200 & 300 SERIES
4
NOTE: The bowl should always be drained before water or
contaminant levels reach the bottom of the depressurizer
cone. Check daily with the engine off. Always open the
draincock completely to flush particulates out. Failure to
do so could cause a leaky valve.
A. DAHL Units Mounted HIGHER Than Fuel Storage Tank
1. Turn engine off.Vent the DAHL filter to allow draining.
2. Open the primer plug and then open the draincock and drain
all contaminants.
DRAINING WATER ___________________________________________________
SERVICING
3. Close the draincock and follow the priming instructions
shown below.
B.DAHL Units Mounted LOWER Than Fuel Storage Tank
1. Turn engine off and close shut-off valve. (Valved Manifold
units may be drained and elements replaced with the engine
running at idle. Close inlet and outlet valves to islolate the
filter being serviced.)
2. Open the draincock completely and drain all contaminants.
3. Close the draincock and follow the priming instructions
shown below.
A. When To Replace
As a general guideline, depending on fuel quality and engine use,
elements should be replaced as follows:
1. DAHL 201 and 301 are 2 micron elements which can be
used approximately 1000 hours or 40,000 miles. (DAHL
201-W and 301-W are 10 micron elements for use in winter
or severe applications and DAHL 201-30 and 301-30 are
30 micron elements.)
2. If you have a vacuum gauge, the first replacement should be
made at the very first indication of power loss at high RPMs.
Make a note of the vacuum gauge reading at this point. The
differences in various fuel system requirements make it
impossible to predict what this reading will be. Mark the
reading on the gauge dial or the unit for future element
replacement.
B. HowToReplace Contaminated Element
1. Open the draincock completely to empty the bowl and flush
particulates out. Failure to do so could cause a leaky valve.
2. Loosen the T-Bolt handle to release the filter body from the
lid. (It is not necessary to completely remove the T-Bolt
from the DAHL filter lid.) Support the filter body with your
hand prior to release.
3. Remove the element with a turning motion. At this point,
ELEMENT REPLACEMENT______________________________________________
you may clean the outside of the filter body. Use only clean
diesel fuel or kerosene and wipe clean.
4. Inspect the ejector spring(s) at the bottom of the body.Also
check the centerpipe O-Ring and replace if hard or
damaged.
5. Remove and replace the lid cover gasket. Be sure the lid
groove and body lip are clean. (Grease the lid cover gasket
to hold it in place before positioning.)
C. Reassembly
1. Lubricate the top and bottom element gaskets. Install the
element onto the centerpipe with a turning motion.
2. Fill the filter body with clean diesel fuel to within one inch
of the top.
3. Double check the lid cover gasket position in the lid groove.
4. Attach the body to the lid and hand tighten the T-Bolt handle.
D. Priming
1. Eliminate air — use existing fuel system primer, if so
equipped. If not, remove the primer plug and fill to the top
with clean diesel fuel.
2. Start engine and check for leaks.
NOTE: For any marine or other unit utilizing the heat deflector
shield, clean the shield to removeanyaccumulated
diesel fuel.
Engine starting and power loss problems from the fuel system are
usually caused by one or more of the following:
A. Air Leaks
1. Fittings. Insure the O-Rings on the fittings in the DAHL
filter ports are lubricated and not damaged, cracked or dirty.
NOTE: When using JIC 37°fittings, be sure only mating JIC 37°
fittings are used. Misalignment will occur and air leakage
will result from an attempt to fasten a SAE 45° fitting to
aJIC 37° fitting. Check for fitting looseness, seat dents,
misalignment or unmatched threads. All fittings must be
wrench tight.
2. Bubbles InThe Bowl. If bubbles appear at the depressurizer
cone, a leak is indicated between the fuel tank and the inlet
port.
NOTE: Old fuel lines (rubber hose or metal tubing) may crack
when moved. Check areas around push-on fittings, pipe
adapters, hose clamps, etc. If air bubbles appear at the
draincock, check for particles stuck in the valve seat or a
partly open draincock. Also check for defective,
miscentered or unlubricated bowl gaskets. Check the
bowl plug O-Ring to make sure it is not cracked or
extruded out of place. The bowl plug should be hand
tightened only.
3. Gaskets. If the lid or bowl has been removed, make sure the
gasketgrooves areclean.Inspect thegasketsforproper seating
in the grooves. Lubricate the gasket(s) with oil or grease.
B. Clogging And Restriction
1. Fuel Lines. Check for collapsed lines caused by sharp bends or
excessive turns. Check the tank and/or filter shut-off valve(s).
2. Filter Elements. Early clogging can occur from badly
contaminated fuel (micro-organism growth, rust, sludge, dirt,
etc.) Always carry a spare DAHL element. Asphaltinic
materials (fuel oxidation products), which are normally
harmless to the injection system, can eventually plug original
equipment filters remaining in the fuel system. If problems
persist after the DAHL element has been replaced, also
replace the other fuel filter elements.
3. Filter Inlet. Severely contaminated fuel may cause inlet
plugging. In this event, close the fuel tank supply shut-off
valve (if equipped) and disconnect the inlet line. Remove the
bowl and clean the inlet. Should the depressurizer cone also
be plugged, disassemble and clean out.
4. Bleed Back. If fuel in the DAHL filter bleeds back to the fuel
tank, an air leak or reverse flow valve problem is indicated.
Inspect fuel lines and fittings first as indicated above. If the
reverse flow valve is clogged, use air or clean fuel to flush
out.
C. Malfunction Of Engine Parts
Pre-existing conditions in the pumps and injectors can also
cause power loss and engine starting problems. See your
equipment dealer if the abovetroubleshooting guides do not
cover your problem.
TROUBLESHOOTING
WARNING: Do NOT use gasoline or any form of alcohol or anything containing it inside or outside a DAHL
Model 200 or 300 Series Fuel/Water Separator.
