel's relatively
"spirited" basis).
Were the motor's valves adjusted? A terrible valve (mis)adjustment will
produce the exact symptoms you describe. A compression test will reveal it.
I suspect that your motor's problem is either a terrible valve
adjustment (causes poor compression) or the valve and /or injection
timing are badly off I but can't say so because I don't know the
sequence of events.
Was it running well prior to the timing chain etc. being done?
Or is poor running why the chain was changed?
6. I've owned one of these for 26 years and never heard of having its
"valves cleaned". Whose idea was that?
Run if the same guy wants to rebuild its injection pump because that's
pretty heavy $$ and IMHO he's just guessing what to do next - with your
$$ funding his game.
T.G. Lambach
This is something that you can easily check visually and will either
raise another suspect or eliminate one.
The top of the injection pump has five pipe connections that appear to
be held in place by steel yokes with a hold down nut in each.
There's probably some yellow paint on each nut; it ought to be intact -
as an unbroken seal - indicating the original setting is not been changed.
If so that's good, if not this could be your motor's problem.
The hold down nut on each of these yokes is an adjustment of the fuel
delivery to its nozzle in the motor. Each nozzle in the cylinder head
has an "opening pressure" of about 2,000 psi; when the fuel is pumped
there it opens briefly and sprays into the cylinder and closes. The
yokes regulate the duration of that pressure and if some moron messed
about with the yokes' adjustment the duration could be too short =
insufficient fuel = poor performance.
If you suspect this is the case a Bosch Diesel Injection Service shop
will be able to recalibrate the injection pump for you. They can also
clean and recalibrate the injection nozzles - something to consider if
the exhaust smokes more than you like. The nozzles can be done
independently of the pump.
I hope these ideas help you restore the engine's "default" settings so
you'll be on the road - happily.
T.G. Lambach
"yokes" that I mentioned are in fact hold down straps with TWO nuts -
one at each end and these two nuts have small paint marks/seals. Its
these paint seals that should be inspected.
dougc...@gmail.com
Thanks very much for your thorough response, I've printed out what you
said, and i'm going to hand the info to my mechanic. The poor
acceleration and stalling were happening before the timing chain was
replaced. It was something that the mechanic saw when inspecting the
valves and strongly encouraged me to replace, as he said the tension on
the chain was too loose. I've spend almost $2,000 in repairs so far and
have not had an effect on the original problem...very frustrating.
Well, again thank you, and i'll write again with any updates.
Ernesto
"Tiger" <tige...@hotmail.comn> wrote in message
news:osRmg.1204$uZ5...@fe12.lga...
Tiger's right....veggie oil has much more lubricating ability and is also a
better solvent. Thus, when converting to veggie oil you need to keep an
extra set of filters on hand since the entire fuel supply system will
undergo a good cleaning.
InterociterOperator
Doug - what ended up happening with this rig?
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